Minimally invasive surgery has become a safe and effective treatment that reduces complications and increases patient satisfaction. The incision used for minimally invasive cardiac surgery is about 5cms avoiding full sternotomy. The procedures which have been performed are:

Minimal invasive Mitral Valve Replacement (MIMVR) Minimal invasive Aortic Valve Replacement (MIAVR) Minimal invasive Atrial Septal Defects Closure (MIASD) Minimal invasive Coronary Artery Bypass (MICABG)

Robotic assisted Minimal invasive Coronary Artery Bypass (RAMICABG)

Surgery is done through small incision (Image 1) in the right or left hemithorax or mini sternotomy instead of conventional sternotomy and off pump or on pump surgeries are performed.

Minimally invasive Cardiac surgery (MICS) has been practiced increasingly across the globe since the early part of this century. [1] Although there come alternatives like percutaneous transluminal coronary angioplasty (PCI) and Tran’s catheter aortic valve implantation (TAVI). Majority of patients still need to undergo cardiac surgery. Minimally invasive cardiac surgery aims at avoiding sternotomy and reducing surgical trauma by downsizing the incisions [2]

The complexity and invasiveness of the procedures have presented both a problem and an opportunity to make the procedures less invasive. Beginning with initial attempts at coronary artery bypass surgery through limited access with and without robotics, several other cardiac procedures currently are being performed by minimally invasive approaches. These include Coronary artery bypass grafting, mitral valve repair/replacement, aortic valve repair/replacement, Atrial Septal defect closure etc. The experience with less invasive surgery in other specialties has served as cross-fertilization for minimally invasive cardiac surgery [1]. Potential disadvantages of minimally invasive approaches include longer cardiopulmonary bypass (CPB) time and cross clamp time, difficult deairing, and increased risk of paravalvular leak.

minimally invasive cardiac surgery include a reduction of surgical trauma, increased patient comfort, and shorter hospital stay which assumes that smaller incisions should lead to less postoperative pain and rapid return to full activity. The development of a system for cardiopulmonary bypass (CPB) and cardioplegic arrest that did not require a median sternotomy incision was a breakthrough that helped to widen the application of minimally invasive open-heart surgery [4].

With application of transcatheter aortic valve implantation (TAVI) and its increasing popularity, open sternotomy and aortic valve replacements are significantly decreasing. TAVI programs are led by cardiologist aided by surgeons and in few centres by Surgeons aided by cardiologist which is becoming a combined approach.

Interest in MICS is growing rapidly. When it comes to minimally invasive mitral valve surgeries, while the procedure has traditionally involved making a large incision through the sternum, advancements in technology and surgical methods have made it possible to accomplish the procedure through one or more small thoracic incisions while utilising cameras for assisted vision [8].

The objective of MICS is to preserve the established surgical efficacy of the traditional open approach while minimising the surgical damage to the patient (supposedly to reduce pain, scarring, and inflammatory response). Certain studies, but not all of them, indicate that the least invasive method of mitral valve surgery yields favourable outcomes [8].

A more recent development in the field of minimally invasive cardiac surgery is robotically assisted minimally invasive cardiac surgery (Image 2). Robotic systems have already become an important tool in surgical armoury. Robotic surgery so far remains exclusive and expensive compared to other minimally invasive procedures despite its indisputable benefits of 3D visualization, improved dexterity with 7 ? of motion and elimination of tremors

[4].

Adoption of MICS and robotics by cardiac surgeons requires time consuming training and commitment apart from previously acquired traditional cardiac surgery skills (Image3). To achieve clinical proficiency in MICS procedures, surgeons have to undergo a demanding learning curve.

MICABG is a multivessel procedure which enables total revascularization when diffuse or three-vessel CAD is present. Because thoracotomies are more lateral and frequently smaller, they allow for rib spreading with a lower risk of costochondral or rib injury as well as the use of the left lung's usual space-which is deflated throughout the procedure-to be used for working within the chest. Like in a traditional CABG procedure, LIMA can be easily harvested all the way from the level of the subclavian vein to the bifurcation. This makes it possible to choose the ideal LAD anastomotic site and prevent any potential steal phenomena from LIMA side branches. Because the pericardium is exposed broadly, the coronary arteries and their relationships can easily be seen and distinguished (Image 4). Proximal anastomoses onto the ascending aorta can be regularly accomplished through MICS CABG surgery [10].

Minimally Invasive Coronary Artery Bypass Grafting Dual-Center Experience in 450 Consecutive Patients”: The Journal of American Heart Association 2009 Joseph T. McGinn, Jr, MD; Saif Usman, MD; Harry Lapierre, et al. MICABG is an novel approach that might be accessible to all surgeons and doesn't require any special infrastructure. The goal of MICABG is to lessen the invasiveness of traditional CABG while maintaining the usefulness and longevity of surgical revascularization. Between 2005 and 2008, this study

looked at the safety and viability of MICABG in 450 patients[10].

A 4-6 cm incision was made in the fifth left intercostal region to perform the thoracotomy. To lift and stabilise the heart, they employed an apical positioner and epicardial stabilizer that went through the subxiphoid and left seventh intercostal spaces, respectively [10]. The left anterior descending artery was grafted using the left internal thoracic artery, and the lateral and inferior myocardial regions were grafted using parts of the saphenous vein or radial artery [10]. In 427 cases (94.9%), complete revascularization was accomplished. During their hospital stay, 17 patients had hybrid revascularization, wherein PCI was performed either before to (n = 16) or after to (n = 1) MICABG [10].

Given a mean of 2.1+/-0.7 grafts, 359 patients (79.8%) had two or more grafts. 17 patients (3.8%) underwent sternotomy conversion; 2 had LIMA Injury (0.4%), 5 had bleeding

(1.1%), 6 had hemodynamic instability (1.3%), and 4 had poor exposure (0.9%) [10]. The re- operation rate was 2.7% (n=12), which was due to bleeding in 10 patients (2.2%). Peri operative mortality was 1.3% (6 patients), cause of death- were multi organ failure (3 patients), sepsis (n=2), tamponade (n=1). Peri operative blood transfusion was required for 96 patients (21.3%)

[10].

Other complications were stenotic or occluded graft (0.9%), post-operative stroke (0.4%), wound infection (0.9%), pleural effusion (9.1%). Midterm follow up of 300 patients during a period of 3.5 years showed that10 patients (3.0%) required reintervention with PCI, 8 of them had LIMA T Graft (of 144 patients) occlusion or stenosis [10].

“Minimally Invasive Versus Standard Approach Aortic Valve Replacement: A Study in 506 Patients”: Annals of thoracic surgery 2006 Ihsan Bakir, MD, Filip P. Casselman, MD, PhD, Francis Wellens, et al.

This study was performed to determine whether minimal access AVR offers benefits over the standard approach AVR in the early postoperative period in a center that is experienced in using minimally invasive techniques. Outcome analysis of the patients affirmed that the upper J mini sternotomy approach did not endanger the quality of the procedure, and that this technique is safe and effective for AVR.

It has been demonstrated that MIAVR using a partial upper sternotomy reduces surgical trauma and may also lessen postoperative discomfort, blood loss, and hospital stays [9].

A retrospective analysis of 506 patients who underwent isolated aortic valve replacement was conducted between October 1997 and November 2004. The minimal access J-sternotomy method (group 1) was performed on 232 individuals [9]. Group 2 consisted of 274 patients who received median sternotomy aortic valve replacements [9].

Early mortality was 2.6% (6 patients) in group 1 and 4.4% (12 patients) in group 2, respectively [9]. In comparison to the conventional group, the minimum access group experienced shorter aortic cross clamp and cardiopulmonary bypass times: 61.8 ±16.6 against

69.5 ±16.6 minutes (p < 0.05) and 88.8 ± 23.2 versus 100.2 ±22.6 minutes (p < 0.05), respectively. When comparing the MIAVR group to the standard surgery group, the mean blood loss was reduced (p < 0.05) [9]. The minimal access group experienced shorter ICU and hospital stays: 2.1 ±2.5 days compared to 2.5 ±5.3 days (p < 0.05) and 10.8 ± 7.1 days compared

to 12.8 ± 10.6 days (p < 0.05), respectively [9].

Routinely, isolated aortic valve disorders can be safely treated with aortic valve replacement with a partial upper sternotomy [9]. Atrial fibrillation, pulmonary infections, stroke, and pleural effusion rates did not differ significantly according to the study [9]. Compared to the traditional group, extubation times and ICU stay length were shorter, and there was little statistically significant difference in the aforementioned results [9].

Minimally Invasive Cardiac Valve Surgery Improves Patient Satisfaction While Reducing Costs of Cardiac Valve Replacement and Repair: Annals of Surgery, 1997 Lawrence H. Cohn, M.D., David H. Adams, M.D., Gregory S. Couper, et al

The study compared the quality of valve replacement and repair via minimally invasive incisions with standard aortic and mitral valve replacements. They studied 84 patients during the study period of 1996 to 1997, out of which 41 were aortic surgery and 43 were mitral valve repair or replacement [18].

MIAVR was performed via a right parasternal incision using femoral- femoral bypass in 21 patients and hemi sternotomy in with intrathoracic cannulations in 20 patients. MIMVR were performed using right parasternal incision alone [18].

There were 2(5% in 41 patients) operative mortalities in 84 patients, from multi organ failure, both in aortic patients [18]. Two aortic patients were reoperated, both for bleeding and one patient had an intra-operative aortic dissection at the site of ascending aortic needle vent after mitral valve repair. 27 % in MIAVR and 12% in MIMVR groups had post-operative atrial fibrillation requiring pharmacological treatment or cardioversion or both [18].

There was no wound infection of the thoracic incision. One patient had conversion to sternotomy after aortic valve replacement as the patient sustained coronary sinus injury from retrograde cardioplegia catheter. In the MICS group the average time taken to get back to work was 6 weeks compared to 8 weeks for the conventional group. MICS group returned to normal activities in 4.6 weeks (9.4 weeks in conventional group) [18].

They concluded that MIAVR and MIMVR can be done safely and accurately through small incisions in patients without coronary artery disease. Patient satisfactions were up, return to normal activities were early and required lesser post rehabilitation services comparing the conventional surgeries [18].

Minimally Invasive Versus Conventional Open Mitral Valve Surgery, A Meta-Analysis and Systematic Review: Innovations, Volume 6, 2011 Davy C. H. Cheng, MD,* Janet Martin et al.

This study compared, 35 studies, 2 randomised and 33 non-randomized comparative studies that used thoracotomy through port-access or keyhole, with direct visualisation or with camera or robotic assistance through lateral, parasternal, or xiphoid approaches, versus conv- Mitral valve surgery (MVS), which used a median sternotomy or parasternal approach [8].

When compared to traditional mitral valve procedures, the death rate following MIMVR/Repair was comparable at 30 days (1.2% vs. 1.5%), 1 year (0.9% vs. 1.3%), and 3 years

(0.5% vs. 0.5%), and 9 years (0% vs. 3.7%) [8]. Atrial fibrillation (18% vs. 22%), chest tube drainage (578 vs. 871 mL), transfusions, sternal infection (0.04% vs. 0.27%), time to return to normal activity, and patient scar satisfaction are just a few of the clinical outcomes that show considerable improvement with MIMVR/Repair [8].

In comparison to conventional mitral operations, the analysis revealed a greater 30-day risk of stroke (2.1% vs. 1.2%), aortic dissection/injury (0.2% vs. 0%), groyne infection (2% vs. 0%), and phrenic nerve palsy (3% vs. 0%) for MIMVR/Repair [8]. With MIMVR/Repair, cross- clamp, cardiopulmonary bypass, and operation times were all noticeably longer [8]. Both the length of stay in the hospital and the critical care unit and the ventilation time were decreased

[8].

Without any discernible negative effects on survival longer than a year or the need for long-term valvular reintervention, this study suggests that MIMVR/Repair may be linked to decreased bleeding, blood product transfusion, atrial fibrillation, sternal wound infection, scar dissatisfaction, ventilation time, intensive care unit stay, hospital length of stay, and decreased time to return to normal activity [8].

These potential advantages of MIMVR/Repair, however, can be accompanied by a higher risk of stroke, aortic dissection or damage, phrenic nerve palsy, infections or problems in the groin, and longer procedure times for cardiopulmonary bypass and aortic cross-clamp [8].

Outcomes of less invasive J-incision approach to aortic valve surgery: The Journal of Thoracic and Cardiovascular Surgery, October 2012 Douglas R. Johnston, MD, Fernando

1. Atik, MD, et al

The study compared clinical outcomes of MIAVR with Upper hemi- J sternotomy and conventional AVR during January 1995 to January 2004. Out of 2689 patients, 1193 underwent MIAVR and 1496 underwent AVR using full sternotomy [17]. In order to select 832 well- matched patient pairs (70% of available cases) for this investigation, a propensity score based on 42 characteristics was employed [17].

In-hospital mortality for these patients was 0.9% (8 in each group). Occurrence of stroke, renail failure and myocardial infarction were similar [17]. 24-hour mediastinal drainage was 1/3rd lesser after MIAVR (Median, 250vs 350ml, P<0.0001) and fewer people received transfusion in the less invasive group (24% vs 34%, P <.0001) [17]. The occurrence of respiratory failure was less for those undergone MIAVR. Additionally, their pain level was lower (P<0.0001), and their post-operative hospital stay was shorter (P<0.0001) [17].

MIAVR not only had cosmetic advantages, but less blood product use, pain, respiratory and resource utilization for advantages over full sternotomy. In terms of safety study concluded that its equivalent to full sternotomy [17].

Minimally invasive mitral valve surgery: a systemic review and meta-analysis, European journal of Cardio-thoracic Surgery, September 2008 Paul Modi, Ansar Hassan, et al

In comparison to traditional mitral valve procedures, the effects of MIMVR/Repairs on morbidity and mortality were measured in this meta-analysis [16]. The author examined ten years of research, from 1998 to 2005, including case control studies and randomised control trials. Of these, eleven publications were published, with one RCT and ten case control studies

[16].

It demonstrated equivalent perioperative mortality (1641 patients, OR 0.46, 95% CI 0.15—1.42, p = 0.18), reduced need for reoperation for bleeding (1553 patients, OR 0.56, 95% CI 0.35—0.90, p = 0.02) and shorter duration of hospital stay despite evident longer CPB time and cross clamp times in the minimally invasive group. Long term follow-up data from several

cohort studies suggested that MIMVR/Repairs had equivalent survival and freedom from reoperation [16].

Minimally invasive aortic valve replacement: Initial experience of 1st cardiac surgery department of Onassis Cardiac Surgery Centre. A propensity score adjusted analysis, Hellenic journal of cardiology, November 2019 Antonios Roussakis, MD, PhD, Aikarterini Gavalaki, MD et al

This study included a retrospective analysis of patients who underwent isolated aortic valve replacement via sternotomy or J Hemi sternotomy between March 2016 and February 2019. 42 patients had MI AVR out of the 305 patients who had aortic valve replacements. By using propensity matching based on age, gender, and Euro score-II, 42 more patients were chosen from the conventional AVR group and compared with conventional AVR. The procedure duration (174±28.9min vs 155.6± 9.9min) and total cross clamp time (65.8±16.6 min vs 58.9± 20.6 min) were longer in MIAVR. The study demonstrated a statistically significant decrease in the duration of mechanical ventilation (Median Mechanical ventilation time: MIAVR= 8hrs, IQR:8-9; AVR 8hrs, IQR:8-16) and overall ICU stay (Median ICU time: MIAVR= 32hrs, IQR:26-32; AVR 32hrs, IQR: 32-48). The AVR group's hospital stay was longer by one day [15].

Major post operative complications were found to be like conventional AVR. No significant difference between mortality rates, ICU readmissions or reoperations were found. There was no hospital or 30-day mortality in this study. This study also emphasized the safety and effectiveness of MIAVR with similar rates of perioperative complications and lower ICU and hospital stay compared to the standard approach [15].

An Audit of Minimal Invasive Cardiac Surgery- An Initial Experience of 30 Cases, IOSR Journal of Dental and Medical sciences, July 2016 Dr Dwarakanath Kulkarni, Dr Kamalesh Jain, et al

This article showed initial experience of MICS in a single center. 30 cases were operated either through a mini-sternotomy, anterior thoracotomy, or antero-lateral thoracotomy. Of the 30 cases, 14 were MIMVR, 3 were MIMVR with Tricuspid annuloplasty, 5 cases of MIAVR, 4 cases of MIASD and 4 cases of MICABG. 26 cases were operated on cardiopulmonary bypass and 4 MICABG were operated without CBP [14].

Mean ventilation time in the study was 6 hours, mean ICU stay was 47.8 hours and mean duration of stay in hospital was 7.133 days. They have nil re-explorations and 2 mortalities (6.66%) of which 1 was due to aortic dissection and the other due to LV failure. 2 patients required conversion to conventional sternotomy, due to poor exposure and aortic dissection [14].

The study also showed that MICS group had reduced wound complication rate and faster recovery. It was found that the mean length of scar was 7.233 cm, and no patient had a wound infection. The study concluded that MICS is a novel modality of approach for various cardiac surgeries with good cosmesis, better reduction in post-operative pain and had fewer days of hospitalization. They also had an early recovery and better quality of life [14].

Twenty-year outcomes of minimally invasive direct coronary artery bypass surgery: The Leipzig experience, the journal of Thoracic and Cardiovascular Surgery, 2021 Piroze M. Davierwala MD, Alexabder Verevkin, MD et al

The study involved 2667 patients who had undergone MICABG during the period of May 1996 and December 2018. All patients underwent LIMA (left internal mammary artery) to LAD grafting through a left anterior thoracotomy. The entire cohort was divided into 3 groups based on based on period: group A, 1996-2003(n=1333): group B, 2004-2010 (n=627) and group C, 2011-2018 (n=707). Early post-operative outcomes and group wise characteristics were compared. Long-term survival of all patients was also analyzed, and cox proportional hazards methods were used to identify predictors for late mortality [13].

Mean age group was 64.5± 10.9 years and 25.9% patients were females (691). Group C patients were older with more cardiac risk factors (Log EuroSCORE I = 4.9± 6.9) and comorbidities than other groups. Group wise and overall, in-hospital mortality was1.0%, 0.6,1.0% and 0.9% respectively. The study showed an overall 10 year survival estimate of 77.7±0.9%, 15 year- 66.1±1.2% and 20 year survival estimate of 55.6± 1.6%. The median length of surgery was 103 minutes (IQR of 82-130). A total of 50 patients (1.9%) required CPB, of these 28 were performed electively. Conversion to CPB in remaining 22 patients was because of hemodynamic instability, ventricular fibrillation, bleeding, or inability to identify LAD. They hypothesized that for patients who undergo MICABG for isolated LAD disease,

poorer outcomes were commonly associated with the risk factors in women such as older age, smaller body surface area and coronary vessels, and the less frequent use of LIMA [13].

Traditional coronary artery bypass graft versus totally endoscopic coronary artery bypass graft or robot-assisted coronary artery bypass graft-meta analysis of 16 studies, European Review for Medical and Pharmacological Sciences, 2014 S. Wang, J. Zhou, J. -F.CAI

This study was aimed to establish the advantages and disadvantages of TECABG or RAMICABG compared with traditional CABG. This meta-analysis included 16 studies involving 2290 patients from PubMed and EBSCO databases. They showed lower rates of major adverse cardiovascular or cerebrovascular events (MACCE) for 1 year after the procedure (7.0% vs 12.4%, Odds ratio [OR] 0.53; confidence interval [CI] of 0.38-

0.74;p<0.05) [12].

Subgroup analysis of TECABG and RAMICABG highlighted that TECABG decreased rate of renal failure requiring hemofiltration (OR, 0.25; CI 0.7-0.88), wound infection (OR, 0.11; CI, 0.11-1.99), and stroke (OR, 0.14; CI, 0.02-0.77) during follow-up. TECABG had increased re-exploration for bleeding and MACCE (OR, 2.18; CI, 1.14-4.16, p<0.05) [12].

The study concluded that TECABG and RAMICABG are safe and feasible for CAD and supported the use of the da Vinci robotic system to treat CAD with reduced MACCE after 1 year. There was no increase in rates of MACCE in hospital, graft stenosis, and the need for re intervention compared with CABG [12].

Study Site: Department of Cardiovascular and Thoracic Surgery, Apollo Hospitals, Chennai.         

Study Population: All consenting patients above 18yrs of age admitted to Apollo Hospital undergoing minimally invasive Cardiac surgery fulfilling inclusion and exclusion criteria.

Study Design: Single centre, Hospital-based prospective observational study.

Study Duration: September 2021- April 2023

Sample Size Calculation:

• Since primary goal of the study is to explore the outcomes of minimally invasive cardiac surgery (Including CABG, Valve repair/ replacements and ASD closure)
• A study suggestive of 40% of patients had decreased pain compared to conventional surgery, this is one of the outcomes we are looking at.
• Based on the above background information and using following formula

n= Z2pq/d2 Where,

Z=standard normal variate value=1.96

p= Percentage of patients having decreased pain score =40% q=(1-p)= 60%

d=clinical allowable error= 7%

• By applying above sample size is 190 cases

Inclusion Criteria

• Patients undergoing
• Minimally invasive Coronary artery bypass grafting
• Robotic Assist Minimally Invasive Coronary artery bypass grafting
• Minimally invasive Mitral Valve Replacement
• Minimally invasive Aortic Valve replacement
• Minimally invasive Atrial Septal Defect Closure

Exclusion Criteria

• Patients undergoing median sternotomy.
• Patient undergoing redo cardiac surgery.
• Patient undergoing concomitant procedure.

Data Collection

A study proforma with detailed history and relevant clinical interview will be used in all patients after taking informed consent from the patients. Data will be collected through interviews and observations.•Investigations like Echocardiogram, Complete Blood Count, Liver Function Test, Renal function test and will be done as a part of routine pre and post-operative evaluation, which will be used to obtain necessary data.

Statistical Methods

Sample Size

A minimum sample of 369 needed to study the outcomes of minimally invasive cardiac surgeries such as CABG, Valve repair/replacements and ASD closure. Considering the 40% of the patients had decreased pain compared to conventional surgery, 5% precision and 95% confidence interval.

Statistical Analyses

Descriptive statistics were presented with frequency (percentage) & Mean ± SD for the categorical & continuous factors respectively. Median (IQR) was presented while the data skewed. The normality of the data was checked by using Shapiro-Wilk test. Student’s t- test/Mann Whitney U test were used to determine the significant difference between post- operative factors and status at discharge. Chi-square/Fisher’s exact test were used to determine the association between two independent categorical factors. Kruskal Wallis test was used to determine the significant changes between BMI. P-value < 0.05 considered as statistical significance. All the analysis was carried out by using statistical software SPSS (IBM, 28.0).

Our study contained a total study population of 386 patients who had undergone MICS during the period of September 2021 to April 2023. Out of 386 patients included in the study, mean age of the patients were 58.77 years with 316(81.9 %) males and 70 (18.1%) females.1 patient had a BMI of less than 18.5, majority (251) were in the normal BMI range and 99 were in the range of 25-29.9 (overweight) and 35 patients were obese. 342(88.6%) had normal LV function, 37 had mild to moderate LV dysfunction and 7 had severe LV dysfunction. In this study 90.9 %( 351patients) of the patients had CCS class II symptoms, 7.5% (29) and 1% (4) of them had class III and IV symptoms respectively.

In our data, 74.4% of patients were presented with myocardial infarction. Previous PTCA was done for 33 patients (8.5%) and the rest 353 patients from the study dint have any preoperative coronary intervention. None of these patients had undergone any previous cardiac surgery. Mean serum albumin level of the study was 4.14±0.18, with 93.8 % of them having serum bilirubin level less than 1.2mg/dL. 62.4% were diabetic, 79.3% of patients had dyslipidemia and 71.2 % had hypertension. 35 patients of the 386 patients had chronic kidney disease and

34 patients had eGFR < 60. Here, 7.3 % of the study participants had a history of cerebrovascular accidents and 1.3% of the study population had peripheral vascular disease. Table.3 also shows that 82 patients had lung disease and 11 patients from the study had malignancy.

Out of the 386 patients 108 of them had a Euro-score less than 1, 215 patients had Euro-score of 1-3 and 63 patients had Euro-score more than 3. 99% of the procedures done were on an elective basis and 4 of the procedures were done as an urgent procedure. 3 patients had PA pressure of 30- 55mmHg and the rest of the 383 patients had a PA pressure of less than 30. During the pre-operative stage, 13% of the study participants had poor mobility. 23 patients were having critical pre-operative conditions as described by the Euro-score guidelines.

In this study of 178 patients underwent RAMICABG, 124 had MICABG, 31 underwent MIMVR, 8 had MIMV Repair and 26 patients had MIAVR. In rest of the 19 patients, there was 1 minimally invasive Excision of mediastinal mass, 3 were minimally invasive right or left atrial mass excision, 2 Minimally invasive pericardial drainage and window creation, 5 Minimally invasive atrial septal defect closures, 3 were MIMVR with TV Repair, there was 1 Minimally invasive TV repair, minimally invasive atrial + ventricle septal defect closure + mitral cleft repair, Minimally invasive Coarctation of aorta stenting and minimally invasive extraction of dialysis catheter and insertion of new perm catheter.

Comparing the body mass index, 251 patients had normal BMI, 99 were overweight, 34 were obese and 1 was underweight. Mean hours of ventilation were 11.5+-8.8, in normal BMI group, overweight group had mean of 10.48+-5.631 hrs and obese group had mean of 10.2+-4.7 hrs. The underweight patient had 5 days of ICU stay. The number of days in ICU was higher in the overweight group (2.9 ± 1.3 days), normal and obese group had 2.8 ± 0.9 and 2.8 ± 1.2 days in ICU respectively.

RAMI CABG and MICABG combined accounts for 78.2 % of cases, of which single internal mammary artery were used in 154 patients and bilateral internal mammary were used in 148 patients. The average number of grafts used in a total of above mentioned 302 patients was 2.2. In our study 106 patients underwent single grafts and 134 patients had 2 grafts. The total number of valve cases accounted to be 56 of which 54 had single valve and 2 had double valve replacements. 66.1% of the patients had bioprosthetic valve implantation, 25% had mechanical valves and 8.9% had valve repairs using annuloplasty rings.

Of the 386 patients, 7 patients had conversion to open sternotomy in view of hemodynamic instability and 4 patients had sternotomy conversion during re-exploration. CPB was used in 18.1% of the study population and average bypass time was 168.67 ± 62.39 minutes with an average aortic cross clamp time of 123.91 ± 47.37. Mean hours of ventilation in the study group were 10.92 ± 7.83. The number of days in ICU was 2.80 ± 1.23 days with a median of 3 days and mean number of days in hospital were 4.54± 3.03. Total number of re exploration was 8(2.1%) and of the 386, 2 patients underwent re operation. Average Number of blood products transfused was 1.47 and average number of PRBC transfused was 0.91.

In this study 98.2 % of the study population were discharged to home with a mortality of 1.8% in the total study population. Of the 7 patients who were deceased, 2 of them underwent RAMICABG, 4 had MICABG and the other had MIAVR. In 31 MIMVR and 8 MV Repair cases there was no in hospital mortality. Considering mobility, of 379 live patients, 12.7 % had poor mobility. Were as one of the deceased had poor mobility.

Considering complications, 2.8% had conversion to sternotomy, of which 2 were done due to hemodynamic instability, 1 each in view of heavily calcified coronary arteries, deep intramyocardial coronary arteries and dense lung adhesions. Another 2 conversions occurred due to inadequate internal mammary flow and 4 conversions happened during re explorations. There were 5(1.3%) patients who had inadequate internal mammary artery flow, of which 2 had reduced bilateral IMA flow and others had decreased LIMA flow. In this study 4 patients developed cardiac arrest in the immediate post operative period and re-exploration was done in two such cases. Of the 8 patients who underwent re-exploration, 2 had cardiac tamponade and 4 were done due to high drains.

There were 2 (0.5%) patients who required re-intervention, due to post endarterectomy thrombosis of LAD and graft occlusion, both underwent redo CABG. 2 patients developed post operative atrial fibrillation and another 2 had acute kidney injury post operatively. There was one patient who succumbed to sepsis, post low cardiac output syndrome IABP insertion and cardiac arrest after RAM Our study contained a total study population of 386 patients who had undergone MICS during the period of September 2021 to April 2023. Out of 386 patients included in the study, mean age of the patients were 58.77 years with 316(81.9 %) males and 70 (18.1%) females.1 patient had a BMI of less than 18.5, majority (251) were in the normal BMI range and 99 were in the range of 25-29.9 (overweight) and 35 patients were obese. 342(88.6%) had normal LV function, 37 had mild to moderate LV dysfunction and 7 had severe LV dysfunction. In this study 90.9%(351patients) of the patients had CCS class II symptoms, 7.5% (29) and 1% (4) of them had class III and IV symptoms respectively.

In our data, 74.4% of patients were presented with myocardial infarction. Previous PTCA was done for 33 patients (8.5%) and the rest 353 patients from the study dint have any preoperative coronary intervention. None of these patients had undergone any previous cardiac surgery. Mean serum albumin level of the study was 4.14±0.18, with 93.8 % of them having serum bilirubin level less than 1.2mg/dL. 62.4% were diabetic, 79.3% of patients had dyslipidemia and 71.2 % had hypertension. 35 patients of the 386 patients had chronic kidney disease and 34 patients had eGFR < 60. Here, 7.3 % of the study participants had a history of cerebrovascular accidents and 1.3% of the study population had peripheral vascular disease. Table.3 also shows that 82 patients had lung disease and 11 patients from the study had malignancy.

Out of the 386 patients 108 of them had a Euro-score less than 1, 215 patients had Euro-score of 1-3 and 63 patients had Euro-score more than 3. 99% of the procedures done were on an elective basis and 4 of the procedures were done as an urgent procedure. 3 patients had PA pressure of 30- 55mmHg and the rest of the 383 patients had a PA pressure of less than 30. During the pre-operative stage, 13% of the study participants had poor mobility. 23 patients were having critical pre-operative conditions as described by the Euro-score guidelines.

In this study of 178 patients underwent RAMICABG, 124 had MICABG, 31 underwent MIMVR, 8 had MIMV Repair and 26 patients had MIAVR. In rest of the 19 patients, there was 1 Minimally invasive Excision of mediastinal mass, 3 were Minimally invasive right or left atrial mass excision, 2 Minimally invasive pericardial drainage and window creation, 5 Minimally invasive atrial septal defect closures, 3 were MIMVR with TV Repair, there was 1 Minimally invasive TV repair, minimally invasive atrial + ventricle septal defect closure + mitral cleft repair, Minimally invasive Coarctation of aorta stenting and minimally invasive extraction of dialysis catheter and insertion of new perm catheter.

Comparing the body mass index, 251 patients had normal BMI, 99 were overweight, 34 were obese and 1 was underweight. Mean hours of ventilation were 11.5+-8.8, in normal BMI group, overweight group had mean of 10.48+-5.631 hrs and obese group had mean of 10.2+-4.7 hrs. The underweight patient had 5 days of ICU stay. The number of days in ICU was higher in the overweight group (2.9 ± 1.3 days), normal and obese group had 2.8 ± 0.9 and 2.8 ± 1.2 days in ICU respectively.

RAMI CABG and MICABG combined accounts for 78.2 % of cases, of which single internal mammary artery were used in 154 patients and bilateral internal mammary were used in 148 patients. The average number of grafts used in a total of above mentioned 302 patients was 2.2. In our study 106 patients underwent single grafts and 134 patients had 2 grafts. The total number of valve cases accounted to be 56 of which 54 had single valve and 2 had double valve replacements. 66.1% of the patients had bioprosthetic valve implantation, 25% had mechanical valves and 8.9% had valve repairs using annuloplasty rings.

Of the 386 patients, 7 patients had conversion to open sternotomy in view of hemodynamic instability and 4 patients had sternotomy conversion during re-exploration. CPB was used in 18.1% of the study population and average bypass time was 168.67 ± 62.39 minutes with an average aortic cross clamp time of 123.91 ± 47.37. Mean hours of ventilation in the study group were 10.92 ± 7.83. The number of days in ICU was 2.80 ± 1.23 days with a median of 3 days and mean number of days in hospital were 4.54± 3.03. Total number of re exploration was 8(2.1%) and of the 386, 2 patients underwent re operation. Average Number of blood products transfused was 1.47 and average number of PRBC transfused was 0.91.

In this study 98.2 % of the study population were discharged to home with a mortality of 1.8% in the total study population. Of the 7 patients who were deceased, 2 of them underwent RAMICABG, 4 had MICABG and the other had MIAVR. In 31 MIMVR and 8 MV Repair cases there was no in hospital mortality. Considering mobility, of 379 live patients, 12.7 % had poor mobility. Were as one of the deceased had poor mobility.

Considering complications, 2.8% had conversion to sternotomy, of which 2 were done due to hemodynamic instability, 1 each in view of heavily calcified coronary arteries, deep intramyocardial coronary arteries and dense lung adhesions. Another 2 conversions occurred due to inadequate internal mammary flow and 4 conversions happened during re explorations. There were 5(1.3%) patients who had inadequate internal mammary artery flow, of which 2 had reduced bilateral IMA flow and others had decreased LIMA flow. In this study 4 patients developed cardiac arrest in the immediate post operative period and re-exploration was done in two such cases. Of the 8 patients who underwent re-exploration, 2 had cardiac tamponade and 4 were done due to high drains.

There were 2 (0.5%) patients who required re-intervention, due to post endarterectomy thrombosis of LAD and graft occlusion, both underwent redo CABG. 2 patients developed post operative atrial fibrillation and another 2 had acute kidney injury post operatively. There was one patient who succumbed to sepsis, post low cardiac output syndrome IABP insertion and cardiac arrest after RAMICABG.

Main objective of this study has been to look at the early outcomes of MICS, including MICABG, RAMICABG, MIMVR/Repair and MIAVR. MICS outcomes are in comparison and often superior to that of conventional surgeries.

We have considered parameters like 30 day/ in hospital mortality, hours of ventilation, days in ICU and days of hospital stay for assessment of early outcomes and our observations are as follows.

In this study out of 386 patients who underwent MICS, 178(46.1%), 124 (32.1%) had MICABG, 31(8%) underwent MIMVR, 8 (2.1%) had MIMV Repair and 26 (6.7%) patients had MIAVR. In rest of the 19 (4.9%) patients, there was 1 Minimally invasive Excision of mediastinal mass, 3 were Minimally invasive right or left atrial mass excision, 2 Minimally invasive pericardial drainage and window creation , 5 Minimally invasive atrial septal defect closures, 3 were MIMVR with TV Repair, there was 1 Minimally invasive TV repair, minimally invasive atrial + ventricle septal defect closure + mitral cleft repair, Minimally invasive Coarctation of aorta stenting and minimally invasive extraction of dialysis catheter and insertion of new perm catheter.

There were 7(1.8%) patients who had mortality on 30 day follow up, of which 4 (3.22%) patients underwent MICABG, 2 (1.1%) had RAMICABG and 1(3.8%) had MIAVR. There was no mortality reported in MIMVR or Repairs. Conventional Off CABG has a mortality rate of 1.8% as mentioned by Farrokhyar F et al [21]. S. Wang et al [12] in their study showed 0.1 % in hospital mortality in RAMICABG group and there was 0.8% early mortality for MICABG in a study by Alberto Repossini et al[22]. Another study by Joseph T McGinn et al[10] showed 1.3% perioperative mortality in 450 patients in a dual center experience with 450 patients. In the case of MIAVR a study by Ihsan Bakhir et al[] showed 2.6% mortality for MIAVR and 4.4% mortality for conventional AVR. A meta-analysis on MIMVR and conventional MVR by Davy CH Cheng [8] showed no difference in all-cause mortality between MIMVR and conventional MVR (1.2% and 1.5%). Though, our study had a higher mortality rate for RAMICABG and MIAVR comparing with other studies, it is lower than that for the conventional open procedures.

RAMI CABG and MICABG combined accounts for 78.2 % of cases. The average number of grafts used in a total of above mentioned 302 patients was 2.2±1.03. In our study 106 patients underwent single grafts and 134 patients had 2 grafts. The average number of grafts was 2.1+/- 0.7, 359 patients (79.8%) received 2 or more grafts in the study by McGinn TJ et al[10] .

Of the 386 patients, 7 (1.8%) patients had conversion to open sternotomy in view of hemodynamic instability and 4 (1%) patients had sternotomy conversion during re-exploration. Study by Davy CH et al [8] showed no significant difference in reoperation due to bleeding in MIMVR group and conventional MVR group and 3.7% of patients were converted to open sternotomy. Our study has less conversion rate (2.8%) than above study. Of which 2 were done due to hemodynamic instability, 1 each in view of heavily calcified coronary arteries, deep intramyocardial coronary arteries and dense lung adhesions. Another 2 conversions occurred due to inadequate internal mammary flow and 4 conversions happened during re explorations.

CPB was used in 18.1% of the study population and average bypass time was 168.67 ±62.39 minutes with an average aortic cross clamp time of 123.91 ± 47.37. This was longer comparing conventional procedures. Study by Ihsan Bakir et al [9], showed mean bypass time of 88.8 ± 23.4 in MIAVR cases using a hemi sternotomy. A study by HC Lawerence [] et al showed and average bypass time of 143 min which was larger than of our study.

Mean hours of ventilation in the study group were 10.92 ± 7.83. The number of days in ICU was 2.80 ± 1.23 days with a median of 3 days and mean number of days in hospital were 4.54± 3.03. Study by S Wang et al[12] showed mean ventilation time of 10.4 hrs with ICU stay of 25.6hrs and total hospital stay of 6.7 days, comparing which, our study have comparable hours of ventilation and lesser days in hospital.

• This study highlights only the early outcomes of MICS for a duration of 30 days. A long term follow up for 5 years duration would have been ideal to see results MACCE incidence and the need for any further interventions
• Randomization of patients were not done in this study.
• Cost and affordability was a factor for patients choosing MICS despite its pros and cons. MICS costs slightly higher than conventional and procedures.
• Comparative study of outcomes of various procedure were not done separately in the study.

The realm of minimally invasive cardiac surgery (MICS) is rapidly expanding, offering promising opportunities that demand exceptional surgical proficiency. Within our center, we have undertaken various procedures such as minimally invasive coronary artery bypass grafting (MICABG), robotic-assisted MICABG (RAMICABG), minimally invasive mitral valve repair (MIMVR), minimally invasive aortic valve replacement (MIAVR), and mitral valve repairs through minimally invasive approaches (MIMV Repairs).

Our team conducted a prospective study to assess the early outcomes of these procedures, focusing on metrics such as in-hospital mortality, duration of ventilation, days spent in the intensive care unit (ICU), and overall hospital stay. The results revealed an overall mortality rate of 1.8% and an average ventilation time of 10.9 hours, figures that were benchmarked against existing studies and traditional open sternotomy procedures. Notably, there were no instances of wound infection observed in our study cohort.

In summary, the findings underscore the early benefits of MICS, indicating potential advantages in terms of mitigating postoperative complications and facilitating quicker recovery periods. However, further research is imperative to ascertain the long-term efficacy of MICS and to expand its utilization, thereby enhancing patient care standards in the field of cardiac surgery. As advancements continue to evolve, ongoing investigation will be essential to delineate the full spectrum of benefits offered by MICS and its broader implications for improving patient outcomes.

Table1: Demographic factors.

Table 2: Pre-Operative Factors.

Table 3: Clinical Factors.

Table4: Operative factors.

Table5: Post-Operative Factors.

Table 6: Comparison between Post-Operative Factors With Outcome.

*- Chi-square/Fisher’s exact test; #- Student’s t-test/Mann Whitney U test; Boldface indicates statistical significance.

Table7: Comparison between Post-Operative Factors With BMI.

*-Chi-square/Fisher’s exact test; ^^- Kruskal Wallis test; Boldface indicates statistical significance.

Figure 1: Showing Incision of 5 to 7cms Used In MICABG.

Figure 2: IMA Harvesting Using Da Vinci Robotic System.

Figure 3: MICABG Retractor System and Stabilizer.

Figure 4: Anastomosis Being Performed Over a Small Incision in MICABG.

Figure.5: Pie Chart for Gender Distribution.

Figure.6: Bar Graph for Distribution of LVEF.

Figure.7: Bar Graph for Co-Morbidities.

Figure 8: Bar Graph for Procedures.

Figure 9: Bar Graph for Distribution of BMI.

Figure10: Pie Diagram for Intraoperative Sternotomy Conversion.

Figure 11: Doughnut Graph for Type of Valves.

Figure 12: Doughnut Graph for Complications.

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Abbreviations

CABG    - Coronary Artery Bypass Graft Surgery

MICS     - Minimally Invasive Cardiac Surgery

MICAB - Minimally Invasive Coronary Artery Bypass surgery

RAMICABG        - Robotic Asist Minimally Invasive Coronary Artery Bypass surgery

TECABG               - Totally Endoscopic Coronary Artery Bypass Graft Surgery

MIMV   - Minimally Invasive Mitral Valve

MIMVR - Minimally Invasive Mitral Valve Replacement

MIAVR - Minimally Invasive Aortic Valve Replacement

PCI         - Percutaneous Coronary Intervention

LAD       - Left Anterior Descending artery

GSV        - Great Saphenous Vein

CPB        - Cardio Pulmonary Bypass

IMA       - Internal Mammary Artery

LIMA     - Left Internal Mammary Artery

RIMA    - Right Internal Mammary Artery

MACCE - Major Adverse Cardiac and Cerebrovascular Events

RBC       - Red Blood Cells

CI           - Confidence Interval

CAD       - Coronary artery disease

ECHO    - Echocardiogram

LVEF     - Left Ventricular Ejection Fraction

eGFR      - estimated Glomerular Filtration Rate

EUROScore          - European System for Cardiac Operative Risk Evaluation

ICU        - Intensive Care Unit

ECG       - Electrocardiogram

CXR       - Chest x-ray

ABG       - Arterial Blood Gas

MI          - Myocardial Infarction

PVD        - Peripheral Vascular Disease

PA           - Pulmonary Artery

PAH       - Pulmonary Artery Hypertension

NYHA    - New York Heart Association

CCS        - Canadian Cardiovascular Society of grading angina pectoris

PRC        - Packed Red Cells

PAP        - Pulmonary Artery Pressure

TAVI      - Transcatheter aortic valve implantation

IQR        - Interquartile Range