Obesity Should Not Deter a Surgeon from Selecting a Minimally Invasive Approach for Mitral Valve Surgery

Heart valve surgery and the obesity paradox: A systematic review

Obesity has been associated with increased incidence of comorbidities and shorter life expectancy, and it has generally been assumed that patients with obesity should have inferior outcomes after surgery. Previous literature has often demonstrated equivalent or even improved rates of mortality after cardiac surgery when compared to their lower-weight counterparts, coined the obesity paradox. Herein, we aim to review the literature investigating the impact of obesity on surgical valve interventions. PubMed and Embase were systematically searched for articles published from 1 January 2000 to 15 October 2021. A total of 1315 articles comparing differences in outcomes between patients of varying body mass index (BMI) undergoing valve interventions were reviewed and 25 were included in this study. Patients with higher BMI demonstrated equivalent or reduced rates of postoperative myocardial infarction, stroke, reoperation rates, acute kidney injury, dialysis and bleeding. Two studies identified increased rates of deep sternal wound infection in patients with higher BMI, although the majority of studies found no significant difference in deep sternal wound infection rates. The obesity paradox has described counterintuitive outcomes predominantly in coronary artery bypass grafting and transcatheter aortic valve replacement. Recent literature has identified similar trends in other heart valve interventions. While the obesity paradox has been well characterized, its causes are yet to be identified. Further study is essential in order to identify the causes of the obesity paradox so patients of all body sizes can receive optimal care.

Outcomes of minimally invasive aortic valve replacement in patients with obese body mass indices

BACKGROUND

Minimally invasive heart valve surgery has previously been shown to be safe and feasible in obese patients. Within this population, we investigated the effect of obesity class on the patient outcomes of minimally invasive aortic valve replacement (mini-AVR).

METHODS

A single-center retrospective cohort study of consecutive patients with obese body mass indices (BMIs) who underwent mini-AVR between 2012 and 2020. Patients were stratified into three groups according to Centers for Disease Control and Prevention adult obesity classifications: Class I (BMI: 30.0-<35.0), Class II (BMI: 35.0-<40.0), and Class III (BMI ≥ 40.0). The primary outcomes were postoperative length of stay (LOS), 30-day mortality, and direct cost.

RESULTS

Among 206 obese patients who underwent mini-AVR, LOS (Class I 5 [3-7] vs. Class II 6 [5-7] vs. Class III 6 [5-7] days; p = .056), postoperative 30-day mortality (Class I 2.44% [n = 3] vs. Class II 4.44% [n = 2] vs. Class III 7.89% [n = 3]; p = .200), and costs (Class I $24,118 [$20,237-$29.591] vs. Class II $22,215 [$18,492-$28,975] vs. Class III $24,810 [$20,245-$32,942] USD; p = .683) did not differ between obesity class cohorts.

CONCLUSIONS

Mini-AVR is safe and feasible to perform for obese patients regardless of their obesity class. Patients with obesity should be afforded the option of minimally invasive aortic valve surgery regardless of their obesity class.

Size does matter: Yet BMI extremes are manageable in minimally invasive cardiac surgery

The obesity paradox has been recently challenged in the literature to spotlight a vague and ill-defined relationship between obesity extremes and cardiac morbidity and mortality. Patient size and incision size both remain important determinants of outcomes. Today, with obesity rates rising around the world, extremely obese patients require experienced teams and substantially improved care.

The effects of body mass index on long-term outcomes and cardiac remodeling following mitral valve repair surgery

BACKGROUND

Previous literature has demonstrated equivalent or improved survival post mitral valve (MV) surgery amongst patients with obesity when compared to their normal-weight counterparts. This relationship is poorly understood and the impact of body mass index (BMI) on cardiac remodeling has not been established.

METHODS

In this retrospective, single-center study, we sought to identify the impact that BMI may have on long-term outcomes and cardiac remodeling post-MV repair. Outcomes were compared between patients of varying BMI undergoing MV repair between 2004 and 2018. The primary outcome was mortality and secondary outcomes included stroke, myocardial infarction, reoperation of the MV, rehospitalization, and cardiac remodeling.

RESULTS

A total of 32 underweight, 249 normal weight, 249 overweight, 121 obese, and 50 morbidly obese patients were included in this study. Underweight patients had increased mortality at longest follow-up. Patients with morbid obesity were found to have higher rates of readmission for heart failure. Only underweight patients did not demonstrate a significant reduction in LVEF. Patients with normal weight and overweight had a significant reduction in left atrial size, and patients with obesity had a significant reduction in MV area.

CONCLUSIONS

An obesity paradox has been identified in cardiac surgery. While patients with obesity have higher rates of comorbidities preoperatively, their rates of mortality are equivalent or even superior to those with lower BMI. The results of our study confirm this finding with patients of high BMI undergoing MV repair demonstrating equivalent rates of morbidity to their normal BMI counterparts. While the obesity paradox has been relatively consistent in the literature, the understanding of its cause and long-term impacts are not well understood. Further focused investigation is necessary to elucidate the cause of this relationship.

Robotic mitral valve operations can be safely performed in obese patients

INTRODUCTION

Robotic cardiac surgery offers mitigated risks for obese patients requiring mitral valve surgery. We aimed to study the safety of robotic mitral surgery in the obese patient population by analyzing the outcomes of mitral surgery patients in our center for robotic cardiac surgery.

METHOD

This study retrospectively included 123 consecutive patients who underwent robotic mitral valve operations in a single center for robotic cardiac surgery. Patients with body mass index (BMI) ≥ 30 were compared against patients with BMI < 30 for demographic and operative parameters as well as postoperative outcomes.

RESULTS

Mean BMI was 33.9 ± 2.8 in the obesity group (n = 87) and 25.4 ± 2.7 in the no-obesity group (n = 36). Female gender (80.6% vs. 52.9%, p = .004), diabetes (25.0% vs. 10.3%, p = .036), and hypertension (48.6% vs. 26.4%, p = .018) were more common in patients with obesity. The obesity group was operated with similar cardiopulmonary bypass and total operative times with the no-obesity group. Postoperative drainage and blood transfusion requirements were similar between the groups. Mechanical ventilation times (6.1 ± 2.2 vs. 8.0 ± 4.4 h, p = .003) and intensive care unit stay (20.4 ± 1.6 vs. 29.4 ± 3.7, p = .027) were shorter in the obesity group. Other postoperative outcomes of infection, atrial fibrillation, hospital stay duration, and readmission rates were similar between the groups.

CONCLUSION

Robotic mitral surgery is safe to perform in obese patients. Obesity should not be a contraindication for robotic mitral surgery as obese patients have outcomes similar to nonobese patients despite increased challenges and risk-factors.

Anesthesia for minimally invasive cardiac surgery

Due to its potential benefits and increased patient satisfaction minimal invasive cardiac surgery (MICS) is rapidly gaining in popularity. These procedures are not without challenges and require careful planning, pre-operative patient assessment and excellent intraoperative communication. Assessment of patient suitability for MICS by a multi-disciplinary team during pre-operative workup is desirable. MICS requires additional skills that many might not consider to be part of the standard cardiac anesthetic toolkit. Anesthetists involved in MICS need not only be highly skilled in performing transesophageal echocardiography (TEE) but need to be proficient in multimodal analgesia, including locoregional or neuroaxial techniques. MICS procedures tend to cause more postoperative pain than standard median sternotomies do, and patients need analgesic management more in keeping with thoracic operations. Ultrasound guided peripheral regional anesthesia techniques like serratus anterior block can offer an advantage over neuroaxial techniques in patients on anti-platelet therapy or anticoagulation with low molecular weight or unfractionated heparin The article reviews the salient points pertaining to pre-operative assessment and suitability, intraoperative process and postoperative management of minimally invasive cardiac procedures in the operating theatre as well as the catheterization lab. Special emphasis is given to anesthetic management and analgesia techniques.

Predictive Value of Body Mass Index in Minimally Invasive Mitral Valve Surgery

BACKGROUND

 With this study we aimed to analyze if the separate consideration of body mass index (BMI) could provide any superior predictive values compared with the established risk scores in isolated minimally invasive mitral valve surgery (MIMVS). This might facilitate future therapeutic decision-making, e.g., regarding the question surgery versus transcatheter mitral valve repair (TMVr).

METHODS

 We assessed the relevance of BMI in non-underweight patients who underwent isolated MIMVS. The risk predictive potential of BMI for mortality and several postoperative adverse events was assessed in 429 consecutive patients. This predictive potential was compared with that of European System for Cardiac Outcome Risk Evaluation II (EuroSCORE II) and the Society of Thoracic Surgeons score (STS score) using a comparative receiver operating characteristic curve analysis.

RESULTS

 BMI was a significant numeric predictor of wound healing disorders (p = 0.001) and proved to be significantly superior in case of this postoperative adverse event compared with the EuroSCORE II (p = 0.040) and STS score (p = 0.015). Except for this, the predictive potential of BMI was significantly inferior compared with that of the EuroSCORE II and STS score for several end points, including 30-day (p = 0.029 and p = 0.006) and 1-year (p = 0.012 and p = 0.001) mortality.

CONCLUSION

 Therefore, we suggest that, in the course of decision-making regarding the right treatment modality for non-underweight patients with isolated mitral valve regurgitation, the sole factor of BMI should not be given a predominant weight.

Minimally invasive mitral valve repair

Minimally invasive mitral valve (MV) repair is being increasingly performed over the last 2 decades due to the constantly growing patient demand, since it offers a shorter recovery, less restriction and faster return to normal physical activities, reduction in pain, and superior cosmetic results. However, such procedures have to be performed through small incisions which limit visualization and the freedom of movement of the surgeon, in contrast to conventional operations that are performed through a sternotomy. Therefore, special long surgical instruments are required, and visualization is usually enhanced with advanced port-access two-dimensional (2D) or three-dimensional (3D) thoracoscopic cameras. This makes performance of a minimally invasive MV repair more challenging for the surgeon and is thereby associated with a steep learning curve. Nonetheless, the vast majority of patients who require MV repair are usually good candidates for this less invasive technique, though adequate patient selection is of utmost importance for success. Concomitant cardiac procedures such as ablation surgery for atrial fibrillation or right-sided interventions such as tricuspid valve surgery, heart tumor resection, and atrial septal defect closure can easily be performed using this approach. Short- and long-term results after minimally invasive MV repair are excellent and comparable with those achieved through a sternotomy approach. There are few drawbacks associated with minimally invasive MV repair such as the high technical demands of working through a constrained space and development of complications associated with peripheral cannulation and seldom unilateral pulmonary edema. Nonetheless, high-volume centers have been able to achieve similar operating times, postoperative complication rates, and mid-/long-term outcomes to those obtained through conventional sternotomy. Up-to-date evidence is needed in order to improve recommendations supporting minimally invasive MV repair. Future innovations should concentrate on decreasing complexity and improving reproducibility of minimally invasive procedures in low-volume centers.

Is obesity associated with poorer outcomes in patients undergoing minimally invasive mitral valve surgery?

OBJECTIVES

METHODS

This is a retrospective cohort study of all patients undergoing MIMVS ± concomitant procedures over an 8-year period. Patients were stratified into 2 groups: BMI ≥ 30 kg/m2 and BMI ˂ 30 kg/m2, as per World Health Organization definitions. Baseline characteristics, operative and postoperative outcomes and 5-year survival were compared.

RESULTS

We identified 296 patients (BMI ≥30, n = 41, median 35.3, range 30–43.6; BMI &lt;30, n = 255, median 26.2, range 17.6–29.9). The groups were well matched with regard to baseline characteristics. There was only 1 in-hospital mortality, and this was in the BMI &lt; 30 group. There was no difference in repair rate for degenerative disease (100% vs 96.3%, P &gt; 0.99 respectively) or operative durations [cross-clamp: 122 min interquartile range (IQR) 100–141) vs 125 min (IQR 105–146), P = 0.72, respectively]. There were only 6 conversions to sternotomy, all in non-obese patients. There was no significant difference in any other perioperative or post-operative outcomes. Using the Kaplan–Meier analysis, there was no significant difference in 5-year survival between the 2 groups (95.8% vs 95.5%, P = 0.83, respectively).

CONCLUSIONS

In patients having MIMVS, there is insufficient evidence to suggest that obesity affects either short- or mid-term outcomes. Obesity should therefore not be considered as a contraindication to this technique for experienced teams.

Learning curve predictors for minimally invasive mitral valve surgery; how far should the rabbit hole go?

OBJECTIVE

To analyze predictors that influence the learning curve of minimally invasive mitral valve surgery (MIMVS).

METHODS

Patients who underwent MIMVS between March 2010 to March 2015 were retrospectively analyzed. Predictive factors that influence the learning curve were analyzed.

RESULTS

One hundred and five patients were included in the analysis. Cardiopulmonary bypass (CPB) time in minutes was 158.72 ± 40.98 and the aortic cross-clamp (ACC) time in minutes was 114.48 ± 27.29. There were three operative mortalities, one stroke and five >2+ mitral regurgitation. ACC time in minutes was higher in the low logistic Euroscore II (LES) group (LES < 5% = 118.42 ± 27.94) versus (LES ≥ 5 = 88.66 ± 22.26), P < .05 while creatinine clearance in μmol/L was higher in the LES < 5% group (LES < 5% = 84.32 ± 33.7) versus (LES ≥ 5% = 41.66 ± 17.14), (P < .05). One patient from each group required chest tube insertion for pleural effusion P < .05. The cumulative sum analysis (CUSUM) for the first 25 patients had CPB and ACC times that reached the upper limits. Between 25 to 64 patients the curve remained stable while with the introduction of reoperations and complex surgical procedures the CUSUM reached the upper limits.

CONCLUSIONS

The learning curve is affected by many factors but this should not desist surgeons from approaching this technique. The introduction of high-risk patients in clinical practice should be carefully measured based on surgeon experience.

Morbid Obesity Does not Increase Morbidity or Mortality in Robotic Cardiac Surgery

OBJECTIVE

Morbid obesity (body mass index ≥ 35 kg/m) usually confers a higher perioperative risk in cardiac surgery. Robotic cardiac surgery may have many advantages for these high-risk patients.

METHODS

We retrospectively reviewed patients undergoing robotic cardiac surgery from July 2013 to April 2017 at our institution. We compared the outcomes of morbidly obese patients versus nonobese patients.

RESULTS

A total of 486 patients underwent robotic cardiac surgery (322 men, median age = 65 years). The robotic procedures were the following: totally endoscopic beating heart coronary artery bypass (n = 263), mitral valve surgery (n = 138), arrhythmia surgery (n = 33), adult congenital surgery (n = 16), pericardiectomy (n = 11), and others (n = 25). The cohorts were divided into the following: normal weight (body mass index < 25, n = 123), overweight (body mass index = 25 to < 30, n = 182), obesity (body mass index = 30 to < 35, n = 105), and morbid obesity (body mass index ≥ 35, n = 76). Morbidly obese patients had a higher rate of hypertension, dyslipidemia, and diabetes mellitus compared with normal or overweight patients. There were no significant differences in morbidity, mean length of intensive care unit stay (2.10 ± 4.27 days), and hospital stay (4.48 ± 5.61 days) among the groups. In-hospital mortality was 1.4% (7/486) with nonsignificant difference.

CONCLUSIONS

Outcomes of robotic heart surgery in morbidly obese patients in our center were acceptable. Over a broad range of cardiac surgical procedures, morbid obesity was not associated with increased morbidity or mortality when these procedures were performed using a robotic approach. These findings can be beneficial in managing this challenging group of patients.

Minimally invasive valve surgery in high-risk patients

The use of minimally, or less invasive, approaches to cardiac valve surgery has increased over the past decade. Because of its less traumatic nature, early studies in lower risk patients demonstrated the approach to be associated with an enhanced recovery, increased patient satisfaction, and good operative outcomes. With time, despite a steep learning curve, surgeons expanded this approach to perform more complex procedures, and include patients with more co-morbidity. The aim of this publication is to review the current literature involving the use of minimally invasive valve surgery (MIVS) in higher-risk patients.

Body Mass Index and Mortality Among Adults Undergoing Cardiac Surgery: A Nationwide Study With a Systematic Review and Meta-Analysis

BACKGROUND

In an apparent paradox, morbidity and mortality are lower in obese patients undergoing cardiac surgery, although the nature of this association is unclear. We sought to determine whether the obesity paradox observed in cardiac surgery is attributable to reverse epidemiology, bias, or confounding.

METHODS

Data from the National Adult Cardiac Surgery registry for all cardiac surgical procedures performed between April 2002 and March 2013 were extracted. A parallel systematic review and meta-analysis (MEDLINE, Embase, SCOPUS, Cochrane Library) through June 2015 were also accomplished. Exposure of interest was body mass index categorized into 6 groups according to the World Health Organization classification.

RESULTS

A total of 401 227 adult patients in the cohort study and 557 720 patients in the systematic review were included. A U-shaped association between mortality and body mass index classes was observed in both studies, with lower mortality in overweight (adjusted odds ratio, 0.79; 95% confidence interval, 0.76-0.83) and obese class I and II (odds ratio, 0.81; 95% confidence interval, 0.76-0.86; and odds ratio, 0.83; 95% confidence interval, 0.74-0.94) patients relative to normal-weight patients and increased mortality in underweight individuals (odds ratio, 1.51; 95% confidence interval, 1.41-1.62). In the cohort study, a U-shaped relationship was observed for stroke and low cardiac output syndrome but not for renal replacement therapy or deep sternal wound infection. Counter to the reverse epidemiology hypotheses, the protective effects of obesity were less in patients with severe chronic renal, lung, or cardiac disease and greater in older patients and in those with complications of obesity, including the metabolic syndrome and atherosclerosis. Adjustments for important confounders did not alter our results.

CONCLUSIONS

Obesity is associated with lower risks after cardiac surgery, with consistent effects noted in multiple analyses attempting to address residual confounding and reverse causation.