Impact of Morbid Obesity on Left Ventricular Assist Device Support and Heart Transplantation

Research Article

Austin J Clin Cardiolog. 2019; 5(1): 1062.

Impact of Morbid Obesity on Left Ventricular Assist Device Support and Heart Transplantation

Cohen SE1, Johnson RM1 and Quader M2*

¹Cardio-Thoracic Surgery, Virginia Common Wealth University, USA

²Division of Cardiothoracic Surgery, Virginia Common Wealth University, USA

*Corresponding author: Quader M, Division of Cardiothoracic Surgery, Virginia Common Wealth University, 1200 East Broad St, West Hospital 7th Floor, Richmond VA 23298, USA

Received: May 21, 2019; Accepted: June 13, 2019; Published: June 20, 2019


Background: Limited data suggests that morbid obesity (Body Mass Index- BMI >35 kg/m2) increases complications after Left Ventricular Assist Device (LVAD) implantation and after heart transplantation (HTx). We comprehensively compared LVAD and heart transplantation (HTx) outcomes in patients with and without morbid obesity

Methods: Society of Thoracic Surgeons (STS) and Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) data on LVAD and HTx surgeries at our institution from 2008-2014 was analyzed. Patients were divided into two groups, BMI =35 and BMI <35.

Results: Of the 157 LVADs implanted, 121 (77%) were in patients with a BMI ‹35 and 36 (23%) were in patients with a BMI =35. Morbidly obese patients were younger (47 ± 12.7 yrs vs. 55 ± 13.4 yrs), had more females (44% vs. 24%), had higher right heart catheterization pressures, and fewer prior myocardial infarctions (22% vs. 46%), all p ‹0.05. Preoperative morbidities, INTERMACS class, and LVAD implantation designation were comparable between both groups. The BMI =35 group had more postoperative and device complications, but only bleeding requiring reoperation (42% vs. 22% p=0.03) and mean number of driveline infections were statistically significant (2.4 ± 1.7 vs. 1.2 ± 0.5 p=0.02). At a mean follow-up of 27.3 ± 20.5 months, fewer morbidly obese patients received a HTx (19% vs. 33% p=0.15) after a relatively longer wait times (619 ± 372 vs. 403 ± 342 days, p=0.1). After HTx, morbidly obese patients had more reoperations (57% vs. 15% p=0.03).

Conclusion: Morbidly obese patients requiring LVAD support encounter higher postoperative complications and wait longer for heart transplantation, however HTx and graft survival is comparable.


LVAD: Left Ventricular Assist Device; HTx: Heart Transplantation; CHF: Congestive Heart Failure; BTT: Bridge To Transplantation; BMI: Body Mass Index; ISHLT: International Society for Heart and Lung Transplantation; MCS: Mechanical Circulatory Support; DT: Destination Therapy; BTR: Bridge to Recover; BiVAD: RVAD + LVAD; STS :Society of Thoracic Surgeons; INTERMACS: Interagency Registry for Mechanically Assisted Circulatory Support; CABG: Coronary Artery Bypass Graft; PRA: Panel-Reactive Antibody; UNOS: United Network for Organ Sharing ;


Congestive Heart Failure (CHF) affects 5.1 million people in the United States with over 550,000 new cases per year and contributes to about 287,000 deaths per year [1]. The current standard of treatment for patients with end stage heart failure is heart transplantation (HTx), however, the pool of viable donor hearts is not sufficient to meet the needs of patients with end stage heart failure [2]. Therefore, when a donor heart becomes available, it is imperative to allocate it to a patient who is most likely to benefit. The discrepancy between supply and demand of donor hearts, has led to the increasing use of continuous flow Left Ventricular Assist Devices (LVADs) as a Bridge to Transplantation (BTT) [3,4].

An important factor in patient selection for both LVAD support and HTx is patient’s Body Mass Index (BMI). The 2013 International Society for Heart and Lung Transplantation (ISHLT) guidelines for Mechanical Circulatory Support (MCS) state that “surgical risk and attendant comorbidities must be carefully considered prior to MCS in the morbidly obese patient (BMI = 35) [5].”

The ISHLT published listing criteria for HTx in 2016, which states that candidates should lose weight to achieve a BMI = 35 kg/ m2 before listing for cardiac transplant because a pre-transplant BMI >35 is associated with a worse outcome after cardiac transplantation [6]. However, studies supporting this data are conflicting and limited [7-12].

The aims of this study are to compare patient outcomes with and without morbid obesity, who received LVAD and subsequent HTx. The study outcomes included (a) post-operative LVAD morbidity and mortality (b) wait time to heart transplant (c) long-term LVAD complications and (d) post-heart transplant morbidity and mortality (e) survival after HTx.

This study is important for 3 reasons. Limited number of studies have followed morbidly obese patients through LVAD and heart transplantation, which is important as increasingly more obese patients are being bridged with an LVAD. Secondly, the ISHLT listing criteria for heart transplantation were only supported by level C evidence, which is by a consensus opinion of experts and not based on scientific data. Lastly, although weight loss to a BMI of ‹35 is recommended before listing, weight loss is difficult and unattainable for many patients with advanced heart failure [13].


The study population was comprised of 157 patients with advanced heart failure who received an LVAD (Heart Mate II -Thoratec Corp, Pleasanton, California, or Heart Ware HVAD, Framingham, Massachuset) at Virginia Commonwealth University from December 2008 through January 2014. All indications for LVAD implantation, BTT, Destination Therapy (DT) and Bridge to Recover (BTR) were included in the study. We excluded patients who were under 18 years old, and were undergoing repeat LVAD implantation for any reason and those who had a planned BiVAD (RVAD + LVAD) implantation.

We divided the patients into two groups based on BMI before LVAD surgery; a morbidly obese group (BMI = 35 kg/m2) and a nonmorbidly obese group (BMI < 35 kg/m2). We used a cut-off BMI of 35 per National Institutes of Health directive guidelines [14]. Our hospital’s Institutional Review Board approved this study and the need for individual informed consent was waived.

We retrospectively collected data on each patient from the Society of Thoracic Surgeons (STS) and Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) databases as well as reviewed patient’s electronic medical records. A detailed analysis of the data was performed with SAS 9.3 software (SAS Institute Inc, Cary, NC). Categorical variables were analyzed using the Fisher’s exact test and were reported as percentages. Continuous variables were analyzed using the Wilcoxon rank sum test or the Student’s t-test and were reported as mean or median values with standard deviations. Statistical comparisons were two-tailed and a P-value of ‹0.05 was considered statistically significant. Survival analysis was determined by the Kaplan-Meier method and survival between the two groups was performed using the log-rank test.


Baseline LVAD patient characteristics are summarized in (Table 1). Of the 157 patients who received an LVAD, 36 (23%) were in BMI = 35 and 121 (77%) were in BMI ‹35 groups. The mean BMI of the BMI = 35 and ‹35 groups was 41.6 ± 5.5, and 27.8 ± 4.1 respectively. Our study population included a range of BMI’s: underweight BMI ‹18.5 (n=3, 0.02%), normal weight BMI 18.5-24.99 (n=28, 17.83%), overweight BMI 25-29.99 (n=48, 30.57%), obesity class I 30-34.99 (n=42, 26.75%), obesity class II 35-39.99 (n=16, 10.19%), and obesity class III >40 (n=20, 12.74%). Obesity class II and III were included in morbidly obese group.