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Obesity in Bridge to Transplant Continuous-Flow LVAD Patients
Study Questions:
Do obese patients have worse post–left ventricular assist device (LVAD) implantation outcomes? And, does implantation of an LVAD allow for weight loss?
Methods:
The study cohort was comprised of heart failure patients in the United Network for Organ Sharing (UNOS) database who underwent LVAD implantation as bridge to transplantation from May 2004 and April 2014, with follow-up through June 2014. The patients were grouped according to World Health Organization classification body mass index (BMI): underweight (BMI <18.5 kg/m2), normal (BMI 18.5-24.99 kg/m2), overweight (BMI 25-29.99 kg/m2), obese class I (BMI 30-34.99 kg/m2), and obese class II or greater (BMI >35 kg/m2). The primary endpoint was freedom from mortality or delisting while on device support. Secondary endpoints included mortality on LVAD support, delisting on LVAD support, complications (thromboembolism, device infection, device malfunction, or life-threatening ventricular arrhythmia) requiring UNOS listing status upgrade, change in BMI group while on device support, and post-transplantation survival.
Results:
The study investigators found that among patients in the study cohort of 3,856 patients [3,245 (84.2%) with a Heartmate II and 611 (15.8%) with an HVAD], the risk of death or delisting was not significantly different between BMI groups (p = 0.347). There was no increased risk of death (p = 0.234) or delisting (p = 0.918). The risk of complication requiring UNOS status upgrade was increased for those with class II obesity or greater (hazard ratio [HR], 1.48; p = 0.004), driven by increased infection and thromboembolism (HR, 1.59; p = 0.058), but not among any other group. Thromboembolism was more common among those with greater BMI. The risk of device malfunction or life-threatening ventricular arrhythmias was fairly uniform across all BMI categories. Obese patients had worse post-transplantation outcomes. Changes in BMI group were uncommon after LVAD implantation. Only 15.5% of patients with class II obesity or greater were able to lose enough weight to move to a lower BMI group at the time of transplantation or delisting. Similarly, a small number of patients with class I obesity were able to move to a lower group (9.6%); however, a comparable amount moved to a higher BMI group (7.4%). Among patients who were obese and were successfully bridged to transplantation, the prevalence of lowering BMI while on LVAD support was similarly low (10.1% class I obesity and 19.3% class II and greater obesity, p = 0.90). More overweight patients on LVAD (BMI 25-29.99 kg/m2) gained weight than lost weight.
Conclusions:
The authors concluded that obese patients had similar freedom from death or delisting while on LVAD support. However, class II obese (BMI >35 kg/m2) or greater patients had an increased risk of complications requiring UNOS status upgrade compared with those with normal BMI during LVAD support and decreased post-transplantation survival. They also concluded that weight loss on device therapy was possible, but uncommon.
Perspective:
The findings of this retrospective study are important because this suggests that the heart transplant team must not have too much hope that a given patient will lose weight after LVAD implantation. It would be interesting to know whether obesity has a similar impact on patients who receive LVAD therapy as destination therapy.
Keywords: Arrhythmias, Cardiac, Body Mass Index, Heart Failure, Heart Transplantation, Heart-Assist Devices, Obesity, Overweight, Primary Prevention, Thromboembolism, Weight Gain, Weight Loss
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