Severely Underweight: Is It a Risk Factor for Poor Outcomes in Post-Heart Transplant Patients?

Purpose Obesity has been noted as a risk factor for poor outcome after heart transplantation (HTx). Cardiac cachexia has also been reported to be a risk factor for poor outcome, however no threshold has been noted for this patient population. Body mass index (BMI) greater than 35 kg/m2 is a noted threshold for declined patients for HTx, but a lower BMI has not been established. In this study, we reviewed the UNOS database to evaluate underweight patients awaiting HTx to assess whether there is a risk for poor outcomes post-HTx. Methods Between 2000 and 2020, we assessed 16,457 patients from the UNOS database and divided the patients according to BMI groupings below. Patients were divided by CDC BMI definitions: severely underweight (BMI less than 15.0 kg/m2), moderately underweight (15.0 to 16.0 kg/m2), mildly underweight (16.0 to 18.5 kg/m2), and healthy weight (18.5 to <25.0 kg/m2). Endpoints included 1-year survival and freedom from graft failure. Results There was no significant difference in BMI underweight groups compared to healthy weight group in 30-day, 6-month, and 1-year survival or freedom from graft failure. (see table) Conclusion There does not appear to be decreased post-heart transplant outcome for mild, moderate, or severely underweight patients. Being severely underweight should not be an absolute contraindication for heart transplant. However, larger number of severely underweight patients are needed to confirm these findings. Obesity has been noted as a risk factor for poor outcome after heart transplantation (HTx). Cardiac cachexia has also been reported to be a risk factor for poor outcome, however no threshold has been noted for this patient population. Body mass index (BMI) greater than 35 kg/m2 is a noted threshold for declined patients for HTx, but a lower BMI has not been established. In this study, we reviewed the UNOS database to evaluate underweight patients awaiting HTx to assess whether there is a risk for poor outcomes post-HTx. Between 2000 and 2020, we assessed 16,457 patients from the UNOS database and divided the patients according to BMI groupings below. Patients were divided by CDC BMI definitions: severely underweight (BMI less than 15.0 kg/m2), moderately underweight (15.0 to 16.0 kg/m2), mildly underweight (16.0 to 18.5 kg/m2), and healthy weight (18.5 to <25.0 kg/m2). Endpoints included 1-year survival and freedom from graft failure. There was no significant difference in BMI underweight groups compared to healthy weight group in 30-day, 6-month, and 1-year survival or freedom from graft failure. (see table) There does not appear to be decreased post-heart transplant outcome for mild, moderate, or severely underweight patients. Being severely underweight should not be an absolute contraindication for heart transplant. However, larger number of severely underweight patients are needed to confirm these findings.