Risk Factors of Waiting List Mortality for Patients Awaiting Heart Transplant

Waiting list mortality for patients awaiting heart transplant has significantly improved in the recent era and appears to be associated with increasing use mechanical circulatory support (MCS). With proposed changes to the heart organ allocation system, we assessed the risk factors associated with waiting list mortality at 180 days to identify high risk patients that need to be prioritized for transplant in this era of MCS support. United Network of Organ Sharing (UNOS) database for thoracic organ transplant was requested and available dataset was queried to identify patients with age >/=18 years who were listed for heart transplant from 1999 to 2013. Patients who received heart transplant within 180 days of listing and received MCS after 180 days of listing were excluded from final analysis. Patients taken off the waitlist due to improvement or worsening were excluded. A logistic regression model was created to assess the risk factors associated with 180 days mortality on waiting list. There were 33,837 patients of which 7371 patients were included in the final dataset after applying inclusion and exclusion criteria. A total of 1111 (15%) patients died and 6260 (85%) were still waiting for a donor heart at 180 days after listing. The logistic regression model (area under ROC=84%) showed that higher age, mean pulmonary artery pressure, creatinine and lower albumin as well as initial listing status 1A, initial need for ventilator and inotropic support, blood group AB (vs. O) were significant predictors of 6 month waitlist mortality. Use of continuous flow MCS and rhythm control device in particular was protective against the 6 month waitlist mortality (Table 1). A logistic regression model can be very useful in predicting waitlist mortality of patients listed for heart transplant and objectively determine priority of patients for organ allocation. From this analysis, patients that are not candidates for continuous flow MCS support should have the highest priority for donor heart allocation.