Incidence, Predictors, and Reversibility of Left Ventricular Dysfunction After Brain Death: The Donor Heart Study

Abstract

<h3>Purpose</h3> Left ventricular (LV) dysfunction after brain death often prompts non-use of potential donor hearts for transplant, but little is known regarding its incidence, reversibility, and impact on outcomes. Shedding light on these unknowns was a primary aim of the Donor Heart Study -a first-of-its-kind, multisite, prospective study of potential heart donors. <h3>Methods</h3> We enrolled potential donors (n = 4333) at 8 organ procurement organizations across the United States from February 2015-May 2020. Data were collected on donor management, serial labs, and diagnostic tests. These included a transthoracic echocardiogram (TTE) performed within 48 hours after brain death and, if LV dysfunction was present, a repeat TTE 24 ± 6 hours later. LV dysfunction was defined as an ejection fraction (LVEF)<50%, as ascertained by a single expert reviewer, and was considered reversible if LVEF was >50% on the second TTE. LASSO models identified predictors of initial LV dysfunction and its reversibility. A conditional inference ("decision") tree was fit to identify threshold values that predict reversibility. <h3>Results</h3> An initial TTE was performed and interpretable for 3794 donors, and 493 (13%) had LV dysfunction. Significant predictors of LV dysfunction included: higher levels of troponin, nt-pro B-type natriuretic peptide (nt-proBNP), and lactate; higher mean arterial pressure, body temperature, use of vasopressors, and thyroid hormone; younger age; low body mass index (BMI≤ 20 kg/m2); and elevated blood urea nitrogen:creatinine ratio. A second TTE was performed for 224 donors with LV dysfunction and 130 (58%) of these demonstrated reversibility. Donors with baseline nt-proBNP levels >11,137 pg/ml were less likely to have LVEF improvement (30% vs 62%, p=0.008). Low BMI and reductions in serial nt-proBNP and lactate levels were the strongest predictors of reversibility. 59% of donor hearts with normal LV function were accepted for transplant, compared to 47% with reversible dysfunction and 29% with persistently low LVEF. <h3>Conclusion</h3> LV dysfunction after brain death is common among potential heart donors, but is reversible in the majority of cases. Commonly measured clinical variables are predictive of LV dysfunction and its subsequent improvement. Our results can better inform decisions made during donor management and evaluation, and can help guide donor heart acceptance.