Outcomes among heart transplant recipients following acute coronary syndrome: A nationwide population based study

Background: For patients with refractory heart failure despite optimal medical therapy, orthotopic heart transplantation (OHT) remains the treatment of choice. Since transplanted hearts have variable cardiac denervation and acute coronary syndrome often presents as a silent myocardial infarction or with atypical symptoms, the true impact of ACS on outcomes within this population needs more study. The aim of this study is to evaluate in-hospital mortality in post-transplant patients with ACS.

Methods: Utilizing data from the 2002-15 Nationwide Inpatient Sample database, patients with a primary diagnosis of acute coronary syndrome among those with prior heart transplantation were included. A risk adjusted regression analysis was performed to assess if ACS post-OHT had an independent impact on the risk of in-hospital mortality. A 2:1 propensity matching was used to match ACS patients with and without OHT, respectively to assess differences in mortality.

Results: A total of 3,224,073 patients with a primary diagnosis of acute coronary syndrome were included, of which 842 (0.03%) were heart-transplant recipients. The type of ACS: NSTEMI (76.0% vs 74.5%; p = 0.32) and STEMI (24.8% vs 26.7%; p = 0.21) between heart transplant and non-heart transplant patients was similar in both groups. Following ACS, patients with heart transplant were more likely to have accompanying shock of any etiology (15.6% vs 3.8%; p < 0.001) and cardiogenic shock (11.2% vs 2.6%; p < 0.001) compared to those with native hearts. OHT patients also had significantly higher in-hospital mortality (14.3% vs. 3.7%; p < 0.001) that remain significant following regression analysis (aOR 3.6, 95% CI 2.8-4.5; p < 0.001) irrespective of the presence of cardiogenic shock compared to native hearts. This relationship remained consistent following propensity matching where patients with OHT had significantly higher in-hospital mortality (13.5% vs. 7%; p < 0.001).

Conclusions: ACS following OHT was more likely to have accompanying cardiogenic shock. ACS in the setting of prior OHT remained a strong independent predictor of higher mortality as compared to native hearts.