Incidence and Clinical Significance of Hyperkalemia Following Heart Transplantation

Abstract

Introduction Hyperkalemia post-heart transplantation (HT) is common and related to immunosuppressive medications, particularly calcineurin inhibitors with concomitant use of prophylactic antibiotics, mainly trimethoprim-sulfamethoxazole as well as comorbidities like diabetes and renal insufficiency. Most patients are managed with potassium chelating agents and deviations from standard post-transplant protocol. This study aims to report the incidence and clinical significance of hyperkalemia following HT. Methods We retrospectively reviewed medical records of all patients that underwent HT at our institution between 4/2014-12/2018. We excluded multi-organ transplant recipients. We defined mild, moderate and severe hyperkalemia as serum potassium >5.0, >5.5 and >6.0 mEq/L, respectively. Patients who experienced moderate or severe hyperkalemia within 1 year (HK group) were compared to the other patients (Non-HK group). Results We included 143 HT patients, mean age was 53±13 years old and 105 (73%) were male. Thirty-four (24%) patients had a history of hyperkalemia within 1 month prior to HT, and only 9 (6%) patients had a history of moderate or severe hyperkalemia. During 1 year following HT, freedom from mild, moderate and severe hyperkalemia was 5%, 38% and 76%, respectively (Figure A). Fifty-four percent of the patients required treatment with polystyrene sulfonate or patiromer. Sulfamethoxazole-trimethoprim was stopped due to hyperkalemia in 36% of patients. Overall survival was numerically lower in the HK group (93% vs 98% in 1-year, P=0.185 and 87% vs 98% in 2-year, P=0.066), and infection-free survival was significantly lower in the HK group (34% vs 55% in 1-year, P=0.011 and 26% vs 45% in 2-year, P=0.015, Figure B). Multivariate logistic analysis using recipient and operative factors identified pre-HT GFR as a significant predictor of the HK group (odds ratio 0.790, 95% confidence interval 0.643-0.970, P=0.024). Conclusions The incidence of hyperkalemia following HT is extremely high, and more than half of patients require treatment for hyperkalemia within the first year. Importantly hyperkalemia was related to an increase in the rate of infections at 2 years.