Pharmacologic Therapy for Engraftment Arrhythmia Induced by Transplantation of Human Cardiomyocytes

Background Engraftment arrhythmias (EAs) are observed in large animal studies of intramyocardial transplantation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) for myocardial infarction. Although transient, the risk posed by EA presents a barrier to clinical translation. Objectives We hypothesized that clinically approved antiarrhythmic drugs can prevent EA-related mortality as well as suppress tachycardia and arrhythmia burden. Methods hPSC-CM were transplanted into the infarcted porcine heart by surgical or percutaneous delivery to induce EA. Following a screen of antiarrhythmic agents, a prospective study was conducted to determine the effectiveness of amiodarone plus ivabradine in preventing cardiac death and suppressing EA. Results EA was observed in all subjects, and amiodarone-ivabradine treatment was well-tolerated. None of the treated subjects experienced the primary endpoint of cardiac death, unstable EA or heart failure compared to 5/8 (62.5%) in the control cohort (hazard ratio 0.00; 95% confidence interval, 0–0.297; p = 0.002). Overall survival including two deaths in the treated cohort from immunosuppression-related infection showed borderline improvement with treatment (hazard ratio 0.21; 95% confidence interval, 0.03–1.01; p = 0.05). Without treatment, peak heart rate averaged 305 ± 29 beats per min (bpm), whereas in treated subjects peak daily heart rate was significantly restricted to 185±9 bpm (p = 0.006). Similarly, treatment reduced peak daily EA burden from 96.8 ± 2.9% to 76.5 ± 7.9% (p = 0.003). Antiarrhythmic treatment was safely discontinued after approximately one-month of treatment without recrudescence of arrhythmia. Conclusions The risk of engraftment arrhythmia following hPSC-CM transplantation can be reduced significantly by combined amiodarone and ivabradine drug therapy. Condensed Abstract Engraftment arrhythmia (EA) is a transient but serious complication of cardiac remuscularization therapy. Using a porcine model of cardiac remuscularization and EA, ivabradine and amiodarone were independently effective in suppressing tachycardia and arrhythmia, respectively. Baseline amiodarone combined with adjunctive ivabradine successfully prevented cardiac death, unstable EA and heart failure (hazard ratio 0.00; 95% confidence interval, 0–0.297; p = 0.002) and significantly suppressed peak daily heart rate and arrhythmia burden (p=0.006 and 0.003, respectively). Antiarrhythmic treatment was successfully discontinued after one-month without recrudescence of arrhythmia. We conclude that EA can be suppressed by combined amiodarone and ivabradine drug therapy.