Ventricular arrhythmias and myocardial inflammation: Long-term follow-up of patients with suspected myocarditis

Abstract

Background: Inflammatory heart disease is known to be associated with ventricular arrhythmias (VA) and impaired ventricular function at presentation or during follow-up. We aimed to investigate the need for implanted cardioverter defibrillator (ICD) due to ventricular dysfunction and occurrence of VA during long-term follow-up in patients admitted with suspected myocarditis.

Methods: Between 2000 and 2016, 191 patients (age 43 ± 13 years, 71% male, mean left ventricular ejection fraction (LVEF) 33 ± 15%) with clinically suspected myocarditis, who underwent endomyocardial biopsies (EMB), were prospectively enrolled and followed up in 6-months-intervals (median follow-up was 83 (49-156) months). The primary endpoint was deterioration of cardiac function (LVEF ≤ 35%) or occurrence of VA leading to ICD implantation.

Results: According to EMB results, patients were stratified in three diagnostic groups: acute myocarditis (5%), chronic myocarditis (50%) and dilated cardiomyopathy (DCM) (45%). An ICD implantation was performed in 58 patients (30%, n = 38 for primary prevention). Besides LVEF at baseline, chronic myocardial inflammation was the only independent predictor of ICD implantation for primary prevention (hazard ratio 2.48 (95% confidence interval 1.02-5.5); p = 0.045). VA requiring ICD therapy occurred in 29 of 58 patients (50%) after a median of 14 (2-37) months without a significant difference between presence and absence of myocardial inflammation.

Conclusions: Nearly one third of patients with suspected myocarditis require an ICD due to impaired LVEF or occurrence of VA. Half of these patients experienced VA with adequate ICD therapy.

Keywords: Heart failure; Implanted cardioverter defibrillator; Myocardial inflammation; Ventricular arrhythmia.