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

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.