Prognostic electrocardiographic parameters in patients with suspected myocarditis

The objective of this study was to investigate the prognostic value of electrocardiographic (ECG) parameters for outcome in patients acutely admitted with myocarditis without previous heart failure who underwent endomyocardial biopsy.

Between 1995 and 2009, 186 consecutive patients (age: 43.4 ± 13.9 years) acutely admitted with clinically suspected myocarditis were enrolled and followed up for a mean of 55.1 ± 105.1 months. Electrocardiograms recorded before myocardial biopsy were analysed for rhythm, conduction times, signs of hypertrophy, and repolarization abnormalities. The primary endpoint was time to cardiac death or heart transplantation. The mean QRS duration was 90.3 ± 24.3 ms; 158 patients had a normal QRS duration (<120 ms) and 21 patients had a prolonged QRS duration (≥ 120 ms). During follow-up, 15.8% of patients with a normal QRS duration reached the primary endpoint compared with 42.8% of patients with a prolonged baseline QRS duration [hazard ratio (HR) 3.43; 95% confidence interval (CI) 1.78-6.01; P < 0.001]. The increased risk predicted by a prolonged QRS duration was robust after adjusting for covariates (HR 2.83; CI 1.07-7.49; P = 0.012). A QTc prolongation ≥ 440 ms (P = 0.011), an abnormal QRS axis (P = 0.012), and premature ventricular beats (P = 0.018) were significant monovariate predictors but did not prove to be independent predictors for survival in multivariate analysis. Q-waves and repolarization abnormalities were neither associated with the primary endpoint nor with immunohistological signs of inflammation. Other ECG parameters were not significantly related to outcome.

A prolonged QRS duration is an independent predictor for cardiac death or heart transplantation in patients with suspected myocarditis.