Predictors of outcome in patients with suspected myocarditis

Background - The objective of this study was to identify the prognostic indicators in patients with suspected myocarditis who underwent endomyocardial biopsy. Methods and Results - Between 1994 and 2007, 181 consecutive patients ( age, 42 +/- 15 years) with clinically suspected viral myocarditis were enrolled and followed up for a mean of 59 +/- 42 months. Endomyocardial biopsies were studied for inflammation with histological ( Dallas) and immunohistological criteria. Virus genome was detected by polymerase chain reaction. The primary end point was time to cardiac death or heart transplantation. In 38% of the patients ( n = 69), the Dallas criteria were positive. Immunohistological signs of inflammation were shown in 50% ( n = 91). Genomes of cardiotropic virus species were detected in 79 patients ( 44%). During follow- up, 22% of the patients ( n = 40) reached the primary end point. Three independent predictors were identified for the primary end point, namely New York Heart Association class III or IV at entry ( hazard ratio, 3.20; 95% confidence interval, 1.36 to 7.57; P = 0.008), immunohistological evidence of inflammatory infiltrates in the myocardium ( hazard ratio, 3.46; 95% confidence interval, 1.39 to 8.62; P = 0.008), and beta- blocker therapy ( hazard ratio, 0.43; 95% confidence interval, 0.21 to 0.91; P = 0.027). Ejection fraction, left ventricular end- diastolic pressure, and left ventricular end- diastolic dimension index were predictive only in univariate, not in multivariate, analysis. Neither the Dallas criteria nor the detection of viral genome was a predictor of outcome. Conclusions - For patients with suspected myocarditis, advanced New York Heart Association functional class, immunohistological signs of inflammation, and lack of beta-blocker therapy, but not histology ( positive Dallas criteria) or viral genome detection, are related to poor outcome.