Long-term evolution and prognostic stratification of biopsy-proven active myocarditis

Active myocarditis is characterized by large heterogeneity of clinical presentation and evolution. This study describes the characteristics and the long-term evolution of a large sample of patients with biopsy-proven active myocarditis, looking for accessible and valid early predictors of long-term prognosis.

From 1981 to 2009, 82 patients with biopsy-proven active myocarditis were consecutively enrolled and followed-up for 147±107 months. All patients underwent clinical and echocardiographic evaluation at baseline and at 6 months. At this time, improvement/normality of left ventricular ejection fraction (LVEF), defined as a LVEF increase > 20 percentage points or presence of LVEF≥50%, was assessed. At baseline, left ventricular dysfunction (LVEF<50%) and left atrium enlargement were independently associated with long-term heart transplantation-free survival, regardless of the clinical pattern of disease onset. At 6 months, improvement/normality of LVEF was observed in 53% of patients. Persistence of New York Heart Association III to IV classes, left atrium enlargement, and improvement/normality of LVEF at 6 months emerged as independent predictors of long-term outcome. Notably, the short-term reevaluation showed a significant incremental prognostic value in comparison with the baseline evaluation (baseline model versus 6 months model: area under the curve 0.79 versus 0.90, P=0.03).

Baseline left ventricular function is a marker for prognosis regardless of the clinical pattern of disease onset, and its reassessment at 6 months appears useful for assessing longer-term outcome.