Long-Term Follow-Up of Biopsy-Proven Myocarditis: Predictors of Mortality and Incomplete Recovery
What are predictors of poor outcome in patients with viral myocarditis?
This was a single-center analysis of consecutive patients with biopsy-proven viral myocarditis (myocardial inflammation and viral genome), who underwent cardiac magnetic resonance imaging (CMR) within 5 days of presentation. The primary endpoints of interest were all-cause mortality and cardiac mortality.
Of the 222 patients with viral myocarditis, 203 (91.5%) completed a median 4.7 years of follow-up and 77 of these had a follow-up CMR. Median [interquartile range] patient age was 52 [40-54] years. By CMR, mean left ventricular ejection fraction (LVEF) was 45%, LV end-diastolic volume was 167 ml, and late gadolinium enhancement (LGE) was present in 108 (53%) at diagnosis. All-cause mortality was 19% (n = 28), cardiac mortality was 15%, and sudden cardiac death was 9.9%. On univariate analysis, older age, worse New York Heart Association (NYHA) class, and CMR abnormalities (including lower LVEF, LV dilation, LGE) were associated with increased risk of death on follow-up. LGE was associated with an adjusted 8.4-fold (p = 0.004) higher risk of death and 12.8 risk of cardiac death (p < 0.01). In the 77 patients with follow-up CMRs, NYHA class >1 at hospital presentation was associated with a higher likelihood of persistent myocardial dysfunction on follow-up.
The authors concluded that viral myocarditis affords a high risk of death and LGE is associated with poor outcome.
Patients with myocarditis tend to be young and outcome can be highly variable. In this analysis, the authors show that patients with biopsy-proven myocarditis warrant close clinical follow-up, especially if abnormalities on CMR are noted. Examining survival based on the presence of LGE, the survival curves separated late (more than 1 year after presentation). Because LGE represents scar, LGE likely identifies a ventricle less likely to recover after the initial viral insult. While this is a low-powered study due to the fact that it is a single-center analysis of an uncommon disease, LGE identified 97% (28 of 29) of patients who had a cardiac death from myocarditis. However, only 28% (28 of 99) of myocarditis patients with LGE died. While CMR sensitivity for the detection of myocarditis is poor (53%), it identifies higher risk myocarditis patients. Patients with myocarditis who have LGE should be watched closely for several years. However, data are insufficient to become complacent in those without LGE.
Keywords: Biopsy, Gadolinium, Virus Diseases, Myocarditis, Magnetic Resonance Imaging
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