Good Prognosis for Clinical Acute Myocarditis, Regardless of Systolic Function

The long-term prognosis following clinical acute myocarditis was found to be good, regardless of systolic function, according to study results published in The American Journal of Medicine.

This was a retrospective analysis of 320 patients (84% men; mean age, 37 years) clinically diagnosed with acute myocarditis. Patients were divided into 2 groups based on their left ventricular ejection fraction (LVEF) at presentation (<50% or ≥50%). Clinical features were evaluated by electrocardiogram. The study’s primary endpoint was the occurrence of major adverse cardiac events. Secondary endpoints included 30-day, 6-month, and 1-year mortality, as well as the need for escalating therapy.

The mean LVEF in this cohort at presentation was 54±9%. Reduced LVEF was observed in 60 patients. Patients with LVEF <50% vs ≥50% were found to be more likely to have ST depression or T wave inversion (33% vs 18%, respectively; P =.007), higher troponin levels at admission (12.7 µL vs 5.5 µL, respectively; P =.001), and higher peak troponin levels (18.8 µL vs 8.4 µL, respectively; P <.001). 

Patients with reduced vs normal LVEF were more likely to be treated with steroids during hospitalization (20% vs 9%, respectively; P =.01), but there was no significant difference in steroid prescription rates at discharge.

Major adverse cardiac events, including acute decompensated congestive heart failure, ventricular arrhythmias, and in-hospital mortality, occurred in 25 patients (8%). Patients with reduced vs normal LVEF were more likely to experience adverse cardiovascular events (25% vs 4% respectively; P <.001).

Multivariable analysis indicated that patients with reduced vs normal LVEF were at increased risk for adverse cardiovascular events (hazard ratio, 4.30; 95% CI, 1.59-11.49; P <.001).

Escalating therapy was needed infrequently (n=3), and there were no cases of mortality at 30 days, 6 months, or 1 year.

Study limitations include the use of patient data from a single center in Israel, which may not be representative of global practices.

“The overall prognosis of patients with clinically diagnosed acute myocarditis is reassuring with relatively low complication rates,” the study authors concluded. “Although those admitted with an LVEF <50% are at a higher risk of in-hospital adverse events, these risks are not necessarily translated into higher long-term mortality.”

Reference

Younis A, Matetzky S, Mulla W, et al. Epidemiology characteristics and outcome of patients with clinically diagnosed acute myocarditis. Am J Med. 2020;133(4):492‐499. doi:10.1016/j.amjmed.2019.10.015