Outcome of Fulminant vs. Nonfulminant Myocarditis
What are the outcomes and changes in left ventricular ejection fraction (LVEF) in a large cohort of patients with fulminant (FM) compared with nonfulminant (NFM) acute myocarditis?
The authors conducted a retrospective study on a cohort comprised of 187 consecutive patients (173 [93%] adults and 15 of pediatric age [<15 years]) with a diagnosis of acute myocarditis (onset of symptoms <1 month). Patients requiring inotropes and/or mechanical circulatory support were considered to have FM (55 %), while the remaining 132 patients (71%) were hemodynamically stable and classified as NFM. The study authors also performed a subanalysis in 130 adult patients with acute viral myocarditis and viral prodrome within 2 weeks from the onset, which included 34 v-FM vs. 96 v-NFM. They excluded patients with giant-cell, eosinophilic myocarditis or cardiac sarcoidosis, and subjects <15 years of age from the latter subanalysis.
In the study cohort (n = 187), the in-hospital mortality was 18.2% (10 deaths) in the FM group compared with 0% (p < 0.0001) in the NFM group; the composite of mortality and heart transplantation (HTx) was 25.5% (10 deaths and 4 HTx) and 0% (p < 0.0001), respectively. Long-term HTx free survival at 9 years was lower in FM than NFM (64.5% vs. 100%, log rank p < 0.0001). Despite greater improvement in LVEF during hospitalization in FM vs. NFM forms (median, 32%; interquartile, 20-40% vs. 3%, 0-10%, respectively; p < 0.0001), the proportion of patients with LVEF <55% at last follow-up was higher in FM vs. NFM (29% vs. 9%, relative risk, 3.32; 95% confidence interval, 1.45-7.64; p = 0.003). None of the patients with LVEF >55% at discharge had a significant decrease in LVEF at follow-up. Similar results regarding survival and changes in LVEF in FM vs. NFM were observed in the subgroup (n = 130) with viral myocarditis. In these patients with acute viral myocarditis, in-hospital mortality was 11.8% (4 deaths) in the v-FM group compared to 0% (p < 0.0001) in the v-NFM group. Kaplan-Meier curves of transplant free survival showed worse outcome in the v-FM compared with v-NFM group at 9 years of follow-up (80.7% vs. 100%, respectively; log rank p < 0.0001).
The study authors concluded that patients with FM have an increased mortality and need for HTx, compared to those with NFM. FM patients have a more severely impaired LVEF at admission that, despite steep improvement during hospitalization, remains lower than that in patients with NFM at long-term follow-up. These findings are at odds with previous studies showing better prognosis in FM due to viral myocarditis.
This is an important study because it confirms, what most astute clinicians know, that the natural history of myocarditis is variable. An important takeaway from this retrospective study is that the approach to hemodynamically unstable patients requires early consideration for mechanical circulatory support or cardiac transplantation even when the etiology is considered to be of viral origin.
Keywords: Cardiac Surgical Procedures, Heart Failure, Heart Transplantation, Hemodynamics, Hospital Mortality, Myocarditis, Prodromal Symptoms, Risk, Stroke Volume, Survival, Treatment Outcome, Ventricular Function, Left
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