Clinical characteristics associated with sustained ventricular arrhythmia among acute myocarditis patients: a multicenter case-control study

BACKGROUND: Clinical features associated with sustained ventricular arrhythmias (sVA) during acute myocarditis (AM) are poorly defined. OBJECTIVE: Identify simple clinical characteristics of arrhythmogenic AM patients who develop sVA during acute-phase hospitalization. METHODS: Case-control study of AM patients hospitalized in two tertiary centers from 2000 to 2020. Patients with documented sVA during AM hospitalization (cases) were compared with AM patients without VA (controls). Patients with history of myocardial infarction, heart failure or VA were excluded. Univariate and multivariable analyses were used to evaluate clinical parameters associated with occurrence of sVA during AM hospitalization. RESULTS: Study included 41 cases with sVA and 137 controls without any VA during AM hospitalization period. VAs included monomorphic VT and polymorphic VT/VF in 24/41 (58.5%) and 17/41 (41.5%) cases, respectively. Older age, syncope, palpitations, hemodynamic instability, intraventricular conduction delay on ECG, and reduced LV function (LVF) were associated with increased sVA occurrence on univariate analysis. Multivariable model including age, gender, admission ECG, and LVF revealed age (OR 1.027/year, 95% CI [1.015, 1.052]; p = 0.038), intraventricular conduction delay (OR 5.55, 95% CI [2.237, 8.346]; p < 0.001), and reduced LVF (OR 4.38, 95% CI [1.783, 9.081]; p = 0.002) to be independently associated with sVA. Applying these characteristics, we could delineate AM patients with differing prevalence of sVA during hospitalization. CONCLUSIONS: Few clinical parameters, readily available upon admission, including older age, intraventricular conduction delay, and reduced LVF, are associated with acute-phase sVA in AM. Once validated by larger studies, these parameters may assist decision-making regarding level of care and ECG monitoring.