Prognostic value of baseline and follow-up ECG in patients with biopsy-proven fulminant myocarditis

Abstract Background Fulminant myocarditis represents a life-threatening condition with poor outcomes characterized by increased short- and long-term mortality and need for heart transplant. Treatment largely relies on mechanical support and immunosuppressive therapy guided by histologic and virology findings but reliable short-term prognostic markers guiding therapy and management are still lacking. We hypothesised that baseline and short-term ECG evolution may provide relevant easily accessible prognostic information in these patients. Purpose We sought to assess the prognostic value of baseline and short-term follow-up ECG in patients affected by fulminant myocarditis. Methods We retrospectively enrolled patients with biopsy-proven fulminant myocarditis according to current diagnostic criteria. We evaluated baseline and follow-up ECG (performed 3 to 7 days after admission) together with clinical, laboratory and histologic data. The primary endpoint was a composite of in-hospital mortality or need for urgent heart transplantation. Results We enrolled 39 patients (22/39 M, 56.4%) and a mean age of 38 years. Histology demonstrated lymphocytic myocarditis in 35/39 cases, 2 eosinophilic and 1 giant cell myocarditis, 1 sarcoidosis. All patients received vasopressor and/or inotrope therapy with 19/39 requiring mechanical circulatory support. Follow-up ECGs were performed after 4.8±1.3 days from admission. The primary endpoint was reached in 7/39 patients (17.9%) with 5 deaths and 2 urgent cardiac transplants. These patients more commonly required mechanical (85.7% vs 40.6%, p=0.044) or extracorporeal membrane oxygenator (85.7% vs 12.5%, p<0.001) support and showed higher lactate levels on admission (11.0±7.3 vs 4.2±3.1 mmol/L, p=0.001). They also more frequently had cardiac arrest as first clinical presentation (50. 0% vs 9.7%, p=0.022) and sustained ventricular tachycardia (71.4% vs 15.6%, p=0.007) in the acute phase. Patients with a worse outcome showed persistence of low voltages (< 5 mm in all peripheral leads) at follow-up ECG (100.0% vs 37.5%, p=0.003) with lower R wave amplitude in lead II (1.1±0.9 vs 4.0±2.6 mm, p=0.004), III (0.7±0.5 vs 2.5±2.2 mm, p=0.043), aVF (0.9±0.7 vs 3.0±2.0 mm, p=0.01) and V6 (3.0±2.8 vs 7.5±4.2 mm, p=0.011) and reduced S wave amplitude in V1 (2.6±3.9 vs 6.4±4.4 mm, p=0.047), V2 (3.9±3.9 vs 10.2±6.7 mm, p=0.035), V3 (3.3±3.2 vs 10.7±6.7 mm, p=0.007) leads. Low QRS voltages at baseline ECG were not associated with worse prognosis (71.4% vs 46.9%, p=0.407). No significant difference in terms of steroid (85.7% vs 78.1%, p=0.929) or other immunosuppressive (14.3% vs 31.2%, p=0.366) therapy was observed between the groups. Conclusions In patients with fulminant myocarditis, persistence of low QRS voltages at 5-day follow-up ECG is associated with adverse in-hospital outcomes. Short-term ECG evolution can identify high-risk patients requiring earlier and more intensive mechanical and pharmacological treatment.