Isolated Atrial Myocarditis With Atrial Standstill

Myocarditis typically affects ventricles, whereas isolated atrial myocarditis is rare, causing conduction abnormalities, atrial standstill, and right heart failure.

Two weeks after a respiratory infection, a 35-year-old man developed dyspnea, leg edema, and bradycardia. Electrocardiogram revealed a narrow QRS escape rhythm without P waves, and N-terminal pro-B-type natriuretic peptide was elevated. Echocardiography showed severe right ventricular dysfunction with massive tricuspid regurgitation. Cardiac magnetic resonance demonstrated atrial late gadolinium enhancement and mild edema, whereas electrophysiological testing confirmed atrial standstill and atrioventricular block.

This case highlights isolated atrial myocarditis as a rare cause of atrial dysfunction, marked by postcapillary pulmonary hypertension and prominent V waves, despite normal mitral valves. Rapid atrial fibrosis progression resulted in silent atria, confirmed by magnetic resonance imaging and electrophysiology. Further research is required to clarify pathophysiology and establish effective management.

Isolated atrial myocarditis is a rare cause of atrial standstill and atrioventricular block. Comprehensive multimodality imaging is essential for accurate diagnosis and management.