Not So Innocent After All: Cardiomyopathy Induced by 'Benign' Premature Atrial Contractions.

Premature atrial contractions (PACs) are not generally considered a cause of arrhythmia-induced cardiomyopathy, although a high PAC burden has been reported to induce this entity in several cases. We present the case of a 36-year-old man who presented with severe left ventricular systolic dysfunction and was subsequently found to have frequent monomorphic PACs (28% burden). Cardiac magnetic resonance imaging excluded ischemic, infiltrative, and inflammatory cardiomyopathies. As the frequent PACs were considered a potential cause of the cardiomyopathy, electroanatomic mapping localized a single ectopic focus at the coronary sinus ostium, and radiofrequency catheter ablation was successfully performed. At 3-month follow-up, left ventricular ejection fraction improved to 50%, left ventricular dimensions decreased, and marked reverse remodeling was observed. This case highlights frequent PACs as a reversible cause of cardiomyopathy and emphasizes the importance of early recognition and catheter ablation in selected patients.