Regression of a dilated cardiomyopathy after radiofrequency ablation of incessant supraventricular tachycardia

Incessant supraventricular tachycardia has been demonstrated to result in a dilated cardiomyopathy in both animal models and humans. l-3 The phenomenon occurs in the absence of preexisting cardiac abnormalities. Termination of the tachycardia may lead to regression of myocardial dysfunction and normalization of left ventricular volume and systolic function. 1-4 The precise mechanisms responsible for the tachycardia-induced cardiomyopathy have not been elucidated. Hypotheses include depletion of myocardial high-energy phosphate stores, altered myocardial sarcoplasmic reticulum calcium ion transport,?, 6 abnormalities of myocardial blood flo~,~ and alterations in the myocardial capillary vasculature.8 We present a patient with an incessant supraventricular tachycardia and dilated cardiomyopathy who underwent successful radiofrequency catheter ablation of an atrioventricular nodal reentry pathway and regained normal biventricular volume and systolic function within a 3-week period. A 49-year-old woman with a history of chronic obstructive lung disease arrived at the emergency department in respiratory distress. Three weeks before presentation, the patient underwent a presurgical evaluation for an otolaryngologic procedure. At that time examination revealed an elevated pulse, and an electrocardiogram displayed a supraventricular tachycardia at a rate of 150 beats/min. The patient denied palpitations and reportedly was “asymptomatic,” so ther,apy was not initiated. Ten days later she was reevaluated by her primary care physician and, despite persistence of the tachycardia, continued to be “asymptomatic.” Several laboratory studies were ordered, and the patient was instructed to return in 2 weeks. During the interim, she had progressive dyspnea, orthopnea, and fatigue, and sought medical assistance.