Tachycardiomyopathy is a potentially reversible cause of heart failure. It can be induced by supraventricular or ventricular arrhythmias. When these are treated, systolic function improves or normalizes. We report a 20 year-old male with deterioration of left ventricular function and dilated cardiomyopathy secondary to an incessant atrial tachycardia that was treated with radiofrequency catheter ablation. After the procedure, the patient experienced a significant improvement of his ventricular function.