Coronary artery fistula is a rare but well-documented complication of right ventricular endomyocardial biopsy, particularly in the adult population. Typically, these fistulae never reach clinical or hemodynamic significance, but some may cause coronary steal and ventricular dysfunction. We report a case of a significant coronary artery fistula requiring device closure in the cardiac catheterization laboratory with subsequent improvement of clinical symptoms and cardiac function.