Introduction: Ventricular perforation during radiofrequency ablation of ventricular tachycardia is a recognized serious complication that carries high morbidity and mortality. Perforation is often associated with local intramyocardial injury due to excess heat induced by catheter, 'steam pop'. The complication usually requires emergency surgical repair. Case presentation: We present a case, when the catheter found its way into the epicardium during left ventricular (LV) electroanatomic mapping without any serious complication. Angiography through the ablation catheter confirmed the diagnosis of LV coronary sinus fistula. Discussion: Contrast injection through the irrigation port of the ablation catheter is a useful way of delineating anatomical anomalies during electrophysiology procedure.