Inducible ventricular flutter and fibrillation predict for arrhythmia occurrence in coronary artery disease patients presenting with syncope of unknown origin

Introduction: Ventricular fibrillation and ventricular flutter (cycle length ≤230 msec) induced at electrophysiologic studies are thought to be nonspecific findings in patients presenting with syncope of unknown origin. However, there are limited data on the prognosis of these patients in long-term follow-up. Methods and Results: We followed 274 consecutive patients with coronary artery disease presenting with syncope or presyncope who underwent electrophysiologic studies from January 1992 to June 1999 and assessed the risk of subsequent arrhythmias stratified by the electrophysiologic result at the time of their presentation with syncope. Ventricular fibrillation was induced in 23 patients (8%); ventricular flutter in 24 (9%), sustained ventricular tachycardia in 41 (15%); and nonsustained ventricular tachycardia 42 (15%). In 37 ± 25 months of follow-up, there have been ventricular arrhythmias in 34 patients, including 3 (13%) of 23 who had induced ventricular fibrillation, and 7 (30%) of 24 with induced ventricular flutter, compared to 13 (32%) of 41 with sustained ventricular tachycardia, 7 (17%) of 42 with nonsustained ventricular tachycardia, and only 4 (3%) of 144 noninducible patients (P < 0.001 for induced ventricular fibrillation and ventricular flutter vs noninducible patients). The inducibility of ventricular fibrillation and ventricular flutter were independent risk factors for arrhythmia occurrence in follow-up. Conclusion: Ventricular fibrillation and ventricular flutter induced at electrophysiologic studies have prognostic significance for arrhythmia occurrence in patients presenting with syncope. These induced arrhythmias may not be as nonspecific as previously thought and treatment should be considered for these patients.