13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-192

Role of the epicardial mapping in identifying patients with postmyocardial infarction pleomorphic ventricular tachycardia suitable for radiofrequency catheter ablation

Claudio Tondo, Corrado Carbucicchio, Stefania Riva, Gaetano Fassini, Paolo Della Bella.
Institute of Cardiology, University of Milan, CNR, Centro Cardiologico Fondazione Monzino, IRCCS, Milan, Italy

Introduction

In the most recent years, radiofrequency catheter ablation (RFCA) has become an alternative therapeutical approach for treating post myocardial (MI) recurrent drug refractory ventricular tachycardia (VT). The acute success rate, in the most experienced laboratories, ranges from 70% to 75%¹ with recurrence rate of the same clinical VT in over 20% of patients during the follow-up. Although these results are encouraging, especially because related to patients presenting with monomorphic, haemodynamically tolerated VTs, therefore allowing extensive, accurate mapping, there is still a proportion of patients with rapid and/or multiple VT morphologies who do not currently benefit from RFCA. Potential reasons for this include a more complex substrate not entirely identified by currently accepted endocardial mapping criteria, or insufficient lesion created by conventional RF current delivery in those cases in which an epicardial origin of VT is suspected. Accurate mapping along with pacing maneuvers are mandatory to identify the critical area of the reentry circuit, that is the area of slow conduction, a desirable goal for ablation². In order to better characterize the reentry circuit in post-MI VT, and therefore for identifying successful ablation sites, we have recently introduced, as standard procedure, a multisite epicardial recording in conjunction with conventional endocardial mapping in patients with recurrent post-MI VT³. However, for the specific purpose of this study, we focus our attention on those patients with pleomorphic haemodynamically unstable VTs undergoing RFCA, and their relationship with findings obtained from multisite epicardial mapping. In a population of 56 patients, RFCA was not performed in 7 patients because of induction of multiple^3-8, fast, untolerated VTs, leading to internal automatic cardioverter defibrillator (AICD) implant. During the follow-up, AICD discharge was documented in 5 patients. In the effort to elucidate the electrophysiologic substrate of these patients, the results of the epicardial mapping performed in 16 patients with post-MI VT were retrospectively analyzed.