Anatomic and electrophysiologic correlates of ventricular tachycardia requiring left ventricular stimulation.

In 108 patients with reproducible initiation of ventricular tachycardia by programmed ventricular stimulation, the ventricular tachycardia was initiated only by left ventricular stimulation in 12 (11 percent). Programmed ventricular stimulation included single and double extrastimuli extrastimuli at three cycle lengths and bursts of rapid pacing to cycle lengths of 250 ms. Clinical, electrocardiographic, angiographic, hemodynamic and electrophysiologic data were available in 74 of 96 patients with ventricular tachycardia initiated by right ventricular stimulation (Group A) and in all 12 patients with ventricular tachycardia initiated only by left ventricular stimulation (Group B). there were no significant differences between Groups A and B in clinical characteristics, hemodynamics or presence and site of infarction or aneurysm. Comparison of electrophysiologic variables revealed no significant differences between Groups A and B mean A-H interval (92 +/- 22 versus 89 +/- 15 ms, respectively), H-V interval (59 +/- 15 versus 59 +/- 15 ms) or right ventricular (241 +/- 38 versus 260 +/- 40 ms) or left ventricular (232 +/- 28 versus 251 +/- 42 ms) effective refractory period. Ventricular tachycardia with right bundle branch block and superior axis was more prevalent in Group B (92 percent versus 31 percent, p less than 0.001) but was observed in 32 patients in Group A. It is concluded that 11 percent of patients with clinically documented sustained ventricular tachycardia will require left ventricular programmed stimulation to reproducibly initiate the tachycardia. No clinical, anatomic, electrocardiographic or electrophysiologic features can predict whether left ventricular programmed stimulation will be required. Because initiation of ventricular tachycardia by programmed ventricular stimulation has important prognostic and therapeutic implications in such patients, stimulation should be performed from the left ventricle when the tachycardia is not initiated by stimulation from the right ventricle.