[Evaluation of ventricular tachycardia by endocavitary stimulation. Apropos of 46 cases].

Thirty six patients (21 coronary artery disease, 8 cardiomyopathy, 3 mitral valve prolapse and 4 apparently normal) underwent endocavitary stimulation studies. The protocol consisted in delivering one or two right ventricular extrastimuli and twice the diastolic threshold either during spontaneous rhythm (S2 and S2-S3) or a paced ventricular rhythm (S1-S2 and S1-S2-S3). In 9 patients overdrive ventricular pacing at 150-200 bpm was required. Thirteen of the 15 documented sustained ventricular tachycardias could be induced by electrical stimulation (87%). In addition, 9 sustained ventricular tachycardias were induced in patients in whom the symptomatology corresponded to poorly tolerated tachycardia but in whom the documented arrhythmia was non-sustained ventricular tachycardia (4 cases), frequent ventricular extrasystoles with doublets (2 cases) or rare, isolated ventricular extrasystoles (3 cases). The method was less sensitive in non-sustained ventricular tachycardia in which the arrhythmia was induced in 10 of the 17 cases (59%). An antiarrhythmic drug was selected on the basis of these studies in 28 patients, 21 of whom had sustained ventricular tachycardia. There were 6 therapeutic failures with a follow-up of 6 to 24 months, three of which were observed in patients with coronary artery disease and a precarious haemodynamic state. This subgroup is not suitable for this type of evaluation. After reviewing other published series the authors emphasise the value of these investigations in chronic sustained ventricular tachycardia, in ventricular tachycardia with cardiovascular collapse and in the assessment of syncope of unknown origin. However, the systematic investigation of repetitive ventricular responses after ventricular stimulation in patients at high risk of sudden death remains controversial.