Value of post-operative programmed ventricular stimulation after map-guided surgery for ventricular tachyarrhythmias--epicardial versus endocardial stimulation.

To assess the efficacy of map-guided antitachycardia surgery, induction of ventricular tachycardia has mostly been performed using endocardial stimulation. In addition, epicardial stimulation can be done using temporary epicardial wires, thus not requiring post-operative catheterization. However, the diagnostic value of epicardial versus endocardial stimulation for the post-operative evaluation of patients undergoing map-guided surgery for drug-refractory ventricular tachycardia is not known, especially with regard to the induction of non-clinical tachyarrhythmias. Therefore, we compared the results of epicardial and endocardial programmed ventricular stimulation in 58 consecutive patients in whom pairs of steel wires were placed over the right ventricle during surgery. The stimulation protocol consisted of single and/or double premature stimuli during sinus rhythm and paced ventricular drives of 500, 430, 370 and 330 ms. Pre-operatively, all patients had inducible monomorphic ventricular tachycardia by endocardial stimulation. Post-operatively, 36 patients were not inducible by either epicardial or endocardial programmed ventricular stimulation, whereas epicardial and endocardial stimulation induced the clinical ventricular tachycardia in six patients and non-clinical ventricular tachycardia in three patients (45/58 patients, 77% concordant). However, in two patients the clinical ventricular tachycardia was induced only by endocardial programmed ventricular stimulation. Non-clinical ventricular tachycardia was inducible in three patients by epicardial stimulation only, and in eight patients by endocardial stimulation only (13/58 patients, 23% discordant). Thus, in 77% of patients an identical result of programmed ventricular stimulation was obtained using epicardial and endocardial stimulation, whereas the results were discordant in 23%. Therefore, epicardial stimulation alone is not sufficient for the post-operative evaluation after map-guided surgery.