Risks and Bene~ts of Catheter Ablation of Ventricular Tachycardia in Patients with an Implantable Cardioverter-De~brillators VT ablation in patients with ICD’s Michaud and Morady

Patients with an implantable cardioverter-de~brillator (ICD) may receive frequent shocks or antitachycardia pacing for monomorphic ventricular tachycardia (MVT) despite suppressive drug therapy. Antitachycardia pacing is often well-tolerated but not always effective. High voltage cardioversion is usually painful and may cause severe, disabling anxiety for some patients. Therefore, catheter ablation is an important adjunct to medical therapy in patients with coronary artery disease (CAD) who have frequent shocks for episodes of MVT. In 56–100% of selected patients, hemodynamically-tolerated MVT can be successfully ablated with radiofrequency energy [1,2,3,4,5,6]. Herein we review the indications, bene~ts and risks of radiofrequency ablation of MVT in patients with CAD and an ICD. Willems et al. [4] published the ~rst series of patients with catheter ablation of MVT as an adjunct to ICD therapy. Among 6 patients, 5 had MVT originating in a healed myocardial scar related to CAD and the other patient had bundle branch reentry. Four of 6 patients had incessant MVT at the time of the procedure and the remaining 2 had frequent ICD shocks. The MVT in all patients was successfully ablated, but 2 of 6 patients continued to had relatively frequent ICD shocks during the follow-up period. Radiofrequency ablation of MVT decreases ICD shocks and improves quality of life, as shown in a prospective study of 21 consecutive patients with CAD and a previous myocardial infarction [6]. Their mean ejection fraction was 22% and they had failed an average of 2.5 suppressive drugs; 16 of 21 were taking amiodarone at the time of the ablation procedure and 18 of 21 were on multiple antiarrhythmic drugs. Antiarrhythmic medications were continued through the procedure and inde~nitely thereafter. The patients had received an average of 17 shocks for MVT in the month before ablation and one patient had received 54 shocks. Fourteen of 21 patients had their spontaneous MVT(s) recorded on a 12-lead ECG and the MVT cycle length was available in the remainder of patients by stored electrogram analysis from the ICD. An induced MVT was presumed to be clinically-important if it matched the morphology and cycle length recorded on a 12-lead ECG or the cycle length alone in those patients without 12-lead ECG documentation. Twenty-six MVT’s in 21 patients were felt to be responsible for clinical symptoms prior to the ablation procedure. A total of 85 MVT’s (range 1 to 15 per patient) were inducible with a mean cycle length of 430 ms. Twenty additional inducible MVT’s were targeted for ablation besides the 26 MVT’s felt to be responsible for the majority of clinical symptoms. The remaining 39 MVT’s were poorly tolerated and could not be mapped. The patients underwent an average of 1.4 procedures and 12 radiofrequency energy applications. The procedures lasted on average 93 minutes from the onset of mapping to the last radiofrequency application and averaged 50 minutes of _uoroscopy time. The mapping techniques have been previously described and do not require sophisticated recording systems [7,8]. Concealed entrainment was the most useful criterion for a successful radiofrequency application. Thirty-six of 46 targeted MVT’s (78%) were successfully ablated. If the MVT was well-tolerated, the success rate was 89%. Sixteen of 21 patients had a successful procedure as de~ned by elimination of the clinically-important MVT (76%). A signi~cant complication occurred in only one patient who required a dual chamber pacemaker after a successful ablation of a high septal MVT. The average number of ICD therapies per month for patients followed for an average of 1 year (range 1 to 32 months) was signi~cantly decreased in the 16 patients who underwent a successful ablation procedure (59 6 80 vs 0.5 6 1, p50.01). Among the patients with unsuccessful procedures, the difference in monthly ICD therapies did not reach statistical signi~cance (358 6 661 vs 1.5 6 2, p50.3). There were no predictors of a successful ablation. A quality-of-life questionnaire was distributed to all patients within 1 month of the last follow-up date. This score signi~cantly improved in patients with a successful procedure but not in patients with a failed ablation. The bene~ts of catheter ablation as an adjunct to ICD therapy in patients with hemodynamically-tolerated MVT are clear from the results of Strickberger et.al. [6]. Patients with successful ablation had fewer