Can ICD Electrograms Help Ventricular Tachycardia Ablation?: Results From the Multicenter Randomized AIDEG-VTA Trial

Abstract

Background: The results of ablation of sustained monomorphic ventricular tachycardia (SMVT) are suboptimal. For many patients with implantable cardioverter-defibrillators (ICDs), ICD electrograms (ICD-EGs) provide the only available information on SMVT. ICD-EGs have the ability to distinguish morphologically distinct SMVT and can be used for pace mapping.

Objectives: This study aimed to evaluate whether using ICD-EG information during an ablation procedure influences outcomes.

Methods: Patients with structural heart disease and SMVT documented by an ICD-EG, undergoing ablation, were randomly assigned in a 1:1 ratio to either an ablation incorporating ICD-EG data during the procedure (intervention group) or to conventional ablation. The ICD-EG obtained during induced SMVT and pace mapping was compared to ICD-EG from spontaneous SMVT to target the "clinical" SMVT for ablation. Ablation could be performed during SMVT (if tolerated), during sinus rhythm ("substrate ablation"), or both.

Results: A total of 15 centers randomized 260 patients. Characterization of induced SMVT as clinical/nonclinical and pace mapping were more frequent in the intervention group. Most patients underwent pure substrate ablation (65%), with complementary ablation during SMVT in 26%, showing no significant difference between groups. No differences were found in acute efficacy. In the intention-to-treat analysis, the primary endpoint of SMVT recurrence within 6 months postablation occurred in 46 (36%) patients in the intervention group and 59 (46%) in the conventional group (HR: 0.73; 95% CI: 0.49-1.07; P = 0.11). In the per-protocol analysis, SMVT recurrence at 6 months postablation reached statistical significance (HR: 0.66; 95% CI: 0.44-0.99; P = 0.045). During the entire follow-up period (44 ± 29 months), SMVT recurrence occurred in 67% and 76% (HR: 0.80; 95% CI: 0.60-1.08; P = 0.14). The number of SMVT episodes was significantly lower in the intervention group (HR: 0.45; 95% CI: 0.24-0.84; P = 0.013), as was the rate of electrical storm (23% vs 41%; HR: 0.54; 95% CI: 0.34-0.85; P = 0.007). There were no differences in ICD shocks.

Conclusions: In patients with structural heart disease and ICD-documented SMVT, using ICD-EG information during the ablation procedure to focalize ablation toward the clinical ventricular tachycardia is associated with a nonsignificant decrease in SMVT recurrence rate, a significant reduction in the number of ventricular tachycardia episodes, and a lower rate of arrhythmic storm.

Keywords: ablation; electrical storm; electrogram; implantable cardioverter-defibrillator; ventricular tachycardia.