Impact of Substrate Modification by Catheter Ablation on Implantable Cardioverter–Defibrillator Interventions in Patients With Unstable Ventricular Arrhythmias and Coronary Artery Disease

Abstract

Background— The implantable cardioverter–defibrillator (ICD) is the standard therapy to prevent sudden cardiac death in patients with coronary artery disease and unstable ventricular tachyarrhythmias. The prospective multinational SMS (Substrate Modification Study) was designed to assess whether prophylactic ablation of the arrhythmogenic substrate reduces or prevents the recurrence of ventricular tachycardia/ventricular fibrillation in such patients. Methods and Results— Of 111 patients included in an intention-to-treat analysis, 54 were randomly assigned catheter ablation plus ICD implantation (ablation group: 68±8 years; 47 men), whereas 57 were assigned ICD implantation without catheter ablation (ICD-only group: 66±8 years; 46 men). Primary study end point was the time to first recurrence of ventricular tachycardia/ventricular fibrillation. ICD episodes were assessed and verified by an independent board. Patients were followed up for 2.3±1.1 years. The primary end point was reached by 25 ablation patients and 26 ICD-only patients. Two-year event-free survival was estimated at 49.0% (95% confidence interval, 33.3%–62.9%) in the former and 52.4% (36.7%–65.9%) in the latter groups. Comparison of episode incidence revealed no significant difference in the primary end point ( P =0.84). In an Andersen–Gill regression model with multiple end point recurrences, the difference between the study arms significantly favored catheter ablation for both the primary end point and all but one of the predefined subgroups of detected arrhythmia events. Conclusions— SMS failed to meet the primary end point of time to first ventricular tachycardia/ventricular fibrillation recurrence. However, catheter ablation did reduce the total number of ICD interventions during the duration of follow-up. Clinical Trial Registration— https://clinicaltrials.gov . Unique identifier: NCT00170287.

Mortality Implications of Appropriate Implantable Cardioverter Defibrillator Therapy in Secondary Prevention Patients: Contrasting Mortality in Primary Prevention Patients From a Prospective Population‐Based Registry

“…The first implication is that prophylaxis of shocks and ATP by recommending a strategy that mitigates the likelihood of ventricular arrhythmia in patients with ICDs may have mortality implications. Two randomized trials have evaluated the effect of prophylactic ventricular tachycardia catheter ablation as an addition to ICD in the ischemic cardiomyopathy population . Although the findings of those trials cannot be extrapolated to our population, one could hypothesize that decreasing the burden of shocks or delaying the appearance of ventricular arrhythmia could translate into a better survival.…”

“…Two randomized trials have evaluated the effect of prophylactic ventricular tachycardia catheter ablation as an addition to ICD in the ischemic cardiomyopathy population. 20,21 Although the findings of those trials cannot be extrapolated to our population, one could hypothesize that decreasing the burden of shocks or delaying the appearance of ventricular arrhythmia could translate into a better survival. The second clinical implication of our study is that patients presenting with an appropriate shock or ATP whether they received an automatic implantable cardioverter/defibrillator for primary or secondary indication has mortality implications.…”

Ten‐year trends in catheter ablation for ventricular tachycardia vs other interventional procedures in Australia

“…Despite significant improvements in the management of predisposing conditions, especially coronary artery disease (CAD), the incidence of VT has increased when comparing older RCTs where the recurrence rate was 33% to contemporary RCTs which has a recurrence rate between 42%‐45% . In those with idiopathic VT, a recent population‐based study found rates had increased from 12.7 to 16.2 (per 100 000) over a 6‐year period .…”

“…Despite significant improvements in the management of predisposing conditions, especially coronary artery disease (CAD), the incidence of VT has increased when comparing older RCTs where the recurrence rate was 33% 5 to contemporary RCTs which has a recurrence rate between 42%-45%. 7,8 In those with idiopathic VT, a recent population-based study found rates had increased from 12.7 to 16.2 (per 100 000) over a 6-year period. 22 Paralleling increasing rates of VT is recent local data showing a three-fold increased rate of ICD implantation over a similar period 3 that incurs significant additional costs on the healthcare system.…”

“…4 Catheter ablation is an established adjunct to antiarrhythmic drugs for the management of drug-refractory ventricular arrhythmias. Multiple randomized control trials (RCTs), [5][6][7][8] and observational studies 9,10 have demonstrated that CA reduces VT burden and recurrence. Recent technological advances in cardiac mapping and ablation have made the procedure more rapid, safe, and efficacious than the past.…”