Electrical storm in patients with implantable cardioverter-defibrillator in the era of catheter ablation: Implications for better rhythm control.

BACKGROUND: The modern era of cardiology has changed the population of implantable cardioverter-defibrillator (ICD) recipients. Identifying predictors of electrical storm (ES) in contemporary ICD patients could improve risk stratification, therapeutic strategies, and mortality.

OBJECTIVE: The purpose of this study was to address these points in a real-world setting.

METHODS: In 330 consecutive patients (65 ± 11 years, 81% male, left ventricular ejection fraction 29% ± 9%) with ICD implanted because of ischemic (n, 204) or nonischemic dilated cardiomyopathy (n, 126), we analyzed the prevalence, predictors, and outcome of ES (≥3 separate VT/VF episodes within 24 hours) therapy.

RESULTS: During a median of 21 months (range 17-36 months), 23 patients (7%) had ES. Secondary prevention (61% vs 24%, P <.01), single-chamber devices (57% vs 38%, P = .02), and prior appropriate (96% vs 24%, P < .001) and inappropriate (30% vs 9%, P = .004) therapies were more prevalent in these patients. In ES patients, first appropriate therapy occurred more often in the first year after implantation than in the rest of the cohort (85% vs 45%, P = .008), and mortality was significantly higher (22% vs 2%, P < .001). Multivariate Cox regression analysis showed that secondary prevention (hazard ratio [HR] 2.83, 95% confidence interval [CI] 1.21-6.61, P = .016) and prior appropriate (HR 88.99, 95% CI 11.73-675, P < .001) and inappropriate (HR 2.83, 95% CI 1.14-7.0, P = .04) therapies were independent predictors of ES.

CONCLUSION: ES is not uncommon in ICD recipients. A secondary prevention indication and the occurrence of both appropriate and inappropriate ICD therapies increase the risk for ES. Prompt initiation of aggressive treatment, especially catheter ablation, should be considered for these patients.