Elsevier

American Heart Journal

Volume 156, Issue 5, November 2008, Pages 847-854
American Heart Journal

Clinical Investigation
Electrophysiology
Electrical storm in patients with biventricular implantable cardioverter defibrillator: Incidence, predictors, and prognostic implications

https://doi.org/10.1016/j.ahj.2008.06.035Get rights and content

Background

The aim of the present study was to evaluate the incidence, predictors, and related outcomes of patients with heart failure (HF) treated with cardiac resynchronization therapy with an implantable cardioverter defibrillator (CRT-D) who experienced electrical storm (ES). Electrical storm was defined as the occurrence of ≥3 episodes in 24 hours of sustained ventricular tachyarrhythmias.

Methods

A total of 631 patients with HF (90% male, mean 66 ± 9 years) consecutively received a CRT-D device. At baseline, the mean left ventricular ejection fraction was 26% ± 7%, the QRS duration was 164 ± 33 milliseconds, and the mean New York Heart Association class was 3.3 ± 0.3.

Results

During a mean follow-up of 19 ± 11 months, 2,419 ventricular tachyarrhythmia episodes were appropriately detected in 141 (22%) patients. Electrical storm occurred in 45 (7%) of 631 patients. Kaplan-Meier analysis and multivariable Cox regression showed that ES is more frequent in secondary prevention (hazard ratio 2.3, 95% CI 1.2-4.3, P = .015) and in nonischemic patients (hazard ratio 2.0, 95% CI 1.1-3.8, P = .028). In patients who presented ES, CRT was associated with only marginal nonsignificant improvements of New York Heart Association class and left ventricular ejection fraction. Hospitalizations and death due to HF were more frequent in patients with ES compared with those without ES, amounting to 16.8 (4.3) versus 8.6 (0.9) per 100 patient-years (P = .018) and 7.7 versus 2.7 per 100 patient-years (P = .014), respectively.

Conclusions

Electrical storm affect only 7% of CRT-D recipients and occurred more frequently in nonischemic patients with HF with biventricular implantable cardioverter defibrillators implanted for secondary prevention. Electrical storm was associated with worse HF morbidity and mortality.

Section snippets

Methods

The InSync ICD Italian Registry is a prospective observational registry including patients with refractory HF, on optimized medical therapy, with LV dysfunction, and wide QRS complex, who received a CRT-D. For the purpose of this study, patients with HF in stable New York Heart Association (NYHA) class III to IV, with LV ejection fraction (LVEF) ≤35%, and QRS complex ≥120 milliseconds implanted with a Medtronic CRT-D device (Medtronic, Inc, Minneapolis, MN), were evaluated. Six hundred

Patient population

Six hundred thirty-one patients (90% male, mean age 66 ± 9 years) were enrolled in the study. Demographic and baseline clinical characteristics of the study population are shown in Table I. All patients had indication to biventricular pacing for CRT because of HF. Mean LVEF was 26% ± 7%, and mean QRS width was 164 ± 33 milliseconds. Two hundred sixty-four patients received a CRT-D device for secondary prevention of SCD1, 2, 3: Fifty-five of (20.8%) 264 patients were cardiac arrest survivors,

Discussions

This is the first study investigating the problem of ES in patients with HF implanted with CRT-D. Independent predictors of ES were found to be non–coronary artery disease (CAD) etiology and secondary prevention indication for an ICD. The role of baseline LVEF ≤25% in predicting ES, as reported for patients receiving single- or dual-chamber ICDs, was not confirmed by the present study for patients with HF treated with CRT-D. Compared with patients without ES, patients who experienced ES

Conclusions

In patients with HF treated with CRT-D, ES was not so frequent, being present in 7.1% of the overall population, with a rate of 4.5 patients per 100 patient-years. Electrical storm was higher in secondary prevention and in nonischemic patients. In patients with ES, NYHA functional class and LVEF improved marginally; moreover, patients with ES presented greater cardiovascular and, particularly, HF-related morbidity and mortality. These findings suggest that ES may be an indicator of gradually

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      Most patients receive CRT with a defibrillator (CRT-D) because the indications for an implantable cardioverter-defibrillator (ICD) overlap with those for CRT. Electrical storm, which is commonly defined as the occurrence of 3 or more separate episodes of ventricular tachyarrhythmia requiring ICD therapies within 24 h [2], is associated with worse heart failure-related morbidity and survival among patients who receive CRT-D [3,4]. CRT may increase LV transmural dispersion of repolarization, leading to ventricular tachyarrhythmia and electrical storm induced by epicardial LV pacing [4–6].

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    See Appendix for the complete group of the InSync ICD Italian Registry Investigators.

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