Comparison of ventricular tachyarrhythmia characteristics in patients with idiopathic dilated or ischemic cardiomyopathy and defibrillators implanted for primary prevention.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy for primary prevention is well established in ischemic cardiomyopathy (ICM). Data on the role of ICDs in patients with dilated cardiomyopathy (DCM) and no history of ventricular tachyarrhythmia (VT/VF) are more limited. HYPOTHESIS: DCM patients with an impaired left ventricular ejection fraction (LVEF) still represent a low arrhythmic risk subgroup in clinical practice. METHODS: ICD stored data of DCM patients with an LVEF ≤35% was compared to data of ICM patients meeting Multicenter Automatic Defibrillator Implantation Trial (MADIT) eligibility criteria. VT/VF occurrences and electrical storm (ES) events were analyzed. RESULTS: There were 652 patients followed for 50.9 ± 33.9 months. There were 1978 VT and 241 VF episodes analyzed in 66 out of 203 patients (32.5%) with DCM and in 118 out of 449 patients (26.3%, P = 0.209) with ICM. Freedom of appropriate ICD treatment due to VT/VF or ES events did not differ in both patient populations (log-rank, P>0.05). In patients presenting with VT/VF episodes, mean event rates were comparable in both patient populations (3.2 ± 14.1 for DCM and VT vs 3 ± 13.9 for ICM and VT [P = 0.855], 0.4 ± 1.3 for DCM and VF vs 0.4 ± 1.8 for ICM and VF [P = 0.763], and 0.2 ± 0.7 for DCM and ES vs 0.2 ± 1 for ICM and ES [P = 0.666]). CONCLUSIONS: DCM patients with prophylactic ICDs implanted due to heart failure and patients fulfilling MADIT criteria reveal comparable patterns of VT/VF/ES events during long-term follow-up. Incidence, mean number of events, and time to first event did not differ significantly. Findings support the current guidelines for prophylactic ICD therapy in DCM patients with heart failure.

Predictors of electrical storm recurrences in patients with implantable cardioverter-defibrillators.

AIMS: To determine prevalence and predictors of electrical storm recurrences (ES-Rs) in patients with implantable cardioverter-defibrillators (ICDs) as electrical storms (ESs) represent serious clinical events carrying a high risk of mortality. METHODS AND RESULTS: Single-centre study analysing data of consecutive patients receiving an ICD between 1993 and 2008. Electrical storm was defined as ≥ 3 separate ventricular tachyarrhythmic (VT/VF) episodes ≤ 24 h. Nine hundred and fifty-five patients [mean left ventricular ejection fraction (LVEF) 35.7 ± 15.6%] were prospectively followed for 54.2 ± 35.5 months. In 274 of 955 patients (28.7%), 2871 VT/VF episodes were observed. One hundred and fifty-three ES episodes occurred in 63 of 955 patients (6.6%). Thirty-two of 63 patients (50.8%) experienced ≥ 2 ES episodes. Twenty-six of 32 patients (81.2%) with ES-Rs experienced the second ES episode within 1 year after the initial event. Cox regression analysis identified an LVEF ≤ 30% (OR 2.2; 95% CI 1.021-4.856; P = 0.044) and a patient's age >65 years (OR 3.5; 95% CI 1.207-10.176; P = 0.021) to be predictive for ES-Rs. Patients with angiotensin-converting enzyme (ACE) inhibitor therapy were less likely to experience ES-Rs (OR 0.39; 95% CI 0.187-0.817; P = 0.013). CONCLUSIONS: Electrical storm events are not rare in a 'real-world' patient population with ICDs (6.6% in 4.5 years). The risk for ES-Rs, especially within the first year after the initial event, is high. Left ventricular ejection fraction ≤ 30%, age >65 years, and a lack of ACE inhibitor therapy are independent predictors of ES-R.