ELECTRICAL STORM: CLINICAL PREDICTORS AND RISK FACTORS IN PATIENTS WITH IMPLANTED CARDIOVERTERS-DEFIBRILLATORS

To develop methods of early diagnostics and to reveal risk factors of ventricular arrhythmias (VA) and electrical storm (ES) in patients with chronic heart failure (CHF), 459 patients (men: 87%) aged 64.07±12.11 years were included into the study. The study subjects were assessed and treated in 1999 through 2014 in four general hospitals in St. Petersburg, Russia. For prevention of sudden cardiac death (SCD) and therapy of CHF, 125 single-chamber cardioverters-defibrillators (ICD) (27.2%), 167 dual-chamber ICD (36.4%), and 167 cardiac resynchronization therapy defibrillators (CRT D) (36.4%) were implanted. Implantation of ICD or CRT D was made for primary prevention of SCD in 68.7% of cases. The study subject follow-up period lasted for 6.2±2.8 years. The study subjects were distributed into two following groups: Group I (n=38) included patients with electric storm and Group II (n=421), patients without electric storm. The annual incidence of ICD shocks was 319 ones, without significant difference in patients with and without ES. In 13.2% of patients, ES occurred within the first year after implantation of ICD or CRT D. The following most significant risk factors of ES were revealed: QRS complex width, mean heart rate (HR), left ventricular (LV) ejection fraction (EF), end-diastolic diameter (EDD) of LV, end-systolic diameter (ESD) of LV, LV hypertrophy, extent of mitral insufficiency, LV diastolic dysfunction, number of episodes of antitachycarditic pacing, number of ICD shocks per year, and changes in CHF functional class. In 1999 through 2014, 22.9% of patients with ICD or CRT D deceased (15% of patients due to CHF deterioration, 5.2% of patients due to ES., and 2.7% of patients due to extracardiac causes). Mortality of patients with CHF progression was significantly higher than in subjects with stable or improving CHF (p<0.005). The survival analysis showed no significant difference between the study groups during first two years of follow-up. After the third year of follow-up, a significantly increased mortality of patients with ES was observed; after the fifth year, survival of patients with ES decreased to 30%, as opposed to 99% reported in the patient group without ES.

chronic heart failure, ventricular tachyarrhythmia, electrical storm, implantable cardioverter-defibrillator, cardiac resynchronization therapy

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