Device Use Patterns and Clinical Outcome of Implantable Cardioverter Defibrillator Patients with Moderate and Severe Impairment of Left Ventricular Function

Abstract

The beneficial effects of implanted cardioverter defibrillator (ICD) therapy in patients with malignant ventricular tachyarrhythmias and variable degrees of left ventricular (LV) dysfunction are debated. ICD use and patient survival were examined in 128 patients with malignant ventricular arrhythmias and moderate or severe LV dys function. Group I included 64 patients with moderate LV dysfunction (LV ejection fraction of > 30%) and group H, 64 patients with severe LV dysfunction (LV ejection fracfion of ≤ 30%). Follow‐up period ranged from 1 to 78 months. The two groups were similar in age, incidence of coronary artery disease and presenting arrhythmia. The mean LV ejection fraction in group I was 44%± 8% and group II was 22%± 5% (P < 0.0001). At 4 years of follow‐up, 66% of patients from group I and 62% from group II (P = NS) had ICD activation for presumed ventricular tachyarrhythmia. Survival was calculated using actuarial analysis. Arrhythmic or sudden death mortality at 4 years of follow‐up was 4% in group I and 7% in group II (P = NS). Cardiac mortality was for group I, 7% (P < 0.05), 12% (fP < 0,01), 15% (P < 0.01), and 15% (P < 0.01) for follow‐up years 1, 2, 3, and 4, respectively. For group II, cardiac mortality was 27%, 36%, 41%, and 41% for follow‐up years for 1, 2, 3, and 4, respectively. The majority of cardiac deaths in both groups was observed in the first 2 years of follow‐up. However, in both groups, cardiac mortality was comparable in patients who did (users) and did not (nonusers) experience appropriate ICD shocks. Thus, the incidence of long‐term ICD use is comparable in patients with moderate and severe LV dysfunction. Cardiac mortality is higher in patients with severe LV dysfunction in the first 4 years of follow‐up irrespective of device use. The comparable long‐term clinical outcome of ICD users and non users in patients with moderate or severe LV dysfunction can be related to elimination of arrhythmic mortality. Long‐term patient survival in ICD recipients with severe LV dysfunction remains substantial even at 4 years of follow‐up.