Automatic Implantable Cardioverter Defibrillators and Survival of Patients with Left Ventricular Dysfunction and Malignant Ventricular Arrhythmias

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Abstract
A study was made to assess survival after insertion of automatic implantable cardioverter defibrillators in high-risk patients who have malignant ventricular arrhythmias and left ventricular dysfunction. Seventy consecutive patients with clinical sustained ventricular tachycardia or fibrillation whose arrhythmia could not be controlled by medication as determined by programmed electrical stimulation, and who had an automatic cardioverter defibrillator implanted were studied. All patients received an implantable defibrillator. Two-year survival was 93.4% (95% CI, 87n to 99.8) and projected survival based on recurrence of malignant arrhythmias was 60.3% (CI 47.3 to 73.3; P < 0.002). In the 25 patients with left ventricular ejection fraction less than 30%, actual survival was 86.7% (CI, 72.3 to 91.1) and projected survival was 56.9% (CI, 35.9 to 77.9%; P = 0.025). Projected survival percentages are similar to survival figures reported in the literature for such high-risk patients. There was only one sudden death; the remaining deaths were not arrhythmic in nature. Of the 65 patients who were alive at the end of follow-up, 13 were in New York Heart Association Class I; 44, Class II; 5, Class III; and 3, ClassIV. The automatic implantable cardioverter defibrillator is probably highly effective in preventing arrhythmic mortality even in high-risk patients. Such treatment does not appear to significantly impair a patients''s functional status.