Efficacy of the automatic implantable cardioverter-defibrillator in prolonging survival in patients with severe underlying cardiac disease

Abstract

The ability of the automatic implantable cardioverter-defibrillator to prolong overall survival, particularly in patients with significantly depressed cardiac function, has not been well documented. Of 119 patients who received the implantable defibrillator in this institution, 40 had a left ventricular ejection fraction less than 30% (Group A) and 79 had an ejection fraction greater than or equal to 30% (Group B). For each group, cumulative survival was compared with the projected survival if the implantable defibrillator had not been used. Projected survival was based on the assumption that the first appropriate shock would have resulted in death without the defibrillator. For Group A, the 3 year cumulative survival rate was 67 +/- 12% versus a projected survival rate of 6 +/- 15% (p less than 0.001). For Group B, the 3 year cumulative survival rate was 96 +/- 3% versus a projected survival rate of 46 +/- 8% (p less than 0.001). Both the cumulative and projected survival rates for patients in Group A were significantly worse than for patients in Group B (p less than 0.01). The projected survival rates for both Groups A and B were comparable with the observed survival rate in similar patients treated without the implantable defibrillator. In summary, the implantable cardioverter-defibrillator significantly prolonged overall survival, even in patients with poor cardiac function. The technique of estimating projected survival appears to allow a realistic estimate of the reduction in mortality achieved by the defibrillator.

ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

“…319,322,323 Multiple analyses have supported the notion that patients with reduced LV function may experience greater benefit with ICD therapy than with drug therapy. 320,[335][336][337][338] All patients undergoing evaluation for ICD therapy should be given optimum medical treatment for their underlying cardiovascular condition. 16 Patients experiencing cardiac arrest due to VF that occurs more than 48 hours after an MI may be at risk for recurrent cardiac arrest.…”

Task Force on Sudden Cardiac Death of the European Society of Cardiology

“…The ICD was originally designed to prevent SCD in patients with life-threatening, sustained ventricular arrhythmias [223][224][225][226] . It was soon demonstrated that ICDs were effective in the reversion of sustained ventricular tachycardia and fibrillation [227][228][229][230] .…”

Potential Benefit From Implantable Cardioverter-Defibrillator Therapy in Patients With and Without Heart Failure

“…2,3 Small retrospective studies have used the incidence of "appropriate" therapies delivered by the devices to estimate the potential benefit from ICD implantation. 2,4 As a more rigorous variant of this approach, we previously suggested use of the recurrence of fast (Ͼ240 bpm) ventricular tachyarrhythmias documented by the memory of the device to calculate hypothetical mortality curves. 5 This was based on the assumption that the tachyarrhythmia would have been lethal had it not been terminated by the device.…”