Automatic implantable cardioverter-defibrillator: Patient survival, battery longevity and shock delivery analysis

Abstract

The automatic implantable cardioverter-defibrillator (AICD) has been shown to reduce the mortality rate of patients with malignant ventricular tachyarrhythmias. This report describes experience with implantation of 36 automatic implantable cardioverter-defibrillators (AID-B and AID-BR models) in 22 persons over a 44 month patient follow-up period (mean 19.6 months). There were five deaths: two patients died suddenly 22 and 29 months, respectively, after their second implant, one died of congestive heart failure, one died of respiratory failure and one died of catheter sepsis. Although 11 (50%) of the 22 patients never received a countershock for a ventricular tachyarrhythmia and are still alive, the other 11 received one or more spontaneous countershocks. Nine patients (41%) experienced spurious shocks during the follow-up period. Assuming that the first shock for presumed ventricular tachyarrhythmia prevented death, the hypothetical cumulative survival of patients at 42 months would have been 34 +/- 14.1% in the absence of an automatic implantable cardioverter defibrillator rather than the actual survival rate of 59 +/- 16.8%. The cumulative device survival of the 36 AID-B units was 92 +/- 5.62% at 15 months but diminished to 37 +/- 14.4% by 20 months. No unit lasted longer than 22 months. There were 12 battery depletions. The number of shocks emitted did not influence unit longevity. The manufacturer's elective replacement indicator is of uncertain validity. Six units remained active 7 to 17 months after surpassing their replacement indicator. The automatic implantable cardioverter-defibrillator prolongs the life of many patients with otherwise intractable arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Cost-Effectiveness of Implantable Cardioverter–Defibrillators

“…[4][5][6][7][8][9][10][11]16,[20][21][22][23][24][25][26][27][28][29][30] The effectiveness of the ICD, as compared with control therapy, in reducing the hazard ratio for death varied among the trials in relation to their annual rate of death from any cause (correlation coefficient, ¡0.76) (Fig. [4][5][6][7][8][9][10][11]16,[20][21][22][23][24][25][26][27][28][29][30] The effectiveness of the ICD, as compared with control therapy, in reducing the hazard ratio for death varied among the trials in relation to their annual rate of death from any cause (correlation coefficient, ¡0.76) (Fig.…”

Implantable Cardioverter Defibrillator Events in Patients with Asymptomatic Nonsustained Ventricular Tachycardia:

“…Multiple studies have shown that implantable cardioverter defibrillators (ICDs) reduce sudden cardiac death in high risk patients who present with sustained ventricular arrhythmias, 1–20 and the majority of these patients will receive the first defibrillator shock within the first 6 to 7 months following implantation 6 , 16 , 21,22 . Most patients presenting with sustained ventricular arrhythmias will eventually receive appropriate defibrillator shock therapy, with the cumulative incidence of appropriate therapy of 13%‐47% after 1 year, and 63%‐80% after 4 to 5 years in high risk patients 7 , 13 , 23 .…”

Current status of antitachycardia devices.

“…The probability density function can sometimes be satisfied by SVT with wide QRS complexes or, conversely, may be insensitive to relatively narrow or "spikey" VT. As a result, the device can discharge during tachycardias other than VT. As mentioned previously, nonsustained ventricular tachyarrhythmias can also trigger device discharge due to the "committed" nature of the current AICD. Due to these problems, questionably appropriate or spurious device discharges occur commonly with an incidence of 8-41% in different series.64656773, 75 The lack of telemetry in the current generation of the AICD makes determination of the appropriateness of a discharge in a conscious patient very difficult. Interactions with antibradycardia pacemakers have largely arisen from sensing difficulties.76 Unipolar pacemaker spikes as well as paced complexes can be sensed by the AICD, leading to double counting and satisfaction of rate criteria for device discharge.…”