There had been several studies relating to the automated defibrillator and cost-effectiveness of it. The Multi-center Automated Defibrillator Implantation Trial (MADIT) took up a study to decide the same. The study showed improved survival in selected asymptomatic patients with coronary disease and un-sustained ventricular tachycardia.
To decide the cost-effectiveness of the automated defibrillator the patients were regularly followed up and their use of healthcare services was taken in to account. These included visits to hospitals or physicians, laboratory tests procedures, medications etc. To decide the cost-effectiveness the study was randomized against the use of defibrillators and other conventional medical treatments.
The incremental cost-effectiveness ratios were calculated by relating these costs to the increased survival associated with the use of the defibrillator. The average survival for the defibrillator group over a 4-year period was 3.66 years compared with 2.80 years for conventionally treated patients.
Sensitivity analyses showed that the incremental cost-effectiveness ratio would be reduced to equivalent to twenty three thousand dollars per life-year saved if transvenous defibrillators were used instead of the older devices, which required thoracic surgery for implantation. The study came to the conclusion that an implanted cardiac defibrillator is cost-effective in selected individuals at high risk for ventricular arrhythmias.
These implantable cardioverter defibrillators also demonstrated improvement in survival of post-myocardial-infractions patients with low ejection fractions. Known variation in effectiveness and cost-effectiveness among different populations raises the question of how to identify patients for whom ICD therapy is appropriate.
Investigators have evaluated the usefulness of a variety of diagnostic tests or clinical markers to identify patients at high risk of sudden cardiac death, but to date none has proven highly predictive. These indicators include ejection fraction, signal-averaged electrocardiography, T-wave alternans, heart rate variability, baroreceptor responsiveness, un-sustained ventricular tachycardia, and electrophysiologic testing.
Although the ICD should be more effective for patients at a higher risk of sudden cardiac death; if patients at high risk of sudden cardiac death are also at high risk of non-sudden cardiac death, the benefit of an ICD may be attenuated.