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Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular
A J Moss1, W J Hall, D S Cannom
1Department of Medicine, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
Insights
Implanted cardioverter-defibrillators significantly improve survival in high-risk myocardial infarction patients prone to ventricular tachycardia. This prophylactic therapy offers a survival benefit compared to conventional medical treatments.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Patients with myocardial infarction and left ventricular dysfunction experiencing unsustained ventricular tachycardia face a high mortality risk (approx. 30% within two years).
- Identifying effective interventions to improve survival in this high-risk population is crucial.
Purpose of the Study:
- To evaluate the efficacy of prophylactic therapy using an implanted cardioverter-defibrillator versus conventional medical therapy in improving survival rates.
- To assess the impact of defibrillator implantation on mortality in patients with prior myocardial infarction and left ventricular dysfunction.
Main Methods:
- A randomized trial involving 196 patients with prior myocardial infarction, reduced ejection fraction (<0.35), and documented ventricular tachycardia.
- Patients were assigned to either an implanted defibrillator group (n=95) or conventional medical therapy group (n=101).
- The study employed a two-sided sequential design with overall mortality as the primary endpoint over a five-year follow-up period.
Main Results:
- The defibrillator group experienced significantly fewer deaths (15) compared to the conventional therapy group (39) over an average follow-up of 27 months.
- The hazard ratio for overall mortality in the defibrillator group was 0.46 (95% CI, 0.26 to 0.82; P=0.009), indicating a substantial survival benefit.
- No significant influence of antiarrhythmic therapies such as amiodarone or beta-blockers was observed on the hazard ratio.
Conclusions:
- Prophylactic implantation of cardioverter-defibrillators significantly improves survival in high-risk patients with prior myocardial infarction and ventricular tachyarrhythmia.
- Implanted defibrillators represent a superior therapeutic strategy compared to conventional medical therapy for this patient cohort.
Background:
Unsustained ventricular tachycardia in patients with previous myocardial infarction and left ventricular dysfunction is associated with a two-year mortality rate of about 30 percent. We studied whether prophylactic therapy with an implanted cardioverter-defibrillator, as compared with conventional medical therapy, would improve survival in this high-risk group of patients.
Methods:
Over the course of five years, 196 patients in New York Heart Association functional class I, II, or III with prior myocardial infarction; a left ventricular ejection fraction < or = 0.35; a documented episode of asymptomatic unsustained ventricular tachycardia; and inducible, nonsuppressible ventricular tachyarrhythmia on electrophysiologic study were randomly assigned to receive an implanted defibrillator (n = 95) or conventional medical therapy (n=101). We used a two-sided sequential design with death from any cause as the end point.
Results:
The base-line characteristics of the two treatment groups were similar. During an average follow-up of 27 months, there were 15 deaths in the defibrillator group (11 from cardiac causes) and 39 deaths in the conventional-therapy group (27 from cardiac causes) (hazard ratio for overall mortality, 0.46; 95 percent confidence interval, 0.26 to 0.82; P=0.009). There was no evidence that amiodarone, beta-blockers, or any other antiarrhythmic therapy had a significant influence on the observed hazard ratio.
Conclusions:
In patients with a prior myocardial infarction who are at high risk for ventricular tachyarrhythmia, prophylactic therapy with an implanted defibrillator leads to improved survival as compared with conventional medical therapy.