Correspondence
Electrophysiologic Testing to Identify Patients at Risk for Sudden Death
N Engl J Med 2000; 343:1813-1814December 14, 2000
- Article
To the Editor:
As participants in the Multicenter Unsustained Tachycardia Trial, we are concerned that the tone of the article by Buxton et al. (June 29 issue)1 did not reflect what we believe to be the marked inadequacy of the use of a negative electrophysiologic study for risk stratification (with respect to the need for an implantable cardioverter–defibrillator) among patients who have coronary artery disease, a left ventricular ejection fraction of 40 percent or less, and asymptomatic, unsustained ventricular tachycardia.
The two-year and five-year rates of cardiac arrest or death from arrhythmia were 12 percent and 24 percent, respectively, among the 1397 patients in the registry (who did not have inducible arrhythmias or who had only unsustained ventricular tachycardia), as compared with 18 percent and 32 percent, respectively, among the 353 patients with inducible tachyarrhythmias who were randomly assigned to receive no antiarrhythmic treatment. We believe that although statistically significant, these differences are clinically and practically unimportant, reflecting unacceptably high rates of death from arrhythmia in association with a negative electrophysiologic study. Patients with inducible sustained ventricular tachyarrhythmias who received implantable cardioverter–defibrillators had significantly lower rates of cardiac arrest or death from arrhythmia than those who received therapy guided by the results of electrophysiologic testing or no antiarrhythmic therapy.2
Are we to leave patients unprotected merely because they do not have inducible tachyarrhythmias? The improved outcomes with the use of implantable cardioverter–defibrillators, the low rates of implantation-related complications, and the serious limitations of electrophysiologic testing suggest that such patients, like their counterparts with inducible tachyarrhythmias, should be advised to receive an implantable cardioverter–defibrillator as an initial strategy until studies demonstrate that this approach is not the treatment of choice for these high-risk patients. Electrophysiologic testing should be reserved for uses other than risk stratification (e.g., the assessment of sinus-node function, the conduction system, syncope, supraventricular tachycardia, and ablation). Since cost is an issue, we believe that pressure needs to be placed on the manufacturers of implantable cardioverter–defibrillators to lower substantially the cost of this lifesaving therapy.
2 ReferencesMarc D. Meissner, M.D.
Randy A. Lieberman, M.D.
Wayne State University, Detroit, MI 482011
Buxton AE ,Lee KL ,DiCarlo L , et al. Electrophysiologic testing to identify patients with coronary artery disease who are at risk for sudden death. N Engl J Med 2000;342:1937-1945
Full Text | Web of Science | Medline2
Buxton AE ,Lee KL ,Fisher JD , et al. A randomized study of the prevention of sudden death in patients with coronary artery disease. N Engl J Med 1999;341:1882-1890
Full Text | Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: We agree that the negative predictive value of the electrophysiologic study in the population we studied is not optimal. Ideally, we should be able to identify every patient who is at risk for sudden death and institute cost-effective prophylaxis. This possibility does not exist at present. However, as Drs. Meissner and Lieberman are well aware, the two-year rate of sudden death of 12 percent in the registry population (those without inducible tachyarrhythmias) was almost identical to that reported in the earlier studies (8 to 13 percent) on which our study design was based. Thus, the observed outcome should come as no surprise. One needs to exercise great care in the interpretation of such event rates, because they are unadjusted for other prognostic differences between the registry patients and the randomized patients. Indeed, we know that in the group of patients who underwent randomization, there was a much higher proportion who were receiving beta-blockers.
The five-year rate of sudden death of 24 percent indicates that the results of a single diagnostic test, such as an electrophysiologic study, are not likely to remain valid during prolonged follow-up in patients with a progressive condition such as coronary artery disease. Thus, patients such as those in our study require continuous observation and periodic reevaluation.
Not only was the risk of death from arrhythmia significantly lower among registry patients than among those with inducible ventricular tachycardias who were randomly assigned to receive no antiarrhythmic therapy, but also the percentage of deaths that were classified as caused by arrhythmia was lower among registry patients than among randomized patients (45 percent vs. 54 percent, P=0.055). Thus, one would expect the survival benefit that might accrue from the use of implantable cardioverter–defibrillators in registry patients to be smaller than in randomized patients. The mortality rate among registry patients may have been elevated by the underuse of beta-adrenergic–blocking agents (only 35 percent of patients in this group received this treatment). Contemporary treatment guidelines stress the importance of the use of these agents in patients who have coronary disease and abnormal ventricular function.
To our knowledge, no data have demonstrated that implantable cardioverter–defibrillators can improve survival among patients such as those enrolled in our registry. Such trials are now under way or are being planned. Until data demonstrate that implantable cardioverter–defibrillators confer a significant survival benefit in such patients, we cannot agree that such devices should be used in all patients.
Alfred E. Buxton, M.D.
Brown University School of Medicine, Providence, RI 02905Kerry L. Lee, Ph.D.
Duke University School of Medicine, Durham, NC 27705
