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ICD beneficial when used earlier than nine months
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NEW ORLEANS – A recent substudy analysis suggests that implantable cardioverter defibrillators should be used without delay in patients with ejection fraction less than 35% and ventricular arrhythmia.
Kelley Anderson, MD, Marshfield Clinic in Wisconsin, said that his subanalysis of ICD trial data did not support the decision by the Centers for Medicare and Medicaid Services to approve the use of ICDs in patients with cardiomyopathy longer than nine months. “These results do not support that national coverage decision,” he said.
“On the contrary, these results suggest that any delay in ICD implantation will reduce survival benefit,” Anderson said at the Heart Rhythm Society 26th Annual Scientific Sessions.
Anderson presented a subanalysis of DEFINITE (Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation), which enrolled 458 patients with left ventricular dysfunction and nondilated cardiomyopathy. Patients were randomized to standard oral therapy for heart failure or standard oral therapy plus ICD.
DEFINITE enrolled patients with any duration of nonischemic dilated cardiomyopathy. Anderson and colleagues’ substudy divided patients into duration of three months or less, longer than three months, nine months or less, or longer than nine months. Baseline characteristics were similar among the groups.
When researchers observed the mortality benefit among patients with nonischemic dilated cardiomyopathy three months or less, they found that ICD patients had about a 90% chance of survival to 2,000 days, while patients on standard therapy had about a 70% chance of survival (P=.049).
Among patients who had nonischemic dilated cardiomyopathy longer than three months, the survival rate was the same at 2,000 days at about 70% (P=.483).
For patients with nonischemic dilated cardiomyopathy of nine months or less, the survival rate with ICD therapy was about 84% at 2,000 days, compared to about 72% on standard therapy (P=.058).
If patients had displayed nonischemic dilated cardiomyopathy for more than nine months, the survival benefit was less than 70% in both groups (P=.635).
When arrhythmic death was evaluated as a separate outcome, the mortality benefit was statistically significant in the short duration but not in the longer duration groups.
Anderson said the study was limited by the fact that the original DEFINITE trial was not designed to assess the impact of time of diagnosis of nonischemic dilated cardiomyopathy. “Any analysis based on a post-hoc hypothesis may be less reliable than those based on a prespecified hypothesis,” Anderson said. – by Jeremy Moore
For more information:
- Anderson KP. Patients with recently diagnosed nonischemic cardiomyopathy benefit from ICD implantation. Presented at the Heart Rhythm Society 26th Annual Scientific Sessions. May 4-7, 2005. New Orleans.