Relation between time from myocardial infarction to enrolment and patient outcomes in the Multicenter UnSustained Tachycardia Trial

Abstract

Aims: We sought to assess the relation between time from myocardial infarction (MI) to enrolment and patient outcomes and to examine the association between these outcomes and implantable cardioverter defibrillator (ICD) therapy.

Methods and results: We analysed the Multicenter UnSustained Tachycardia Trial database (n = 1650). In examining all endpoints, Cox proportional hazards models were used to adjust for potential confounders. There was no significant association between time from MI to enrolment and any of the outcomes (P > 0.1). Inducibility by an electrophysiology study (EPS) was associated with a higher risk of arrhythmic death or cardiac arrest [adjusted hazard ratio (HR) 2.51; 95% confidence interval (CI) 1.64-3.84] and all-cause death (adjusted HR 1.45; 95% CI 1.04-2.03) only in patients who had an MI <or=6 months prior to enrolment. ICD therapy was associated with improved survival in patients who had an MI <or=6 months (adjusted HR 0.35; 95% CI 0.17-0.74) and >6 months before enrolment (adjusted HR 0.34; 95% CI 0.21-0.54).

Conclusion: The risk of arrhythmic death or cardiac arrest and all-cause death did not vary as a function of time from the most recent MI to enrolment. Inducibility by an EPS was associated with worse outcomes only in patients with an MI <or=6 months prior to enrolment. Although ICD therapy was associated with improved survival regardless of the time from MI to enrolment, this finding needs to be verified by a randomized clinical trial.

Figure 1

Distribution of time from myocardial infarction to enrolment (≤1 month, >1 month to ≤6 months, >6 months to ≤36 months, >36 months).

Figure 2

Inducibility by an electrophysiology study by time from myocardial infarction to enrolment (≤1 month, >1 month to ≤6 months, >6 months to ≤36 months, >36 months).

Figure 3

(A) Unadjusted arrhythmic death or cardiac arrest by time from myocardial infarction to enrolment. (B) Unadjusted all-cause death by time from myocardial infarction to enrolment. This analysis only included patients who did not receive an implantable cardioverter defibrillator within 90 days after enrolment and were discharged following the index hospitalization on no antiarrhythmic medications.

Figure 4

Unadjusted arrhythmic death or cardiac arrest by time from myocardial infarction to enrolment and inducibility by an electrophysiology study. This analysis only included patients who did not receive an implantable cardioverter defibrillator within 90 days after enrolment and were discharged following the index hospitalization on no antiarrhythmic medications.