Duration of evidence-based medical therapy and the hazard for atherothrombotic events following percutaneous coronary intervention

Abstract

Background: Patients who undergo coronary artery stent procedures are at risk for late atherothrombotic events, including stent thrombosis. The relationship between the duration during which evidence-based medical therapies are utilized after coronary artery stenting and the risk of late atherothrombotic events is not well characterized.

Methods: In a retrospective cohort study linking a hospital-based percutaneous coronary intervention registry with a health maintenance organization claims dataset, we related the duration of medical therapy utilization during follow up to the hazard for death, myocardial infarction, unstable angina, transient ischemic attack or stroke following a coronary artery stent procedure. Multivariable Cox models were employed in which medical treatments were entered as time-varying covariates; data were stratified by stent type and time period.

Results: The median [interquartile range, IQR] duration of follow up was 832 [460, 1420] days. During this time, 86 ischemic events occurred in 84 of 386 patients at a median [IQR] of 260 [110, 658] days. The incidence of atherothrombotic events following coronary artery stenting was highest during the first post-procedure year and declined substantially thereafter. Multivariable predictors of incident ischemic events included multivessel coronary artery disease (HR 2.01 [95% CI 1.30-3.11], p=0.0018) and longer duration angiotensin converting enzyme (ACE) inhibitor/angiotensin receptor blocker (ARB), beta blocker or statin therapy (HR 0.52 [95% CI 0.28-0.99], p=0.045).

Conclusions: The use of longer-term ACE inhibitor/ARB, beta blocker or statin therapy was associated with a significantly lower risk; these risk reductions were of greater magnitude than those associated with clopidogrel.