Single and dual antiplatelet therapy in elderly patients of medically managed myocardial infarction

Ting-Tse Lin,Hsiu-Yun Lai,Chao-Lun Lai,K Arnold Chan,Yen-Yun Yang,Mei-Shu Lai

doi:10.1186/s12877-018-0777-4

Abstract

BackgroundsTo examine the comparative effectiveness between dual and single antiplatelet therapies in real-world, medically managed elderly patients with acute myocardial infarction (AMI).MethodsThis retrospective study identified very elderly (> 85 years) patients, who were medically managed, with their first AMI from the Taiwan National Health Insurance claims database from 2007 to 2010. Patients were classified as dual antiplatelet therapy (DAPT) group, aspirin only group and clopidogrel only group. Study outcomes included all-cause death, cardiovascular death and gastrointestinal bleeding. Treating DAPT group as the reference, we employed a multivariable Cox regression model to compare the relative risks of outcomes between 3 groups using pairwise comparison approach.ResultsAmong 1469 patients with incident ST-elevation myocardial infarction (STEMI, 14%) or non-STEMI (86%), 390 patients were prescribed DAPT, 549 aspirin only, and 530 clopidogrel only. After 9 months of follow-up, aspirin only group had similar risks of all-cause death (adjusted HR 1.21, 95% CI 0.77–1.89, p = 0.41), cardiovascular death (adjusted HR 1.16, 95% CI 0.66–2.04, p = 0.60) and gastrointestinal bleeding (adjusted HR 1.66, 95% CI 0.77–3.57, p = 0.20) in comparison with DAPT group. Clopidogrel users had a higher risk of all-cause death (adjusted HR 1.50, 95% CI 1.00–2.25, p = 0.049) but similar risks of cardiovascular death and gastrointestinal bleeding when compared with DAPT.ConclusionsAmong very elderly patients who were medically managed after AMI, single antiplatelet therapy had comparable protective effect as DAPT. But clopidogrel only strategy was associated with a higher risk of all-cause death.

Highlights

Antiplatelet therapy has been considered the standard treatment for secondary prevention of ischemic events and mortality after acute myocardial infarction (AMI) [1, 2]
The mean age was 88 years and the AMI presentations were comparable among three groups, with non-ST elevation MI (NSTEMI) predominant but with less male patients in clopidogrel only group
Patients prescribed with aspirin only or clopidogrel only were more likely to have hypertension and chronic pulmonary disease but less likely to have diabetes and prescriptions of statins, Angiotensin-converting-enzyme inhibitor (ACEI)/Angiotensin receptor blocker (ARB), and beta-blockers at discharge in comparison with dual antiplatelet therapy (DAPT) group

Summary

Introduction

Antiplatelet therapy has been considered the standard treatment for secondary prevention of ischemic events and mortality after acute myocardial infarction (AMI) [1, 2]. The benefit of dual antiplatelet therapy (DAPT) has been established in the Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) trial, which showed improved outcomes among patients with non-ST elevation MI (NSTEMI) after treatment with DAPT [3]. Among patients with AMI, DAPT limits early steps of platelet aggregation and adhesion in the formation of coronary arteries thrombi, and. A large proportion of patients with NSTEMI in clinical practice were managed medically [8, 9], with low rate of prescriptions of DAPT [10, 11]. Elderly population are less likely to receive evidence-based therapies [16], but are apt to be managed medically [17]

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