The prevalence, risk factors and prognosis of aspirin resistance in elderly male patients with cardiovascular disease.

Abstract

Aspirin resistance is recognized in different population. However, the prevalence and clinical events of aspirin resistance in elderly male patients with cardiovascular disease (CVD) have not been reported.
We enrolled 304 elderly male patients with CVD receiving daily aspirin therapy (≥ 75 mg) more than 1 month. Platelet aggregation was measured by light transmission aggregometry (LTA) and thrombelastography platelet mapping assay (TEG). The median follow-up time was 1.8 years. The primary outcome was the composite of death, myocardial infarction, unstable angina, stroke and transient ischemic attack.
By LTA, 25 (8.2%) of elderly patients were aspirin resistant and 106 (34.9%) patients were semiresponders. According to TEG, 62 patients (20.4%) were found to be resistant to aspirin therapy. Of the 62 patients with aspirin resistance by TEG, 21 patients were aspirin resistant by LTA. Twenty-two of the 106 semiresponders by LTA were aspirin resistant by TEG. Patients with aspirin resistance or aspirin semiresponders were at increased risk of the composite outcome compared with aspirin-sensitive patients by LTA (18.3% vs 9.8%, Hazard ratio (HR) = 1.864, 95% confidence interval (CI): 1.046-3.324 p = 0.039). However, aspirin resistance was not associated with an increased risk of clinical vascular events compared to aspirin-sensitive patients by TEG (17.7% vs 10.9%, p = 0.452). In addition, Cox proportional hazard regression modeling demonstrated that aspirin resistance or semiresponders (HR = 3.050, 95% CI: 1.464-6.354, p = 0.003) and diabetes (HR = 2.055, 95% CI: 1.060-3.981, p = 0.033) were associated with major adverse long-term outcomes.
Aspirin resistance or semiresponders, defined by LTA, are associated with an increased risk of adverse clinical events in elderly male patients with CVD.