Clinical management of acute coronary syndrome in Hong Kong

Abstract

Purpose: Aspirin low responsiveness or “aspirin resistance” has been reported with a prevalence rate of 5.5% to 60% depending on compliance, method, definition and study population. We aimed to assess the prevalence of aspirin responsiveness in a multiethnic Asian cohort planned for percutaneous coronary intervention (PCI). Methods: Of 323 patients screened, 237 patients receiving 75 mg aspirin daily for ≥2 days prior to angiography were recruited in Sarawak General Hospital (Malaysia) between 18/10/2010 and 14/3/2011 with prior written informed consent. Possible noncompliant patients were excluded. Platelet aggregation levels were analysed withmultiple electrode aggregometry (MEA) and expressed as AU*min. 157 patients who had MEA readings with correlation coefficient of ≥0.98 and difference from mean curve of <20% were included for analysis. Patients with MEA of ≥300 AU*min were classified as aspirin low responders. Results: 83.4% of patients were males with mean age of 56.7 years old. 54.1% of patients were Chinese, 23.6% Malays, 22.9% Ibans and 8.9% other ethnic minorities. Median (interquartile range) MEA was 141.0 (86.0) AU*min, 126.0 (74.0) AU*min and 153.0 (98.0) AU*min among Chinese, Malays and Ibans, respectively (p=0.129 Chinese vs. Malays, p=0.777 Chinese vs. Ibans, p=0.115 Malays vs. Ibans). Based on 300 AU*min as cut-off, 10 patients (6.4%) were aspirin low responders, with Ibans accounting for 50%, Chinese 40% and Malays 10%. Median (interquartile range) MEA of responders vs. low responders was 140.0 (78.8) AU*min vs. 439.5 (92.5) AU*min (p=0.001) among Chinese, 125.5 (73.0) AU*min vs. 844.0 (0) AU*min (p=0.092) among Malays and 131.0 (89.0) AU*min vs. 546.0 (174.0) AU*min (p<0.0001) among Ibans. Conclusion: There is a low prevalence of poor aspirin responders in our multiethnic Asian cohort. Aspirin low responsiveness rate was highest among the Iban and Chinese ethnic groups, suggesting a role of ethnicity on aspirin response.