Predictors of successful acetylsalicylic acid resistance suppression after percutaneous coronary revascularisation.

BACKGROUND AND AIM

There is no established management of resistance to acetylsalicylic acid (ASA) in patients with coronary artery disease (CAD). We hypothesised that simply doubling the usual daily dose of ASA could be effective in overcoming ASA resistance.

METHODS

Our study comprised 40 subjects with CAD (male 67.5%, mean age 60.5 ± 8.8 years, mean body mass index 26.9 ± 2.7 kg/m² and median aspirin reaction unit [ARU] value obtained with a Verify Now Aspirin Test 612 [573-634]) with resistance to 75 mg/daily ASA defined as ARU ≥ 550. According to the overcoming of resistance or lack there of in a repeated test after four weeks of 150 mg daily ASA treatment, we defined two subsets: subjects who regained ASA sensitivity, and those who did not.

RESULTS

Successful overcoming of ASA resistance was observed in 62.5% of patients. Multivariate analysis regression confirmed that two variables independently determined successful ASA resistance suppression: male gender (OR 6.88; 95% CI 1.29-36.75; p = 0.024), and ARU for 75 mg daily (OR 0.97 per unit at 75 mg; 95% CI 0.94-0.99; p = 0.039). ROC analysis indicated that the threshold value at which ARU at 75 mg ASA treatment was predictive of successful ASA resistance overcoming was ≤ 608 ARU. Using a simple point score (one point for male gender and one for initial ARU ≤ 608), we found that ASA resistance was overcome in 8%, 36% and 56% of patients, when zero, any single, or two predictors were present.

CONCLUSIONS

ASA resistance overcoming by dose doubling can be achieved more often in males and in subjects with lower ARU value at ASA 75 mg.