Impact of initial clinical presentation on clopidogrel low response.

BACKGROUND

Large interindividual variability exists in clopidogrel response. Clopidogrel low response correlates with poor prognosis after percutaneous coronary intervention. Some authors also suggest intraindividual variability over time.

AIM

To assess the impact of initial clinical presentation on clopidogrel low response.

METHODS

In this prospective study, clopidogrel response was assessed in 100 patients. Fifty patients presenting with acute coronary syndromes (ACS group) were compared with 50 patients with stable coronary artery disease matched 1:1 for age, sex, body mass index and diabetes (stable group). All patients were tested 18-24h after a 600 mg loading dose of clopidogrel using the VerifyNow-P2Y12 test (results expressed as platelet reaction units [PRUs]). Patients under chronic clopidogrel therapy or treated with glycoprotein IIb/IIIa inhibitors, bivalirudin or thrombolytics were excluded.

RESULTS

Mean age was 61 ± 12 years in each group; 28% of patients in each group were diabetic; mean body mass index was 27.6 ± 5.6 kg/m(2) in the ACS group and 27.9 ± 5.9 kg/m(2) in the stable group (p=0.80). Mean PRU values were 197 ± 81 in the ACS group and 159 ± 94 in the stable group (p=0.03). By multivariable analysis, the ACS group was significantly associated with a higher PRU value (p=0.02). There were significantly more clopidogrel low responders (PRU value>230) in the ACS group (38% vs. 18%; p=0.04).

CONCLUSION

Our study confirms that initial clinical presentation, especially ACS, is a strong predictor of clopidogrel low response; this suggests that the evolution of coronary artery disease for one patient influences the clopidogrel response over time. These results are in accordance with recent trials showing a benefit for more aggressive antiplatelet therapy in ACS patients.