RESISTANCE TO CLOPIDOGREL ASSESSED BY VASP PHOSPHORYLATION IS A NEGATIVE PROGNOSTIC FACTOR IN PATIENTS UNDERGOING ELECTIVE PCI FOR STABLE CAD. ANALYSIS FROM LABORATORY SUBSTUDY OF PRAGUE 8 TRIAL

 Purpose. Resistance to clopidogrel is an unfavourable prognostic factor in patients undergoing PCI for acute coronary syndromes. The aim of this analysis was to assess long-term prognosis of patients who are resistant to clopidogrel and are undergoing elective PCI for stable CAD.
 Methods. For the purpose of this analysis, patients randomized in the PRAGUE 8 trial were included. These patients (n=92) underwent elective PCI for proven or suspected stable CAD, and their platelet reactivity measurement by VASP was performed before and 12 hours after the 600mg clopidogrel loading dose. VASP phosphorylation data were expressed as a platelet reactivity index (PRI). Patients were divided into 2 groups according to their PRI values.
Resistance to clopidogrel (clopidogrel non-responder) was defined as patient with PRI more than 50% 12hours after after 600mg clopidogrel loading dose.
Patients were followed for 24 months. The occurrence of death, myocardial infarction, revascularization (PCI or CABG), and stroke was analysed.
 Results: Results are summarized in table 1. Nonresponders to clopidogrel had significantly higher occurrence of MI as compared to responders(7/45 15.56% vs. 1/47 2.13%, p=0,029). Combined clinical endpoint (death/MI/stroke) was signifivantly higher in nonresponders (11/45 24.44% vs. 3/47 6.67%, p=0,02). 

	nonresponders		responders
	n=45	%	n=47	%	p
death	2	4,44%	1	2,13%	0,613
MI	7	15,56%	1	2,13%	0,029
stroke	2	4,44%	1	2,13%	0,613
revascularisation	3	6,67%	2	4,26%	0,674
deaths/MI/Stroke	11	24,44%	3	6,67%	0,020
deaths/MI/Stroke/rePCI	11	24,44%	5	10,64%	0,102

Conclusions. Resistance to clopidogrel assessed by VASP is a significant predictor of long-term prognosis in patients undergoing elective PCI for stable CAD.