Severe left ventricular systolic dysfunction is independently associated with high on-clopidogrel platelet reactivity.

OBJECTIVE

The purpose of the present study was to investigate the association between left ventricular systolic function and the response to clopidogrel.

METHODS

The efficacy of clopidogrel was measured by the vasodilator-stimulated phosphoprotein phosphorylation 20 ± 4 h after 600 mg of clopidogrel. High on-clopidogrel platelet reactivity (HCPR) was defined as a platelet reactivity index (PRI) ≥50%. The 30-day combined incidence of death, non-fatal acute coronary syndrome, re-percutaneous coronary intervention (PCI), stent thrombosis, and stroke was also investigated.

RESULTS

The study group consisted of 519 patients undergoing PCI. The values (mean and 95% confidence interval) of the PRI were as follows: 40.4% (37.8-43.0) in patients with left ventricular ejection fraction (LVEF) >50%, 42.4% (39.3-45.6) in patients with LVEF 35-50%, and 46.7% (40.6-52.9) in patients with LVEF <35% (p = 0.013). The proportions of patients with HCPR were 35.9% in patients with LVEF ≥35 and 51.9% in patients with LVEF <35% (p = 0.022). After adjustment for variables that significantly influenced clopidogrel efficacy, LVEF <35% was found to be independently associated with HCPR (p = 0.039). The 30-day combined clinical endpoint occurred in 18% of patients with LVEF <35% and in 7.3% of patients with LVEF ≥35% (p = 0.026). The 30-day incidence of all-cause mortality was 14% in patients with LVEF <35 and 1.0% in patients with LVEF ≥35% (p < 0.001).

CONCLUSION

An LVEF <35% was found to be independently associated with HCPR.