Abstract 2361: Higher Clopidogrel Loading Dose is Associated With Less Frequent Ischemic Complications Following PCI: Insights from the NHLBI Dynamic Registry
Background: Clopidogrel pre-treatment has reduced ischemic outcomes following percutaneous coronary intervention (PCI) in multiple randomized trials. Comparative data suggest that higher loading doses (600 mg) may be more effective than lower doses (300 mg) in this setting.
Methods: We examined the association between clopidogrel loading dose, 300 mg (n=187) or 600 mg (n=202), and ischemic outcomes following PCI among consecutive patients enrolled in Waves 4 (2004) and 5 (2006) of the NHLBI Dynamic PCI Registry.
Results: Demographic characteristics, most traditional cardiovascular risk factors and procedural indications were similar in both clopidogrel pre-treatment groups. Patients in the 300 mg group were significantly more likely to have chest pain on admission, multivessel coronary disease, prior coronary revascularization, a history of heart failure and planned GP IIb/IIIa inhibitor use during PCI but were less likely to have diabetes or to receive aspirin within the 24 hours pre-PCI. In unadjusted analyses, higher clopidogrel loading doses were associated with less frequent prolonged chest pain after the procedure (1.0 vs. 4.8%, p=0.023), fewer Q wave MI (0 vs. 2.1%, p=0.037) or any MI (0 vs. 4.3%, p=0.003) before discharge, and a lower incidence of MI at 30 days (0.5 vs. 5.9%, p=0.002). In a propensity adjusted Cox proportional hazards model accounting for age, race, diabetes, heart failure, acute MI, prior coronary revascularization, pre-PCI aspirin, recruitment wave and clinical center, pre-treatment with a 300 mg clopidogrel loading dose was associated with a greater hazard for MI at 30 days than a 600 mg dose (HR 10.57 [95% CI 1.10 –101.71], p=0.04). The elevated hazard of MI associated with a 300 mg clopidogrel loading dose was evident in both the in-hospital and short-term post-discharge period.
Conclusions: In this contemporary North American PCI registry, a 600 mg pre-procedure clopidogrel loading dose was associated with a more favorable clinical outcome than a 300 mg dose and may be the preferred strategy before PCI.