Temporal trends and practice variations in clopidogrel loading doses in patients with non-ST-segment elevation myocardial infarction, from the National Cardiovascular Data Registry.

BACKGROUND: A higher loading dose of clopidogrel achieves a more rapid and consistent degree of platelet inhibition than standard dosing, although the clinical benefit of higher doses has not been clearly established. The use of the different doses in clinical practice is not known. We evaluated the patient, procedural, and hospital characteristics associated clopidogrel loading doses given to patients with non-ST-segment elevation myocardial infarction (NSTEMI).
METHODS: The National Cardiovascular Data Registry ACTION Get With the Guidelines Registry was queried for patients with NSTEMI admitted from 2007 to 2008. Demographic, clinical, and procedural information were collected on standardized data forms. Patients were categorized according to the clopidogrel loading dose received. Temporal trends in the use of different doses were evaluated in quarterly time intervals.
RESULTS: Between January 1, 2007, and December 31, 2008, the use of a 600-mg clopidogrel loading dose increased steadily from 36.4% to 45.5%, whereas the use of 300 mg decreased slightly from 40.1% to 37.1%. Patients loaded with clopidogrel before cardiac catheterization were more likely to receive 300 mg, whereas those receiving a loading dose at the time of catheterization more often received 600 mg. The temporal increase in the use of 600 mg clopidogrel loading doses was not explained by temporal changes in periprocedural loading, use of early invasive management of patients with NSTEMI, or use of antithrombotics or glycoprotein 2b/3a inhibitors.
CONCLUSIONS: Higher loading dose clopidogrel increased between 2007 and 2008. Higher-dose clopidogrel was more frequently used in lower-risk patients undergoing an early invasive strategy and receiving periprocedural loading.