Contemporary patterns of discharge aspirin dosing after acute myocardial infarction in the United States: results from the National Cardiovascular Data Registry (NCDR)

Background: Accumulated data suggest that low-dose aspirin after myocardial infarction (MI) may offer similar efficacy to higher dose aspirin with reduced risk of bleeding. Few data are available on contemporary aspirin dosing patterns after MI in the United States

Methods and results: Aspirin dosing from 221 199 patients with MI (40.2% ST-segment-elevation MI) from 525 US hospitals enrolled in the National Cardiovascular Data Registry's (NCDR's) Acute Coronary Treatment and Intervention Outcomes Network Registry-Get with the Guidelines were described, overall and in clinically relevant subgroups. High-dose aspirin was defined as 325 mg and low dose as 81 mg. Between January 2007 and March 2011, 60.9% of patients with acute MI were discharged on high-dose aspirin, 35.6% on low-dose aspirin, and 3.5% on other doses. High-dose aspirin was prescribed at discharge to 73.0% of patients treated with percutaneous coronary intervention and 44.6% of patients managed medically. Among 9075 patients discharged on aspirin, thienopyridine, and warfarin, 44.0% were prescribed high-dose aspirin. Patients with an in-hospital major bleeding event were also frequently discharged on high-dose aspirin (56.7%). A 25-fold variation in the proportion prescribed high-dose aspirin at discharge was observed across participating centers.

Conclusions: Most US patients with MI continue to be discharged on high-dose aspirin. Although aspirin dosing after percutaneous coronary intervention largely reflected prevailing guidelines before 2012, high-dose aspirin was prescribed with similar frequency in medically managed patients and to those in categories expected to be at high risk for bleeding. Wide variability in the proportional use of high-dose aspirin across centers suggests significant influence from local practice habits and uncertainty about appropriate aspirin dosing.