Objective In acute coronary syndromes, switching between thienopyridines is frequent. The aims of the study were to assess the association between switching practices and quality of care.

Methods Registry study performed in 213 French public university, public non-academic and private hospitals. All consecutive patients admitted for acute myocardial infarction (MI; <48 hours) between 1/10/2010 and 30/11/2010 were eligible. Clinical and biological data were recorded up to 12 months follow-up.

Results Among 4101 patients receiving thienopyridines, a switch was performed in 868 (21.2%): 678 (16.5%) from clopidogrel to prasugrel and 190 (4.6%) from prasugrel to clopidogrel. Predictors of switch were ST segment elevation MI presentation, admission to a cardiology unit, previous percutaneous coronary intervention, younger age, body weight >60 kg, no history of stroke, cardiac arrest, anaemia or renal dysfunction. In patients with a switch, eligibility for prasugrel was >82% and appropriate use of a switch was 86% from clopidogrel to prasugrel and 20% from prasugrel to clopidogrel. Quality indicators scored higher in the group with a switch and also in centres where the switch rate was higher.

Conclusions As applied in the French Registry on Acute ST-elevation and non ST-elevation Myocardial Infarction (FAST-MI) registry, switching from one P2Y12 inhibitor to another led to a more appropriate prescription and was associated with higher scores on indicators of quality of care.