Background Despite significant pharmacological and mechanical advancements in PCI, The optimal value of activated clotting time (ACT) during percutaneous coronary intervention (PCI) with unfractionated heparin remains controversial. No data are available on the relation between the ACT at the end of the procedure (final ACT) and the clinical outcomes after transradial PCI.

Methods A total of 682 consecutive patients with acute coronary syndrome after transradial Stenting were enrolled into our study, final ACT was available in 658 (96%). All patients were pretreated with aspirin and clopidogrel. After radial sheath insertion, patients received 70 IU/kg unfractionated heparin. Baseline clinical characteristics, procedural success rate, major bleeding and occurrence of major adverse cardiac events (MACE, a composite of death, myocardial infarction or target lesion revascularisation) during 30 days and 1 year follow-up were recorded.

Results The median final ACT value was 312 s (IR 262 to 352). At 30 days, the rate of MACE, from the lower to upper groups was 2.7%, 4.0%, and 2.0%, respectively (p>0.05), and the rate of major bleeding was 1.2%, 0.9% and 0.6%, respectively (p>0.05). During the 1 year of follow-up, the incidence of myocardial infarction was less with the greatest ACT value (>320 s) than in the other 2 groups (4.0%, 7.9%, and 7.6%, respectively; p320 seconds remained associated with a 42% relative reduction in myocardial infarction (OR 0.51, 95% CI 0.24 to 0.89, p<0.05). The rate of major bleeding was 0.9%, 0.6% and 0.3%, respectively (p>0.05). Death and target vessel revascularisation remained similar in all groups for 320 seconds appears protective after transradial coronary stenting, and this benefit was maintained for <or =1 year. With a transradial approach and antiplatelet therapy, greater ACT values did not correlate with an increased risk of bleeding.