Effect of operator and institutional volume on clinical outcomes after percutaneous coronary interventions performed in Canada and the United States: a brief report from the Enhanced Suppression of the Platelet glycoprotein IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) study.

BACKGROUND: The Enhanced Suppression of the Platelet glycoprotein IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial compared the use of eptifibatide with placebo in 2064 coronary intervention patients. It was previously reported that Canadian patients had reduced rates of 30-day and one-year death, myocardial infarction (MI) or target vessel revascularization (TVR) compared with patients in the United States (US). OBJECTIVE: To examine whether operator or institutional volume differences explain the regional variation in clinical outcome. METHODS AND RESULTS: Each site received an operator and institutional volume survey. Fifty-seven sites (62%) returned complete data on 1338 patients. In this smaller cohort, Canadian patients had reduced rates of 30-day and one-year death, MI or TVR compared with US patients (6.3% versus 10.3% and 14.9% versus 20.1%, respectively; P<0.05 for both comparisons). Among 176 physicians with a median of 13 years experience, the median operator volume was 200 cases per year. Operators with fewer than 100 cases per year had higher rates of 30-day death, MI or TVR (13.2% versus 8.7%; P=0.18) and large MI (7.7% versus 3.3%; P=0.06) than those with 100 or more cases per year. The median institutional volume was 1064 cases per year. Canadian and US centres had similar operator and institutional volumes. By multivariate modelling, operator volume was not predictive of adverse clinical events. However, the rates of 30-day and one-year death, MI or TVR fell by 3% for every 100 patients treated by the institution (OR 0.97; P=0.058 and P=0.002, respectively). Enrollment in Canada was associated with improved outcomes at 30 days (OR 0.50; P=0.001) and one year (OR 0.66; P=0.001) despite inclusion of volume variables in the models. CONCLUSIONS: In the ESPRIT study, institutional volume was associated with a modest reduction in risk of death, MI or TVR over short- and long-term follow-up periods. The Canadian and US investigators and institutions selected in ESPRIT had similar annual procedural volumes. Therefore, volume variables did not explain the differential risk of clinical events observed for patients enrolled in the two countries.

Clopidogrel in interventional cardiology: questions answered and questions remaining.

Clopidogrel is appropriate as a replacement for ticlopidine when used in combination with acetylsalicylic acid in the setting of percutaneous coronary intervention (PCI). Compared with ticlopidine, clopidogrel has comparable efficacy in reducing adverse cardiac events and a lower risk of hematological toxicity; both medications have been associated with rare cases of the very serious syndrome of thrombotic thrombocytopenic purpura. Clopidogrel should preferably be initiated with a loading dose of 300 mg before PCI, because most cases of thrombotic stent occlusion occur shortly after stent implantation, and attainment of target platelet inhibition is delayed for several days if a loading dose is not given. Bypass surgery in patients recently treated with clopidogrel appears to be associated with a significant increase in hemorrhagic complications. Long term therapy with clopidogrel after PCI may decrease late thrombotic stent occlusion and late vascular events; this hypothesis is currently being evaluated in randomized trials. By inhibiting platelet activation, clopidogrel may have a mechanism of benefit that is independent of the potent inhibition of platelet aggregation produced by the glycoprotein IIb/IIIa inhibitors.