Background: Most patients with acute myocardial infarction (AMI) are admitted to hospitals without percutaneous transluminal coronary angioplasty (PTCA) facilities or are initially managed in a prehospital mobile unit. Thrombolysis remains the most readily available reperfusion treatment in those settings, but the optimal subsequent strategy in those patients is unclear. If a mechanical recanalization is likely to be performed in an emergency, it is probably desirable that the patient receives abciximab, the glycoprotein IIb/IIIa antagonist with the strongest evidence of benefit for angioplasty in AMI.
Objective: The aim of this trial is to compare the effects on clinical outcome and cost-effectiveness of 2 strategies after immediate treatment with abciximab and half-dose reteplase for ST-elevation AMI: to manage the patients conservatively (referring them for rescue PTCA only if needed) or to immediately send all patients for emergency coronary angioplasty.
Methods: The Combined Abciximab RE-teplase Stent Study in Acute Myocardial Infarction (CARESS in AMI) is an open, prospective, randomized, multicenter clinical trial conducted in patients with high-risk ST-segment elevation AMI treated within 12 hours from symptom onset in hospitals without PTCA facilities or in a prehospital mobile intensive care unit. Apart from contraindications to thrombolysis, the main exclusion criteria are age > or =75 years and a past history of CABG surgery or a percutaneous coronary intervention procedure involving the infarct-related artery. Enrollment will be performed in hospitals without PTCA facilities or directly in the ambulance if a dedicated system is in place for prehospital diagnosis and treatment of AMI. Patients will receive half-dose reteplase and full-dose abciximab and will subsequently be randomized to conventional medical therapy (with referral for emergency rescue PTCA allowed in selected cases) or emergency angioplasty. The primary end point is the 30-day combined incidence of mortality, reinfarction, and refractory ischemia. In order to obtain a 95% power (2-sided) to detect a 42% reduction in the primary end point, 900 patients are required in each arm of the study. Secondary end points include the 1-year composite end point of mortality, reinfarction, refractory ischemia, and hospital readmission because of heart failure; resource use at 30 days and 1 year; and the incidence of inhospital stroke and bleeding complications in the 2 groups.
Results: Seventy-four patients have been randomized (as of March 10, 2004); results are expected in June 2005.
Conclusion: This study will establish whether angioplasty must be started as soon as possible in all patients who receive combined pharmacologic reperfusion with the glycoprotein IIb/IIIa inhibitor abciximab and half-dose thrombolysis or whether it can be postponed or skipped in patients with signs of successful reperfusion, with obvious organizational advantages.