The Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry in patients with unstable angina

Clinical approaches to the prevention of the potentially catastrophic conse quences of coronary ischemic phenomena such as unstable angina and suspecte d non-Q-wave myocardial infarction (MI) differ across the world. in additio n to prevailing physician beliefs in different societies, the level of acce ss to catheterization laboratories largely determines whether an interventi onist or conservative strategy is adopted. The Organization to Assess Strat egies for Ischemic Syndromes (OASIS)-a prospective registry of approximatel y 8,000 patients with acute myocardial ischemia with no ST elevation, treat ed in 95 hospitals across 6 countries-furnished a unique window into region al differences in clinical management and the frequency and timing of invas ive procedures (i.e., angiography, percutaneous transluminal coronary angio plasty [PTCA], and coronary artery bypass graft [CABG] surgery), as well as the outcomes of these trends. At 6 months after symptom onset, patients in the United States and Brazil, where the catheterization laboratory facilit ies are more accessible, underwent significantly (p <0.001) more angiograph y (69.4%), PTCA (23.6%), and CABG (25.2%) than in Canada and Australia, whe re the corresponding rates were 48.4%, 17.0%, and 16.8% (p <0.001), respect ively; and in Hungary and Poland, where the respective rates were 23.5%, 5. 8%, and 10.9% (p <0.001). This relatively aggressive approach led at 6 mont hs to a more substantial decrease in refractory angina in the United States and Brazil than in Canada and Australia (20.4% vs 13.9%; p <0.001), but no improvement in rates of cardiovascular mortality and MI (10.5% versus 10.5 %; p = 0.36). There was a significant (p less than or equal to 0.012) incre ase in stroke, (1.9% vs 1.3%; p = 0.010) and major bleeding (1.9% vs 1.1%; p = 0.009) events. Furthermore, an inverse correlation emerged between base line cardiovascular risk status and frequency of angiography and PTCA inter ventions preferentially for low-risk compared with high-risk patients. In c oncert with findings from other recent randomized trials, the OASIS Registr y data suggest that although there are fewer hospital readmissions for unst able angina, there is a trend toward increased rates of death, MI, and stro ke. These data urge a cautious approach to the use of invasive procedures i n patients with unstable angina unless future trials demonstrate a clear be nefit with on aggressive approach. (C) 1999 by Excerpta Medico, Inc.