Factors associated with failure of medical therapy in patients with unstable angina and non-Q wave myocardial infarction - A TIMI-IIIB database study

Context Current management of patients with unstable angina and non-Q wave myocardial infarction generally consists of intensive medical therapy, with angiography and revascularization sometimes limited to those who fail such therapy. Aim To determine if certain baseline characteristics are predictive of pati ents who fail medical therapy, since such patients could then be expeditiou sly directed to a more invasive strategy in a cost-effective manner. Methods The study cohort consisted of the 733 patients in the Thrombolysis in Myocardial Ischemia (TIMI) IIIB study who were randomized to conservativ e strategy. Patients were to be treated with bedrest, anti-ischaemic medica tions, aspirin, and heparin, and were to undergo risk-stratifying tests, co nsisting of an exercise test with ECG and thallium scintigraphy, scheduled to be performed within 3 days prior to, or 5 days after, hospital discharge and 24 h Holter monitoring scheduled to begin 2-5 days after randomization . Baseline clinical and ECG characteristics were compared between patients who 'failed' medical therapy and those who did not 'fail'. Failure was defi ned using clinical end-points (death, myocardial infarction, or spontaneous ischaemia by 6 weeks after randomization) or a strongly positive risk-stra tifying test. For each test an ordered failure profile of results was calcu lated and consisted of death, myocardial infarction, or rest ischaemia occu rring prior to performance of the test, a markedly abnormal test result, an d no abnormality. Results Clinical end-points occurred in 241 (33%) patients and were more li kely to occur in patients who at presentation were older, had ST-segment de pression on the qualifying EGG, or were being treated with heparin or aspir in. Characteristics independently predictive of developing a clinical event or an abnormal exercise treadmill test included: ST-segment depression on the qualifying EGG, history of prior angina, family history of premature co ronary disease (i.e. onset <55 years of age), prior use of heparin or aspir in, and increasing age. By combining these baseline risk characteristics fo r each outcome the incidence of developing a clinical event ranged from 8% if none was present to 63% if all six were present, and of developing a mar kedly abnormal risk stratifying test from 8-21% if none were present to app roximately 90% if all six were present. Conclusions Baseline characteristics associated with developing a clinical event or a markedly abnormal risk stratifying test were similar: rest angin al episode accompanied by ST-segment depression and occurring despite treat ment with aspirin and heparin, a history of angina, older age, and family h istory of coronary disease. Patients with these characteristics are appropr iate candidates for expeditious cardiac catheterization and consideration f or revascularization, while patients without them may be suitable for medic al management alone.