Exercise performance-based outcomes of medically treated patients with coronary artery disease and profound ST segment depression

OBJECTIVES We sought to determine the relationship between exercise duratio n and cardiovascular outcomes in patients with profound (greater than or eq ual to2 mm) ST segment depression during exercise treadmill testing (ETT). BACKGROUND Patients with stable symptoms but profound ST segment depression during ETT are often referred for a coronary intervention on the basis tha t presumed severe coronary artery disease (CAD) will lead to unfavorable ca rdiovascular outcomes, irrespective of symptomatic and functional status. W e hypothesized that good exercise tolerance in such patients treated medica lly is associated with favorable long-term outcomes. METHODS We prospectively followed 203 consecutive patients (181 men; mean a ge 73 years) with known stable CAD and greater than or equal to2 mm ST segm ent depression who are performing ETT according to the Bruce protocol for a n average of 41 months. The primary end point was occurrence of myocardial infarction (MI) or death. RESULTS Eight (20%) of 40 patients with an initial ETT exercise duration le ss than or equal to6 min developed MI or died, as compared with five (6%) o f 84 patients who exercised between 6 and 9 min and three (3.8%) of 79 pati ents who exercised greater than or equal to9 min (p = 0.01). Compared with patients who exercised less than or equal to6 min, increased ETT duration w as significantly associated with a reduced risk of MI/death (6 to 9 min: re lative risk [RR] = 0.25, 95% confidence interval [CI] 0.08 to 0.76; >9 min: RR = 0.14, 95% CI 0.04 to 0.53). This protective effect persisted after ad justment for potentially confounding variables. We observed a 23% reduction in MI/death for each additional minute of exercise the patient was able to complete during the index ETT. CONCLUSIONS Optimal medical management in stable patients with CAD with pro found exercise-induced ST segment depression but good MT duration is an app ropriate alternative to coronary revascularization and is associated with l ow rates of MI and death. (C) 2000 by the American College of Cardiology.