Patterns of exercise treadmill test performance in patients with left main coronary artery disease: detection dependent on left coronary dominance or coexistent dominant right coronary disease

The exercise treadmill test (ETT) performance of 60 patients with angiographically documented left main coronary artery (LMCA) disease (LMD) was analyzed to determine the spectrum of ETT response in this distinct subset of patients with coronary disease (CAD). The location and extent of CAD was also determined to assess its effect on exercise response in patients having LMD. The ST segment response indicated ischemia in 46 patients (77%), and only one patient (2%) achieved a maximum predicted heart rate (HR) with a negative ST segment response. During ETT exertional hypotension developed in six patients (10%), frequent ventricular ectopic beats occurred in 19 patients (32%), and ST segment elevation occurred in five patients (8%). A "markedly positive" ETT response, defined as either ≥ 2.0 mm ischemic ST segment depression, a positive ST segment response in stage I of the Bruce protocol, termination of the exercise test in stage I or II, or the development of exertional hypotension was observed in 53 patients (88%). A "benign" treadmill test response, defined as either a negative test at the maximum predicted HR or the ability to exercise at least to stage IV, was observed in only four patients (7%). Patterns of coronary anatomy were divided into group I (nine patients), where only portions of the myocardium were in jeopardy of ischemia (patients with an obstruction in the LMCA but with a normal dominant right coronary artery [RCA]); and group II (51 patients), where the entire myocardium was in jeopardy (patients with LMD and either a dominant left coronary artery or a dominant RCA which was obstructed). There was a significantly higher prevalence in group II vs group I of exercise-induced frequent ventricular ectopic beats (19 patients vs 0 patient), termination of the treadmill test in stage I (28 patients vs 0 patients), and marked ischemic ST segment depression ≥ 2.0 mm (30 patients vs 2 patients), all p