Usefulness of exercise electrocardiography and thallium scintigraphy in unstable angina pectoris in predicting the extent and severity of coronary artery disease.

The safety and efficacy of exercise electrocardiography and thallium scintigraphy early in the course of unstable angina pectoris were assessed 4.6 +/- 1.6 days after admission in 67 patients with unstable angina that stabilized after medical therapy. Coronary arteriography was performed in all patients 5.4 +/- 2.4 days after admission. There was no difference in clinical, exercise or scintigraphic variables between patients with stenoses less than 50% and patients with 1-vessel coronary artery disease (CAD) defined as a diameter stenosis greater than or equal to 50%. Patients with 3-vessel CAD had a significantly shorter exercise duration than patients with less than 50%-diameter narrowing (5.5 +/- 2.2 vs 8.3 +/- 3.3 minutes, respectively), lower exercise heart rate (119 +/- 20 vs 149 +/- 22 beats/min) and systolic blood pressure (156 +/- 29 vs 166 +/- 33 mm Hg), more frequent chest pain (76 vs 20%) and more pronounced ST depression (-1.48 +/- 1.37 vs -0.33 +/- 0.72 mm). In addition, thallium defect size on exercise was greater in the patients with 2-vessel CAD (159 +/- 132 degrees) and 3-vessel CAD (255 +/- 132 degrees) than in patients with no CAD (28 +/- 319 degrees) or 1-vessel CAD (73 +/- 78 degrees), p greater than or equal to 0.05. Multiple regression analysis demonstrated that thallium defect size was the best predictor of extent of CAD, with exercise heart rate and presence of chest pain during exercise also predictive of extent of CAD.(ABSTRACT TRUNCATED AT 250 WORDS)