Different degrees of ischemic threshold stratified by the dipyridamole-echocardiography test

Dipyridamole-echocardiography (echo) testing, exercise stress testing and coronary arteriography were performed in 141 patients with effort chest pain. Patients were separated into 5 groups according to the dose of dipyridamole needed to induce ischemia (0.56 mg/kg over 4 minutes vs 0.84 mg/kg over 10 minutes) and to the time of onset of the asynergy with the small dose (within vs beyond 3 minutes after the end of dipyridamole administration): group 1--early positive response to a small dose (33 patients); group 2--late positive response to a small dose (29 patients); group 3--negative response to a small dose, positive response to a large dose (17 patients); group 4a--negative response to both large and small doses, with significant coronary artery disease (CAD) (32 patients); and group 4b--negative response to small and large doses, without CAD (30 patients). All patients in groups 1, 2 and 3 had significant CAD. The rate-pressure product on exercise stress testing was measured at 0.10 mV of ST-segment shift in patients with a positive response and at peak exercise in patients with a negative response. Rate-pressure product significantly separated group 1 and group 2 from each other (157 +/- 46 and 229 +/- 33 mm Hg X beats/min X 1/100, respectively, mean +/- standard deviation) and from group 3, group 4a and group 4b (284 +/- 40, 290 +/- 51, and 298 +/- 45 mm Hg X beats/min X 1/100); values in the 3 latter groups overlapped.2+ Thus, the dipyridamole-echo test can stratify groups of patients with different levels of ischemia threshold on effort.