TRANSESOPHAGEAL ASSESSMENT OF CORONARY FLOW VELOCITY RESERVE DURING REGULAR AND HIGH-DOSE DIPYRIDAMOLE STRESS-TESTING

To assess the effect of regular and high-dose dipyridamole on coronary flow velocity in the left anterior descending artery (LAD), and to de termine whether assessment of coronary flow velocity reserve (CVFR) is more sensitive for detection of ischemia than standard echocardiograp hic criteria, 47 patients were studied prospectively: 16 patients with stenosis of the LAD, 18 patients with angiographically normal LADs, a nd 13 patients with minimal disease. Patients underwent trans-esophage al echocardiographic study of wall motion and LAD flow velocity at bas eline and at hyperemia, and for angina and electrocardiographic change s. The mean CFVR values after 0.56 mg/kg and after 0.84 mg/kg of dipyr idamole were similar: 2.52 +/- 0.87 versus 2.62 +/- 0.90. A CFVR <2.3 (normals mean -2 SDs) was more sensitive (88% at both doses) for the d etection of underlying coronary obstruction than was wall motion monit oring (44% and 75%, respectively). The combination of CFVR <2.3 and wa ll motion monitoring was more sensitive than either index alone (94% a t both 0.56 and 0.84 mg/kg). The rate-pressure product was not signifi cantly different at the two doses of dipyridamole. When flow response is the end point of stress testing, as with transesophageal monitoring , the 0.56 mg/kg dose of dipyridamole is adequate, but when ischemia i s the end point (as with wall motion monitoring by 2-dimensional echoc ardiography), the dose of 0.84 mg/kg is more sensitive.