Usefulness of dipyridamole stress echocardiography for predicting graft patency after coronary artery bypass grafting

Noninvasive techniques often provide controversial results in patients who have coronary artery bypass grafts (CABGs). Vasodilator stress echocardiography allows semi-simultaneous imaging of CABG flow and segmental left ventricular wall motion. To assess the comparative and additive value of regional flow and function for noninvasive evaluation of graft patency status, we evaluated 110 consecutive patients who underwent CABG and who were scheduled for coronary angiography. All patients underwent stress echocardiography with dipyridamole (0.84 mg/kg) and atropine (1 mg), including wall motion analysis by 2-dimensional echocardiography and Doppler evaluation of flow reserve of each CABG. Echocardiographic findings were compared with angiographic data. Four patients had inadequate acoustic windows. The remaining 106 patients had 226 grafts performed. Stress echocardiography showed 67% sensitivity, 91% specificity, and 71% accuracy for identification of 50% to 100% stenosis in the graft or in the recipient coronary vessel. There was a fair agreement with angiography (kappa coefficient 0.60). Identification of impaired coronary bypass flow reserve (i.e., <1.9 for internal mammary grafts and <1.6 for saphenous vein grafts) by Doppler had 91% sensitivity, 88% specificity, and 89% accuracy for graft stenosis. There was good agreement with angiographic findings (kappa 0.77). The combination of the 2 techniques achieved 93% sensitivity, 93% specificity, and 93% accuracy, showing a very good agreement with the patency status of the grafts as evaluated at angiography (kappa 0.85). The combined assessment of wall motion and flow reserve in patients who underwent CABG is feasible and provides an accurate estimate of graft patency status by increasing sensitivity of stress echocardiography and specificity of Doppler flow reserve.