Observation of the ischemic cascade in humans using contrast echocardiography during dobutamine stress

Abstract

Experimental studies have postulated the ischemic cascade and the present study was designed to elucidate whether it can be observed in the clinical setting. Fifty-three patients suspected of having coronary artery disease were studied. Myocardial perfusion abnormalities (MPA) and wall motion abnormalities (WMA) were assessed simultaneously by infusion of Levovist during dobutamine stress echocardiography. Time-intensity data of myocardial opacification were fitted for Y=A (1-e-βt) from which the rate of increase (β) of intensity were derived both at rest and during stress. Wall motion was also given a score. Bright opacification was observed in 50 patients: 25 showed significant stenosis (>50%) in the left anterior descending artery (group II) on coronary angiography and 25 did not (group I). Significant differences were found in the β ratio (stress/rest) between the 2 groups at a low-dose (2.0±0.3 vs 1.5±0.5, p<0.05) and at a high-dose of dobutamine (2.7±1.0 vs 1.1±0.5, p< 0.001), whereas the wall motion score differed only at a high-dose. Of the 25 patients in group II, MPA preceded WMA in 12, both occurred at the same stage in 12, and neither MPA nor WMA was seen in 1. These data prove the ischemic cascade clinically, using contrast echocardiography, by demonstrating that MPA precede WMA during dobutamine stress in patients with coronary stenosis.