Myocardial blood volume and perfusion reserve responses to combined dipyridamole and exercise stress: a quantitative approach to contrast stress echocardiography.
BACKGROUND
Qualitative interpretation of myocardial contrast echocardiography (MCE) improves the accuracy of wall-motion analysis for assessment of coronary artery disease (CAD). We examined the feasibility and accuracy of quantitative MCE for diagnosis of CAD.


METHODS
Dipyridamole/exercise stress MCE (destruction-replenishment protocol with real-time imaging) was performed in 90 patients undergoing quantitative coronary angiography, 48 of whom had significant (> 50%) stenoses. MCE was repeated with exercise alone in 18 patients. Myocardial blood flow (A*beta) was obtained from blood volume (A) and time to refill (beta).


RESULTS
Quantification of flow reserve was feasible in 88%. The mean A*beta reserve in the anterior wall was significantly impaired for patients with left anterior descending coronary artery disease (n = 28) compared with those with no disease (1.6 +/- 1.2 vs 4.0 +/- 2.5, P < or = .001). This reflected impaired beta reserve, with no difference in the A reserve. Applying a receiver operating characteristic curve derived cutoff of 2.0 for A*beta reserve, quantitative MCE was 76% sensitive and 71% specific for the diagnosis of significant left anterior descending coronary artery stenosis. Posterior circulation results were similar, with 78% sensitivity and 59% specificity for detection of posterior CAD. Overall, quantitative MCE was similarly sensitive to qualitative approach for diagnosis of CAD (88% vs 93%), but with lower specificity (52% vs 65%, P = .07). In 18 patients restudied with pure exercise stress, the mean myocardial blood flow reserve was less than after combined stress (2.1 +/- 1.6 vs 3.7 +/- 1.9, P = .01).


CONCLUSIONS
Quantitative MCE is feasible for the diagnosis of CAD with dipyridamole/exercise stress. Dipyridamole prolongs postexercise hyperemia, augmenting the degree of hyperemia at the time of imaging.
Moir
Stuart
S
University of Queensland, Brisbane, Australia.
Haluska
Brian A
BA
Jenkins
Carly
C
McNab
Duncan
D
Marwick
Thomas H
TH
D001811:Blood Volume Determination / Q000379:methods; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging*; D003326:Coronary Circulation; D004176:Dipyridamole; D004452:Echocardiography / Q000379:methods*; D005080:Exercise Test; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014665:Vasodilator Agents / Q000627:therapeutic use; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology
D014665:Vasodilator Agents; D004176:Dipyridamole