Differential value of adenosine myocardial contrast echocardiography and dobutamine stress echocardiography in evaluating functional significance of coronary artery stenosis in a porcine model

Aim Myocardial contrast echocardiography (MCE) during adenosine induced hyperemia is an experimental method that detects flow limiting coronary artery stenosis by visualizing myocardial perfusion defects. Noninvasive detection of flow limiting coronary artery stenosis in clinical routine is a frequent domaine of dobutamine stress echocardiography (DSE) visualizing ischemia related regional wall motion abnormalities. This study investigated the values of adenosine MCE and DSE in the detection of functionally significant coronary artery stenosis in an experimental open chest pig model. Methods A total of 28 proximal LAD stenoses were instrumented in 12 animals. Reduction of coronary blood flow reserve (Delta CFR [%]) was calculated as a marker of functional significance of coronary artery stenosis (mild to moderate stenosis: Delta CFR less than or equal to 50%; severe stenosis: Delta CFR > 50%). Fractional area shortening (FAS) and wall thickening (WT) were calculated to evaluate regional wall motion. Peak myocardial contrast intensities (PCI) were measured following aortic root injections of Levovist' to detect myocardial perfusion defects. Results As a group, severe stenosis significantly reduced wall motion response to dobutamine (Delta FAS: 12.0 +/- 3.0%, vs. 20 +/- 3.0% without stenosis, p < 0.05; Delta WT: 2.2 +/- 0.9 mm vs. 0.0 +/- 0.8 mm without stenosis, p < 0.05) and diminished myocardial opacification during hyperemia (PCI: 59 +/- 8 units vs. 143 +/- 16 units without stenosis, p < 0.05). Mild to moderate stenosis did not influence wall motion but reduced myocardial opacification (PCI 89 +/- 14 units vs. 143 +/- 16 units). PCI correlated more closely with alterations in CFR (r = -0.7, p < 0.0001) than did FAS (r = -0.5, p < 0.002) or WT (r = -0.2, p = 0.3). Conclusion Adenosine myocardial contrast echocardiography detects flow limiting coronary artery stenosis and compares favorably to regional wall motion analysis during dobutamine infusion.