Assessment of coronary artery disease with second harmonic myocardial perfusion contrast echocardiography

To assess the relationship between myocardial regional perfusion using second harmonic myocardial contrast echocardiography (MCE) by venous injection of Levovist and coronary artery stenosis detected by coronary angiography to determine whe ther MCE can be used to detect coronary artery disease (CAD) and its sensitivity and specificity for detecting CAD.

Thirty-six patients who underwent coronary artery angiography and MCE formed the study groups. Ten myocardial segments (5 each in the apical two- and four-chamber views) from the images were scored for detecting myocardial perfusion as follows: 1, normal perfusion; 2, decreased perfusion; and 3, perfusion defect. The arteries were classified as normal or diseased. The diseased arteries were classified into three groups according to the perfusion scores.

There were significant differences in coronary diameter stenosis among the different perfusion score groups (P < 0.001). There were 10 total occluded arteries, and the myocardial perfusion scores were different because of different collateral circulation. In the normal perfusion group (Group A), the coronary diameter stenosis was 65% +/- 12%, and the myocardial perfusion score index was 1 +/- 0.00. In the decreased perfusion group (Group B), the average coronary diameter stenosis was 82% +/- 8%, and the myocardial perfusion score was 1.93 +/- 0.16. The diameter stenosis was less than 85% in 63% of the coronary arteries (including diameter stenosis < or = 75% in 12% of the vessels). The diameter stenosis was 85%-90% in 22% of the coronary arteries and > 90% in 15% of the arteries. In the perfusion defect group (Group C), the average diameter stenosis was 90% +/- 6%, and the myocardial perfusion score index was 2.89 +/- 0.24. The diameter stenosis was > or = 85% in 94% of the coronary arteries, and the diameter stenosis was < 85% and > 75% only in 6% of the coronary arteries. The overall sensitivity and specificity of MCE in identifying angiographic coronary diameter stenosis was 67% and 100%, respectively. The false negative rate was 32.6% for the 108 coronary arteries. Further subdivided analysis showed the sensitivities in Groups A, B and C were 0, 100%, and 100%, respectively. The sensitivity increased with increased lumen diameter stenosis of coronary arteries.

There is a close relationship between coronary artery stenosis and MCE perfusion scores. MCE with venous injection of new generation contrast can define the presence of CAD and lesion graded classifications. Some disagreements between perfusion score and coronary diameter of stenosis may indicate other factors such as different collateral circulation, which should be further investigated. As artery stenosis increases, the sensitivity of MCE is increased.