Quantitative stress echocardiography in coronary artery disease using contrast-based myocardial blood flow measurements: prospective comparison with coronary angiography

Abstract

Aim: To test whether quantitative stress echocardiography using contrast-based myocardial blood flow (MBF, ml.min⁻¹.g⁻¹) measurements can detect coronary artery disease in humans.

Methods: 48 patients eligible for pharmacological stress testing by myocardial contrast echocardiography (MCE) and willing to undergo subsequent coronary angiography were prospectively enrolled in the study. Baseline and adenosine-induced (140 μg.kg⁻¹.min⁻¹) hyperaemic MBF was analysed according to a three-coronary-artery-territory model. Vascular territories were categorised into three groups with increasing stenosis severity defined as percentage diameter reduction by quantitative coronary angiography.

Results: Myocardial blood flow reserve (MBFR)—that is, the ratio of hyperaemic to baseline MBF, was obtained in 128 (89%) territories. Mean (SD) baseline MBF was 1.073 (0.395) ml.min⁻¹.g⁻¹ and did not differ between territories supplied by coronary arteries with mild (<50% stenosis), moderate (50%–74% stenosis) or severe (≥75% stenosis) disease. Mean (SD) hyperaemic MBF and MBFR were 2.509 (1.078) ml.min⁻¹.g⁻¹ and 2.54 (1.03), respectively, and decreased linearly (r2 = 0.21 and r2 = 0.39) with stenosis severity. ROC analysis revealed that a territorial MBFR <1.94 detected ≥50% stenosis with 89% sensitivity and 92% specificity.

Conclusion: Quantitative stress testing based on MBF measurements derived from contrast echocardiography is a new method for the non-invasive and reliable assessment of coronary artery disease in humans.