Quantitative assessment of microcollateral recruitment during coronary occlusion using real-time intravenous myocardial contrast echocardiography

The value of quantitative real-time myocardial contrast echocardiography for detection of angiographically significant coronary artery disease

BACKGROUND

Real-time (RT) myocardial contrast echocardiography (MCE) is a novel method for the assessment of regional myocardial perfusion. We sought to evaluate the feasibility and diagnostic accuracy of quantitative RT-MCE in predicting significant coronary stenosis, with reference to quantitative coronary angiography.

HYPOTHESIS

RT-MCE can identify anatomically significant coronary artery stenosis in selected patients. RT-MCE is probably an effective method for detection of angiographically significant coronary artery stenosis.

METHODS

Thirty-five patients (mean age, 59.94 ± 10.63 years; 25 males) scheduled for coronary angiography underwent RT-MCE at rest, and shortly afterward underwent gated single-photon emission computed tomography (gated-SPECT). Coronary angiography was performed within 1 week after RT-MCE in all patients. The observing indexes included the images of RT-MCE that were analyzed quantitatively from microbubble replenishment curves for myocardial perfusion by using the Q-Lab software. The sensitivity and specificity of RT-MCE for quantitative detection of coronary artery disease (CAD) were obtained. The receiver operator characteristic (ROC) curves were used to assess the differences of accuracy in ischemic segments with A, β and A × β respectively. The sensitivity and specificity of gated-SPECT and RT-MCE for assessment of CAD were calculated using a 4-score method.

RESULTS

A total of 513 segments among 595 segments in 35 patients were obtained. The cutoffs for A, β and A × β were 4.58, 0.64, and 2.73, and the sensitivity and specificity of quantitative RT-MCE for detection of CAD were 86.0%, 80.2%, 88.9%, and 84.1%, 64.6%, 79.9%, respectively. Meanwhile, the sensitivity and specificity of semiquantitative analysis for assessment of CAD were 66.7% and 61.8%. The ROC curve area of A and A × β was 0.91 and 0.90 in the middle segments. The ROC area of A was 0.52 in the base segments. The sensitivity and specificity of gated-SPECT for assessment of CAD were 84.8% and 82.7%, respectively. The sensitivity of multi-indexes RT-MCE increased. The sensitivity was 89.1%, 90.4%, and 96.3% by A + β, A + A × β, and β + A × β.

CONCLUSIONS

Quantitative RT-MCE is an effective method for the detection of coronary artery stenosis. Quantitative RT-MCE is segmented for assessment to ischemic myocardium. RT-MCE with multi-indexes has a valuable application for assessment of CAD surpassing SPECT.

[Update on cardiac imaging techniques: echocardiography, cardiac magnetic resonance, and multidetector computed tomography]

This article contains a review of the most important publications on cardiac imaging that have appeared during 2008. During the year, we assisted with the clinical implementation of three-dimensional real-time transesophageal echocardiography, with the use of echocardiography for selecting patients for and monitoring those who underwent percutaneous aortic valve replacement (the majority of centers performing the technique were still in the learning phase), and with the emergence in the clinic of techniques for studying myocardial deformation. Also reviewed are the most significant developments in the application of echocardiography to coronary heart disease and cardiac resynchronization therapy and in 2 other techniques whose use is constantly increasing: cardiac magnetic resonance and multidetector cardiac computed tomography. The review ends with a description of the current state of the art in contrast echocardiography, with particular emphasis on safety in the context of recommendations made by the US Food and Drug Administration at the end of 2007.