A New Semi-Quantitative Parameter to Assess Functionally Significant Coronary Disease Using Myocardial Contrast Echocardiography.

Background: Quantitative flow ratio (QFR) can identify functionally significant coronary disease non-invasively. Myocardial contrast echocardiography (MCE) is a non-invasive and effective procedure for detecting abnormalities in hemodynamic coronary artery stenosis. Currently, there is no research confirming the correlation between MCE and QFR. This study aims to compare the capacity of the perfusion index (PI) from MCE to diagnose functionally significant coronary disease in patients with chest pain. The investigators use QFR as the gold standard for comparison.

Methods: 112 patients referred for coronary angiography (CAG) due to suspicion of coronary artery disease (CAD) were included. 64 patients with functionally significant coronary disease were diagnosed. 48 patients were defined as CAD without functionally significant coronary disease. MCE was performed 24 h before angiography. PI was calculated for each triggering interval by adding the perfusion scores of segments and dividing by the number of segments. Logistic regression analyses were performed to evaluate the association among functionally significant coronary disease, echocardiographic and clinical parameters. Spearman correlation analysis was used to investigate the correlation between PI and QFR. A receiver operating characteristic (ROC) curve was used to assess the capability of echocardiographic and clinical parameters to diagnose functionally significant coronary disease.

Results: Patients with functionally significant coronary disease had the worse perfusion in MCE compared with those without functionally significant coronary disease. In multivariable logistic regression analysis, global perfusion index (GPI) (OR: 43.409, p < 0.001) was associated with functionally significant coronary disease in patients with CAD. Based on the Spearman correlation analysis. Left anterior descending artery (LAD)-PI showed a strong negative correlation with LAD-QFR (r = -0.652, p < 0.01). ROC curves showed LAD-PI to be superior to GPI, left circumflex artery PI (LCX-PI) and right coronary artery PI (RCA-PI) in identifying functionally significant coronary disease.

Conclusions: The PI derived from MCE has diagnostic value for functionally significant coronary disease with QFR ≤0.80 in 1 or more vessels, with LAD-PI showing the highest diagnostic efficiency. GPI is independently associated with functionally significant coronary disease, but among the branch PIs, LAD-PI has the highest diagnostic efficiency.