The coronary flow reserve in patients with coronary slow flow and diagnostic value of myocardial work indices for coronary slow flow

ObjectiveTo explore the coronary flow reserve (CFR) in patients with coronary slow flow (CSF) and the diagnostic value of non-invasive myocardial work indices derived from echocardiography for CSF. MethodsA retrospective study was conducted on 65 patients who underwent coronary angiography at the Zhongshan Hospital (Xiamen Branch), Fudan University due to angina pectoris, coronary artery risk factors, or electrocardiographic abnormalities from August 2020 to November 2023. Patients were divided into two groups based on the corrected TIMI frame count (cTFC): the CSF group (n＝35) and the normal coronary blood flow velocity group (control group, n＝30). Both groups underwent an adenosine triphosphate (ATP) drug load test to measure their coronary flow reserve (CFR). Conventional indices and myocardial work indices via echocardiography and two-dimensional speckle-tracking imaging (2D-STI) were acquired: left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left ventricular ejection fraction (LVEF), E/e' ratio, global longitudinal strain (GLS), global constructive work (GCW), global wasted work (GWW), global work index (GWI), and global work efficiency (GWE). Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic value of myocardial work indices for CSF. ResultsThere was no significant difference in CFR values between the two groups, but the proportion of CSF group with CFR less than 2 was higher than that of the control group (P＝0.023). Compared with the control group, the CSF group showed significantly lower levels of GLS, GWI, and GCW (P＜0.05). ROC curve analysis revealed that the GLS diagnostic threshold for CSF was −19.5%, with a sensitivity of 64.7%, specificity of 78.6%, and AUC of 0.793. Among the myocardial work indices, the AUC of GWI was the highest (0.825), with a sensitivity of 88.2% and specificity of 75.0%. ConclusionsSome CSF patients retain coronary microcirculatory blood flow reserve function, but the proportion of patients with reduced CFR function is increasing. The left ventricular myocardial work indices can identify early myocardial work abnormalities and monitor myocardial ischemic damage in CSF patients.