Slow Coronary Flow is Related to Increased Carotid Intima-Media Thickness but Not Pulse Wave Velocity

Background and Objectives: Slow coronary flow (SCF) is characterized by delayed contrast dye opacification without significant stenosis of epicardial coronary arteries. However, the pathophysiology and clinical implications of SCF are not fully understood. Some reports have suggested that SCF might be caused by atherosclerosis in the coronary artery microvasculature. Measuring carotid intima-media thickness (IMT) and pulse wave velocity (PWV), which are non-invasive and simple diagnostic tools, was developed to detect subclinical atherosclerosis. Thus, we determined IMT and PWV, and their possible relationship in a SCF group and a normal coronary flow (NCF) group of patients. Subjects and Methods: We included 101 patients who complained of chest pain but had a normal coronary angiogram. Thrombolysis in Myocardial Infarction frame count (TIMI frame count, TFC) was evaluated in the left and right coronary arteries. We defined SCF as a TFC of more than 25. Carotid IMT was measured by ultrasonography in both common carotid arteries. PWV was calculated from pulse transit time between the brachial and ankle arteries. Results: Fifteen patients were included in the SCF group and 86 patients in the NCF group. Male patients (n=11, 73.3%) were significantly more common in the SCF group than in the NCF group (n=37, 43.0%, p<0.05). The TFC of the SCF and NCF groups were 28.8${\pm}$3.5 and 15.7${\pm}$4.5, respectively. The carotid IMT in the SCF group increased significantly compared to that in the NCF group (1.2${\pm}$0.3 mm vs. 0.8${\pm}$0.1 mm, p<0.01). However, no significant difference in PWV was observed between the two groups. Conclusion: SCF may reflect early atherosclerotic changes in the coronary artery microvasculature.