Relationship between carotid artery stiffness and total serum homocysteine in coronary slow flow phenomenon: a high-resolution echo-tracking study.

Background: Coronary slow flow phenomenon (CSFP) is not uncommon in conventional coronary angiography. A disorder of serum homocysteine (tHcy) metabolism may play a role in the pathogenesis of slow coronary flow. Moreover, elevated tHcy concentration is closely associated with atherosclerosis. We aimed to evaluate the relationship between carotid artery stiffness and serum tHcy levels in patients with CSFP.

Methods: This was a case-control study. The study population comprised 146 patients with newly diagnosed stable angina, including 73 patients with CSFP and 73 patients with normal coronary flow. All participants underwent conventional coronary angiography, carotid ultrasonography, and biochemical examination.

Results: The carotid artery stiffness parameters of β index (β), pressure-strain elastic modulus (Ep), and local pulse wave velocity (PWV) in the CSFP group were significantly higher than those in the control group (β: 10.75±2.16 9.02±2.11, P=0.007; Ep: 147.41±41.22 116.21±39.21, P=0.004; PWV: 7.45±1.23 6.16±1.20, P=0.003), However, arterial compliance (AC) was lower in the CSFP group than the control group (0.52±0.11 0.69±0.24, P=0.008). The mean thrombolysis in myocardial infarction (TIMI) frame count and the tHcy concentration in the CSFP group were significantly higher than those in the control group (48.60±1.30 24.50±3.80, P=0.001; 19.95±4.00 9.12±2.72, P=0.009). The tHcy concentration was positively correlated with β (R value =0.494, P<0.0001), Ep (R value =0.469, P<0.0001), and PWV (R value =0.436, P<0.0001), but negatively correlated with AC (R value =-0.230, P=0.022). The predictors of CSFP were tHcy concentration, left PWV, right PWV, left β index, and right β index. Among them, the left β index and right β index were the best indictors for predicting CSFP. The cutoff values of left β index, right β index, left PWV, and right PWV were 9.3, 9.3, 6.7, and 6.6, respectively.

Conclusions: Our data showed that serum tHcy levels were elevated in patients with CSFP compared with the control group. Carotid artery stiffness parameters were correlated with tHcy. The best predictors of CSFP were left β index and right β index. These findings may contribute to a better understanding of systemic vascular disorders in patients with coronary slow flow, rather than simply attributing such disorders to a single and isolated lesion of the epicardial coronary artery.