In the present study, atherosclerosis-related data, including ABI, BaPWV, PP, and AIx@75, differed significantly among the three groups. With aggravation of coronary artery stenosis, indicators of arteriosclerosis included decreased ABI and SEVR and increased BaPWV, PP, and AIx@75. Atherosclerosis is an independent cardiovascular risk factor and a predictor of all-cause cardiovascular mortality in many diseases [21, 22]. The gold-standard noninvasive method to measure central arterial stiffness is the pulse wave velocity test [23, 24]. Currently, age is generally accepted as an independent risk factor for coronary atherosclerosis. Many clinical trials have confirmed the correlation between the aforementioned indicators and CVD. Indicators commonly used to evaluate the degree of atherosclerosis include SBP, PP, AIx@75, ABI, and BaPWV. PP may be a major determinant of small-artery disease, which usually manifests as expanded arterial stiffness. PP and SBP are independent risk factors for CHD. Brachial PP is an independent risk factor for CHD [25, 26]. AIx is an indirect marker of arterial stiffness [27, 28]. Weber et al. found that a higher AIx correlated with a higher risk of CHD [29]. The aortic AIx values were significantly higher in the CHD group than in the control group [30]. The pulse wave velocity is an independent predictor of cardiovascular events after adjusting for risk factors of CHD. However, a recent study has shown that BaPWV predicts total mortality but not CVD incidence [31]. In this study, BaPWV showed an increasing trend with aggravation of coronary artery stenosis but no correlation with the SYNTAX score in patients with CHD. These results suggested that the carotid–femoral pulse wave velocity is better than BaPWV in representing the degree of central atherosclerosis. Our findings were consistent with those of Tritakis et al., whose multivariate analysis showed that decreased coronary flow reserve correlated negatively with AIx [32]. Age-related arterial stiffness is more common in the aorta than in the peripheral arteries [33]. ABI measurements are used in clinical practice to diagnose PAD. An ABI of 0.9 indicates the existence of PAD and is associated with an independent risk of cardiovascular events [34]. In patients with CHD, arteriosclerosis increases the post-systolic load of the left ventricle, resulting in increased oxygen demand. Coronary stenosis diminishes diastolic coronary artery perfusion pressure and oxygen delivery. This imbalance in oxygen supply and demand between the coronary artery and the myocardium leads to subendocardial ischemia. In the present study, ABI was low in patients with CHD and associated with high SYNTAX scores. However, it remained within the normal range and not was not consistent with PAD. Even slight changes in ABI affect the evolution of arteriosclerotic lesions. The ABI, BaPWV, and AIx are arterial stiffness parameters. Therefore, this method may not determine the severity of CAD. Arterial elasticity measures can identify an increased cardiovascular risk; nonetheless, CAD should only be confirmed using additional techniques [35]. Therefore, we used a more representative indicator of coronary ischemia, i.e., SEVR.
SEVR is a noninvasive method to assess myocardial perfusion and the prognostic value of CVD [36]. It is significantly low in patients with zero- and three-vessel CHDs [37]. In this study, it was lower in the high stenosis group than in the control and low stenosis groups classified according to the SYNTAX score. Further, it was lower in the low stenosis group than in the control group, although without statistical significance. The severity of atherosclerotic CHD lesions correlates with low SEVR. In addition, the link between SEVR and the SYNTAX score persists even after accounting for numerous conventional risk factors of atherosclerosis, including cholesterol and low-density-lipoprotein cholesterol levels, SBP, and the heart rate. Patients with CHD showed a negative correlation between SEVR and the SYNTAX score. Severe coronary stenosis is accompanied by a gradual decrease in SEVR. The coronary arteries are located in the outer membrane of the heart. As coronary artery stenosis increases, subendocardial myocardial ischemia gradually worsens, and the SEVR decreases proportionally.
The severity of coronary atherosclerosis is inherently linked to age. In patients with more frequent unfavorable cardiovascular events, the low SEVR and ABI and high AIx are mostly linked to the systemic nature of atherosclerosis and the concurrent existence of atherosclerosis in various arterial regions. In this regard, at the time of chest pain consultation, patients with apparently decreased SEVR show a significantly higher chance of coronary stenosis than those with normal SEVR. Significant decline in SEVR is a hallmark of myocardial ischemia. As a preliminary screening method for CHD, SEVR has advantages of accessibility, repeatability, and low cost.
In the present study, even in the participants with normal coronary arteries, SEVR was lower than 1.3, suggesting an association with the presence of other diseases, such as hypertension and diabetes simultaneously. Thus, the presence of comorbidities other than CHD affects SEVR. Further, patients with severe coronary stenosis had lower SEVR, possibly because of more significant subendocardial myocardial ischemia in the presence of severe coronary stenosis. Many clinical tests can represent subendocardial myocardial ischemia, including cardiac magnetic resonance and myocardial nuclear examinations, but they require higher financial and physical costs. This study validates a non-invasive, inexpensive and convenient means of detecting the severity of coronary heart disease.
This study has some limitations. Many clinical tests reveal subendocardial myocardial ischemia, including cardiac magnetic resonance imaging and myocardial nuclear scanning. SEVR is superior to both these tests for noninvasive testing.