In this study we showed a positive correlation between arterial stiffness parameters and CAD proved with coronary angiography. Also, our study showed the correlation between PWV and ISR.
Some previous studies showed the correlation between arterial stiffness and CAD [
20‐
22]. In the most of them CAD was proved with non-invasive methods. Several studies demonstrated the correlation between CAD examined with coronary angiography and arterial stiffness. Liu et al. showed positive correlation between arterial stiffness measured by Sphygmocor and CAD proved with multi slice computed tomography coronary angiography [
23]. Imanishi et al. concluded that high brachial–ankle PWV is an independent predictor for the presence of CAD, especially in men [
24]. Contrary to our investigation, the arterial stiffness in the mentioned studies was proved with different devices and at different blood vessels or coronary artery disease was not identified at coronary angiography. Only one study investigated the correlation between CAD and PWV measured by Arteriograph. Similar to our study, they found the positive correlation between CAD examined with coronary angiography and arterial stiffness [
7]. However, despite high differences between PWV and AIx in the control and CAD group, we also did not find the correlation between the CAD grades (defined by SYNTAX score) with PWV and AIx. But still, in this study we proved a correlation between arterial stiffness and left main stenosis. However, Cho et al. showed the correlation between AIx and the grade of CAD in patients aged less than 65 years, but not in the older ones [
25]. The correlation was not found in patients above 65 years. In our opinion, it is not realistic to expect that even this method can determine the level of CAD. Also, the measuring of arterial elasticity is developed in order to asses an increased cardiovascular risk but some other specific methods should be used to confirm and prove CAD.
Furthermore, we investigated a correlation between ISR and arterial stiffness. The correlation between PWV and ISR was found, but not between AIx and ISR. Arterial stiffness is strongly dependent on the balance of two major proteins, elastin and collagen [
26]. Normally, there is a tightly regulated balance between synthesis and degradation of these two proteins. Therefore, if there is an increased collagen production and reduced degradation in the whole vascular system, arterial stiffness will be increased and more likely an ISR will occur [
27]. After the stent insertion some inflammatory changes in the coronary artery wall such as endothelial degradation, macrophage infiltration and smooth muscle cell proliferation could occur. Also, the inflammation in arteries increases the extracellular matrix proteins and collagen synthesis contributing to the ISR [
28,
29]. BMS causes neointimal hyperplasia after implantation and leads to ISR and reintervention in more than 20 % of patients by 6 months [
10,
11]. Similarly to our study, Ueda et al. showed the correlation between aortic stiffness and restenosis after balloon angioplasty [
30]. However, mechanisms including collagen turnover in ISR and restenosis after balloon angioplasty are different. Stenting causes an even greater increase in collagen accumulation compared with balloon angioplasty [
28,
31,
32]. Accordingly, the same author showed the correlation between aortic AIx and ISR [
14], although the correlation between Aix and ISR was not found in our study. Recently, Mahfouz et al. proved the association of ISR and arterial elasticity [
16]. All studies that have found a correlation between the extent of ISR and arterial stiffness were performed with various devices and methods. All results can contribute to a better understanding of ISR and help to make a decision considering stent implantation. In the cases of high PWV and other risks factors for ISR a cardiologist may be guided to implant DES. Moreover, this could be very useful in a cath lab with limited finances.