Backgrounds:
The aim of the present study is to investigate the relationship between physiological coronary artery stenosis severity and lesion instability by Optical Coherence Tomography (OCT) in patients with stable angina pectoris (SAP).
Methods and Results:
We investigated 198 culprit lesions of 180 SAP patients who underwent OCT imaging and fractional flow reserve (FFR) measurement before PCI procedure. Physiological coronary stenosis severity was assessed by FFR analysis, and lesions were divided into two groups on the basis of FFR values; severe stenosis group (group S): FFR <0.75 (n=78, 39%), moderate stenosis group (group M): FFR ≥0.75 (n=120, 61%) according to the previous study. Thin-capped fibroatheroma (TCFA) was defined as lipid-rich plaque (lipid arc ≥90°) with fibrous cap thickness <70μm. The median FFR values in total lesions, group S, and group M were 0.77 (interquartile range [IQR]: 0.69—0.83), 0.65 (0.57—0.72), and 0.81 (0.78—0.87), respectively. There were no significant differences in patient characteristics expect for the frequency of previous myocardial infarction (S: 15%, M: 38%, P <0.01) and previous PCI (S: 29%, M: 60%, P <0.01). In angiographic analysis, there were significant differences in the frequency of culprit lesion location in LAD (S: 72%, M: 49%, P <0.01), minimum lumen diameter (S: 1.07±0.36 mm, M: 1.35±0.32 mm, P <0.01), % diameter stenosis (S: 58.9 % [53.1—70.8], M: 52.8 % [47.7—57.5], P <0.01), and lesion length (S: 13.7 mm [10.6—17.5], M: 11.5 mm [9.2—14.5], P = 0.02) between the two groups. In OCT analysis, there were significant differences in the lipid arc (S: 200° [160—232], M: 168° [143—211], P <0.01), CT (S: 110 μm [63—157], M: 140 μm [93—197], P <0.01), and frequency of TCFA (S: 27%, M: 9%, P <0.01) between the two groups. Subgroup analysis of LAD lesions showed similar results between the two groups.
Conclusions:
Lesions of physiologically severe coronary stenosis in SAP were associated with lesion instability assessed by OCT. These findings may challenge the concept that lesions responsible for acute coronary syndromes are mild in most cases provided that plaque rupture of TCFA evenly results in coronary events in the wide range of stenosis severity in patients with SAP.
Tissue Doppler echocardiography improves the diagnosis of coronary artery stenosis in stable angina pectoris
