Abstract 4187: Culprit Lesions Located in the Proximal Segments of the Coronary Arteries Have Thinner Fibrous Cap and Greater Incidence of Plaque Rupture: An Optical Coherence Tomography Study
Background: The location of culprit lesions (CLs) in patients with acute coronary syndromes (ACS) has recently attracted investigators’ interest. Recent studies have shown that the majority of the CLs are located in the proximal segments of the coronary arteries. We hypothesized that CLs of patients with ACS have distinct morphological characteristics according to the location.
Methods: We included consecutive patients with ACS that underwent cardiac catheterization within 24 hours from symptom onset. After completion of diagnostic coronary angiography, the culprit lesion of the angiogram was clearly identified and classified as proximal or distal depending on the distance from the ostium. OCT study was then performed in all culprit lesions. Fibrous cap thickness (FCT) was measured in the thinnest part of the plaque of every CL. The presence of plaque rupture was also recorded. Plaque rupture was defined as the presence of fibrous cap discontinuity.
Results: Forty-six patients (n=46 lesions) were enrolled in the study. Twenty eight of the patients (60.87%) had FCT≤65 μm. Mean FCT was 61±32μm for the LAD (n=22), 67±29 μm for the LCX (n=3) and 59±27 μm for the RCA (n=21) (p=0.92). A rupture was found in 42% of the LAD lesions (n=11), in 33% of the LCX lesions (n=1) and in 67% (n=14) of the RCA lesions (p=0.38). Twenty-six of the culprit lesions were located in the distal part of the coronary arteries and 20 proximally. In the group of the distal CL, 50% had thin cap (n=23), while in the group of proximal CL 75% (n=13) presented such morphology (p=0.08). Mean FCT of the group with proximal location of the culprit lesion was 49±20μm versus 70±32μm of the group of distal CL (p=0.01). A rupture was found in 75% of the proximal lesions (n=15) and in 42.3% (n=11) of the distal lesions (p=0.03).
Conclusions: Culprit lesions in the proximal segments of the coronary arteries have thinner fibrous cap than culprit lesions located in the distal part of the coronary arteries. Our findings implicate that the higher incidence of ACS amenable to plaques located more proximally may be due to morphologic discrepancies of the proximal lesions.