New insights into fibrous cap thickness of vulnerable plaques assessed by optical coherence tomography.

OBJECTIVE: Vulnerable plaques with fibrous cap thickness (FCT) of ≤65 µm are prone to rupture and/or thrombosis. However, plaques with FCT > 65 µm cause acute myocardial infarction and even sudden death. We aimed to investigate the relationship between 65 < FCT ≤ 80 µm and plaque rupture and/or thrombosis using optical coherence tomography (OCT). METHODS: OCT was performed on culprit lesions in 502 consecutively enrolled patients to identify FCT. Patients were classified into three groups according to FCT: Group A (FCT ≤ 65 µm, n = 147), Group B (65 < FCT ≤ 80 µm, n = 84) and Group C (FCT > 80 µm, n = 271). Clinical and laboratory data was collected from the inpatient medical record system. RESULTS: Plaques with thinner FCT, especially < 65 µm, were more susceptible to rupture and/or thrombosis (P < 0.001). Plaques with FCT between 65 and 80 µm had a higher probability of rupture and/or thrombosis than those with FCT > 80 µm (P < 0.001). In multivariable analysis, FCT ≤ 65 µm and 65 < FCT ≤ 80 µm were independent predictors for plaque rupture ([FCT ≤ 65 µm vs. FCT > 80 µm]: OR = 8.082, 95% CI = 4.861 to 13.435, P < 0.001; [65 < FCT ≤ 80 µm vs. FCT > 80 µm]: OR = 2.463, 95% CI = 1.370 to 4.430, P = 0.003), thrombosis ([FCT ≤ 65 µm vs. FCT > 80 µm]: OR = 25.224, 95% CI = 13.768 to 46.212, P < 0.001; [65 < FCT ≤ 80 µm vs. FCT > 80 µm]: OR = 3.675, 95% CI = 2.065 to 6.542, P < 0.001) and plaque rupture with thrombosis ([FCT ≤ 65 µm vs. FCT > 80 µm]: OR = 22.593, 95% CI = 11.426 to 44.674, P < 0.001; [65 < FCT ≤ 80 µm vs. FCT > 80 µm]: OR = 4.143, 95% CI = 1.869 to 9.184, P < 0.001). CONCLUSIONS: OCT-assessed 65 < FCT ≤ 80 µm was independently associated with increased risk of plaque rupture and/or thrombosis compared with FCT > 80 µm.