Assessment of echo-attenuated plaque by optical coherence tomography and its impact on post-procedural creatine kinase-myocardial band elevation in elective stent implantation.

OBJECTIVES: This study examined morphological characteristics of echo-attenuated plaques by optical coherence tomography (OCT) and evaluated their influence on creatine kinase-myocardial band (CK-MB) elevation after percutaneous coronary intervention (PCI) in patients with elective stent implantation. BACKGROUND: Recent intravascular ultrasound studies have described atherosclerotic plaques with echo attenuation (EA) without associated bright echoes that are correlated with no-reflow phenomenon after PCI. METHODS: We studied 135 native de novo culprit coronary lesions in 135 patients with normal pre-PCI CK-MB levels (28 with unstable angina; 107 with stable angina) who underwent intravascular ultrasound and OCT examinations before elective stent implantation. The lesions were divided into 2 groups based on the presence or absence of EA, and OCT findings were compared. We then determined predictors of post-PCI CK-MB elevation. RESULTS: EA was found in 47 (34.8%) lesions and was associated with the presence of OCT-derived thin-capped fibroatheroma, ruptured plaques, greater lipid content, intravascular ultrasound-derived large reference and plaque area, lesion eccentricity, and microcalcification. Elevated CK-MB levels were observed in 36 (26.7%) lesions, and significantly more frequently in lesions with EA than without. In multivariable analysis, EA (odds ratio [OR]: 3.49; 95% confidence interval [CI]: 1.53 to 7.93; p = 0.003) and OCT-derived ruptured plaque (OR: 2.92; 95% CI: 1.21 to 7.06; p = 0.017) were independent predictors of post-PCI CK-MB elevation. CONCLUSIONS: Atherosclerotic plaques with EA were associated with characteristics considered to be high risk or unstable. OCT examination showed an additive predictive value to the presence of EA for post-PCI CK-MB elevation.

In vivo critical fibrous cap thickness for rupture-prone coronary plaques assessed by optical coherence tomography.

AIMS: The widely accepted threshold of <65 µm for coronary plaque fibrous cap thickness was derived from postmortem studies of ruptured plaques and may not be appropriate for in vivo rupture-prone plaques. We investigated the relationship between fibrous cap thickness and plaque rupture using optical coherence tomography (OCT). METHODS AND RESULTS: We studied 266 lesions (103 from patients with acute coronary syndrome and 163 from patients with stable angina) before percutaneous coronary intervention using OCT. Ruptured and non-ruptured lipid-rich plaques were identified and the thinnest and most representative fibrous cap thickness were determined. Cap thickness was reliably measured in 71 ruptured and 111 non-ruptured plaques. From the ruptured plaques, the median thinnest cap thickness was 54 µm (50-60). The median most representative cap thickness was 116 µm (103-136). For non-ruptured plaques, the median thinnest cap thickness was 80 µm (67-104) and 182 µm (156-216) for most representative cap thickness. In 95% of ruptured plaques, the thinnest cap thickness and most representative cap thickness were <80 and <188 µm, respectively. The best cut-offs for predicting rupture were <67 µm (OR: 16.1, CI: 7.5-34.4, P < 0.001) for the thinnest cap thickness and <151 µm (OR: 35.6, CI: 15.0-84.3, P < 0.001) for most representative cap thickness. These two measures were modestly correlated (r(2) = 0.39) and both independently associated with rupture. CONCLUSION: In vivo critical cap thicknesses were <80 µm for the thinnest and <188 µm for most representative fibrous cap thickness. Prospective imaging studies are required to establish the significance of these values.

Impact of plaque morphology on creatine kinase-MB elevation in patients with elective stent implantation.

BACKGROUNDS: The association between percutaneous coronary intervention (PCI) and subsequent myonecrosis has been widely recognized, and worse prognosis has been reported among patients with elevated post-PCI biomarkers. We used optical coherence tomography (OCT) to study the relationship between pre-PCI plaque morphology and post-PCI creatine kinase-MB (CK-MB) elevation. METHODS: One hundred and twenty-five patients with normal pre-PCI CK-MB levels underwent OCT examination before nonemergency stent implantation. Patients were divided into two groups according to the presence (Group CK, n=35) or absence (Group NCK, n=90) of post-PCI CK-MB elevation ≥ upper limit of the normal range. Clinical and the OCT findings were compared between the two groups. RESULTS: Elevated CK-MB levels was observed in 35 patients (28%). The CK-MB elevation was associated with elevated white blood cell count, type B2/C lesions, the presence of thin cap fibroatheroma (TCFA), plaque rupture, and lipid quadrants. In the multivariate analysis, the presence of TCFA (OR 4.68, 95% CI 1.88-11.64, p=0.001) and type B2/C lesions (OR 4.20, 95% CI 1.30-13.59, p=0.02) were independent predictors of post-PCI CK-MB elevation. CONCLUSIONS: TCFA and angiographically complex lesion morphology can predict post-PCI CK-MB elevation in patients treated with elective stent implantation. OCT may be useful in stratifying the risk for nonemergency stent implantation.

Assessment of acute injuries and chronic intimal thickening of the radial artery after transradial coronary intervention by optical coherence tomography.

AIMS: Transradial coronary intervention (TRI) introduces a trauma to the radial artery (RA), possibly influencing quality as a bypass conduit if subsequently used. We sought to determine the acute and chronic effects of TRI on the RA by optical coherence tomography (OCT). METHODS AND RESULTS: Immediately after TRI completion, 73 RAs in 69 patients were examined. The sheath was pulled back 2 cm distal to the puncture site, and OCT imaging was performed. The acute injuries and intimal thickening were compared between first-TRI RAs and repeat-TRI RAs. Intimal tears were observed in 49 RAs (67.1%) and were more frequent in the distal than in the proximal RA (P = 0.001). Medial dissections were not uncommon (26 RAs, 35.6%). The frequency of acute injury was significantly higher in repeat-TRI RAs (P < 0.001). Intima/medial area, the maximum intimal thickness/medial thickness ratio, and per cent narrowing were all significantly greater in repeat-TRI RAs in the distal and proximal RA. Multivariate analysis revealed that a repeated TRI procedure was the only independent predictor of intimal thickening. CONCLUSION: Optical coherence tomography clearly demonstrated significant acute injuries and chronic intimal thickening of RA after TRI. Further study should evaluate the impact of these effects when TRI RAs are subsequently used as conduits, on long-term graft patency and on clinical outcomes after bypass surgery.