Optical coherence tomography in coronary atherosclerosis assessment and intervention.

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Optical coherence tomography and coronary angioscopy assessment of healed coronary plaque components.

PURPOSE: Histopathological or intracoronary image assessment of healed plaques (HPs) has been reported. However, the lesion characteristics of HPs remains undetermined yet. We assessed the healed plaque components in patients with coronary artery lesions using multiple imaging modalities. METHODS: We enrolled 33 stable angina pectoris (SAP) patients with 36 native coronary culprit lesions with angiography severe stenosis and without severe calcification undergoing pre-intervention optical coherence tomography (OCT) and coronary angioscopy (CAS). HPs were defined as layered phenotype on OCT. Lesion morphologies and plaque characteristics of HPs were assessed using OCT and CAS. RESULTS: HPs were observed in 19 lesions (52.8%). HP lesions had higher frequent B2/C lesions (89.4% vs. 52.9%, p = 0.02), worse pre-PCI coronary flow (corrected thrombolysis in myocardial infarction count 21.6 ± 13.5 vs. 13.8 ± 6.2, p = 0.047) and greater lumen-area stenosis (79.6 ± 10.6% vs. 68.0 ± 21.6%, p = 0.047) than non-HP lesions. HP lesions had higher prevalence of OCT-thin-cap fibroatheroma (TCFA) (31.6% vs. 0.0%, p = 0.02), OCT-macrophage (89.5% vs. 41.2%, p = 0.004), and CAS-red thrombus (89.5% vs. 41.2%, p = 0.004) than non-HP lesions. The combination of 3 features including OCT-TCFA, macrophages, and CAS-red thrombus showed higher predictive valuer for HPs on OCT than each single variable. Post-PCI irregular tissue protrusion was more frequently observed in lesions with HPs than in those without (52.6% vs. 13.3%, p = 0.03). CONCLUSIONS: SAP lesions with HPs might have more frequent vulnerable plaques with intraplaque inflammation and thrombus than those without, suggesting that layered phenotype on OCT might reflect not only healing process but also potential risks for future coronary events.

Intravascular Ultrasound and Angioscopy Assessment of Coronary Plaque Components in Chronic Totally Occluded Lesions.

BACKGROUND: The in vivo lesion morphologies and plaque components of coronary chronic total occlusion (CTO) lesions remain unclear.Methods and Results:We investigated 57 consecutive CTO lesions in 57 patients with stable angina pectoris undergoing elective percutaneous coronary intervention with intravascular ultrasound (IVUS) and coronary angioscopy (CAS) examination. All CTO lesions were classified according to the proximal angiographic lumen pattern; tapered-type (T-CTO) and abrupt-type (A-CTO). The differences in the intracoronary images of these lesion types were evaluated according to the location within the CTO segment. A total of 35 lesions (61.4%) were T-CTO. T-CTO lesions had higher frequencies of red thrombi (proximal 71.4%; middle 74.3%; distal 31.4%; P<0.001) and bright-yellow plaques (yellow-grade 2-3) (48.6%; 74.3%; 2.9%; P<0.001) at the proximal or middle than at the distal subsegment; A-CTO lesions showed no significant differences among the 3 sub-segments. At the middle subsegment, T-CTO lesions showed higher frequencies of positive remodeling (51.4% vs. 18.2%, P=0.01) and bright-yellow plaques (74.3% vs. 13.6%, P<0.001) compared with A-CTO lesions. Multivariate analysis identified bright-yellow plaque as an independent predictor (odds ratio, 7.25; 95% confidence interval, 1.25-42.04; P=0.03) of the occurrence of periprocedural myocardial necrosis. CONCLUSIONS: The combination of IVUS and CAS analysis may be useful for identifying lesion morphology and plaque components, which may help clarify the pathogenetic mechanism of CTO lesions.

Efficacy of pressure parameters obtained during contrast medium-induced submaximal hyperemia in the functional assessment of intermediate coronary stenosis in comparison with instantaneous wave-free ratio.

BACKGROUND: Despite evidence demonstrating the benefits of percutaneous coronary intervention guided by fractional flow reserve (FFR), FFR evaluation has not been widely adopted. We sought to compare the diagnostic performances of instantaneous wave-free ratio (iFR) to a novel contrast medium-induced index in FFR prediction, hypothesizing that the latter parameter would offer superior diagnostic agreement with FFR. METHODS & RESULTS: We studied 132 intermediate stenoses in 97 patients prospectively. iFR was measured first, followed by intracoronary injection of 6 mL contrast medium at 3 mL/s to obtain end-diastolic instantaneous distal coronary pressure/aortic pressure ratio (Pd/Pa) 60 ms before the electrocardiographic R-wave (C-ED-Pd/Pa). Subsequently, conventional hyperemic FFR was measured as a reference standard. Of the 132 lesions, 120 were available for final analysis. The FFR values of 95/120 lesions (79.2%) were between 0.60 and 0.90. C-ED-Pd/Pa values (median 0.79 [interquartile range 0.69-0.87]) were significantly lower than FFR values (0.81 [0.75-0.88], P<0.01), whereas iFR values (0.91 [0.86-0.94], P<0.01) were significantly higher. Correlation coefficients with FFR were 0.78 (standard error of the estimate [SEE] 0.067, P<0.0001) and 0.93 (SEE 0.052, P<0.0001) for iFR and C-ED-Pd/Pa, respectively (P<0.001). The areas under the receiver operating characteristic curves were 0.88 and 0.96 for iFR and C-ED-Pd/Pa, respectively (P<0.01). Diagnostic accuracy was 85.0% and 92.5% for iFR and C-ED-Pd/Pa, respectively (P=0.06). CONCLUSIONS: C-ED-Pd/Pa is a novel, practical, and accurate measure for the physiological assessment of intermediate coronary stenosis compared to iFR.

Efficacy of pressure parameters obtained during contrast medium-induced submaximal hyperemia in the functional assessment of intermediate coronary stenosis.

BACKGROUND: Despite evidence demonstrating the superiority of percutaneous coronary intervention guided by fractional flow reserve (FFR), FFR evaluation has not been widely adopted. We sought to determine the diagnostic performance of baseline conditions and contrast medium-induced pressure indices in predicting FFR. We hypothesized that the contrast medium-induced end-diastolic pressure parameter would offer superior diagnostic agreement with FFR, compared to other indices. METHODS & RESULTS: Ninety-one intermediate stenoses in 75 patients were studied prospectively. The baseline distal coronary pressure to aortic pressure ratio (Pd/Pa) and end-diastolic instantaneous Pd/Pa 60 ms before the electrocardiographic R-wave (ED-Pd/Pa) were measured; then, after intracoronary injection of 6 mL contrast medium at 3 mL/s, Pd/Pa (C-Pd/Pa) and end-diastolic Pd/Pa (C-ED-Pd/Pa) were obtained. Subsequently, conventional FFR was measured as a reference standard. Of the 91 lesions, 11 (12.1%) were excluded because of suboptimal data acquisition, leaving 80 for final analysis. C-ED-Pd/Pa values (median 0.80 [interquartile range 0.70-0.88]) were significantly lower than conventional FFR (0.83 [0.75-0.89], P<0.01), whereas Pd/Pa (0.93 [0.90-0.96], P<0.01), ED-Pd/Pa (0.91 [0.87-0.93], P<0.01), and C-Pd/Pa (0.85 [0.79-0.90], P<0.05) were significantly higher. Correlation coefficients (R) with conventional FFR were 0.74 (standard error of the estimate [SEE] 0.067, P<0.0001), 0.78 (SEE 0.062, P<0.0001), 0.85 (SEE 0.052, P<0.0001), and 0.93 (SEE 0.037, P<0.0001) for Pd/Pa, ED-Pd/Pa, C-Pd/Pa, and C-ED-Pd/Pa, respectively. Diagnostic accuracy was 81.2%, 83.8%, 87.5% and 93.8% for Pd/Pa, ED-Pd/Pa, C-Pd/Pa, and C-ED-Pd/Pa, respectively. CONCLUSIONS: Among baseline indices and contrast-induced pressure parameters, C-ED-Pd/Pa is a novel, feasible, and high-performance measure for the physiological assessment of intermediate coronary stenosis.

Quantitative assessment of tissue prolapse on optical coherence tomography and its relation to underlying plaque morphologies and clinical outcome in patients with elective stent implantation.

BACKGROUND: Tissue prolapse (TP) is sometimes observed after percutaneous coronary intervention (PCI), but its clinical significance remains unclear. We investigated the relationship between TP volume on optical coherence tomography (OCT) after PCI and underlying plaque morphologies and the impact of TP on clinical outcomes. METHODS: We investigated 178 native coronary lesions with normal pre-PCI creatine kinase-myocardial band (CK-MB) values (154 lesions with stable angina; 24 with unstable angina). TP was defined as tissue extrusion from stent struts throughout the stented segments. All lesions were divided into tertiles according to TP volume. The differences in plaque morphologies and 9-month clinical outcomes were evaluated. RESULTS: TP volume was correlated with lipid arc (r=0.374, p<0.0001) and fibrous cap thickness (r=-0.254, p=0.001) at the culprit sites. The frequency of thin-cap fibroatheroma (TCFA) was higher in the largest TP tertile (≥ 1.38 mm(3)) (p=0.015). In multivariate analysis, right coronary artery lesion (odds ratio [OR]: 2.779; p=0.005), lesion length (OR: 1.047; p=0.003), and TCFA (OR: 2.430; p=0.022) were related to the largest TP tertile. Lesions with post-PCI CK-MB elevation (>upper reference limit) had larger TP volume than those without (1.28 [0.48 to 3.97] vs. 0.70 [0.16 to 1.64] mm(3), p=0.007). The prevalence of cardiac events during the 9-month follow-up was not significantly different according to TP volume. CONCLUSIONS: TP volume on OCT was related to plaque morphologies and instability, and post-PCI myocardial injury, but not to worse 9-month outcomes.