Tetsumin Lee

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.

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 Coronary Plaque Morphology Assessed by Optical Coherence Tomography on Cardiac Troponin Elevation in Patients With Elective Stent Implantation

Background—Mild elevations of cardiac troponin frequently occur after percutaneous coronary intervention (PCI), and patients with elevated post-PCI biomarkers have a worse prognosis. We used optical coherence tomography (OCT) to study the relationship between pre-PCI plaque morphology and post-PCI cardiac troponin I elevations. Methods and Results—One hundred thirty-one patients with normal pre-PCI cardiac troponin I levels underwent OCT before nonemergency stent implantation. Clinical and OCT findings were compared between patients with (n=31, 23.7%) and without (n=100, 76.3%) post-PCI cardiac troponin I of >3×upper reference limit (post-PCI myocardial infarction [MI]). After PCI, long-term follow-up data were collected. Post-PCI MI was associated with angiographic lesion length, type B2/C lesions, presence of thin-cap fibroatheroma, and fibrous cap thickness. In multivariable analysis, presence of thin-cap fibroatheroma (odds ratio, 10.47; 95% confidence interval, 3.74 to 29.28; P<0.001) and type B2/C lesions (odds ratio, 3.74; 95% confidence interval, 1.41 to 9.92; P=0.008) were predictors of post-PCI MI. At a median follow-up of 12 months, cardiac event-free survival was significantly worse in patients with post-PCI MI (log-rank test &khgr;2=8.9; P=0.003). Cox proportional hazards analysis showed that post-PCI MI (hazard ratio, 3.67; 95% confidence interval, 1.39 to 9.65; P=0.009) and ejection fraction (hazard ratio, 0.96; 95% confidence interval, 0.92 to 0.99; P=0.029) were independent predictors of adverse cardiovascular events during follow-up. Conclusions—Type B2/C lesions and the presence of OCT-defined thin-cap fibroatheroma can predict post-PCI MI in patients treated with elective stent implantation, who may require adjunctive therapy after otherwise successful PCI.

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.

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.

Plaque morphologies and the clinical prognosis of acute coronary syndrome caused by lesions with intact fibrous cap diagnosed by optical coherence tomography

BACKGROUND Pathological studies have suggested that acute coronary syndrome (ACS) may be caused by culprit lesions with intact fibrous cap (IFC), including plaque erosions. This study sought to evaluate the morphological features and clinical outcomes of patients with ACS caused by lesions with IFC. METHODS A total of 318 patients with ACS who underwent optical coherence tomography (OCT) of a culprit lesion were investigated. The culprit lesions were categorized as follows: those with plaque rupture (PR group), those with an IFC (IFC group), and those with a massive thrombus precluding plaque visualization (MT group). Intravascular ultrasound (IVUS) was performed in 297 patients. Clinical follow-up data were collected regarding adverse cardiac events, including death, myocardial infarction, revascularization, and congestive heart failure requiring hospitalization. RESULTS Culprit lesions were categorized into 141 RPs, 131 IFCs, and 46 MTs. IFC group exhibited a smaller remodeling index and less frequently attenuated plaques on IVUS. Three hundred and seven patients (96.5%) were followed for a median follow-up duration of 576 days. Adverse cardiac events were observed in 93 patients (30.3%). Kaplan-Meier analysis demonstrated a significantly lower event rate in IFC group compared with the RP and MT groups. Cox proportional hazard analysis demonstrated that an IFC and multivessel disease were independent predictors of adverse events [hazard ratio 0.57, 95% confidence interval (CI) 0.33-0.98, p=0.043 and hazard ratio 1.72, 95% CI 1.09-2.73, p=0.021]. CONCLUSIONS Culprit lesions with IFC showed smaller remodeling indices by IVUS, and were associated with better long-term prognosis compared with those with plaque rupture.

Relationship Between Subclinical Cardiac Troponin I Elevation and Culprit Lesion Characteristics Assessed by Optical Coherence Tomography in Patients Undergoing Elective Percutaneous Coronary Intervention

Background—The prevalence of subclinical, cardiac troponin I (cTnI) elevation in stable patients undergoing elective percutaneous coronary intervention and its relationship to culprit lesion characteristics assessed by optical coherence tomography (OCT) are unknown. Methods and Results—We studied 206 native de novo culprit coronary lesions from 206 patients with stable angina pectoris who underwent OCT before elective percutaneous coronary intervention. Patients were divided into 2 groups according to the presence (cTnI group; n=47; 22.8%) or absence (non-cTnI group; n=159; 77.2%) of cTnI ≥0.03 ng/mL at admission. The clinical and OCT findings were compared between these 2 groups. No significant difference was found in the clinical presentation between the groups except for the serum C-reactive protein levels and presence of multivessel disease. By OCT, cTnI elevation was associated with the presence of thin-cap fibroatheromas, a greater lipid arc, and a longer lipid length. In a multivariable analysis, the presence of positive C-reactive protein levels (odds ratio, 4.38; 95% confidence interval, 1.90–10.08; P=0.001) and OCT-derived thin-cap fibroatheromas (odds ratio, 2.89; 95% confidence interval, 1.22–6.86; P=0.016) were independent predictors of cTnI elevation. Periprocedural myocardial injury, defined as postpercutaneous coronary intervention peak cTnI levels >1.0 ng/mL (5× the upper reference limit), occurred more often in patients with cTnI elevation at admission (cTnI group: 41% versus non-cTnI group: 18%; P=0.001). Conclusions—The presence of subclinical cTnI elevation at admission was not uncommon and was associated with OCT-derived unstable plaque morphology in patients undergoing elective percutaneous coronary intervention, and may help to identify patients with stable angina pectoris at high risk for periprocedural myocardial injury.

Preprocedural fractional flow reserve and microvascular resistance predict increased hyperaemic coronary flow after elective percutaneous coronary intervention.

Epicardial focal coronary artery stenosis, diffuse coronary disease, and microvascular resistance (MR) may limit coronary flow. The purpose of percutaneous coronary intervention (PCI) is to increase coronary flow by targeting epicardial lesions. After PCI, MR might change and affect coronary flow. We investigated whether PCI influences MR using the index of microcirculatory resistance (IMR) and if pre‐PCI fractional flow reserve (FFR) or MR predicts the post‐PCI change in hyperaemic coronary flow.

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.

The Influence of Elective Percutaneous Coronary Intervention on Microvascular Resistance: a Serial Assessment Using the Index of Microcirculatory Resistance

This study investigates whether hyperemic microvascular resistance (MR) is influenced by elective percutaneous coronary intervention (PCI) by using the index of microcirculatory resistance (IMR). Seventy-one consecutive patients with stable angina pectoris undergoing elective PCI were prospectively studied. The IMR was measured before and after PCI and at the 10-mo follow-up. The IMR significantly decreased until follow-up; the pre-PCI, post-PCI, and follow-up IMRs had a median of 19.8 (interquartile range, 14.6-28.9), 16.2 (11.8-22.1), and 14.8 (11.8-18.7), respectively (P < 0.001). The pre-PCI IMR was significantly correlated with the change in IMR between pre- and post-PCI (r = 0.84, P < 0.001) and between pre-PCI and follow-up (r = 0.93, P < 0.001). Pre-PCI IMR values were significantly higher in territories with decreases in IMR than in those with increases in IMR [pre-PCI IMR: 25.4 (18.4-35.5) vs. 12.5 (9.4-16.8), P < 0.001]. At follow-up, IMR values in territories showing decreases in IMR were significantly lower than those with increases in IMR [IMR at follow-up: 13.9 (10.9-17.6) vs. 16.6 (14.0-21.4), P = 0.013]. The IMR decrease was significantly associated with a greater shortening of mean transit time, indicating increases in coronary flow (P < 0.001). The optimal cut-off values of pre-PCI IMR to predict a decrease in IMR after PCI and at follow-up were 16.8 and 17.0, respectively. In conclusion, elective PCI affected hyperemic MR and its change was associated with pre-PCI MR, resulting in showing a wide distribution. Overall hyperemic MR significantly decreased until follow-up. The modified hyperemic MR introduced by PCI may affect post-PCI coronary flow.