Frequency and Distribution of Sheet and Nodular Calcification in Coronary Arteries in Japanese Patients.

Whether a nodular calcification (NC), which is the precursor to intracoronary thrombosis, is focally or diffusely distributed in the coronary tree has major implications for ongoing efforts to identify. This study aimed to investigate the frequency and spatial distribution patterns of sheet calcification (SC) and NC in a 3-vessel examination of autopsied human hearts.A total of 323 coronary artery specimens from 110 cadavers were obtained from autopsy cases. After fixation and decalcification, the coronary artery trees were cut every 5 mm into 4-µm transverse cross-sections for histological assessment. An SC was defined as a plate-like calcification of > 1 quadrant of the vessel or > 3 mm in diameter, and NC as nodular calcium deposits separated by fibrin, and a deposit size > 1 mm in diameter.Of the 6,306 histological cross-sections, SCs and NCs were identified in 1,627 (26%) and 233 (4%) cross-sections, respectively. SCs and NCs had a similar distribution pattern in all 3 coronary arteries. In the left anterior descending artery (LAD), NCs were predominantly located in the proximal segment: the first 45 mm from the LAD ostium (72%) and the first 60 mm from the LAD ostium (84%), respectively. However, NCs were evenly distributed throughout the length of the coronary artery in the right coronary artery (RCA) and left circumflex artery (LCX).NCs coexisted with SCs, and tended to cluster in predictable parts within the proximal segments of the LAD, but were evenly distributed throughout the RCA and LCX in coronary arteries from cadavers.

Short- and mid-term influence of drug-coated stent implantation on structural and functional vascular healing response: An optical coherence tomography and acetylcholine testing study.

OBJECTIVE: This study investigated the effect of a drug-coated stent (DCS) that has a novel microporous abluminal surface without a polymer on 1-month and 1-year functional and morphological healing response as assessed using acetylcholine (Ach) testing and optical coherence tomography (OCT). BACKGROUND: DCS is expected to induce favorable morphological and physiological arterial healing after its implantation. METHODS: A total of 11 patients who underwent vascular response examinations 1-month and 1-year after the index PCI with DCS implantation were enrolled. The vascular response was evaluated by the functional response test by acetylcholine infusion, the morphological response test by OCT. RESULTS: Although 94.5% of the DCS struts were covered by homogeneous smooth neointima at 1 month, the percentage of neointimal coverage increased to 98.5% at 1 year (p = .02). Conversely, the proportion of uncovered struts and malapposed struts at 1 year were 1.2 and 0.7%, respectively. Furthermore, the coronary vasomotor response to incremental doses of Ach were impaired especially in the distal segments at each period, although the responses to Ach at 10-6 mol/L in the distal segment tended to improve over time from baseline to 1 month and 1 year later (-19 ± 20%, -9 ± 17%, and -5 ± 14%, respectively; p = .27). CONCLUSIONS: The morphological assessment of DCS with OCT revealed a high degree of strut coverage and apposition at 4 weeks after implantation. The impaired endothelium-dependent vasomotor response tended to improve chronologically from baseline to 1 month and 1 year later.

The incidence, natural history, and predictive factors for tissue protrusion after drug-eluting stent implantation.

OBJECTIVES AND BACKGROUND: Although tissue protrusion (TP) between the stent struts after stent implantation has been implicate as a potential factor of stent failure, the incidence, natural history, and predictive factor of TP after stent implantation remains unclear. This prospective study evaluated the fate of TP after drug-eluting stent (DES) deployment using optical coherence tomography (OCT). METHOD AND RESULT: This study analyzed TP for 42 lesions after DES in which three serial OCTs, including preprocedure, postprocedure, and 1-month after the procedure were performed. TP was classified into the five groups: (a) persistent, (b) progressive, (c) healed, (d) regressive, and (e) late-acquired. Immediately after the procedure, 100 TPs in 37 lesions (88%) were identified. Of those, 53 (53%) were persistent, 3 (3%) were progressive, 20 (20%) were healed, and 24 (24%) were regressed at 1-month follow-up. Seven TPs in five patients (13%) were observed only at 1-month follow-up (late-acquired). CONCLUSION: In lesions with late-acquired TP, calcified nodule was identified as an underlying plaque morphology on preprocedural OCT. A serial OCT analysis found TP occurred not only immediately after DES implantation, but also 1-month after DES implantation.

Additional decrease in fractional flow reserve in the left anterior descending artery after hand-grip exercise during pharmacological coronary hyperemia.

Maximal hyperemia at the time of fractional flow reserve (FFR) measurement is generally induced by vasodilators, even when hyperemia at the onset of angina symptoms is caused by exercise stress. This study was designed to evaluate whether pharmacological hyperemia could be used as a substitute for exercise-induced hyperemia during FFR measurement. Twenty-two patients with angiographically intermediate stenosis in the left anterior descending artery (LAD) were prospectively enrolled. FFR measurements were repeated in the following two conditions while the pressure-wire was positioned in the same segment; (1) during pharmacological hyperemia induced by intracoronary administration of 2 mg nicorandil, (2) immediately after isotonic hand-grip exercise for 90 s (50% of maximum voluntary contraction) followed by intracoronary administration of 2 mg nicorandil. Isotonic hand-grip exercise increased systolic blood pressure (130 ± 19 versus 150 ± 22 mmHg, p < 0.001), heart rate (71 ± 11 versus 79 ± 13 bpm, p < 0.001), and cardiac output (5.1 ± 1.2 versus 5.9 ± 1.5 L/min, p < 0.001), which indicated an increased afterload on the left ventricle. After the hand-grip exercise, FFR significantly decreased from 0.86 ± 0.06 to 0.84 ± 0.06 (p < 0.001). A percent increase in systolic blood pressure and cardiac output after hand-grip exercise strongly correlated with ΔFFR (r = - 0.65, p < 0.001 and r = - 0.55, p < 0.001, respectively). An increase in cardiac output with hand-grip exercise during pharmacological hyperemia could induce an additional decrease in FFR for lesions located in the LAD.

Influence of different physiological hemodynamics on fractional flow reserve values in the left coronary artery and right coronary artery.

BACKGROUND: Although the left coronary artery (LCA) has a flow profile in that most blood flow occurs during diastole rather than systole, the right coronary artery (RCA) has a flow pattern that is less diastolic dominant. This study assessed whether coronary pressure waveforms distal to stenoses with the same fractional flow reserve (FFR) was the same between the LCA and RCA. METHODS: A total of 347 vessels from 318 patients who underwent FFR measurements were included. Conventional FFR was calculated as the ratio of the mean coronary distal pressure (Pd) to the mean aortic pressure (Pa) at maximal hyperemia. The pressure drop ratios in systole (PDRsystole) and diastole (PDRdiastole) were calculated as the sum of (Pa minus Pd) divided by the sum of Pa at the intracoronary diastolic and systolic pressure phases, respectively. RESULTS: Analysis of covariance of the regression line of correlation between conventional FFR and PDRsystole revealed that the slope was significantly greater in the RCA than in the left anterior descending artery (LAD) and left circumflex artery (LCX) (-0.765, -0.578, and -0.589, p < 0.001). On the other hand, the regression line of correlation between conventional FFR and PDRdiastole found that the slope was significantly greater in the LAD and LCX than in the RCA (-1.349, -1.318, and -1.223, p < 0.001). CONCLUSIONS: The pressure waveform distal to the stenosis differs between the LCA and RCA. In the LCA, the decrease in diastolic pressure mainly contributed to the drop in FFR, whereas in the RCA, it was the decrease in systolic pressure.

Distribution of pressure gradients along the left anterior descending artery in patients with angiographically normal arteries.

OBJECTIVES: This study tested the hypothesis that there is no decline of coronary pressure from the proximal to the distal left anterior descending coronary artery (LAD) of humans and swine. BACKGROUND: In the daily clinical practice, the fractional flow reserve (FFR) in the LAD is frequently lower than that in the other arteries in the presence of a similar degree of stenosis. METHODS: Twenty-six patients with angiographically normal LAD were prospectively enrolled. The coronary pressure ratio (mean distal/proximal coronary pressures at hyperemia) was measured at five different positions: 12, 10, 7, and 5 cm distal from the LAD ostium, and at the ostium of the LAD. The coronary pressure measurement was further investigated in a swine model without atherosclerosis. RESULTS: The coronary pressure ratio during maximum hyperemia gradually decreased in proportion to the distance from the ostium (average: 0.85 ± 0.06 at 12 cm distal to the ostium). This finding was confirmed in swine model. The degree of the coronary pressure decrease during maximum hyperemia was similar in patients with and without evidence of minor plaque on intravascular ultrasound, however it was strongly associated with the amount of myocardium mass in the territory of the LAD. CONCLUSIONS: Intracoronary pressure gradually decreases in proportion to the distance from the ostium in the LAD of humans and swine, regardless of the presence of minor atherosclerotic plaques. The degradation degree of the coronary pressure ratio during maximum hyperemia is enlarged in the presence of larger amount of myocardium mass in the territory of the LAD.

Differential influence of lesion length on fractional flow reserve in intermediate coronary lesions between each coronary artery.

OBJECTIVES: This study evaluated whether the influence of lesion length on functional significance is similar between each target artery. BACKGROUND: In the presence of a similar moderate degree of stenosis, the fractional flow reserve (FFR) in the left anterior descending coronary artery (LAD) is more often <0.80 than in the other arteries. METHODS: A total of 221 lesions with intermediate stenosis on coronary angiography that underwent FFR measurement for the evaluation of myocardial ischemia were enrolled. Quantitative coronary angiographic analysis including percent diameter stenosis and lesion length was performed. The area under the receiver operating characteristics (ROC) curve was estimated for the best cutoff value as a predictor of FFR value of ≤0.80 for each coronary artery. RESULTS: Although lesion length was similar among the lesions with an FFR >0.80 at different locations, the mean lesion length was significantly longer for lesions in the right coronary artery (RCA) with an FFR ≤0.80 than for those in the LAD and left circumflex artery (13.4 ± 3.4 vs. 8.6 ± 3.1 vs. 12.0 ± 3.7 mm, p < .001). ROC analysis demonstrated that the optimal cutoff value of lesion length for predicting an FFR ≤0.80 was 10.0 mm in the LAD (0.56 area under the curve [AUC], 48% sensitivity, and 76% specificity), whereas 13.1 mm in the RCA (0.84 AUC, 67% sensitivity, and 93% specificity). CONCLUSIONS: The impact of lesion length on myocardial ischemia is different for each coronary artery. A longer lesion length is required in the RCA than in the LAD to achieve an FFR ≤0.80.

Impact of optical coherence tomography-derived neointimal tissue morphology on development of very late in-stent restenosis.

OBJECTIVES: This study evaluated the progression of very late in-stent restenosis (VL-ISR) by analyzing four serial coronary angiography (CAG) images and its correlation with neointimal tissue characterization of the VL-ISR lesions on optical coherence tomography (OCT). BACKGROUND: Recently, VL-ISR is occasionally observed beyond a few years after drug-eluting stents (DESs) implantation. METHODS: This study analyzed 50 VL-ISR lesions after DES in which 4 serial CAGs over a period of 2 years, including at baseline procedure, 9 months after baseline procedure, 12 months before VL-ISR, and at the time of VL-ISR, were performed. Neointimal tissue characteristics by OCT were categorized as homogeneous, heterogeneous with invisible strut (Type I), heterogeneous with visible strut (Type II), speckled (Type III), or heterogeneous with sharply delineated border (Type IV). RESULTS: From the development process, 23 VL-ISRs (46%) were categorized as rapid progression and 27 (54%) as gradual progression. The five categories of neointimal tissue composition significantly differed between lesions with rapid and gradual progression. Homogeneous neointima and Type IV heterogeneous neointima were observed only in lesions with gradual progression. Moreover, most Type I heterogeneous neointima was identified in lesions with gradual progression. Instead, main neointimal tissue components of lesions with rapid progression were Type II (43%) and Type III (43%) heterogeneous neointima. CONCLUSION: The progression rate of in-stent atherosclerotic changes is gradual, whereas organized thrombus could be associated with an increased risk of rapid neointimal growth. The two types of stenosis progression provide a new insight into the mechanism of VL-ISR development after DES implantation.

Impact of IVUS-Derived Vessel Size on Midterm Outcomes After Stent Implantation in Femoropopliteal Lesions.

Purpose: To identify intravascular ultrasound (IVUS) findings that predict midterm stent patency in femoropopliteal (FP) lesions. Materials and Methods: A retrospective analysis was undertaken of 335 de novo FP lesions in 274 consecutive patients (mean age 72.4±8.2 years; 210 men) who had IVUS assessment before and after successful stent implantation. The mean lesion length was 13.2±9.8 cm. The primary outcome was primary patency at 24 months, defined as freedom from major adverse limb event (MALE) and in-stent restenosis (ISR). MALE was defined as major amputation or any target lesion revascularization (TLR). ISR was defined by a peak systolic velocity ratio >2.4 by duplex ultrasonography. Logistic regression analyses were performed to identify independent predictors of stent patency at 24 months; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Receiver operator characteristic (ROC) curve analysis was performed to determine the optimal threshold for prediction of stent patency at 24 months. Results: Over the 24-month follow-up, 18 (7%) patients died and 43 (15%) of 286 lesions were responsible for MALE (42 TLRs and 1 major amputation). Primary patency was estimated at 82.5% (95% CI 78.1% to 86.9%) at 12 months and 73.2% (95% CI 67.9% to 78.5%) at 24 months. Multivariable analysis revealed that longer lesion length (OR 0.89, 95% CI 0.82 to 0.97, p<0.01) was an independent predictor of declining patency, while cilostazol use (OR 3.45, 95% CI 1.10 to 10.78, p=0.03) and increasing distal reference external elastic membrane (EEM) area (OR 1.18, 95% CI 1.02 to 1.37, p=0.03) were associated with midterm stent patency. ROC curve analysis identified a distal reference EEM area of 29.0 mm2 as the optimal cut-point for prediction of 24-month stent patency (area under the ROC curve 0.764). Kaplan-Meier estimates of 24-month primary patency were 83.7% (95% CI 78.3% to 89.2%) in lesions with a distal EEM area >29.0 mm2 vs 53.1% (95% CI 42.9% to 63.3%) in those with a distal EEM area ≤29.0 mm2 (p<0.001). Conclusion: In FP lesions with a larger distal vessel area estimated with IVUS, stent implantation can be considered as a reasonable treatment option, with the likelihood of acceptable midterm results.

Effect of neointimal tissue morphology on vascular response to balloon angioplasty in lesions with in-stent restenosis after drug-eluting stent deployment: an optical coherence tomography analysis.

This study aimed to evaluate the vascular response to balloon angioplasty for drug-eluting stent (DES) in-stent restenosis (ISR) lesions based on our novel optical coherence tomography (OCT) classification to establish the optimal treatment strategy for ISR lesions after DES implantation. A total of 104 ISR lesions after DES implantation were imaged by OCT and categorized into the following six patterns: type I-homogeneous high-intensity tissue, type II-heterogeneous tissue with signal attenuation, type III-speckled heterogeneous tissue, type IV-mixed tissue containing poorly delineated region with invisible strut, type V-mixed tissue containing sharply delineated low-intensity region, and type VI-bright protruding tissue with an irregular surface. Serial volumetric OCT analysis was performed before and after balloon dilation to evaluate the vascular response to balloon angioplasty. After balloon dilation, the minimal decrease in neointimal volume was noted in type I lesions and maximal in type III lesions. In contrast, the increase in stent volume was significantly more in type I lesions than others. Neointimal tissue characterization by OCT allows us to provide useful information about the vascular response to balloon dilation, which can influence the therapeutic strategy for DES ISR lesions.

Optical coherence tomography characteristics of in-stent restenosis after drug-eluting stent implantation: a novel classification and its clinical significance.

This study aimed to establish a novel classification of in-stent restenosis (ISR) morphological characteristics after drug-eluting stent (DES) implantation as visualized by optical coherence tomography (OCT) and determine its clinical significance. A total of 133 lesions with intrastent restenosis after DES implantation were imaged by OCT. Neointimal tissue characteristics were categorized according to the classical classification as either homogeneous, heterogeneous, or layered. Then all tissues were also classified into six types as follows: homogeneous high-intensity tissue (type I), heterogeneous tissue with signal attenuation (type II), speckled heterogeneous tissue (type III), heterogeneous tissue containing poorly delineated region with invisible strut (type IV), heterogeneous tissue containing sharply delineated low-intensity region (type V), or bright protruding tissue with an irregular surface (type VI). The kappa value for interobserver agreement between the two observers was higher in the modified classification than in the classical classification (0.97 and 0.72, respectively). Most lesions classified as type V and VI were likely to be identified in patients on hemodialysis and located at the ostial right coronary artery. The duration from stent implantation to ISR was significantly longer in types IV and VI than in others. The incidence of stent fracture was significantly higher in types I and IV. This new modified classification enabled us to classify most ISR lesions easily with higher reproducibility. The clinical significance of neointimal restenotic tissue classification by OCT became clear while using the modified classification.

Shortened red blood cell age in patients with end-stage renal disease who were receiving haemodialysis: a cross-sectional study.

BACKGROUND: The causes of anaemia in patients with end-stage renal disease include a relative deficiency in erythropoietin production and complex clinical conditions. We aimed to investigate the underlying mechanisms of anaemia in patients with end-stage renal disease who were undergoing maintenance dialysis by measuring erythrocyte creatine levels. METHODS: In a cross-sectional study, we evaluated 69 patients with end-stage renal disease who were receiving haemodialysis (n = 55) or peritoneal dialysis (n = 14). Erythrocyte creatine level, a quantitative marker of mean red blood cell (RBC) age, was measured. RESULTS: The mean RBC age was significantly shorter in the haemodialysis group than in the peritoneal dialysis group (47.7 days vs. 59.8 days, p < 0.0001), although the haemoglobin levels were comparable between the groups. A Spearman correlation coefficient analysis revealed that shortened RBC age positively correlated with transferrin saturation (r = 0.54), ferritin level (r = 0.47), and haptoglobin level (r = 0.39) but inversely related with reticulocyte (r = - 0.36), weekly doses of erythropoiesis-stimulating agents (ESAs; r = - 0.62), erythropoietin resistance index (r = - 0.64), and intradialytic ultrafiltration rate (r = - 0.32). CONCLUSIONS: Shortened RBC age was observed in patients who were receiving maintenance haemodialysis and was associated with iron deficiency, greater haptoglobin consumption, higher ESA requirements, and poor erythropoietin responsiveness, as well as with greater intradialytic fluid extraction.

Utility and Validity of Intracoronary Administration of Nicorandil Alone for the Measurement of Fractional Flow Reserve in Patients With Intermediate Coronary Stenosis.

BACKGROUND: Intracoronary (IC) administration of nicorandil has been proposed as an alternative choice of hyperemic agent for fractional flow reserve (FFR) measurements. This study evaluated the utility and validity of IC nicorandil administration alone to induce maximal hyperemia.Methods and Results:Two-hundred-seven patients with coronary artery disease listed for coronary angiography with FFR were prospectively enrolled. FFR was measured after (1) IC administration of nicorandil 2 mg (ICNIC2 mg); (2) continuous intravenous (IV) adenosine triphosphatase (ATP) infusion at 150 µg/kg/min (IVATP150); (3) IV ATP infusion at 210 µg/kg/min (IVATP210); (4) IC administration of 0.5 mg nicorandil during IVATP150 (ICNIC0.5 mg+IVATP150); (5) IC administration of 1 mg nicorandil during IVATP150 (ICNIC1 mg+IVATP150); and (6) IC administration of 2 mg nicorandil during IVATP150 (ICNIC2 mg+IVATP150). The average FFR values and the rate of achieving maximum hyperemia after ICNIC2 mg, IVATP150, IVATP210, ICNIC0.5 mg+IVATP150, ICNIC1 mg+IVATP150, and ICNIC2 mg+IVATP150 were 0.85±0.08, 0.89±0.08, 0.85±0.09, 0.84±0.08, 0.83±0.08, 0.83±0.08 (P<0.01), and 92%, 54%, 91%, 96%, 99%, 99% (P<0.01), respectively. The incidence of systolic aortic pressure drop, chest discomfort, and transient atrioventricular block increased in a dose-dependent manner after IV ATP infusion, but almost no adverse effects were observed after ICNIC2 mg. CONCLUSIONS: ICNIC2 mg produced a more pronounced hyperemia than continuous IV ATP, and might be the preferred method for assessment of FFR.

Effect of Tofogliflozin on Systolic and Diastolic Cardiac Function in Type 2 Diabetic Patients.

PURPOSE: Recent studies have shown that sodium glucose cotransporter 2 (SGLT2) inhibitors have a favorable effect on cardiovascular events in diabetic patients. However, the underlying mechanism associated with a favorable outcome has not been clearly identified. The purpose of this study was to investigate the effect of tofogliflozin, SGLT2 inhibitor, on systolic and diastolic cardiac function in patients with type 2 diabetes mellitus (T2DM). METHODS: We enrolled 26 consecutive T2DM out-patients on glucose-lowering drugs who initiated tofogliflozin and underwent echocardiography before and ≥ 6 months after tofogliflozin administration. During this period, we also enrolled 162 T2DM out-patients taking other glucose-lowering drugs as a control group. Propensity score analysis was performed to match the patient characteristics. As a result, 42 patients (tofogliflozin group 21 patients and control group 21 patients) were finally used for analysis. Left ventricular systolic function was assessed by measuring 2D-echocardiographic left ventricular ejection fraction (LVEF) and diastolic cardiac function by pulsed wave Doppler-derived early diastolic velocity (E/e'). RESULTS: There were no significant differences in patient characteristics and echocardiographic parameters at baseline. The change in LVEF from baseline to follow-up was 5.0 ± 6.9% in the tofogliflozin group and - 0.6 ± 5.5% in the control group; difference significant, p = 0.006. The change in E/e' was - 1.7 ± 3.4 in the tofogliflozin group and 0.7 ± 4.1 in the control group; difference significant, p = 0.024. CONCLUSIONS: In addition to conventional oral glucose-lowering drugs, additional tofogliflozin administration had a favorable effect on left ventricular systolic and diastolic function in patients with T2DM.

Microbubble contrast enhancement of neointima after drug-eluting stent implantation: an optical coherence tomography study.

Microvessels within neoatherosclerosis are associated with vulnerability and increase from the early to the very late phase after drug-eluting stent implantation. Microbubble contrast agents have been suggested to enhance tissue microvasculature for optical coherence tomography (OCT) imaging. The present study investigated whether OCT signal intensity of neointima within stented segments was enhanced after intracoronary administration of microbubble contrast agents. A total of 40 patients who underwent follow-up coronary angiography after drug-eluting stent implantation were enrolled. At the time of follow-up coronary angiography, OCT images of the stented segments were recorded before and after intracoronary administration of microbubble contrast agents. Mean OCT signal intensity of neointima after microbubble administration significantly increased [95.5 (85.7, 106.2) vs. 96.5 (88.7, 109.9), p = 0.001]. Multivariate analysis demonstrated the relationship between diabetes and greater neointima enhancement. The change in the OCT signal intensity of neointima following microbubble administration tended to be higher in diabetic patients than in non-diabetic patients [4.6 (0.6, 8.5) vs. 1.4 (- 1.1, 3.0), p = 0.05]. These findings suggest that this methodology may allow identification of neovascularization in neointima and evaluation of vulnerability of neoatherosclerosis. Microvessels in neointima may be a future target of pharmacological and interventional innovations for preventing stent failure.

Assessment of strut coverage of everolimus-eluting platinum chromium stent 2 weeks after implantation by optical coherence tomography.

The SYNERGY coronary stent is new-generation drug-eluting stents, which has a thin-strut platinum-chromium platform with everolimus in a biodegradable polymer applied to the abluminal surface. It would be speculated that favorable arterial healing with early strut coverage could be achieved. The present study investigated the degree of strut coverage using optical coherence tomography (OCT) 2 weeks after SYNERGY implantation and clinical factors contributing to strut coverage. A total of 29 patients who underwent staged percutaneous coronary intervention (PCI) to residual lesions 2 weeks after the index PCI with SYNERGY stent implantation were enrolled. At the time of staged PCI, OCT examinations of the SYNERGY stent were performed for conventional OCT analysis on both cross-sectional and strut level. SYNERGY stent showed a high level of strut coverage and apposition, and the percentage was 82.4 ± 12.4% and 96.2 ± 5.0%, respectively. The lesion complexity was significantly related to greater strut coverage on univariate analysis; however, it was found to be insignificant in multivariate analysis. Our findings suggest early arterial healing after SYNERGY stent implantation.

Efficacy of 2.5-mg Prasugrel in Elderly or Low-Body-Weight Patients.

BACKGROUND: Due to concern about bleeding complications, a maintenance dose of prasugrel 2.5 mg may be used in elderly or low-body-weight patients in Japan. There is little information, however, on the efficacy and safety of a 2.5-mg maintenance dose of prasugrel. Methods and Results: In this single-center, prospective, open-label, cross-over study, a total of 44 elderly (≥75 years old) or low body-weight (<50 kg) Japanese patients >1 month after percutaneous coronary intervention who were treated with aspirin 81-100 mg and clopidogrel 75 mg were randomized to either prasugrel 2.5 mg or 3.75 mg instead of clopidogrel for 14 days, with a cross-over directly to the alternate treatment for another 14 days. Platelet inhibition was assessed with the VerifyNow assay (Accumetrics, San Diego, CA, USA) at 3 time points: baseline; day 14; and day 28. P2Y12 reaction units (PRU) ≤95 was defined as low on-treatment platelet reactivity (LPR), and PRU ≥262 as high on-treatment platelet reactivity (HPR). The prevalence of LPR was 2.2% in patients treated with clopidogrel, 2.2% in those with prasugrel 2.5 mg, and 22.7% in those with prasugrel 3.75 mg (P<0.001). Clopidogrel resulted in the higher prevalence of HPR compared with 2.5-mg and 3.75-mg prasugrel (40.9% vs. 18.2% vs. 6.8%, P<0.001). CONCLUSIONS: Prasugrel 2.5 mg may be more appropriate in elderly or lower-body-weight Japanese patients.

Atherosclerotic Component of the Yellow Segment After Drug-Eluting Stent Implantation on Coronary Angioscopy　- An Ex-Vivo Validation Study.

BACKGROUND: Coronary angioscopy (CAS) is used to comprehensively evaluate vascular responses after drug-eluting stent (DES) implantation. This study sought to evaluate the capability of CAS for evaluating DES strut coverage grade and color grade of the intima compared with histological images in coronary autopsy specimens. Methods and Results: A total of 23 DES extracted from 11 autopsy hearts were imaged by CAS. All stent segments were graded as white or yellow according to the luminal surface color, and thrombus was evaluated according to a previous report. Neointimal coverage over the DES was graded as 0 (stent struts fully visible) to grade 3 (stent struts fully embedded and invisible). Of 76 segments, neointimal coverage was graded as 0 in 35 (46%), 1 in 22 (29%), 2 in 8 (11%), and 3 in 11 (14%). The neointimal thickness increased significantly with increasing neointimal coverage grade on angioscopy. Neointimal color was graded as white in 40 (53%) and yellow in 36 segments (47%). Histological analysis revealed that yellow neointima contained fibroatheroma, foam cells accumulation or superficial calcium deposition. A thrombus was identified in 13 segments. Thrombi adherent around the stent strut were partly intimal erythrocyte accumulation around the strut. CONCLUSIONS: In-stent yellow segment had atherosclerotic components. CAS could evaluate vascular status comprehensively after DES implantation.

Impact of analysis interval size on the quality of optical frequency domain imaging assessments of stent implantation for lesions of the superficial femoral artery.

OBJECTIVES: This study aimed to investigate the influence of analysis interval size on optical frequency domain imaging (OFDI) assessment of stent therapy for lesions of the superficial femoral artery (SFA). BACKGROUND: No consensus or validating data are available with respect to the methodology of intravascular imaging analysis for the peripheral arteries. METHODS: OFDI was performed for 30 SFA lesions, during endovascular therapy and at the 6-month follow-up. Initially, lumen and stent borders were traced at 1-mm axial intervals. Volumes were calculated using a PC-based software, and the volume index (VI) was defined as the volume divided by the stent length. Two additional OFDI analyses were performed using 2-mm and 5-mm intervals, thereby reducing the number of cross-sectional image frames analyzed. RESULTS: The mean stent length was 89.7 ± 35.2 mm. The mean difference in baseline minimum lumen area (MLA) was 0.4 mm2 between MLA values from the 1-mm and 2-mm interval analyses, and 2.2 mm2 between MLA values from the 1-mm and 5-mm interval analyses. In volumetric analysis, there were excellent correlations and good agreements for stent, lumen, and neointimal VI measurements obtained on the basis of different analysis intervals. CONCLUSIONS: Using large intervals in OFDI analyses of SFA lesions resulted in few differences in measurement variability of volumetric parameters. However, planar analysis for MLA assessment can be susceptible to high variability when large intervals are applied. © 2016 Wiley Periodicals, Inc.