Difference of ruptured plaque morphology between asymptomatic coronary artery disease and non-ST elevation acute coronary syndrome patients: an optical coherence tomography study

BACKGROUND

Autopsy studies have reported that rupture of a thin-cap fibroatheroma and subsequent thrombus formation is the major mechanism leading to acute coronary syndrome (ACS). However, it is not clear why only some plaque ruptures lead to ACS. Optical coherence tomography (OCT) is a high-resolution imaging modality which is capable of investigating detailed coronary plaque morphology in vivo. The objective of this study was to determine whether ruptured plaque morphology assessed by OCT differs between asymptomatic coronary artery disease (CAD) and non-ST elevation acute coronary syndrome (NSTEACS).

METHODS

We examined ruptured plaque morphology using OCT in 80 patients, 33 with asymptomatic CAD and 47 with NSTEACS.

RESULTS

The frequency of lipid-rich plaque and intracoronary thrombus was significantly lower in asymptomatic CAD than in NSTEACS (61% vs. 85%, p = 0.013 and 9% vs. 83%, p < 0.001, respectively). Although maximal ruptured cavity cross-sectional area (CSA) was similar in both groups, lumen area at the rupture site and minimal lumen area were significantly larger in asymptomatic CAD than in NSTEACS (3.78 ± 1.50 mm(2) vs. 2.70 ± 1.55 mm(2), p = 0.003 and 2.75 ± 0.99 mm(2) vs. 1.72 ± 0.90 mm(2), p < 0.001, respectively).

CONCLUSIONS

OCT revealed that the morphology of ruptured plaques differs between asymptomatic CAD and NSTEACS in terms of lumen area and the frequency of lipid-rich plaques and thrombi. These morphological features may be associated with the clinical presentation of CAD.

Assessment of circumferential endocardial extent of myocardial edema and infarction in patients with reperfused acute myocardial infarction: a cardiovascular magnetic resonance study

T2 weighted (T2W) images on cardiovascular magnetic resonance (CMR) visualizes myocardial edema, which reflects the myocardial area at risk (AAR) in reperfused acute myocardial infarction (AMI). Late gadolinium enhancement (LGE) demonstrates myocardial infarction. LGE images cover the whole left ventricle, but T2W images are obtained from a few slices of the left ventricle due to the long sequence time, so the quantification of AAR of the entire left ventricle is difficult. We hypothesize that we can quantify AAR with only LGE images if there is a strong correlation between the circumferential endocardial extent of myocardial edema and infarction. Thirty patients with first AMI were enrolled. All patients underwent successfully reperfusion therapy and CMR was performed within the first week after the event. We measured the circumferential extent of edema and infarction on short-axis views (T2 angle and LGE angle), respectively. A total of 82 short-axis slices showed transmural edema on T2W images. Corresponding LGE images were analyzed for the circumferential extent of infarction. The median [interquartile range] of T2 angle and DE angle were 147° [116°-219°] and 134° [104°-200°] in patients with LAD culprit lesion, 91° [87°-101°] and 85° [80°-90°] in LCX, and 110° [94°-123°] and 104° [89°-118°] in RCA, respectively. T2 angle was well correlated with LGE angle (r = 0.99, P < 0.01). There is a strong correlation between the circumferential extent of edema and infarction in reperfused AMI. Thus, T2 weighted imaging can be skipped to quantify the amount of AAR.

Impact of glucose fluctuation and monocyte subsets on coronary plaque rupture

BACKGROUND AND AIMS

It remains unclear whether glycemic fluctuation can affect plaque rupture in acute myocardial infarction (AMI). Here we investigate the impact of glucose fluctuation on plaque rupture, as observed by optical coherence tomography (OCT), and monocyte subsets in patients with AMI.

METHODS AND RESULTS

We studied 37 consecutive patients with AMI. All patients underwent OCT examination, which revealed 24 patients with plaque rupture and 13 patients without plaque rupture at the culprit site. Peripheral blood sampling was performed on admission. Three monocyte subsets (CD14(+)CD16(-), CD14(bright)CD16(+), and CD14(dim)CD16(+)) were assessed by flow cytometry. Glycemic variability, expressed as the mean amplitude of glycemic excursion (MAGE), was determined by a continuous glucose monitoring system 7 days after the onset of AMI. MAGE was significantly higher in the rupture patients than in the non-rupture patients (P=0.036). Levels of CD14(bright)CD16(+) monocytes from the rupture patients were significantly higher than those from the non-rupture patients (P=0.042). Of interest, levels of CD14(bright)CD16(+) monocytes correlated positively and significantly with MAGE (r=0.39, P=0.02).

CONCLUSION

Dynamic glucose fluctuation may be associated with coronary plaque rupture, possibly through the preferential increase in CD14(bright)CD16(+) monocyte levels.

Relation of albuminuria to coronary microvascular function in patients with chronic kidney disease

The relation between albuminuria and coronary microvascular function in patients with chronic kidney disease (CKD) has not been fully investigated. Therefore, we sought to assess whether albuminuria is associated with coronary flow velocity reserve (CFVR) impairment in patients with CKD. Coronary flow study was prospectively performed in 175 patients with CKD. CFVR of the left anterior descending artery was measured to evaluate coronary microvascular function using transthoracic echocardiography. We divided the patients into 5 groups according to the stages of CKD and analyzed the effect of albuminuria. CFVR gradually decreased with an increase in CKD stages. CFVR in patients with albuminuria was lower than those without albuminuria. In groups with CKD stages 2 and 3, the patients with albuminuria showed lower CFVR than those without albuminuria. Multiple logistic regression analysis revealed that albuminuria, age, and gender were independently associated with CFVR impairment. Of these factors, albuminuria was the most powerful predictor with the risk ratio of 12.4 for CFVR impairment. In conclusion, the more the CKD stages progressed, the more severe CFVR was impaired. Albuminuria was associated with CFVR impairment in patients with CKD; even in mild-to-moderate CKD, patients with albuminuria showed further reduced coronary vasodilator capacity.

Time-of-flight secondary ion mass spectrometry with transmission of energetic primary cluster ions through foil targets

We developed time-of-flight (TOF) secondary ion (SI) mass spectrometry that provides informative SI ion mass spectra without needing a sophisticated ion beam pulsing system. In the newly developed spectrometry, energetic large cluster ions with energies of the order of sub MeV or greater are used as primary ions. Because their impacts on the target surface produce high yields of SIs, the resulting SI mass spectra are informative. In addition, the start signals necessary for timing information on primary ion incidence are provided by the detection signals of particles emitted from the rear surface of foil targets upon transmission of the primary ions. This configuration allows us to obtain positive and negative TOF SI mass spectra without pulsing system, which requires precise control of the primary ions to give the spectra with good mass resolution. We also successfully applied the TOF SI mass spectrometry with energetic cluster ion impacts to the chemical structure characterization of organic thin film targets.

Impact of myocardial supply area on the transstenotic hemodynamics as determined by fractional flow reserve

OBJECTIVES

The aim of this study was to investigate the impact of myocardial area supplied by the coronary artery on fractional flow reserve (FFR).

BACKGROUND

Various factors other than the degree of epicardial stenosis influence the physiological significance of a coronary artery stenosis.

METHODS

A total of 296 coronary lesions in 217 patients were analyzed by quantitative coronary angiography and FFR. Myocardial area supplied by the coronary artery distal to the stenosis was evaluated by angiography using a modified version of the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) score.

RESULTS

Percent diameter stenosis of the coronary lesion was 57 ± 15% (mean ± standard deviation). FFR <0.80 was seen in 132 (45%) lesions. FFR was significantly correlated with minimum lumen diameter (r = 0.584, P <0.001), percent diameter stenosis (r = -0.565, P <0.001), lesion length (r = -0.306, P <0.001), and myocardial supply area (r = -0.504, P <0.001). Multivariate logistic analysis demonstrated that minimum lumen diameter (odds ratio [OR] = 0.031, 95% confidence interval [CI] = 0.013-0.076, P < 0.001), lesion length (OR = 1.038, 95% CI = 1.009-1.069, P = 0.001), and myocardial supply area (OR = 1.113, 95% CI = 1.079-1.147, P <0.001) were independent determinants for FFR <0.80.

CONCLUSIONS

FFR, which is the index of physiological significance of coronary artery stenosis, is influenced by myocardial supply area distal to the stenosis as well as by its own minimal lumen diameter and lesion length.

Acceleration time of systolic coronary flow velocity to diagnose coronary stenosis in patients with microvascular dysfunction

BACKGROUND

The aim of this study was to test whether acceleration time of systolic coronary flow velocity could contribute to the diagnosis of coronary stenosis in patients with microvascular dysfunction, on the basis of the hypothesis that systolic coronary flow is less influenced by microvascular function because of compressed myocardium.

METHODS

Coronary flow velocity was assessed in the left anterior descending coronary artery during hyperemia with intravenous adenosine by echocardiography in 502 patients who were scheduled for coronary angiography because of coronary artery disease and significant valvular disease. Coronary flow velocity reserve (CFVR) and the percentage acceleration time (%AT), as the percentage of the time from the beginning to the peak of systolic coronary flow over systolic time during hyperemia, were calculated. The diagnostic ability of CFVR and %AT for angiographic coronary artery stenosis was then analyzed. As invasive substudies, fractional flow reserve and %AT by a dual-sensor (pressure and Doppler velocity) guidewire were measured simultaneously with %AT on transthoracic echocardiography (n = 14).

RESULTS

Patients with coronary stenosis had significantly lower CFVR (1.7 ± 0.4) and greater %AT (65 ± 9%) compared with those without stenosis (2.6 ± 0.6 and 50 ± 13%, respectively). Percentage acceleration time by Doppler echocardiography was in good agreement with %AT (r = 0.98) and fractional flow reserve (r = 0.74) invasively measured by dual-sensor guidewire. Cutoff values of CFVR and %AT were determined as 2.0 and 60% in receiver operating characteristic curve analysis. The sensitivity, specificity, and accuracy of CFVR to detect coronary stenosis were 71.1%, 77.3%, and 75.4%, while those of %AT were 83.4%, 71.8%, and 75.4%, respectively. In addition, %AT provided high accuracy to detect coronary stenosis, especially in patients with previous myocardial infarctions, valvular disease, and left ventricular hypertrophy (81.1%, 84.1%, and 73.4%, respectively).

CONCLUSIONS

The %AT of systolic coronary flow velocity is a promising marker to diagnose coronary stenosis in patients with microvascular dysfunction.

Acute-phase glucose fluctuation is negatively correlated with myocardial salvage after acute myocardial infarction

BACKGROUND

It remains unclear whether glycemic fluctuation immediately after acute myocardial infarction (AMI) can affect myocardial damage. This study investigated the impact of glucose fluctuation on myocardial salvage following successful recanalization of primary AMI.

METHODS AND RESULTS

A total of 36 consecutive patients with AMI were studied. Glycemic variability, as indicated by the mean amplitude of glycemic excursion (MAGE), was measured on a continuous glucose monitoring system. Three subsets (CD14(+)CD16(-), CD14(++)CD16(+) and CD14(+-)CD16(+)) were measured on flow cytometry 1, 2, 3, 4 and 5 days after AMI onset. A 2-h oral glucose test was performed in 23 patients who had no previous diagnosis of diabetes and/or glycated hemoglobin <6.5%, after the onset of AMI at 2 weeks. Plasma active glucagon-like peptide (GLP)-1 level was measured in each sample. The extent of myocardial salvage 7 days after AMI was evaluated on cardiovascular magnetic resonance imaging. MAGE and the peak CD14(+)CD16(-) monocyte level were significantly negatively correlated with myocardial salvage index (MSI). MAGE was significantly correlated with peak CD14(+)CD16(-) monocyte level. Of interest, plasma GLP-1 level was significantly positively correlated with MSI and significantly negatively correlated with MAGE.

CONCLUSIONS

Glucose fluctuations during the acute phase of AMI affect MSI, indicating that manipulation of glucose variability from peak to nadir might be a potential therapeutic target for salvaging ischemic damage.

Comparison of diagnostic accuracy between multidetector computed tomography and virtual histology intravascular ultrasound for detecting optical coherence tomography-derived fibroatheroma

Histopathological studies have reported that optical coherence tomography (OCT) can accurately detect fibroatheroma that is involved in not only culprit lesion of acute coronary syndrome but also no-reflow phenomenon after percutaneous coronary intervention. Studies have demonstrated superiority of OCT in plaque characterization and interruption of arterial wall component. At current, multidetector computed tomography (MDCT) and virtual histology intravascular ultrasound (VH-IVUS) are considered as alternative imaging devices for coronary plaque characterization. This study aimed to compare the diagnostic accuracy for detecting fibroatheroma between MDCT and VH-IVUS using OCT as the reference standard. Forty-three lesions from 27 patients assessed by MDCT, VH-IVUS, and OCT were included in this study. Fibroatheroma was defined by OCT as a signal-poor region with a fast signal drop-off and little or no signal backscattering within the lesion. From 43 lesions, OCT revealed 21 fibroatheromas. Ring-like sign assessed by MDCT and positive remodeling assessed by IVUS were more frequently observed in OCT-fibroatheroma than non-OCT-fibroatheroma. The remodeling index of OCT-fibroatheroma assessed by MDCT and IVUS were higher than those of non-OCT-fibroatheroma. The sensitivity, specificity, positive predict values, negative predict values and accuracy of ring-like sign by MDCT and VH-IVUS for detecting OCT-fibroatheroma were 43, 95, 90, 64, 70 % and 71, 45, 56, 63, 58 %, respectively. Our results suggest that both accuracies of MDCT and VH-IVUS to detect OCT-fibroatheroma are insufficient. We need to apply appropriate device for searching vulnerable plaque.

Scanning electron microscopic analysis of polymer damage in drug-eluting stents during multiple stenting

Polymer damage of drug-eluting stents (DES) during percutaneous coronary intervention procedure could be associated with stent restenosis. We assessed the damage to the drug-containing polymer of DES during multiple stenting in a phantom model by using scanning-electron microscopy (SEM). Unexpanded sirolimus-eluting stent (SES; n = 15) was delivered through the formerly expanded SES (n = 15) in a bended polytetrafluoroethylene plastic tube. The stent was subcategorized into 4 segments (S), including distal (S1), mid distal (S2), mid proximal (S3) and proximal segments (S4), for qualitative SEM assessment. Polymer damage, such as detachments, missing or tears, was observed not only in the outer surface of the unexpanded stents (100%) but also in the inner surface of the formerly expanded stents (100%). There was a significant difference in the frequency of polymer damage among the 4 segments in the unexpanded stents (S1 vs. S2 vs. S3 vs. S4: 86.7 vs. 80.0 vs. 53.3 vs. 40.0%, p = 0.022) and the formerly expanded stents (S1 vs. S2 vs. S3 vs. S4: 80.0 vs. 73.3 vs. 73.3 vs. 40.0%, p = 0.041). The damage was distributed more frequently in distal part than proximal part of either unexpanded stents (S1 vs. S4, p = 0.0079) and the formerly expanded stents (S1 vs. S4, p = 0.0079). Delivery of DES through a formerly expanded DES could cause damage to drug-containing polymer of the stents.

Experimental Assessment of Dispersion Failure of Glass Fiber Reinforced Plastics in a Twin Screw Extruder

To investigate the conditions necessary for glass fiber bundle dispersion in the polymer compounding process, we developed a method for experimentally quantifying dispersion failure in this study. We employed a co-rotating twin-screw extruder in our experiment and investigated the dependence of frequency of occurrence of dispersion failure on screw configurations (a forward kneading disk (FKD) and a backward mixing screw (BMS) with different screw configurations), throughput (Q), and screw speed (Ns). From our experiments, we found that increasing the production rate promotes the occurrence of dispersion failure when a FKD is used. Dispersion failure is markedly suppressed when a BMS is used. We thus found that the production rate could be increased by using a BMS with a large length-to-diameter (L/D) ratio.

Asialoglycoprotein receptor scintigraphy with 99mTc-galactosyl human serum albumin (99mTc-GSA) as an early predictor of survival in acute liver failure

This study evaluated the usefulness of asialoglycoprotein receptor scintigraphy with 99mTc-galactosyl human serum albumin (99mTc-GSA scintigraphy) as an early predictor for prognosis of acute liver failure. Forty-eight patients with acute liver failure and without a past history of chronic liver disease were enrolled. Patients were divided into survival and non-survival groups by 28-day mortality. 99mTc-GSA scintigraphy to detect uptake ratio of the heart at 15 minutes to that at three minutes (HH15) and uptake ratio of the liver at 15 minutes to the liver plus the heart at 15 minutes (LHL15), and measurements of serum total bilirubin, hepatocyte growth factor and prothrombin time were performed immediately after the diagnosis of acute liver failure. Areas under the receiver operating characteristic curves were used to compare the prognostic ability of total bilirubin, hepatocyte growth factor, prothrombin time, HH15 ratio, LHL15 ratio and the model for end-stage liver disease score. Clinical characteristics of patients in the survival group (n=20) and in the non-survival group (n=28) were not significantly different. HH15 and LHL15 uptake ratios in the survival group were 0.670 and 0.875, and they were significantly lower and higher than those in the non-survival group, respectively. All patients with LHL15 <0.760 died, and the area under the receiver operating characteristic curve for LHL15 were significantly larger than the areas under the receiver operating characteristic curves of serum variables and model for end-stage liver disease score. In summary, in patients with acute liver failure without chronic liver disease, HH15 and LHL15 of 99mTc-GSA scintigraphy are more useful variables in predicting prognosis than serum variables and model for end-stage liver disease score.