Head to head comparison between the conventional balloon occlusion method and the non-occlusion method for optical coherence tomography.

BACKGROUND: Optical coherence tomography (OCT) has been introduced as a high-resolution imaging modality for the coronary arteries. The current OCT system, however, has a serious limitation in that the image acquisition method requires a soft balloon occlusion to avoid signal scattering from red blood cells. PURPOSE: The purpose of this study was to compare OCT images from the conventional balloon occlusion method and a non-occlusion image acquisition method, the continuous-flushing method, in the clinical setting. METHODS: OCT was performed with the conventional balloon occlusion method and the continuous-flushing method sequentially in 23 patients with stable angina. The image quality and quantitative measurements of OCT images were directly compared between the two methods. RESULTS: There were no adverse events related to the OCT procedure in any patients. There were no changes in systolic blood pressure and heart rate during the OCT procedure. ST-segment elevation (>2 mm) was recorded in 22 of 23 (96%) patients with the balloon occlusion method, but it was only observed in 1 of 23 (4%) patients with the continuous-flushing method (p<0.01). There were no differences in the visible length (the balloon occlusion method 28.6±2.3 mm vs. the continuous-flushing method 29.2±1.6 mm, p=0.49), image quality, or quantitative measurements between the two methods. CONCLUSIONS: OCT imaging with the continuous-flushing method could be performed safely and obtained similar quality images compared with the balloon occlusion method. OCT can be used to observe the proximal site of coronary arteries with this new technique.

Relation of microchannel structure identified by optical coherence tomography to plaque vulnerability in patients with coronary artery disease.

Increased neovascularization in atherosclerotic plaques is associated with plaque vulnerability. The high resolution of optical coherence tomography (OCT) might provide a chance to directly visualize plaque neovascularization in vivo. The aim of the present study was to investigate the relation between microchannels in culprit plaques identified by OCT and plaque vulnerability in patients with coronary artery disease. A total of 63 consecutive patients with coronary artery disease who had undergone both OCT and intravascular ultrasound before any interventions to examine culprit lesion morphologies were enrolled. Microchannel was defined as a no-signal tubuloluminal structure on the cross-sectional optical coherence tomographic image. Microchannels were found in 24 (38%) of the 63 patients. The patients were divided into 2 groups according to the presence or absence of microchannels. The frequency of plaque rupture tended to be greater in the microchannel group (50% vs 28%, p = 0.11). The thickness of the fibrous cap (median 60 vs 100 microm, p = 0.001) was significantly less in the patients with microchannels, and significant differences were found in the frequency of thin-cap fibroatheroma (54% vs 21%, p = 0.012) and positive remodeling (67% vs 36%, p = 0.02) between the 2 groups. The high-sensitivity C-reactive protein levels in the microchannel group was significantly greater than those in the no-microchannel group (median 0.27 vs 0.13 mg/dl, p = 0.015). Moreover, increased microchannel counts were associated with greater high-sensitivity C-reactive protein levels (p = 0.01). In conclusion, a significant relation was found between the presence of microchannels in plaques identified by OCT and plaque vulnerability in patients with coronary artery disease.

Impact of heterogeneity of human peripheral blood monocyte subsets on myocardial salvage in patients with primary acute myocardial infarction.

OBJECTIVES: We examined whether distinct monocyte subsets contribute in specific ways to myocardial salvage in patients with acute myocardial infarction (AMI). BACKGROUND: Recent studies have shown that monocytes in human peripheral blood are heterogeneous. METHODS: We studied 36 patients with primary AMI. Peripheral blood sampling was performed 1, 2, 3, 4, 5, 8, and 12 days after AMI onset. Two monocyte subsets (CD14(+)CD16(-) and CD14(+)CD16(+)) were measured by flow cytometry. The extent of myocardial salvage 7 days after AMI was evaluated by cardiovascular magnetic resonance imaging as the difference between myocardium at risk (T2-weighted hyperintense lesion) and myocardial necrosis (delayed gadolinium enhancement). Cardiovascular magnetic resonance imaging was also performed 6 months after AMI. RESULTS: Circulating CD14(+)CD16(-) and CD14(+)CD16(+) monocytes increased in AMI patients, peaking on days 3 and 5 after onset, respectively. Importantly, the peak levels of CD14(+)CD16(-) monocytes, but not those of CD14(+)CD16(+) monocytes, were significantly negatively associated with the extent of myocardial salvage. We also found that the peak levels of CD14(+)CD16(-) monocytes, but not those of CD14(+)CD16(+) monocytes, were negatively correlated with recovery of left ventricular ejection fraction 6 months after infarction. CONCLUSIONS: The peak levels of CD14(+)CD16(-) monocytes affect both the extent of myocardial salvage and the recovery of left ventricular function after AMI, indicating that the manipulation of monocyte heterogeneity could be a novel therapeutic target for salvaging ischemic damage.

Relationship between coronary arterial remodeling, fibrous cap thickness and high-sensitivity C-reactive protein levels in patients with acute coronary syndrome.

BACKGROUND: Thin-capped fibroatheroma (TCFA) is a recognized precursor lesion for acute coronary syndrome (ACS). Positive remodeling (PR) is the predominant pattern of arterial remodeling in patients with ACS. The aim of this study was to evaluate the relationship between coronary arterial remodeling, fibrous cap thickness and high-sensitivity C-reactive protein (hs-CRP) concentration in patients with ACS. METHODS AND RESULTS: The 47 consecutive ACS patients were enrolled in this study. Arterial remodeling of culprit plaque was assessed by intravascular ultrasound, and fibrous cap thickness was measured by optical coherence tomography. The remodeling index (RI) was calculated as lesion divided by the reference external elastic membrane cross-sectional area, and PR was defined as RI >1.05 (PR group). TCFA were observed more frequently in the PR group than in the intermediate and negative remodeling (IR/NR) groups (59% vs 17%, P<0.01). RI was inversely correlated with fibrous cap thickness (r=0.47, P=0.02). hs-CRP levels were higher in the PR group than in the IR/NR groups (0.32 +/-0.26 vs 0.18 +/-0.14 mg/dl, P=0.02). CONCLUSIONS: Coronary arterial remodeling, fibrous cap thickness and hs-CRP level in patients with ACS are associated with each other. This result suggests that inflammation simultaneously contributes to both plaque growth and plaque instability.

Coronary microvascular resistance index immediately after primary percutaneous coronary intervention as a predictor of the transmural extent of infarction in patients with ST-segment elevation anterior acute myocardial infarction.

OBJECTIVES: The purpose of this study was to investigate whether microvascular resistance index (MVRI) immediately after primary percutaneous coronary intervention (PCI) can predict the transmural extent of infarction (TEI) defined by contrast-enhanced cardiac magnetic resonance (ce-CMR) in patients with anterior acute myocardial infarction (MI). BACKGROUND: The degree of microvascular damage is an important determinant of myocardial viability and clinical outcomes in acute MI. A novel dual-sensor (pressure and Doppler velocity) guidewire has the ability to evaluate microvascular damage. ce-CMR can accurately discriminate transmural from nontransmural MI, and the TEI by ce-CMR can predict future improvement in contractile function. METHODS: In 27 patients immediately after primary PCI for a first anterior acute MI, MVRI, coronary flow reserve (CFR), deceleration time of diastolic velocity (DDT), and zero flow pressure (Pzf) were measured with a dual-sensor guidewire. TEI was graded from 1 to 4 based on the transmural extent of hyperenhanced tissue (1 = 0% to 25% of left ventricular wall thickness, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = 76% to 100%). Infarct size by ce-CMR was also calculated. RESULTS: Peak creatine kinase-myocardial band values were significantly correlated with MVRI (r = 0.77, p < 0.0001), CFR (r = -0.69, p < 0.0001), DDT (r = -0.75, p = 0.0001), and Pzf (r = 0.75, p < 0.0001). Also, infarct size by ce-CMR was significantly correlated with MVRI (r = 0.78, p < 0.0001), CFR (r = -0.67, p < 0.0001), DDT (r = -0.70, p < 0.0001), and Pzf (r = 0.72, p = 0.0002). Receiver-operating characteristic curve analyses of MVRI, CFR, DDT, and Pzf for predicting transmural MI (TEI-grade 4) demonstrated that the area under the curve tended to be higher for MVRI (0.885) than those for CFR (0.848), DDT (0.862), and Pzf (0.853). The best cut-off value for MVRI was 3.25 mm Hg x cm(-1) x s (sensitivity 75%, specificity 89%). Moreover, increased MVRI was significantly related to increased TEI-grade (p < 0.0001). CONCLUSIONS: MVRI measured immediately after primary PCI is a useful predictor for the TEI in patients with anterior acute MI.

Lipid-rich plaque and myocardial perfusion after successful stenting in patients with non-ST-segment elevation acute coronary syndrome: an optical coherence tomography study.

AIMS: Although some recent guidelines recommend an early invasive strategy for non-ST-segment elevation acute coronary syndrome (NSTEACS), several studies have failed to identify any benefit for very early intervention for NSTEACS. The no-reflow phenomenon may inhibit the expected benefit from very early recanalization for NSTEACS subjects. The aim of this study was to investigate whether optical coherence tomography (OCT) could predict no-reflow in patients with NSTEACS. METHODS AND RESULTS: This study comprised 83 consecutive patients with NSTEACS who underwent OCT and successful emergent primary stenting. On the basis of post-stent TIMI flow, patients were divided into two groups: no-reflow group (n = 14) and reflow group (n = 69). Thin-cap fibroatheroma (TCFA) was defined as a plaque presenting lipid content for >90 degrees , and with thinnest part of the fibrous cap measuring <70 microm. Thin-cap fibroatheroma were more frequently observed in the no-reflow group than in the reflow group (50% vs. 16%, P = 0.005). The frequency of the no-reflow phenomenon increases according to the size of the lipid arc in the culprit plaque. Final TIMI blush grade also deteriorated according to the increase in the lipid arc. A multivariable logistic regression model revealed that lipid arc alone was an independent predictor of no-reflow (odds ratio 1.018; CI 1.004-1.033; P = 0.01). CONCLUSION: Optical coherence tomography can predict no-reflow after percutaneous coronary intervention (PCI) in NSTEACS. The lipid contents of a culprit plaque may play a key role in damage to the microcirculation after PCI for NSTEACS. From our results, it is found that OCT is useful tool for stratifying risk for PCI for NSTEACS.

Feasibility of noninvasive assessment of thin-cap fibroatheroma by multidetector computed tomography.

OBJECTIVES: The purpose of this study was to investigate whether multidetector computed tomography (MDCT) can noninvasively help assess thin-cap fibroatheroma (TCFA). BACKGROUND: Plaque rupture and thrombus formation play key roles in the onset of acute coronary syndrome. TCFA is recognized as a precursor lesion for plaque rupture, and MDCT angiography can potentially help identify plaques prone to rupture. METHODS: We enrolled 105 patients with coronary artery disease (acute coronary syndromes, n = 31; stable angina pectoris, n = 74). Culprit lesions were assessed by both MDCT and optical coherence tomography (OCT). Patients were divided into a TCFA and a non-TCFA group according to OCT findings; clinical and MDCT observations were compared for 2 groups. RESULTS: There were no differences in patients' characteristics between the 2 groups. OCT revealed 25 TCFAs at the culprit site in 105 patients. Acute coronary syndrome was more frequent in the TCFA group than in the non-TCFA group (52% vs. 23%, p = 0.01). High-sensitive C-reactive protein was higher in the TCFA group (0.32 +/- 0.32 mg/dl vs. 0.17 +/- 0.16 mg/dl, p < 0.001). Positive remodeling identified by MDCT was observed more frequently in the TCFA group than in the non-TCFA group (76% vs. 31%, p < 0.001). Computed tomography attenuation value of the culprit plaque in the TCFA group was lower than that in the non-TCFA group (35.1 +/- 32.3 HU vs. 62.0 +/- 33.6 HU, p < 0.001). The frequency of ring-like enhancement in the TCFA group was higher than in the non-TCFA group (44% vs. 4%, p < 0.0001). The sensitivity, specificity, positive predictive value, and negative predictive value of ring-like enhancement for detecting TCFA are 44%, 96%, 79%, and 85%, respectively. By stepwise regression, the ring-like enhancement, high-sensitive C-reactive protein, and diagnosis of acute events were associated with the presence of TCFA at the culprit site. CONCLUSIONS: MDCT can identify differences in plaque morphologies between TCFA and non-TCFA. From our results, MDCT may provide for the noninvasive assessment of vulnerable plaque.

Morphology of exertion-triggered plaque rupture in patients with acute coronary syndrome: an optical coherence tomography study.

BACKGROUND: Plaque rupture and secondary thrombus formation play key roles in the onset of acute coronary syndrome (ACS). One pathological study suggested that the morphologies of plaque rupture differed between rest-onset and exertion-triggered rupture in men who experienced sudden death. The aim of the present study was to use optical coherence tomography to investigate the relationship in patients with ACS between the morphology of a ruptured plaque and the patient's activity at the onset of ACS. METHODS AND RESULTS: The study population was drawn from 43 consecutive ACS patients (with or without ST-segment elevation) who underwent optical coherence tomography and presented with a ruptured plaque at the culprit site. Patients were divided into a rest group and an exertion group on the basis of their activities at the onset of ACS. The thickness of the broken fibrous cap correlated positively with activity at the onset of ACS. The culprit plaque ruptured at the shoulder more frequently in the exertion group than in the rest group (rest 57% versus exertion 93%, P=0.014). The thickness of the broken fibrous cap in the exertion group was significantly higher than in the rest-onset group (rest onset: 50 microm [interquartile median 15 microm]; exertion: 90 microm [interquartile median 65 microm], P<0.01). CONCLUSIONS: The morphologies of exertion-triggered and rest-onset ruptured plaques differ in ACS patients. Our data suggest that a thin-cap fibroatheroma is a lesion predisposed to rupture both at rest and during the patient's day-to day activity, and some plaque rupture may occur in thick fibrous caps depending on exertion levels.

Distribution and frequency of thin-capped fibroatheromas and ruptured plaques in the entire culprit coronary artery in patients with acute coronary syndrome as determined by optical coherence tomography.

The aim of this study was to investigate the distribution and frequency of thin-capped fibroatheromas (TCFAs) within the entire length of culprit coronary arteries in patients with acute coronary syndrome. Our population was drawn from 43 consecutive patients with acute coronary syndrome (with or without ST-segment elevation) who underwent optical coherence tomography to visualize the entire culprit coronary artery using a nonocclusive optical coherence tomographic technique. Patients were categorized divided into a TCFA group or a no-TCFA group on the basis of the optical coherence tomographic findings. There were no differences in baseline characteristics or angiographic findings between the 2 groups. High-sensitive C-reactive protein in the TCFA group was significantly higher than in the no-TCFA group (median 3.3 mg/L, interquartile 3.1, vs 1.7 mg/L, interquartile 2.2, p = 0.03). Plaque rupture was found in 28 patients (65%) and multiple plaque ruptures in 5 patients (12%). Optical coherence tomogram revealed 21 TCFAs in 18 patients (42%). Multiple TCFAs were found in the same vessel in 3 patients (7%). The distribution of TCFAs in the right coronary arteries of our subject population was relatively even (proximal 2 [12%], mid 5 [29%], distal 3 [18%], p = 0.42), whereas TCFAs in the left anterior descending artery were common in proximal sites (proximal 6 [27%], mid 2 [9%], distal 0, p = 0.018). In conclusion, the use of optical coherence tomography to look for TCFAs and identify their distribution when combined with C-reactive protein may contribute to forming a strategy for preventing impending coronary events.

Safety and usefulness of non-occlusion image acquisition technique for optical coherence tomography.

BACKGROUND: Because optical coherence tomography (OCT) requires balloon-occlusion to overcome image attenuation by blood, the present study investigated the safety and usefulness of a new non-occlusive technique. METHODS AND RESULTS: The 40 angina patients were assigned to the continuous-flushing method or the balloon-occlusion method group. The continuous-flushing method was superior for observing proximal lesions compared with the balloon-occlusion method (94% vs 55%, p=0.01). There were no differences between groups in the visible length and image quality. There were no major complications during OCT. CONCLUSIONS: The continuous-flushing method is safe and useful for OCT.