Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging and the Risk of Sudden Cardiac Death in Patients With Coronary Disease and Left Ventricular Ejection Fraction >35%

OBJECTIVES: The aim of this study was to determine whether single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is an effective method of risk stratification for sudden cardiac death (SCD) in patients with coronary artery disease (CAD) and left ventricular ejection fraction (LVEF) >35%. Most victims of SCD have an LVEF >35%.

METHODS: The study population included 4,865 patients with CAD and LVEF >35% who underwent gated SPECT MPI. We used Cox proportional hazard modeling to examine the relationship between patient characteristics and SCD.

RESULTS: The median age of the population was 63 years (25th, 75th percentile: 54, 71 years), and the median LVEF was 56% (25th, 75th percentile: 50%, 64%). The median follow-up for all patients was 6.5 years (25th, 75th percentile: 3.6, 9.3 years). During follow-up, there were 161 SCDs (3.3%). After multivariable adjustment, LVEF, the Charlson index, hypertension, smoking, antiarrhythmic drug therapy, and the summed stress score (SSS) were associated with SCD (all p < 0.05). For each 3-U increase in the SSS, the hazard ratio for SCD was 1.13 (95% confidence interval: 1.04 to 1.23). The addition of perfusion data to the clinical history and LVEF was associated with increased discrimination for SCD events (c-index 0.728). Risk stratification with a derived SPECT nomogram did not result in statistically significant net reclassification improvement (p = 0.26) or integrated discrimination improvement (p = 0.38).

CONCLUSIONS: Among patients with CAD and LVEF >35%, the extent of stress MPI perfusion defects is associated with an increased risk of SCD. Future large prospective studies should address the role of perfusion imaging in the identification of high-risk patients with LVEF >35% who might benefit from ICD implantation.

PMID: 19808541

Meta-Analysis of the Diagnostic Performance of Stress Perfusion Cardiovascular Magnetic Resonance for Detection of Coronary Artery Disease

OBJECTIVES: Evaluation of the diagnostic accuracy of stress perfusion cardiovascular magnetic resonance for the diagnosis of significant obstructive coronary artery disease (CAD) through meta-analysis of the available data.

METHODS: Original articles in any language published before July 2009 were selected from available databases (MEDLINE, Cochrane Library and BioMedCentral) using the combined search terms of magnetic resonance, perfusion, and coronary angiography; with the exploded term coronary artery disease. Statistical analysis was only performed on studies that: (1) used a [greater than or equal to] 1.5 Tesla MR scanner; (2) employed invasive coronary angiography as the reference standard for diagnosing significant obstructive CAD, defined as a [greater than or equal to] 50% diameter stenosis; and (3) provided sufficient data to permit analysis.

RESULTS: From the 263 citations identified, 55 relevant original articles were selected. Only 35 fulfilled all of the inclusion criteria, and of these 26 presented data on patient-based analysis. The overall patient-based analysis demonstrated a sensitivity of 89% (95% CI: 88-91%), and a specificity of 80% (95% CI: 78-83%). Adenosine stress perfusion CMR had better sensitivity than with dipyridamole (90% (88-92%) versus 86% (80-90%), P = 0.022), and a tendency to a better specificity (81% (78-84%) versus 77% (71-82%), P = 0.065).

CONCLUSIONS: Stress perfusion CMR is highly sensitive for detection of CAD but its specificity remains moderate.

PMID: 20482819

Prevalence, Distribution and Risk Factor Correlates of High Pericardial and Intra-thoracic Fat Depots in the Framingham Heart Study

OBJECTIVES: Pericardial and intra-thoracic fat depots may represent novel risk factors for obesity-related cardiovascular disease. We sought to determine the prevalence, distribution and risk factor correlates of high pericardial and intra-thoracic fat deposits.

METHODS: Participants from the Framingham Heart Study (n=3312; mean age 52 years, 48% women) underwent multi-detector CT imaging in 2002-2005; high pericardial and high intra-thoracic fat were defined based on the sex-specific 90th percentile for these fat depots in a healthy reference sample.

RESULTS: For men and women, the prevalence of high pericardial fat was 29.3% and 26.3%, respectively, and high intra-thoracic fat was 31.4% and 35.3%, respectively. Overall, 22.1% of the sample was discordant for pericardial and intra-thoracic fat depots: 8.3% had high pericardial but normal intra-thoracic fat, and 13.8% had high intra-thoracic but normal pericardial fat. Higher body mass index, higher waist circumference (WC) and increased prevalence of metabolic syndrome were more likely in participants with high intra-thoracic fat depots than with high pericardial fat (p<0.05 for all comparisons). High abdominal visceral adipose tissue was more frequent in participants with high intra-thoracic adipose tissue compared to those with high pericardial fat (p<0.001). Intra-thoracic fat, but not WC, was more highly correlated with VAT (r=0.76 and 0.78 in men and women, respectively; p<0.0001) than with SAT (r=0.46 and 0.54 in men and women, respectively; p<0.0001).

CONCLUSIONS: Although prevalence of pericardial fat and intra-thoracic fat were comparable at 30%, intra-thoracic fat correlated more closely with metabolic risk and visceral fat. Intra-thoracic fat may be a potential marker of metabolic risk and visceral fat on thoracic imaging.

PMID: 20525769

Extent of Late Gadolinium Enhancement Detected by Cardiovascular Magnetic Resonance Correlates With the Inducibility of Ventricular Tachyarrhythmia in Hypertrophic Cardiomyopathy

OBJECTIVES: Myocardial fibrosis is frequently identified in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to investigate the role of myocardial fibrosis detected by late gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) as a potential arrhythmogenic substrate in HCM. We hypothesized that the extent of LGE might be associated with the inducibility of ventricular tachyarrhythmias (VT) during programmed ventricular stimulation (PVS).

METHODS: We evaluated retrospectively LGE CMR of 76 consecutive HCM patients, of which 43 presented with one or more risk factors for sudden cardiac death (SCD) and were therefore clinically classified as high-risk patients. Of these 43 patients, 38 additionally underwent an electrophysiological testing (EP). CMR indices and the extent of LGE, given as the % of LV mass with LGE were correlated with the presence of risk factors for SCD and the results of EP.

RESULTS: High-risk patients had a significant higher prevalence of LGE than low-risk patients (29/43 [67%] versus 14/33 [47%]; p=0.03). Also the % of LV mass with LGE was significantly higher in high-risk patients than in low-risk patients (14% versus 3%, p=0.001, respectively). Of the 38 high- risk patients, 12 had inducible VT during EP. LV function, volumes and mass were comparable in patients with and without inducible VT. However, the % of LV mass with LGE was significantly higher in patients with inducible VT compared to those without (22% versus 10 %, p=0.03). The prevalence of LGE was, however, comparable between HCM patients with and those without inducible VT (10/12 [83%] versus 15/26 [58%]; p=0.12). In the univariate analysis the % of LV mass with LGE and the septal wall thickness were significantly associated with the high-risk group (p= 0.001 and 0.004, respectively). Multivariate analysis demonstrated that the extent of LGE was the only independent predictor of the risk group (p=0.03).

CONCLUSIONS: The extent of LGE in HCM patients correlated with risk factors of SCD and the likelihood of inducible VT. Furthermore, LGE extent was the only independent predictor of the risk group. This supports the hypothesis that the extent of fibrosis may serve as potential arrhythmogenic substrate for the occurrence of VT, especially in patients with clinical risk factors for SCD.

PMID: 20492668

Coronary Artery Calcium Score and Risk Classification for Coronary Heart Disease Prediction

OBJECTIVES: : The coronary artery calcium score (CACS) has been shown to predict future coronary heart disease (CHD) events. However, the extent to which adding CACS to traditional CHD risk factors improves classification of risk is unclear. To determine whether adding CACS to a prediction model based on traditional risk factors improves classification of risk.

METHODS: CACS was measured by computed tomography in 6814 participants from the Multi-Ethnic Study of Atherosclerosis (MESA), a population-based cohort without known cardiovascular disease. Recruitment spanned July 2000 to September 2002; follow-up extended through May 2008. Participants with diabetes were excluded from the primary analysis. Five-year risk estimates for incident CHD were categorized as 0% to less than 3%, 3% to less than 10%, and 10% or more using Cox proportional hazards models. Model 1 used age, sex, tobacco use, systolic blood pressure, antihypertensive medication use, total and high-density lipoprotein cholesterol, and race/ethnicity. Model 2 used these risk factors plus CACS. We calculated the net reclassification improvement and compared the distribution of risk using model 2 vs model 1.

RESULTS: During a median of 5.8 years of follow-up among a final cohort of 5878, 209 CHD events occurred, of which 122 were myocardial infarction, death from CHD, or resuscitated cardiac arrest. Model 2 resulted in significant improvements in risk prediction compared with model 1 (net reclassification improvement = 0.25; 95% confidence interval, 0.16-0.34; P < .001). In model 1, 69% of the cohort was classified in the highest or lowest risk categories compared with 77% in model 2. An additional 23% of those who experienced events were reclassified as high risk, and an additional 13% without events were reclassified as low risk using model 2.

CONCLUSIONS: In this multi-ethnic cohort, addition of CACS to a prediction model based on traditional risk factors significantly improved the classification of risk and placed more individuals in the most extreme risk categories.

PMID: 20424251

The Detection of Any Coronary Calcium Outperforms Framingham Risk Score as a First Step in Screening for Coronary Atherosclerosis

OBJECTIVE: The Framingham risk score is often recommended as the starting point for coronary disease screening. We compared the sensitivity of the Framingham risk score for moderate or greater degrees of atherosclerosis to the sensitivity achieved by simple observation of whether any coronary calcium is present. The reference standard was plaque burden as determined by coronary CT angiography.

METHODS: Of 1,416 men (mean age, 51.4 +/- 9.9 [SD] years) and 707 women (56.9 +/- 10.6 years), most were asymptomatic. Plaque burden (segment plaque score) and stenoses burden (Duke prognostic score) were estimated. A segment plaque score > 4 or a Duke prognostic score >3 indicated moderate or greater disease burden.

RESULTS: For a segment plaque score > 4, the presence of any calcium was 98% sensitive in men and 97% sensitive in women, whereas a Framingham risk score >10% was 74% sensitive in men and 36% sensitive in women. The negative likelihood ratio for the presence of calcium was 0.04 in subjects of either sex, whereas, for a Framingham risk score >3, calcium was 97% sensitive in men and 92% sensitive in women, whereas a Framingham risk score >10% was 88% sensitive in men and 35% sensitive in women. The negative likelihood ratio of calcium presence was 0.05 in men and 0.13 in women, whereas the negative likelihood ratio for a Framingham risk score

CONCLUSIONS: If subjects are excluded from further screening because they are in the Framingham low-risk category, almost two thirds of women and a quarter of men with substantial atherosclerosis will be missed. In contrast, the simple observation of any coronary calcium is highly sensitive and moderately specific.

PMID: 20410409

Pericardial Fat Burden on ECG-Gated Noncontrast CT in Asymptomatic Patients Who Subsequently Experience Adverse Cardiovascular Events

OBJECTIVES: We aimed to evaluate whether pericardial fat has value in predicting the risk of future adverse cardiovascular outcomes. Pericardial fat volume (PFV) and thoracic fat volume (TFV) can be routinely measured from noncontrast computed tomography (NCT) performed for calculating coronary calcium score (CCS) and may predict major adverse cardiac event (MACE) risk.

METHODS: From a registry of 2,751 asymptomatic patients without known cardiac artery disease and 4-year follow-up for MACE (cardiac death, myocardial infarction, stroke, late revascularization) after NCT, we compared 58 patients with MACE with 174 same-sex, event-free control subjects matched by a propensity score to account for age, risk factors, and CCS. The TFV was automatically calculated, and PFV was calculated with manual assistance in defining the pericardial contour, within which fat voxels were automatically identified. Independent relationships of PFV and TFV to MACE were evaluated using conditional multivariable logistic regression.

RESULTS: Patients experiencing MACE had higher mean PFV (101.8 +/- 49.2 cm(3) vs. 84.9 +/- 37.7 cm(3), p = 0.007) and TFV (204.7 +/- 90.3 cm(3) vs. 177 +/- 80.3 cm(3), p = 0.029) and higher frequencies of PFV >125 cm(3) (33% vs. 14%, p = 0.002) and TFV >250 cm(3) (31% vs. 17%, p = 0.025). After adjustment for Framingham risk score (FRS), CCS, and body mass index, PFV and TFV were significantly associated with MACE (odds ratio [OR]: 1.74, 95% confidence interval [CI]: 1.03 to 2.95 for each doubling of PFV; OR: 1.78, 95% CI: 1.01 to 3.14 for TFV). The area under the curve from receiver-operator characteristic analyses showed a trend of improved MACE prediction when PFV was added to FRS and CCS (0.73 vs. 0.68, p = 0.058). Addition of PFV, but not TFV, to FRS and CCS improved estimated specificity (0.72 vs. 0.66, p = 0.008) and overall accuracy (0.70 vs. 0.65, p = 0.009) in predicting MACE.

CONCLUSIONS: Asymptomatic patients who experience MACE exhibit greater PFV on pre-MACE NCT when they are compared with event-free control subjects with similar cardiovascular risk profiles. Our preliminary findings suggest that PFV may help improve prediction of MACE.

PMID: 20394896

Microvascular Obstruction: Underlying Pathophysiology and Clinical Diagnosis

Successful restoration of epicardial coronary artery patency after prolonged occlusion might result in microvascular obstruction (MVO) and is observed both experimentally as well as clinically. In reperfused myocardium, myocytes appear edematous and swollen from osmotic overload. Endothelial cell changes usually accompany the alterations seen in myocytes but lag behind myocardial cell injury. Endothelial cells become voluminous, with large intraluminal endothelial protrusions into the vascular lumen, and together with swollen surrounding myocytes occlude capillaries. The infiltration and activation of neutrophils and platelets and the deposition of fibrin also play an important role in reperfusion-induced microvascular damage and obstruction. In addition to these ischemia-reperfusion-related events, coronary microembolization of atherosclerotic debris after percutaneous coronary intervention is responsible for a substantial part of clinically observed MVO. Microvascular flow after reperfusion is spatially and temporally complex. Regions of hyperemia, impaired vasodilatory flow reserve and very low flow coexist and these perfusion patterns vary over time as a result of reperfusion injury. The MVO first appears centrally in the infarct core extending toward the epicardium over time. Accurate detection of MVO is crucial, because it is independently associated with adverse ventricular remodeling and patient prognosis. Several techniques (coronary angiography, myocardial contrast echocardiography, cardiovascular magnetic resonance imaging, electrocardiography) measuring slightly different biological and functional parameters are used clinically and experimentally. Currently there is no consensus as to how and when MVO should be evaluated after acute myocardial infarction.

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Cardiac MRI in Pulmonary Artery Hypertension: Correlations Between Morphological and Functional Parameters and Invasive Measurements

OBJECTIVES: To compare cardiac MRI with right heart catheterisation in patients with pulmonary hypertension (PH) and to evaluate its ability to assess PH severity.

METHODS: Forty patients were included. MRI included cine and phase-contrast sequences, study of ventricular function, cardiac cavity areas and ratios, position of the interventricular septum (IVS) in systole and diastole, and flow measurements. We defined four groups according to the severity of PH and three groups according to IVS position: A, normal position; B, abnormal in diastole; C, abnormal in diastole and systole.

RESULTS: IVS position was correlated with pulmonary artery pressures and PVR (pulmonary vascular resistance). Median pulmonary artery pressures and resistance were significantly higher in patients with an abnormal septal position compared with those with a normal position. Correlations were good between the right ventricular ejection fraction and PVR, right ventricular end-systolic volume and PAP, percentage of right ventricular area change and PVR, and diastolic and systolic ventricular area ratio and PVR. These parameters were significantly associated with PH severity.

CONCLUSIONS: Cardiac MRI can help to assess the severity of PH.

PMID: 20094890

Diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: Proposed Modification of the Task Force Criteria

OBJECTIVES: In 1994, an International Task Force proposed criteria for the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) that facilitated recognition and interpretation of the frequently nonspecific clinical features of ARVC/D. This enabled confirmatory clinical diagnosis in index cases through exclusion of phenocopies and provided a standard on which clinical research and genetic studies could be based. Structural, histological, electrocardiographic, arrhythmic, and familial features of the disease were incorporated into the criteria, subdivided into major and minor categories according to the specificity of their association with ARVC/D. At that time, clinical experience with ARVC/D was dominated by symptomatic index cases and sudden cardiac death victims-the overt or severe end of the disease spectrum. Consequently, the 1994 criteria were highly specific but lacked sensitivity for early and familial disease.

METHODS:  Revision of the diagnostic criteria provides guidance on the role of emerging diagnostic modalities and advances in the genetics of ARVC/D.

RESULTS: The criteria have been modified to incorporate new knowledge and technology to improve diagnostic sensitivity, but with the important requisite of maintaining diagnostic specificity. The approach of classifying structural, histological, electrocardiographic, arrhythmic, and genetic features of the disease as major and minor criteria has been maintained. In this modification of the Task Force criteria, quantitative criteria are proposed and abnormalities are defined on the basis of comparison with normal subject data.

CONCLUSIONS: The present modifications of the Task Force Criteria represent a working framework to improve the diagnosis and management of this condition.

PMID: 20172912

Microvascular Obstruction Remains a Portent of Adverse Remodeling in Optimally-Treated Patients with Left Ventricular Systolic Dysfunction After Acute Myocardial Infarction

OBJECTIVES: Microvascular obstruction (MO) is associated with large acute myocardial infarction (AMI) and lower left ventricular (LV) ejection fraction, and predicts greater remodeling, but whether this effect is abolished by contemporary anti-remodeling therapies is subject to debate. We examined the influence of several infarct characteristics, including MO, on LV remodeling in an optimally-treated post-AMI cohort, using contrast-enhanced cardiac magnetic resonance (ceCMR).

METHODS: 100 patients (mean age 58.9±12 years, 77% male) underwent ceCMR at baseline (~4 days), 12 and 24 weeks. The effects on LV remodeling (i.e. change in LV end-systolic volume index [LVESVi]) of infarct site, transmurality, endocardial extent, and the presence of early and late MO were analyzed.

RESULTS: Mean baseline infarct volume index decreased from 34.0 (21.2) mL/m2 to 20.9 (12.9) mL/m2 at 24 weeks (p<0.001). Infarct site had no influence on remodeling, but greater baseline infarct transmurality (r=0.47, p<0.001) and endocardial extent (r=0.26, p<0.01) were associated with higher LVESVi. Early MO was seen in 69 (69%) of patients and persisted, as late MO, in 56 (56%). Patients with late MO underwent significantly greater remodeling than those without MO (LVESVi +4.1 [13.4] vs. -7.0 [12.7] mL/m2 respectively, p=0.001); those with early MO only displayed an intermediate LVESVi (-4.9 [13.0] mL/m2). Importantly, late MO was seen frequently despite optimal coronary blood flow having been restored at angiography.

CONCLUSIONS: Late MO on pre-discharge ceCMR remains an ominous predictor of adverse LV remodeling despite powerful anti-remodeling therapy, and may be useful in the risk-stratification of survivors of AMI.

PMID: 20348438

Review of Journal of Cardiovascular Magnetic Resonance 2009

There were 56 articles published in the Journal of Cardiovascular Magnetic Resonance in 2009. The editors were impressed with the high quality of the submissions, of which our acceptance rate was about 40%. In accordance with open-access publishing, the articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. We have therefore chosen to briefly summarise the papers in this article for quick reference for our readers in broad areas of interest, which we feel will be useful to practitioners of cardiovascular magnetic resonance (CMR). In some cases where it is considered useful, the articles are also put into the wider context with a short narrative and recent CMR references. It has been a privilege to serve as the Editor of the JCMR this past year. I hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

PMID:

Determinants of Coronary Calcium Conversion Among Patients With a Normal Coronary Calcium Scan: What Is the “Warranty Period” for Remaining Normal?

OBJECTIVES: This study identified the incidence and predictors of conversion of a normal to abnormal coronary artery calcium (CAC) scan during serial CAC scanning over 5 years. Although a normal CAC scan signifies absence of significant atherosclerosis and is used to identify individuals at low clinical risk, the “warranty period” of a normal CAC scan relative to its ability to predict sustained absence of coronary atherosclerosis remains unknown.

METHODS: We assessed frequency of and time to progression, as well as proportional increase of CAC in 422 individuals with normal CAC scan (CAC = 0) undergoing annual CAC scanning for 5 years. Results were compared with those of a referent cohort of 621 individuals with baseline CAC scan (CAC >0).

RESULTS: A total of 106 (25.1%) patients with CAC = 0 developed CAC during follow-up at a mean time to conversion of 4.1 +/- 0.9 years. Incidence of conversion to CAC >0 was nonlinear and was highest in the fifth year. In multivariable analysis, progression to CAC >0 was associated with age, diabetes, and smoking (p < 0.01 for all). Among the 621 individuals with baseline CAC >0, only the presence of CAC itself, rather than CAD risk factors, was predictive of CAC progression. Among propensity score-matched individuals with CAC >0 versus CAC = 0, baseline CAC >0 emerged as the strongest predictor of CAC progression (hazard ratio [HR]: 12.50, 95% confidence interval [CI]: 9.31 to 16.77), followed by diabetes (HR: 2.07, 95% CI: 1.47 to 2.90) and smoking (HR: 1.29, 95% CI: 1.02 to 1.63, p < 0.05 for all).

CONCLUSIONS: Among individuals with CAC = 0, conversion to CAC >0 is nonlinear and occurs at low frequency before 4 years. No clinical factor seems to mandate earlier repeat CAC scanning.

PMID: 20223365

Right Ventricular Involvement in Acute Left Ventricular Myocardial Infarction: Prognostic Implications of MRI Findings

OBJECTIVE. The purpose of this study was to investigate the prevalence and prognostic importance of the cardiac MRI finding of right ventricular involvement in patients with acute ST-segment elevation myocardial infarction (MI).

METHODS. Fifty patients (41 men, nine women; mean age, 58 ± 11 years) with first-ST-segment elevation MI underwent 1.5-T cardiac MRI immediately after successful percutaneous coronary intervention. The cardiac MRI protocol included steady-state free precession cine sequences for functional assessment of the left, right, and both ventricles and inversion recovery FLASH delayed enhancement sequences after contrast administration for the quantification of myocardial damage. The prevalence of right ventricular involvement detected with ECG and echocardiography was compared with the prevalence detected with cardiac MRI, which was the reference standard. Patients underwent follow-up for 32 ± 8 months.

RESULTS. Right ventricular involvement was diagnosed with cardiac MRI in 27 patients (54%): 14 of 30 patients (47%) with inferior ST-segment elevation MI and 13 of 20 patients (65%) with anterior ST-segment elevation MI. ECG and echocardiographic findings showed only moderate agreement with cardiac MRI findings in the detection of right ventricular involvement in inferior acute MI (kappa = 0.38). Patients with right ventricular involvement in anterior ST-segment elevation MI had larger infarcts (delayed enhancement, 25.9% ± 14.5% vs 11.4% ± 10.1%; p = 0.030), lower left ventricular ejection fraction (34.3% ± 8.2% vs 45.2% ± 9.5%; p < 0.015), and lower right ventricular ejection fraction (39.8% ± 6.6% vs 54.9% ± 8.8%; p < 0.001) than those without right ventricular involvement. In a multivariate logistic regression model, right ventricular involvement was a strong independent predictor (odds ratio, 15.8; 95% CI, 4–63%) of major cardiac adverse events.

CONCLUSION. Right ventricular involvement in ST-segment elevation MI is detected more frequently with cardiac MRI than with ECG and echocardiography and is an independent prognostic indicator.

PMID: 20173133

Expert Review Document on Methodology, Terminology, and Clinical Applications of Optical Coherence Tomography: Physical Principles, Methodology of Image Acquisition, and Clinical Application for Assessment of Coronary Arteries and Atherosclerosis

Optical coherence tomography (OCT) is a novel intravascular imaging modality, based on infrared light emission, that enables a high resolution arterial wall imaging, in the range of 10-20 microns. This feature of OCT allows the visualization of specific components of the atherosclerotic plaques. The aim of the present Expert Review Document is to address the methodology, terminology and clinical applications of OCT for qualitative and quantitative assessment of coronary arteries and atherosclerosis.

PMID: 19892716