Coronary Artery Disease: Chow BJ

Chow BJ, Larose E, Bilodeau S, Ellins ML, Galiwango P, Kass M, Sheth T, Jassal DS, Kirkpatrick ID, Mancini GB, Mayo J, Abraham A, White J. · Department of Medicine, University of Ottawa Heart Institute, Ontario, Canada. · Can J Cardiol. · Pubmed #19279980 links to  free full text

This publication has no abstract.

Beanlands RS, Chow BJ, Dick A, Friedrich MG, Gulenchyn KY, Kiess M, Leong-Poi H, Miller RM, Nichol G, Freeman M, Bogaty P, Honos G, Hudon G, Wisenberg G, Van Berkom J, Williams K, Yoshinaga K, Graham J, Anonymous00027, Anonymous00028, Anonymous00029, Anonymous00030, Anonymous00031. · University of Ottawa Heart Institute, Ottawa, Canada. · Can J Cardiol. · Pubmed #17311116 links to  free full text

Abstract: BACKGROUND: Over the past few decades, advanced imaging modalities with excellent diagnostic capabilities have emerged. The aim of the present position statement was to systematically review existing literature to define Canadian recommendations for their clinical use. METHODS: A systematic literature review to 2005 was conducted for positron emission tomography (PET), multidetector computed tomographic angiography and magnetic resonance imaging (MRI) in ischemic heart disease. Papers that met the criteria were reviewed for accuracy, prognosis data and study quality. Recommendations were presented to primary and secondary panels of experts, and consensus was achieved. RESULTS: Indications for PET include detection of coronary artery disease (CAD) with perfusion imaging, and defining viability using fluorodeoxyglucose to determine left ventricular function recovery and/or prognosis after revascularization (class I). Detection of CAD in patients, vessel segments and grafts using computed tomographic angiography was considered class IIa at the time of the literature review. Dobutamine MRI is class I for CAD detection and, along with late gadolinium enhancement MRI, class I for viability detection to predict left ventricular function recovery. Imaging must be performed at institutions and interpreted by physicians with adequate experience and training. CONCLUSIONS: Cardiac imaging using advanced modalities (PET, multidetector computed tomographic angiography and MRI) is useful for CAD detection, viability definition and, in some cases, prognosis. These modalities complement the more widespread single photon emission computed tomography and echocardiography. Given the rapid evolution of technology, initial guidelines for clinical use will require regular updates. Evaluation of their integration in clinical practice should be ongoing; optimal use will require proper training. A joint effort among specialties is recommended to achieve these goals.

Chow BJ, Veinot JP. · Department of Laboratory Medicine, Room 123, Ottawa Hospital, Civic Campus, 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada. · Curr Cardiol Rep. · Pubmed #17059796 No free full text.

Abstract: Cardiovascular disease is the leading cause of mortality and morbidity in developed countries. Evidence challenges the notion that the severity of lesions on angiography is a predictor of future cardiac events. With the recognition that subclinical coronary artery stenoses are responsible for myocardial infarcts and sudden death, it may be important to identify patients with plaque characteristics that may place them at increased risk. Intravascular ultrasound, though invasive, remains the current imaging gold standard. Computed tomography, cardiac magnetic resonance, and single-photon emission CT positron emission tomography are evolving and promising modalities. Functional studies reflecting plaque temperature and molecular imaging reflecting plaque constituents are being developed. We review the pathology of the vulnerable atherosclerotic plaque and recent innovations in imaging modalities to assess plaque complication risk.

Chow BJ, Hoffmann U, Nieman K. · University of Ottawa Heart Institute, Ottawa, Ontario, Canada. · Can J Cardiol. · Pubmed #16239977 links to  free full text

Abstract: Over the past decade, enormous progress has been made in the technology of computed tomography (CT) imaging. Substantial improvements in spatial resolution, temporal resolution, hardware and software now permit imaging of the entire coronary artery tree within a single breath-hold. Several studies have demonstrated a high sensitivity and specificity for the detection of significant coronary artery stenoses. In addition to imaging of the native coronary arteries, CT angiography may also be used to assess arterial and venous bypass grafts, and to detect the presence and composition of atherosclerotic plaque. Because CT angiography images are acquired with electrocardiogram gating, the data sets permit the assessment of left ventricular function (ejection fraction and regional wall motion), left ventricular volumes and, potentially, myocardial perfusion at no extra cost. The practical advantages of CT angiography (in regard to safety and cost) along with its future anticipated advancements make it an attractive alternative to diagnostic coronary angiography.

Yoshinaga K, Chow BJ, Williams K, Chen L, deKemp RA, Garrard L, Lok-Tin Szeto A, Aung M, Davies RA, Ruddy TD, Beanlands RS. · Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. · J Am Coll Cardiol. · Pubmed #16949498 No free full text.

Abstract: OBJECTIVES: The objective was to determine the prognostic value of rubidium-82 (82Rb) positron emission tomography (PET) myocardial perfusion imaging (MPI). BACKGROUND: 82Rb PET MPI accurately diagnoses coronary artery disease (CAD). However, there are limited data evaluating its prognostic value. METHODS: Follow-up (3.1 +/- 0.9 years) was obtained in 367 patients who underwent dipyridamole 82Rb PET MPI. Patients were divided into groups based on their summed stress score (SSS): group I, normal (<4); group II, mild (4 to 7); and group III, moderate (8 to 11) to severe (> or =12). RESULTS: There were significant differences among patients in the 3 SSS groups for hard events (cardiac death and myocardial infarction [MI]) (p < 0.001) and total cardiac events (hard events, revascularization and hospitalization) (p < 0.001). The annual hard events rates were 0.4%, 2.3%, and 7.0% in the normal, mild, and moderate-severe groups, respectively. In adjusted survival models, 82Rb PET SSS was the strongest predictor of total cardiac events and a significant predictor of hard events. Among patients referred for PET after 99mTc single-photon emission computed tomography, the annual total event rate was higher with abnormal versus normal SSS on PET (15.2% vs. 1.3%, p < 0.001). In patients with obesity, the annual total event rate was 11.1% with an abnormal scan and 1.5% with a normal scan (p < 0.001). CONCLUSIONS: This study shows that 82Rb PET MPI has significant prognostic value for predicting cardiac events, including death and MI. It also seems to have prognostic value in patients whose diagnosis remains uncertain after single-photon emission computed tomography MPI and in obese patients. The prognostic value of PET MPI may improve the management of cardiac patients.

Chow BJ, Dennie C, Hoffmann U, So D, de Kemp RA, Ruddy TD, Beanlands RS. · Division of Cardiology, University of Ottawa Heart Institute, Ottawa, ON, Canada. · Can J Cardiol. · Pubmed #17703259 links to  free full text

Abstract: BACKGROUND: The present study compared computed tomographic coronary angiography (CTA) and positron emission tomography (PET) for the detection of significant anatomical coronary artery stenosis as defined by conventional invasive coronary angiography (CICA). METHODS: The study protocol was approved by the local ethics board, and informed consent was obtained from all patients. Of the 26 patients (mean age 57+/-9 years, 18 men) who prospectively underwent CTA and rubidium-82 PET before CICA, 24 patients had a history of chest pain. Images were interpreted by expert readers and assessed for the presence of anatomically significant coronary stenosis (50% luminal diameter stenosis or greater) or myocardial perfusion defects. Diagnostic test characteristics were analyzed using patient-based, territory-based, vessel-based and segment-based analyses. RESULTS: In the 24 patients referred for chest pain, CTA had similar sensitivity to PET, but was more specific (sensitivity 95% [95% CI 72% to 100%] versus 95% [95% CI 72% to 100%], respectively; specificity 100% [95% CI 46% to 100%] versus 60% [95% CI 17% to 93%], respectively) in the detection of patients with anatomical coronary artery stenosis of 50% or greater. On a per-segment basis of all 26 patients, CTA had a sensitivity, specificity, positive predictive value and negative predictive value of 72%, 99%, 91% and 95%, respectively, in all coronary segments. CONCLUSIONS: Coronary CTA has a similar sensitivity and specificity to rubidium-82 PET for the identification of patients with significant anatomical coronary artery disease.

Chow BJ, Ananthasubramaniam K, dekemp RA, Dalipaj MM, Beanlands RS, Ruddy TD. · Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. · J Am Coll Cardiol. · Pubmed #15837254 No free full text.

Abstract: OBJECTIVES: This study assessed the feasibility of treadmill exercise rubidium-82 ((82)Rb) positron emission tomography (PET) and compared image quality and diagnostic content with dipyridamole (82)Rb PET in patients referred for evaluation of coronary artery disease (CAD). BACKGROUND: Dipyridamole stress (82)Rb PET myocardial perfusion imaging (MPI) is an accurate imaging modality used to diagnose CAD and determine prognosis. Although pharmacologic stress is used routinely, exercise treadmill stress may be an alternative and provide clinical information helpful to decision making, particularly for patients unwilling or unable to tolerate pharmacologic stress. METHODS: Fifty patients (mean age, 60 +/- 10 years; 47 men) underwent treadmill exercise and dipyridamole (82)Rb PET. Images were assessed: 1) qualitatively using a 17-segment model and a semiquantitative visual score on a five-point scale and with calculation of summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS); and 2) quantitatively with a 70% threshold for abnormal perfusion and expressed as extent of abnormal perfusion (% left ventricular). RESULTS: Treadmill exercise was preferred by 74% of patients (37 of 50, p < 0.001). The exercise and dipyridamole (82)Rb PET summed scores and quantitative extent of abnormal perfusion were very similar and highly correlated. Results of Bland-Altman analysis showed no significant bias. Image quality was superior with exercise stress with greater myocardial uptake and higher target to background ratios. CONCLUSIONS: Treadmill exercise (82)Rb PET is feasible and provides imaging results of similar diagnostic content and superior image quality compared with dipyridamole stress. Treadmill exercise is a reasonable alternative to pharmacologic stress with (82)Rb PET MPI.

Ananthasubramaniam K, Chow BJ, Ruddy TD, deKemp R, Davies RA, DaSilva J, Beanlands RS. · National Cardiac PET Centre, Department of Medicine, University of Ottawa Heart Institute, Ontario. · Can J Cardiol. · Pubmed #15685303 links to  free full text

Abstract: BACKGROUND: The extent of Q wave 'burden' on electrocardiograms (ECGs) has not been correlated with the extent of scarring and hibernation as determined quantitatively by positron emission tomography (PET). OBJECTIVE: A retrospective study was performed to identify if ECG Q wave burden predicts the extent of scarring or mismatch (hibernating myocardium) as defined by rubidium-82/F-18 fluorodeoxyglucose PET viability imaging. PATIENTS AND METHODS: Eighty-three consecutive patients with coronary artery disease undergoing rubidium-82/F-18 fluoro-deoxyglucose viability imaging (mean age 67.9+/-11 years, with a mean ejection fraction of 27+/-7%) formed the study population. Resting ECG was interpreted for the presence or absence of Q waves using standard ECG criteria for Q wave myocardial infarction. Patients were divided into two groups based on their Q wave burden on ECG (small to moderate scar: zero to four Q waves; large scar: five or more Q waves). Automated analysis was used to calculate the extent of scarring and mismatch (hibernating myocardium) on PET as a percentage of left ventricular myocardium. Mean PET scar and mismatch scores were calculated for the two groups. RESULTS: The mean PET scar scores were significantly different between the small to moderate ECG scar group (13.9+/-7.3% of the left ventricle) and the large scar group (20.6+/-8.1% of the left ventricle; P=0.001). The mismatch scores for the small to moderate scar group (4.6+/-2.8%) were not significantly different from those of the large scar group (4.05+/-2.8%; P=0.7). CONCLUSIONS: ECG Q wave 'burden' was associated with the presence of scars as defined by PET but did not accurately predict the amount of hibernating myocardium.