Identification of Adverse Plaque Characteristics by Coronary MR Angiography

This pilot study will examine 20 stable patients who have undergone a clinically-indicated coronary computed tomography angiography (CCTA) for suspected Coronary Artery Disease. They will be invited to undergo a research coronary Magnetic Resonance Imaging scan with contrast(CMRA). Based upon the subject's heart rate, a beta blocker may be administered as its use has been shown to be effective in producing better images as it widens the arteries.

Researchers will use newly developed non-invasive coronary MRA techniques to compare information shown on the research CMRA with the clinical CCTA. While CCTA has been demonstrated to be able to provide data on adverse plaque characteristics (APC's), the ability of CMRA to evaluate these features is not established.

Inclusion criteria

• Age ≥18 years
• Ability to comprehend and sign informed consent
• Presence of a non-calcified or mixed plaque without high-grade stenosis in the left main or a proximal coronary artery segment AND at least one APC present in this plaque by CCTA (defined as LAP with <30 Hounsfield units or PR with ≥10% increase in the maximal vessel diameter within the plaque as compared to a proximal reference segment as previously described10).

Exclusion criteria

• High-grade stenosis (≥50% stenosis of the left main artery or ≥70% stenosis of another proximal coronary segment);
• Coronary artery stent in the segment with the reference plaque
• Possible pregnancy
• Glomerular filtration rate <45 ml/min
• More than 90 days between CCTA and CMRA study
• Any significant arrhythmia (e.g. atrial fibrillation, frequent ectopy)
• Significant asthma
• History of 2nd or 3rd degree heart block
• Allergy or known intolerance to beta-blockers
• Use of phosphodiesterase inhibitor (e.g. Viagra) within the last 48 hours
• Rapid heart rate (heart rate ≥90 beats/minute)
• Severe aortic stenosis (Aortic valve area <1.0 cm2 or mean gradient >30 mmHg)
• Systolic blood pressure <100 mmHg
• Other contraindication to MRI, including metallic implants (valve replacement, pacemaker, implantable cardiac defibrillator, metallic spine material), intracranial clips, metallic fragments in eyes, and claustrophobia