Accelerated Stress CMR in Coronary Artery Disease

This study will evaluate the diagnostic performance of an accelerated stress CMR protocol, comparing it with that of standard CMR assessment.

This is a prospective, single-centre diagnostic accuracy study comparing the diagnostic performance of (1) accelerated and (2) standard adenosine stress CMR scans in 167 patients with suspected coronary artery disease referred for invasive coronary angiography (which will serve as the reference standard - invasive FFR).

The accelerated scan comprises accelerated cine and gadolinium imaging, with a standard stress scan (0.075mmol/kg gadolinium contrast).

Subjects will undergo both scans pre-angiography (in randomised order), enabling a head-to-head comparison of diagnostic performance (diagnostic accuracy, sensitivity and specificity) for identifying functionally significant coronary disease (as defined by fractional flow reserve \<0.80).

Objectives The primary objective is to determine, in patients with suspected angina, whether the accelerated CMR protocol achieves favourable diagnostic accuracy, using invasive FFR as the reference standard, and also compared with standard CMR assessment.

Secondary objectives include comparing diagnostic performance of the accelerated CMR protocol with that of CT-FFR, a comparison of scan duration (overall and for each component - for standard and accelerated CMR), and patient tolerability and experience for each protocol (accelerated CMR, standard CMR and CTCA), as determined by a self-administered questionnaire rating patient comfort, symptoms experienced and perceived scan duration.

Data analysis

* Imaging data will be interpreted using the 16-segment American Heart Association (AHA) segmentation model
* For visual assessment of perfusion, images will be analysed by two experienced cardiologists, acting independently (differences resolved by consensus).
* For qualitative analysis, perfusion data will be analysed concurrently with late gadolinium images, with inducible ischaemia determined by the presence of a perfusion defect exceeding the area of scar.
* For quantitative analysis, myocardial blood flow (MBF) will be quantified using inline Gadgetron data (flow maps providing segmental flows).
* For qualitative analysis, ischaemia is defined as reversible hypoperfusion in two adjacent segments \[32-segment model\] exceeding the region of scar \[if present\], and for quantitative analysis, using a MBF threshold of 1.9ml/min/g.

Eligibility Criteria:
Inclusion Criteria:

* Patients aged ≥18 years
* Referred for invasive coronary angiography for investigation of chest pain
* Willing and able to give informed consent
* Willing and able (in the Investigators opinion) to comply with all study requirements.
* Willing to allow his or her General Practitioner and consultant, if appropriate, to be notified of participation in the study.
* Able to understand written English

Exclusion Criteria:

* Recent acute coronary syndrome (\< 6 months)
* Severe claustrophobia
* Absolute contraindications to CMR - those with MR conditional or safe devices will be included
* Second-/third-degree atrioventricular block
* Severe chronic obstructive pulmonary disease
* Moderate-severe asthma
* Estimated glomerular filtration rate \<30 ml/min/1.73m2
* Women who are pregnant, breast-feeding or of child-bearing potential (premenopausal women)
* Contraindication to iodinated contrast
* Participants who have participated in a research study involving an investigational product in the past 12 weeks
* Patients unable to understand written English