Coronary heart disease - CE-MARC-2

The clinical question

People with suspected coronary heart disease often have an invasive coronary angiogram to make the diagnosis. This is where a catheter is passed into a blood vessel and directed to the heart to take pictures of the coronary arteries. But in two thirds of cases, the angiogram shows no evidence of a blockage in the coronary arteries. This suggests that doctors might be performing the invasive angiogram test too often.      

The BHF funded the ‘Clinical Evaluation of 3T MAgnetic Resonance imaging for the management of patients with Coronary heart disease’ (CE-MARC 2) trial, led by Professor John Greenwood at the University of Leeds, to find out if a non-invasive test, cardiac magnetic resonance (CMR) scanning, could be used early on in the diagnosis of coronary heart disease. The idea was that using this test first could help to better select people who should have an angiogram.

What did the study involve?

CE-MARC-2 recruited 1202 people with suspected angina chest pain (a symptom of coronary heart disease) from six hospitals in the UK. Participants were randomly split into three groups.

• One group had the first line imaging tests as recommended by the 2010 UK National Institute for Health and Care Excellence (NICE) guidelines for diagnosing coronary heart disease. Here patients have different types of scan depending on their estimated risk of coronary heart disease, including in some cases a CT scan of the coronary arteries (CT angiography) to pick up any narrowed areas.
• The second group had a CMR scan to decide who should have an angiogram. CMR scanning assesses how well the heart is pumping and whether blood flow to the heart is reduced (called ischaemia).
• The third group had myocardial perfusion scintigraphy (MPS), a scan that also looks at the pumping action of the heart and the flow of blood to heart muscle.

If the imaging tests performed in any of the trial groups suggested possible coronary heart disease, the patient had an invasive coronary angiogram to make the diagnosis. Participants in the trial were then followed up for 1 year.

What did the study show?

• CMR scanning in people with suspected coronary heart disease reduced unnecessary angiograms (where there was no evidence of a blockage in the coronary arteries) compared with following the 2010 NICE diagnosis guidelines. 
• The rates of unnecessary angiography within 12 months were 7.5% for CMR and 28.8% in the NICE guidelines group.
• The rates of unnecessary angiography were similar in the CMR and MPS group.
• There was no difference in the number of major cardiovascular events (such as heart attacks) between the three groups.

Why is the study important?

The CE-MARC-2 trial addressed a longstanding dilemma among cardiologists about what type of imaging scan is the best first line test for diagnosing coronary heart disease. Is it better to use an ‘anatomical’ test, like CT angiography, which can detect narrowing of the coronary arteries, but can’t assess if the narrowing is obstructing blood flow to the heart? Or should we use a ‘functional test’, like CMR or MPS, which tells us about the state of blood flow to the heart? The results of the CE-MARC-2 study, favouring functional tests, reinvigorated this debate. 

Professor Greenwood gave his views when presenting the results of the trial at the European Society of Cardiology Congress in Rome in 2016: “Rates of invasive angiography are considered too high among patients with suspected coronary heart disease”.

The results of CE-MARC-2 and other trials will be considered in the upcoming 2019 US guideline for the evaluation and diagnosis of chest pain. In particular, to support the role of CMR as a useful first line test in the diagnosis of stable chest pain. 

With ever increasing advances in imaging techniques, it seems likely that the role of CMR and other types of scan in diagnosing coronary heart disease will be revisited in the future. 

Study details

"Clinical Evaluation of 3T MAgnetic Resonance imaging for the management of patients with Coronary heart disease: the CE-MARC 2 study"
Award reference:  SP/12/1/29062, RG/05/004/18607
Principal Investigator: Professor John Greenwood, University of Leeds
Trial registration number: NCT01664858

Publication details

Greenwood JP, Ripley DP, Berry C, et al. Effect of Care Guided by Cardiovascular Magnetic Resonance, Myocardial Perfusion Scintigraphy, or NICE Guidelines on Subsequent Unnecessary Angiography Rates: The CE-MARC 2 Randomized Clinical Trial. JAMA. 2016;316(10):1051-60.