Horizon Scanning Technology Summary

National Myocardial stress Horizon perfusion magnetic Scanning resonance imaging Centre (MRI) assessment of myocardial blood flow in coronary artery disease

April 2007

This technology summary is based on information available at the time of research and a limited literature search. It is not intended to be a definitive statement on the safety, efficacy or effectiveness of the health technology covered and should not be used for commercial purposes. National Horizon Scanning Centre News on emerging technologies in healthcare Myocardial stress perfusion magnetic resonance imaging (MRI) assessment of myocardial blood flow in coronary artery disease

Target group Assessment of risk for coronary artery disease (CAD) in: • Symptomatic patients with prior coronary indicating stenosis of uncertain significance. • Asymptomatic or symptomatic patients considered to be at intermediate risk of CAD by standard risk factors, with or without equivocal stress tests results (exercise, stress SPECT or stress echo).

Technology description Magnetic resonance imaging (MRI) is a non-invasive, x-ray free imaging technique in which the patient is exposed to radiofrequency waves in a strong magnetic field, and the pattern of electromagnetic energy released in response is detected and analysed by a computer to generate detailed visual images. Cardiovascular magnetic resonance imaging (CMR)a is an application of MRI which takes around 30-45 minutes to perform. It cannot be used in patients with metallic implants such as pacemakers or stents. Claustrophobia during the procedure may be problematic in around 2% of patients.1 CMR is also difficult to perform in patients with irregular cardiac rhythms or who cannot breath-hold for 10-15 seconds.

Myocardial stress perfusion MRI is a specific functional application of CMR that is in development for the evaluation of myocardial blood flow. It requires the use of a contrast agent, and is used to analyse the adequacy of the flow of oxygenated blood to the heart muscle - with impaired blood flow indicating the presence of CAD (myocardial ischemia). Pharmacologic stress is usually induced by administering a coronary vasodilator such as adenosine. The resulting blood flow images are compared with those obtained under normal (unstressed or resting) conditions.

Innovation and/or advantages Myocardial stress perfusion MRI is similar in accuracy to myocardial stress single-photon emission computed (SPECT) and stress , but does not incur the high radiation burden of SPECT. Its use may avoid the need for invasive diagnostic coronary angiography in patients with intermediate risk factors for CAD. At the same sitting, and without additional scanning time, it can also assess left and right ventricular dimensions, function, and cardiac mass.

Place of use Home care e.g. home dialysis Community or residential care e.g. Primary care e.g. used by GPs or district nurses, physio practice nurses ; Secondary care e.g. general, ; Tertiary care e.g. highly specialist ; Emergency care non-specialist hospital services or hospital General public e.g. over the Other: counter

Availability, launch or marketing dates, and licensing plans: Myocardial stress perfusion MRI requires enhanced software and fast gradient magnets with field strengths of at least 1.5 Teslas. There are a number of UK centres using stress

a Also known as cardiac magnetic resonance imaging (CMR). April 2007 2 National Horizon Scanning Centre News on emerging technologies in healthcare perfusion MRI for myocardial perfusion studies in clinical practice, and availability is increasing rapidly.

NHS or Government priority area: Cancer ; Cardiovascular disease Children Diabetes Chronic conditions Mental health Older people Public health Renal disease Women’s health None identified Other:

This topic relates to National Service Framework for coronary heart disease.

Relevant guidance • NICE Technology Appraisal TA073. Angina and myocardial infarction – myocardial perfusion scintigraphy 2003 (review date November 2006). • British Cardiovascular Society working group report on the role of non-invasive imaging in the management of coronary artery disease 2007.2

• European Society of Cardiology and the Society for Cardiovascular Magnetic Resonance consensus panel report. Clinical indications for cardiovascular magnetic resonance (CMR) 2004.3

• American College of Radiology. Practice guideline for the performance and interpretation of cardiac magnetic resonance imaging (MRI) 2006.4 • American College of Cardiology Foundation. Appropriateness criteria for cardiac computed tomography and cardiac magnetic resonance imaging 2006.5 • American College of Cardiology/American Heart Association/American College of Physicians. Clinical competence statement on cardiac imaging with computed tomography and magnetic resonance 2005.6

Clinical need and burden of disease CAD is the leading cause of mortality in the UK, causing 88,271 deaths in England and Wales in 2005,7 and costing the UK economy over £1.7 billion per annum.

The current standard diagnostic method for assessing the need for revascularisation is invasive coronary angiography (ICA), with 201,000 performed in the UK in 2004 (excluding percutaneous coronary intervention).2 Estimates of the number of catheterisations that prove to be negative vary: one US study has suggested 25-50%,8 and a UK expert suggests a local normalcy rate of 14-20%. The ICA procedure is estimated to carry a 1 in 1,000 risk of heart attack or stroke.

Existing comparators and treatments • Myocardial stress single-photon emission computed tomography (stress SPECT). This procedure involves radiation exposure, takes around 30 minutes, and is currently the main technique used for the assessment of myocardial perfusion. • Stress echocardiography with dobutamine (stress echo). This procedure takes around 45 minutes.

Other techniques that can assess myocardial blood flow include: • Exercise electrocardiography (ECG). • Myocardial positron emission tomography (PET). Rarely used in the UK due to high costs and lack of availability.

April 2007 3 National Horizon Scanning Centre News on emerging technologies in healthcare • Invasive coronary angiography (ICA) is the current gold standard for assessing the need for interventional management in coronary artery disease. However, although it can detect obstructive coronary lesions, it cannot detect ischemia (their functional consequence). Diagnostic ICA is costly and invasive, and carries a small risk of serious complications,9 and is usually reserved for high-risk symptomatic patients.

Efficacy and safety A 2004 consensus panel of the European Society of Cardiology and the Society for Cardiovascular Magnetic Resonance concluded that for myocardial stress perfusion, MRI compared well with ICA, PET, and SPECT.10

A summary of evidence of diagnostic accuracy

Myocardial perfusion MRI relative to ICA

Study Sensitivity Specificity Accuracy Detecting stenosis of ≥ 70% in at least one 90% 85% --- coronary artery in 104 patients with CAD.11 Detecting stenosis of ≥ 75% in 84 patients 88% 90% 89% referred for diagnostic ICA.12 Detecting stenosis of ≥ 50% in 48 patients with 87% 85% --- suspected CAD. 13

Myocardial perfusion MRI versus PET

Study Sensitivity Specificity Accuracy Detecting CAD (reduced coronary flow 91% 94% --- reserve) in 48 patients with suspected CAD, as defined by PET.13

Myocardial perfusion MRI and SPECT relative to ICA

Study Sensitivity Specificity Accuracy Detecting abnormal coronary territories in 26 patients with CAD.14 MRI 79% 83% 80% Thallium SPECT 70% 78% 73% Detecting significant stenosis of at least one coronary artery in 69 patients with CAD.11 MRI 94% SPECT 82%

Estimated cost and cost impact Although estimates for the cost of myocardial stress perfusion MRI vary, it is likely to be cheaper than SPECT,15 and more expensive than stress echocardiography.

Potential or intended impact – speculative Myocardial stress perfusion MRI may well become the preferred option if MRI imaging capability were to be expanded through training and capital investment.

Patients ; Reduced morbidity ; Reduced mortality or increased ; Improved quality of life for survival (reduced short-term risk patients and/or carers from ICA and long-term risk of cancer from SPECT radiation) ; Quicker or more accurate ; Earlier identification of disease Changed pathway of care or diagnosis outcome Other April 2007 4 National Horizon Scanning Centre News on emerging technologies in healthcare Services Increased use e.g. length of stay, Service reorganisation required ; Staff training required out-patient visits Decreased use e.g. shorter length of stay, reduced ; Other: reduced demand for SPECT and ICA, but referrals longer procedure times than SPECT possible

Costs Increased unit cost compared to Increased costs: more patients ; Increased costs: capital alternative coming for treatment investment needed ; Savings: cheaper than SPECT; ; Other: staff training needed fewer ICAs

References

1 Francis JM & Pennell DJ. The treatment of claustrophobia during cardiovascular magnetic resonance; use and effectiveness of mild sedation. J Cardiovasc Magn Reson 2000; 2: 139-141. 2 Gershlick A H, de Belder M, Chambers J et al. The role of non-invasive imaging in the management of coronary artery disease – current status and future impact. A report from the British Cardiovascular Society working group. Heart 2007; 93: 423-431. 3 European Society of Cardiology and the Society for Cardiovascular Magnetic Resonance consensus panel report. Clinical indications for cardiovascular magnetic resonance (CMR). Eur Heart J 2004; 25: 1940-1965. 4 American College of Radiology. Practice guideline for the performance and interpretation of cardiac magnetic resonance imaging. 10/01/2006. 5 Appropriateness criteria for cardiac computed tomography and cardiac magnetic resonance imaging. American College of Cardiology Foundation (ACCF) in conjunction with American College of Radiology, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology, North American Society for Cardiac Imaging, Society for Cardiovascular Angiography and Interventions, and Society of Interventional Radiology. J Am College Cardiol 2006; 48: 1475-97. 6 American College of Cardiology/American Heart Association/American College of Physicians. Clinical competence statement on cardiac imaging with computed tomography and magnetic resonance. J Am College Cardiol 2005; 46: 383-402. 7 British Heart Foundation mortality data for ICD code I20-25 ischemic heart diseases (2005), available at http://Hwww.heartstats.orgH 8 Poon M (figures quoted from), Director of Cardiovascular Medicine and the Integrated Imaging Program, Cabrini Medical Centre, New York, USA, reported in Wiley G. 2005; CTA: ‘Watershed, soon to be a flood’. www.imagingeconomics.com/issues/articles/2005-03 9 Scanlon P J, Faxon D P, Audet A M et al. ACC/AHA guidelines for coronary angiography. J Am College Cardiol 1999; 33: 1756-824. 10 Pennell DJ, Sechtem UP, Higgins CB et al. Clinical indications for cardiovascular magnetic resonance (CMR): consensus panel report. European Heart Journal 2004; 25: 1940-1965. 11 Isheda N, Sakuma H, Motoyasu M. et al. Noninfarcted myocardium: correlation between dynamic first-pass contrast-enhanced myocardial MR imaging and quantitative coronary angiography. Radiology 2003; 229: 209- 216. 12 Nagel E, Klein C, Paetsch I et al. Magnetic resonance perfusion measurements for the non-invasive detection of coronary artery disease. Circulation 2003; 108: 432-437. 13 Schwitter J, Nanz D, Kneifel S et al. Assessment of myocardial perfusion in coronary artery disease by magnetic resonance: a comparison with positron emission tomography and coronary angiography. Circulation 2001; 103: 2230-2235. 14 Panting JR, Gatehouse PD, Yang GZ et al. Echo planar magnetic resonance myocardial perfusion imaging: parametric map analysis and comparison with thallium SPECT. J Magn Reson Imaging 2001; 13: 192-200. 15 Yokoyama K, Nitatori T, Kanke N et al. Efficacy of cardiac MRI in the evaluation of ischemic heart disease. Magnetic Resonance in Medical Sciences 2006; 5(1): 33-40.

April 2007 5 National Horizon Scanning Centre News on emerging technologies in healthcare

The National Horizon Scanning Centre is a constituent of the NHS National Institute for Health Research and is managed under contract from the Department of Health's R&D Division. The views expressed in NHSC publications are those of the author(s). They are not necessarily shared by the Department of Health and should not be taken as representing Government policy.

The National Horizon Scanning Centre, Department of Public Health and Epidemiology University of Birmingham, Edgbaston, Birmingham, B15 2TT, England Tel: +44 (0)121 414 7831 Fax +44 (0)121 414 2269 www.pcpoh.bham.ac.uk/publichealth/horizon

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