Raymond Kwong, director of cardiac magnetic resonance imaging at Brigham and Women’s Hospital, associate professor of medicine at Harvard Medical School, and lead investigator of the Stress CMR Perfusion Imaging in the United States (SPINS) study, discusses the high diagnostic and prognostic power of Heart MRIs, as well as their ability to reduce downstream costs for patients.
Susan R Symonds
Kwong, Raymond MD
Multiple studies show that heart magnetic resonance imaging (MRI), a modality for non-invasive, non-radiation assessment of the function and structure of the heart and cardiovascular system, is highly accurate in the detection of obstructive coronary stenosis. According to a study published in New England Journal of Medicine, using the high-quality images Heart MRIs provide to diagnose and guide the treatment of patients with chest pain is as effective as utilising more invasive angiography. Additionally, the American College of Cardiology Foundation and American Heart Association have designated Heart MRI as an appropriate test for the evaluation of patients who have an intermediate to high risk of coronary artery disease (CAD).
Despite multiple studies demonstrating the high diagnostic and prognostic value of Heart MRI and its widespread use in Europe, it continues to be underused in the United States, making up less than 1% of non-invasive imaging tests administered. In an effort to determine if the robust data supporting the use of Heart MRIs holds up in a real-world environment, the Society for Cardiovascular Magnetic Resonance (SCMR), a worldwide organisation of more than 3,000 professionals who work in the field of cardiovascular magnetic resonance (CMR), established a registry in 2013.
The registry includes international and domestic sites and is predominantly comprised of CMR centers with more than 10 years of experience. Currently, the registry includes data on more than 60,000 studies, with about 16% dedicated to evaluating patients with chest pain.
Based on SCMR registry data from 13 participating American sites spanning 11 states, the Stress CMR Perfusion Imaging in the United States (SPINS) study was recently published in the Journal of the American College of Cardiology. Its objective was to evaluate the prognostic value of Heart MRIs and downstream costs of procedures such as invasive angiography or coronary revascularisation in a real-word, multicentre setting.
SPINS consisted of 2,349 patients between the ages of 35 and 85 with suspected ischemia or CAD and no prior history of coronary artery bypass grafting, cardiomyopathy or recent myocardial infarction. The patients underwent a Heart MRI for evaluation of clinical signs and symptoms of ischemia and CAD between 1 January 2008 – 31 December 2013. The study also included a follow-up period of at least four years.
Figure A
Overall, 67% of the patients had normal perfusion and no late gadolinium enhancement to suggest prior infarct. In this group, the investigators found a low annual risk for primary cardiac outcome events (cardiovascular death and heart attacks) and for coronary revascularisation. Patients who demonstrated abnormal perfusion and CMR evidence of prior infarct had an annual six-fold higher risk for primary cardiac outcome events and a 10-fold higher risk for coronary revascularisation in the first year following the Heart MRI (Figures A and B). These results suggest that in a real-word setting at experienced centers, Heart MRI is an effective non-invasive modality for detecting patients with stable chest pain who are at high risk of cardiac events.
Figure B
In addition to evaluating the prognostic value of Heart MRI, SPINS also analysed the impact of downstream costs of subsequent cardiac testing using current Medicare dollar figures. During the first 90 days after a Heart MRI, patients with a normal Heart MRI study incurred a cost that was 10-fold less than the amount those with an abnormal Heart MRI accumulated, primarily as a result of fewer referrals to x-ray coronary angiography ($54 vs. $585) (Figure C). For patients who had a normal Heart MRI, annual costs on downstream cardiovascular tests remained low throughout the 4-year follow-up period. These findings on cardiac prognosis, use of x-ray coronary angiography, and costs on downstream testing during the study’s follow-up period were consistent across all four practice settings at the participating centres — including two types of private practice, university hospitals and government and military institutions.
Figure C
The SPINS study is unique because it demonstrates the power of Heart MRI and is the first to use retrospective registry data from across the U.S. to confirm its prognostic value in a real-world setting. By establishing Heart MRI as an effective and safe gatekeeper to more invasive tests, it can be used to evaluate more patients with heart disease, potentially helping them avoid unnecessary risks and costs.
To learn more about Heart MRIs, visit heartmri.org.
