The Value and Prognosis of Stress CMR Perfusion in the United States

Introduction
Vasodilator stress cardiac magnetic resonance imaging (CMRI) has been shown in multiple studies to be highly accurate in the detection of obstructive coronary stenosis.1 Using stress CMRI to guide management of patients with stable angina has also been shown to be noninferior to an invasive strategy of coronary angiography and fractional flow reserve.2 In addition, the American College of Cardiology Foundation and American Heart Association have designated stress CMRI as an appropriate test for evaluation of symptomatic patients with intermediate to high pretest probability for coronary artery disease.3 Despite these benefits and widespread use of stress CMRI in Europe, this diagnostic modality continues to be underutilized in the United States. The Society for Cardiovascular Magnetic Resonance (SCMR) developed a registry with the intent to evaluate some of these findings and to determine if the robust data supporting stress CMRI hold up in a real-world environment.4

SCMR Registry
The SCMR Registry was developed in 2013 and currently includes data on over 60,000 studies. The registry is world-wide and involves many international (37%) and domestic sites. There is a predominance of CMRI centers with over 10 years of experience, and most are located in tertiary medical centers. This global registry collects demographic data, CMRI study details, and concomitant testing and follow-up information if available. Of all studies in the registry, 16% were driven by the evaluation of chest pain syndrome. More details on the registry can be found on the SCMR Registry page on the SCMR website.4

Stress CMRI Perfusion in the United States
Recently, a study led by Dr. Raymond Kwong evaluated SCMR Registry data from 13 participating American sites spanning 11 states. The intent of SPINS (Stress CMR Perfusion Imaging in the United States (SPINS) Study) was to investigate the prognostic value of stress CMRI and downstream costs in a real-world setting.5

A total of 2,349 intermediate-risk patients referred with suspicion of a myocardial ischemia without a history of prior coronary artery bypass grafting, cardiomyopathy, or recent myocardial infarction was evaluated for cardiac events over a period of 4 years or more following the stress CMRI. Of the cohort, 1,583 (67%) were observed to have a normal CMRI study, which was defined by having no ischemia or late gadolinium enhancement of infarction. Kaplan-Meier event-free survival curves for the primary outcome (cardiac death or acute myocardial infarction) by presence of ischemia and late gadolinium enhancement are shown in Figure 1. Patients with a normal CMRI had low annual risk for primary outcome (<1%) and need for coronary revascularization (1-3%) over study follow-up. On the contrary, those who had evidence of ischemia and infarction experienced a greater than fourfold higher risk for primary outcome and a 10-fold higher need for coronary revascularization in the first year after the stress CMRI.

Figure 1: Stress CMRI Registry for Prognosis and Costs in the United States5

Figure 1
Reprinted with permission from Kwong et al.5

The authors went on to evaluate the impact of downstream costs of subsequent cardiac testing following stress CMRI. Using current Medicare-based payment rates for various cardiac procedures, patients with a normal CMRI had low average annual cost spent on ischemia testing across all years of follow-up, and this pattern was similar across the different practice environments of the participating centers.

Conclusion
SPINS is the first retrospective multicenter registry study that examines the utility of stress CMRI across the United States. Patients with stable chest pain syndrome who had no evidence of ischemia or infarction by CMRI had excellent cardiac prognosis, and they are associated with low downstream utilization and costs in healthcare.

Perspective
In patients with stable chest pain syndromes, stress CMRI provides effective risk stratification in the United States.

References

  1. Gargiulo P, Dellegrottaglie S, Bruzzese D, et al. The prognostic value of normal stress cardiac magnetic resonance in patients with known or suspected coronary artery disease: a meta-analysis. Circ Cardiovasc Imaging 2013;6:574-82.
  2. Nagel E, Greenwood JP, McCann GP, et al. Magnetic Resonance Perfusion or Fractional Flow Reserve in Coronary Disease. N Engl J Med 2019;380:2418-28.
  3. Wolk MJ, Bailey SR, Doherty JU, et al. ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons. J Am Coll Cardiol 2014;63:380-406.
  4. Global Cardiovascular Magnetic Resonance Registry (GCMR) Investigators, Kwong RY, Petersen SE, et al. The global cardiovascular magnetic resonance registry (GCMR) of the society for cardiovascular magnetic resonance (SCMR): its goals, rationale, data infrastructure, and current developments. J Cardiovasc Magn Reson 2017;19:23.
  5. Kwong RY, Ge Y, Steel K, et al. Cardiac Magnetic Resonance Stress Perfusion Imaging for Evaluation of Patients With Chest Pain. J Am Coll Cardiol 2019;74:1741-55.

Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Atherosclerotic Disease (CAD/PAD), Cardiac Surgery and Heart Failure, Cardiac Surgery and SIHD, Interventions and Coronary Artery Disease, Interventions and Imaging, Magnetic Resonance Imaging, Nuclear Imaging, Chronic Angina

Keywords: Cardiac Imaging Techniques, Diagnostic Imaging, Angina, Stable, Coronary Artery Disease, Gadolinium, Retrospective Studies, American Heart Association, Infarction, Prognosis, Disease-Free Survival, Follow-Up Studies, Coronary Stenosis, Chest Pain, Myocardial Infarction, Coronary Artery Bypass, Vasodilator Agents, Registries, Cardiomyopathies, Magnetic Resonance Imaging, Medicare, Magnetic Resonance Spectroscopy, Perfusion Imaging, Probability, Demography


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