Stress Perfusion Imaging to Guide the Management of Patients With Stable Coronary Artery Disease - MR-INFORM

Contribution To Literature:

The MR-INFORM trial showed that MR-perfusion guided management of patients with stable angina is noninferior for MACE at 1 year compared with invasive angiography and FFR.

Description:

The goal of the trial was to assess the utility of magnetic resonance (MR)-based perfusion imaging compared with invasive angiography and fractional flow reserve (FFR) among patients with stable angina on optimal medical therapy (OMT).


Study Design

Patients were randomly assigned in a 1:1 ratio to either invasive angiography + FFR (n = 464) or MR perfusion imaging (n = 454). In the FFR arm, invasive angiography was performed in all patients. FFR was recommended in all arteries >2.5 mm with a stenosis of 40-95%. If FFR <0.8, revascularization (percutaneous coronary intervention [PCI] or coronary artery bypass grafting [CABG]) was recommended. MR perfusion was performed with a 1.5 T scanner using cine imaging. If transmural defect or subendocardial defect >2 segments or in two adjacent slices was found, angiography with the aim of revascularization was recommended. All patients received OMT.

  • Total screened: 16,620
  • Total number of enrollees: 918
  • Duration of follow-up: 1 year
  • Mean patient age: 62 years
  • Percentage female: 28%

Inclusion criteria:

  • Stable angina (Canadian Cardiovascular Society [CCS] class II-III)
    and
  • either ≥2 risk factors (smoking, diabetes, hypertension, hyperlipidemia, positive family history)
    or
  • positive exercise treadmill test

Exclusion criteria:

  • Contraindication to MR or adenosine
  • Atrial fibrillation or frequent ectopic beats
  • Ejection fraction <30%
  • CCS class IV
  • New York Heart Association class III or IV
  • Previous CABG
  • PCI within the previous 6 months
  • Estimated glomerular filtration rate <30 ml/min/1.73 m2
  • Unable to lie supine for 60 minutes
  • Medically unstable

Other salient features/characteristics:

  • Percentage with diabetes: 27%
  • Percentage with known coronary artery disease: 13%

Principal Findings:

Primary endpoint:

  • Major adverse cardiac events (MACE) at 1 year for FFR vs. MR: 3.9% vs. 3.3%, p = 0.62
  • Death: 0.22% vs. 0.89%
  • Myocardial infarction: 1.7% vs. 1.8%
  • Repeat revascularization: 1.9% vs. 0.7%

Secondary outcomes for FFR vs. MR:

  • Negative angiography: 35.6% vs. 8.1% (only 49.6% of MR patients needed invasive angiography)
  • Revascularization during index event: 44.2% vs. 36.0%, p = 0.0053

Interpretation:

The results of this trial indicate that MR-perfusion guided management of patients with stable angina is noninferior for the MACE endpoint at 1 year compared with invasive angiography and FFR. The overall event rate is fairly low with both strategies. This is the first trial to show that MR-perfusion imaging could guide patient management in a high-risk population with the same effectiveness as invasive angiography with FFR.

It is unclear if other functional imaging such as SPECT or dobutamine stress or even CT-FFR would have provided similar results. For instance, patients with stable angina and class II symptoms are likely to undergo one of these tests in routine clinical practice before being referred for invasive angiography. The incremental utility of MR over other imaging modalities is thus unclear. The cost-effectiveness of this strategy also needs to be investigated.

References:

Presented by Dr. Eike C. Nagel at the American College of Cardiology Annual Scientific Session (ACC 2017), Washington, DC, March 17, 2017.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Aortic Surgery, Cardiac Surgery and SIHD, Interventions and Imaging, Angiography, Nuclear Imaging, Chronic Angina

Keywords: ACC17, ACC Annual Scientific Session, Angina, Stable, Angiography, Cardiac Imaging Techniques, Coronary Artery Bypass, Intention to Treat Analysis, Magnetic Resonance Spectroscopy, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Perfusion Imaging, Percutaneous Coronary Intervention, Treatment Outcome, omega-Chloroacetophenone


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