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Prognostic Value of Stress CMR in Known CAD
Quick Takes
- In this cohort of 755 patients with known CAD, assessment of ischemia by CMR enhanced risk classification; 95% of patients with intermediate pretest risk were reclassified into low- or high-risk categories.
- In the absence of ischemia, the annualized risk of cardiovascular death/nonfatal MI was low at 1.8%.
Study Questions:
Does stress cardiac magnetic resonance (CMR) provide clinically relevant risk reclassification in patients with known coronary artery disease (CAD)?
Methods:
The SPINS (Stress CMR Perfusion Imaging in the United States) Registry was a retrospective, multicenter study including patients aged 35-85 years undergoing vasodilator stress CMR from 2008–2013. This analysis included SPINS patients with previously documented CAD, defined as history of myocardial infarction (MI), percutaneous coronary intervention (PCI), or CAD according to coronary angiography. Notable exclusion criteria were history of coronary artery bypass grafting (CABG), MI within 30 days prior to CMR, and left ventricular ejection fraction (LVEF) <40%. The primary outcome was cardiovascular death or nonfatal MI. The secondary outcome comprised major adverse cardiovascular events (MACE): cardiovascular death, nonfatal MI, hospitalization for heart failure (HF) or unstable angina, and unplanned CABG >6 months after the index CMR.
Results:
A total of 755 patients (mean age 64 years, 64% male, 82% with hypertension, 32% with diabetes) were included. Median LVEF was 62% (interquartile range, 52-69%). Ischemia was present in 28% of patients (n = 212), and 46% (n = 346) had late gadolinium enhancement (LGE). Among patients with LGE, 35% (n = 121) had unrecognized MI (UMI), an infarct pattern on imaging without a prior clinical diagnosis of MI. Patients with ischemia had a higher prevalence of LGE (67% vs. 38%, p < 0.001) and UMI (23% vs. 13%, p < 0.001).
Over a median follow-up period of 5.3 years, 97 patients (13%) had cardiovascular death/nonfatal MI, and 210 patients (28%) had MACE. Presence of ischemia, LGE, and LV end-systolic volume index >45 ml/m2 were associated with higher annualized rates of cardiovascular death/nonfatal MI (p < 0.001 for all). In the absence of ischemia, the annualized risk of cardiovascular death/nonfatal MI was low at 1.8%. In multivariable analysis, both ischemia and UMI were significantly associated with nonfatal MI/cardiovascular death (ischemia: hazard ratio [HR], 1.84; 95% confidence interval [CI], 1.17-2.88; p = 0.008; UMI: HR, 2.27; 95% CI, 1.10-4.70; p = 0.027) and MACE (ischemia: HR, 1.77; 95% CI, 1.31-2.40; p < 0.001; UMI: HR, 1.73; 95% CI, 1.11-2.69; p = 0.015). Addition of CMR-assessed ischemia to a risk prediction model reclassified 43% of patients, including 95% of patients with intermediate pretest risk, to low-risk and high-risk categories.
Conclusions:
Vasodilator stress CMR is an effective means of risk stratifying patients with known CAD. The absence of ischemia on stress CMR is associated with a low annual rate of cardiovascular death/nonfatal MI.
Perspective:
Previous analyses from the SPINS registry have addressed use of stress CMR in patients with suspected CAD (Antiochos P, et al., JAMA Cardiol 2020) and reduced LVEF (Ge Y, et al., JACC Cardiovasc Imaging 2020), showing that this modality can be clinically useful in a broad range of patients. One limitation of this work is that all scans were performed in centers with at least 10 years of experience in stress CMR, so the findings may not be generalizable to all settings. The practice of stress CMR remains limited, in part because of widespread availability of nuclear perfusion imaging and relative scarcity of physicians well-trained in CMR.
Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Atherosclerotic Disease (CAD/PAD), Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Acute Heart Failure, Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Magnetic Resonance Imaging, Nuclear Imaging, Hypertension
Keywords: Angina, Unstable, Contrast Media, Coronary Angiography, Coronary Artery Bypass, Coronary Artery Disease, Diagnostic Imaging, Gadolinium, Heart Failure, Hypertension, Ischemia, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Myocardial Infarction, Percutaneous Coronary Intervention, Perfusion Imaging, Risk, Secondary Prevention, Stroke Volume, Vasodilator Agents, Ventricular Function, Left
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