Stress cardiac magnetic resonance imaging was found to lead to the reclassification of guideline-evaluated risk for a significant percentage of patients with suspected myocardial ischemia and no history of coronary artery disease (CAD), according to a study published in JAMA.
In this retrospective analysis, the data of 1698 adults (mean age, 62 years) with suspected myocardial ischemia, ≥2 coronary risk factors and no history of CAD who underwent stress CMR imaging were examined. The study was conducted at 13 centers across 11 states in the United States (median follow-up, 5.4 years). The study’s main outcomes included cardiovascular (CV) death, nonfatal myocardial infarction (MI), major adverse CV events (MACE; ie, CV death, nonfatal MI, hospitalization for heart failure or unstable angina, and late unplanned coronary artery bypass graft surgery).
The rates of CV death/nonfatal MI and MACE were 3.9% and 11.2%, respectively. Patients with vs without CMR-assessed late gadolinium enhancement (LGE) or ischemia had a higher prevalence of CV risk factors (P <.01), higher rates of CV treatment (56.0% vs 44.6%, respectively; P <.01), lower left ventricular ejection fraction (LVEF; 57.5% vs 64.7%, respectively; P <.01), higher left-ventricular end-diastolic volume indexed (71.1 mL/m2 vs 60.9 mL/m2, respectively; P <.01), and higher left-ventricular end-systolic volume indexed (27.5 mL/m2 vs 20.8 mL/m2, respectively; P <.01).
Using American College of Cardiology/American Heart Association guideline-recommended annualized risk categories for CV death/nonfatal MI, patients in this cohort were categorized as being at low (<1% per year), intermediate (1-3% per year), or high (>3% per year) risk. The addition of stress CMR/assessed LVEF, presence of ischemia, and LGE to a model that incorporated the CAD Consortium score, hypertension, smoking, and diabetes offered a net risk reclassification improvement for CV death/nonfatal MI of 0.266 (95% CI, 0.091-0.441) and C statistic improvement of 0.086 (95% CI, 0.022-0.149).
The use of stress CMR imaging reclassified 60.3% of patients in the intermediate pretest risk category (52.4% and 7.9% reclassified as low and high risk, respectively), with corresponding changes in event rates of 0.6%/year and 4.9%/year for and high post-test risk, respectively. The use of stress CMR imaging offered a significant net reclassification improvement for MACE of 0.361 (95% CI, 0.255-0.468), a C statistic improvement of 0.092 (95% CI, 0.054-0.131), and a reclassification of 59.9% of patients in the intermediate pretest risk group (48.7% reclassified as low risk and 11.2% as high risk).
Limitations of the study include its retrospective nature and the lack of data on stress CMR imaging segmental wall motion abnormality, which prevented the researchers from examining the incremental prognostic value of stress CMR for ischemia and infarction.
“Our study offers further evidence that stress CMR imaging may be well poised to assume the role of a gate-keeping noninvasive test, especially in patients in the low to intermediate pretest risk category for CV death and nonfatal MI,” noted the study authors.
Antiochos P, Ge Y, Steel K, et al. Evaluation of stress cardiac magnetic resonance imaging in risk reclassification of patients with suspected coronary artery disease [published online July 29, 2020]. JAMA Cardiol. doi:10.1001/jamacardio.2020.2834