Abnormal cardiac MR stress tests associated with mortality
An abnormal cardiovascular magnetic resonance (CMR) stress test is associated with mortality, according to findings of population study of over 9,000 individuals and 16 different subpopulations, researchers reported Feb.8, 2019, in JAMA Cardiology.
CMR can be used to detect myocardial ischemia and to forecast prognosis. It can depict left ventricular (LV) wall motion and myocardial perfusion with high spatial resolution in virtually any imaging plane. However, it is a rarely used cardiac stress test in the United States, due in part to lack of data on patient outcomes, according to the researchers, led by Robert M. Judd, PhD, co-director of Duke University’s Cardiovascular Magnetic Resonance Center (CMRC) in Durham, NC.
The Duke CMRC routinely performs CMR stress-testing to evaluate coronary artery disease, assess vascular disease, and evaluate congenital heart disease. The Center and six other hospitals in Georgia, Illinois, Minnesota, New York, North Carolina, and Texas identified 9,151 patients who underwent a stress CMR for myocardial ischemia. These patients represented a diverse population ranging in age from 49 to 72 years. Twenty-seven percent had a clinically documented history of obstructive coronary artery disease. Total follow-up data represented 48,000 patient years.
The exams were performed on either a 1.5- or 3.0-T scanner, and consisted of cine imaging to examine regional LV wall motion, stress and rest perfusion imaging to test for ischemia, and late gadolinium enhancement (LGE) imaging to detect myocardial infarction and/or scar. Rest perfusion images were also acquired if stress perfusion images were abnormal.
Participating centers used identical software for image interpretation and reporting. Every 90 days, each center reported any deaths among study participants. An abnormal stress CMR included any abnormal score for wall motion, ischemia, or LGE. Patients with a history of smoking, hypertension, hyperlipidemia, and diabetes had a 1.5-fold higher risk of having an abnormal exam compared to patients without these conditions or habits.
During the 10-year study, 1,517 patients had died. The annual mortality rate was 3.1%. Patients with an abnormal stress CMR and high Framingham risk had a mortality rate of 4.9% per year compared to 2.7% for similar patients with a normal stress CMR. The mortality rate difference between the two groups was even greater for patients at low and moderate Framingham risk: 2.7% for low-risk patients with abnormal stress CMR compared to 0.8% for those with normal exams, and 4.0% for moderate risk patients with abnormal stress CMR compared to 1.4% for those with normal exams.
Nearly 70% of the patients were followed for four years. Stress CMR resulted in a net reclassification improvement of 11.4%, 6.5% for patients who died within four years and 4.9% for patients who survived. An abnormal stress test was strongly associated with mortality for both men and women.
“CMR works as well or better than other exams at identifying heart wall motion, cell death, and the presence of low blood flow. There are a number of reasons for the limited use of stress CMR, including availability of good-quality laboratories, exclusion of patients who cannot undergo magnetization, and a lack of data on patient outcomes,” said Dr. Judd. “But with the findings from this study suggesting that stress CMR is effective in predicting mortality, we provide a strong basis for a head-to-head study between stress CMR and other modalities.”
REFERENCE
- Heitner JF, Kim RJ, Kim HW, et al. Prognostic value of vasodilator stress cardiac magnetic resonance imaging: A multicenter sutdy with 48000 patient-years of follow-up. JAMA Cardiol. Published online February 8, 2019. doi: 10.1001/jamacardio.2019.0035.