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CMR's potential for predicting potentially fatal CVD

The use of MRI to determine heart function has been slow to catch on, but a study from Duke Health researchers shows that stress cardiac MRI not only diagnoses disease, but can also predict which cases are potentially fatal. Results from a large, multi-centre study suggest that cardiac magnetic resonance, or CMR, has potential as a non-invasive, non-toxic alternative to stress echocardiograms, catheterisations and stress nuclear exams in identifying the severity of coronary artery disease.

"We've known for some time that CMR is effective at diagnosing coronary artery disease, but it's still not commonly used and represents less than one percent of stress tests used in this country," said senior author Dr Robert Judd, co-director of the Duke Cardiovascular Magnetic Resonance Centre.

"One of the impediments to broader use has been a lack of data on its predictive value – something competing technologies have," Judd said. "Our study provides some clarity, although direct comparisons between CMR and other technologies would be definitive."

Judd and colleagues analysed data from more than 9,000 patients who underwent CMR at seven US hospitals, encompassing up to 10 years of follow-up. For patients without any history of heart disease and at low risk based on traditional clinical criteria, those with an abnormal CMR scan were 3.4 times more likely to die compared to patients with a normal CMR scan. For the entire patient population, the researchers found a strong association between an abnormal stress CMR and mortality, even after adjusting for patient age, sex, and cardiac risk factors.

"Non-invasive cardiac stress testing is a cornerstone in the clinical management of patients with known or suspected coronary artery disease," Judd said, noting that CMR works as well or better than other exams at identifying heart wall motion, cell death and the presence of low blood flow. In addition, the technology does not require any radiation exposure, which is essential in nuclear stress tests that are by far the most commonly used in the US.

"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," Judd said. "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."

Importance: Stress cardiac magnetic resonance imaging (CMR) is not widely used in current clinical practice, and its ability to predict patient mortality is unknown.
Objective: To determine whether stress CMR is associated with patient mortality.
Design, Setting, and Participants: Real-world evidence from consecutive clinically ordered CMR examinations. Multicenter study of patients undergoing clinical evaluation of myocardial ischemia. Patients with known or suspected coronary artery disease (CAD) underwent clinical vasodilator stress CMR at 7 different hospitals. An automated process collected data from the finalized clinical reports, deidentified and aggregated the data, and assessed mortality using the US Social Security Death Index.
Main Outcomes and Measures: All-cause patient mortality.
Results: Of the 9151 patients, the median (interquartile range) patient age was 63 (51-70) years, 55% were men, and the median (interquartile range) body mass index was 29 (25-33) (calculated as weight in kilograms divided by height in meters squared). The multicenter automated process yielded 9151 consecutive patients undergoing stress CMR, with 48 615 patient-years of follow-up. Of these patients, 4408 had a normal stress CMR examination, 4743 had an abnormal examination, and 1517 died during a median follow-up time of 5.0 years. Using multivariable analysis, addition of stress CMR improved prediction of mortality in 2 different risk models (model 1 hazard ratio [HR], 1.83; 95% CI, 1.63-2.06; P < .001; model 2: HR, 1.80; 95% CI, 1.60-2.03; P < .001) and also improved risk reclassification (net improvement: 11.4%; 95% CI, 7.3-13.6; P < .001). After adjustment for patient age, sex, and cardiac risk factors, Kaplan-Meier survival analysis showed a strong association between an abnormal stress CMR and mortality in all patients (HR, 1.883; 95% CI, 1.680-2.112; P < .001), patients with (HR, 1.955; 95% CI, 1.712-2.233; P < .001) and without (HR, 1.578; 95% CI, 1.235-2.2018; P < .001) a history of CAD, and patients with normal (HR, 1.385; 95% CI, 1.194-1.606; P < .001) and abnormal left ventricular ejection fraction (HR, 1.836; 95% CI, 1.299-2.594; P < .001).
Conclusions and Relevance: Clinical vasodilator stress CMR is associated with patient mortality in a large, diverse population of patients with known or suspected CAD as well as in multiple subpopulations defined by history of CAD and left ventricular ejection fraction. These findings provide a foundational motivation to study the comparative effectiveness of stress CMR against other modalities.

John F Heitner, Raymond J Kim, Han W Kim, Igor Klem, Dipan J Shah, Dany Debs, Afshin Farzaneh-Far, Venkateshwar Polsani, Jiwon Kim, Jonathan Weinsaft, Chetan Shenoy, Andrew Hughes, Preston Cargile, Jean Ho; Robert O. Bonow, Elizabeth Jenista, Michele Parker, Robert M Judd

[link url=""]Duke University Medical Centre material[/link]
[link url=""]JAMA Cardiology abstract[/link]

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