Cardiac magnetic resonance imaging reduces radiation exposure in emergency department patients with chest pain: A secondary analysis from the CMR IMPACT trial.

BACKGROUND

Patients presenting to the Emergency Department (ED) with chest pain who have an indeterminate (detectable to mildly elevated) troponin are often evaluated with tests that use ionizing radiation. We hypothesized that patients initially evaluated with stress cardiac magnetic resonance (CMR) imaging receive less ionizing radiation through one year of follow-up than those initially evaluated with invasive angiography.

METHODS

We conducted a secondary analysis of the CMR-IMPACT trial, which randomized adult patients at 4 U.S. sites (9/2013-7/2018) with a contemporary troponin of 0.006-1.0 ng/mL to either CMR imaging or invasive angiography. Cumulative radiation exposure from coronary computed tomography angiography, nuclear medicine stress imaging, cardiac catheterization, and percutaneous coronary intervention was assessed from index through one year using validated radiation dose estimates. Radiation doses at index and one year were compared between arms using linear regression adjusted for the stratification factors of initial troponin and known coronary artery disease in both intention-to-treat (ITT) and per-protocol (PP) populations.

RESULTS

During the study period, 312 patients were enrolled, with 156 randomized to each arm (CMR vs. invasive angiography). In the ITT analysis, patients in the CMR arm had less radiation exposure at index compared to patients in the invasive angiography arm (4.7 ± 5.7 mSv vs. 7.8 ± 5.8 mSv; p < 0.001). The difference in radiation exposure at one year was 7.5 ± 10.9 mSv vs. 9.5 ± 8.4 mSv (p = 0.06). In the PP analysis, patients receiving CMR (N = 102) had less radiation exposure than those receiving invasive angiography (N = 104) at index (3.5 ± 5.1 mSv vs. 9.3 ± 3.7 mSv; p < 0.001) and one year (5.8 ± 10.9 mSv vs. 11.2 ± 8.1 mSv; p < 0.001).

CONCLUSION

CMR was associated with decreased radiation exposure compared to invasive angiography.