Stress CMR predicts heart disease risk in obese patients

Stress cardiac magnetic resonance (CMR) imaging may help physicians risk stratify obese patients for cardiovascular disease, according to a study that found stress CMR to be feasible in this patient population.

The study was published in the May issue of the Journal of the American College of Cardiology:Imaging.  

Traditional non-invasive imaging techniques may lack sensitivity and have technical limitations in the obese population, including reduced signal-to-noise ratio and attenuation artifacts found with use of SPECT. PET imaging requires the use of radiotracers with a limited availability, higher cost and exposure to larger amounts of ionizing radiation.

“Relative to alternative techniques, stress CMR has high spatial and temporal resolution and is not limited by acoustic windows or image acquisition,” wrote lead author Ravi V. Shah, MD, of Brigham and Women’s Hospital in Boston, and his colleagues. “However, concerns over feasibility in obese patients because of claustrophobia and safety monitoring have limited the adoption of stress CMR in this important, burgeoning population.”

Shah and his colleagues evaluated a cohort of 285 patients with a body mass index of 30 or more and suspected MI as candidates for stress CMR imaging. Their goal was to determine whether this form of imaging effectively predicted future major adverse cardiovascular events (MACE), which they defined as cardiac death or nonfatal MI. They performed CMR imaging according to protocol on 272 patients and achieved diagnostic quality imaging in 255 patients. Patients were followed for a median 2.1 years.

Investigators found CMR-inducible ischemia was a strong independent predictor of MACE. Patients with no inducible ischemia or late gadolinium enhancement (LGE) had a lower annual MACE rate than patients with ischemia or patients with ischemia and LGE (0.3 percent vs. 6.3 percent and 6.7 percent, respectively). Over the course of the 10-year study, 32 patients underwent early coronary revascularization and of the remaining 223 patients, there were nine MACE events, including four cardiac deaths and five nonfatal MI. Inducible ischemia was extent in these individuals.

Their study demonstrated that stress CMR was feasible in obese patients and had prognostic value, they concluded. With obesity growing in the population, imaging techniques and diagnostic tools like stress CMR may prove to be the best means of predicting outcomes and assisting clinicians in best care practices.