Stress cardiac magnetic resonance effective in obese patients

Use of stress cardiac magnetic resonance (CMR) in obese patients is feasible and effective in determining prognoses, according to a study published online April 9 by the Journal of the American College of Cardiology: Cardiovascular Imaging.

Stress imaging methods may be limited by patient size, which is particularly problematic as obese patients are at a higher risk for cardiovascular disease. Despite PET’s ability to sidestep technical issues such as attenuation artifacts and reduced signal-to-noise ratio, other challenges remain. These include ionizing radiation, radiotracer availability and cost, according to lead author Ravi V. Shah, MD, of Brigham and Women’s Hospital in Boston, and colleagues.

Stress CMR, however, “can assess ventricular function, stress and rest perfusion, and viability within a single examination,” wrote the authors. “Relative to alternative techniques, stress CMR has high spatial and temporal resolution and is not limited by acoustic windows or image acquisition.”  

Given concerns about the method’s use in obese patients due to claustrophobia and safety monitoring, Shah et al investigated the feasibility of CMR utilization in obese patients, as well as the prognostic impact of its results on cardiovascular events.

The study’s population included 255 patients with a body mass index greater than or equal to 30 kg/m2 who were referred for vasodilating stress CMR. These patients were followed for major adverse cardiac events (MACE) and analysis was used to identify the prognostic association of inducible ischemia or late gadolinium enhancement (LGE) by CMR beyond traditional clinical risk indices. Nineteen patients, or 7 percent, required sedation. Sixteen patients required scanning with a  70-cm-bore system.

Results indicated that patients without inducible ischemia or LGE experienced a substantially lower annual rate of MACE at 0.3 percent vs. 6.3 percent for ischemia and 6.7 percent for those with ischemia and LGE.

Inducible ischemia was associated independently with MACE, and when patients with early coronary revascularization were censored on the day of revascularization, the presence of inducible ischemia and ischemia extent per segment were both strongly associated with MACE.

“With a growing population of obese patients at significant risk for cardiovascular disease, these results suggest the use of stress CMR to stratify risk in symptomatic obese patients with suspected CAD [coronary artery disease] may be warranted,” the authors concluded.