Vasodilator Stress Perfusion CMR Imaging Is Feasible and Prognostic in Obese Patients

Abstract

This study sought to determine feasibility and prognostic performance ofstress cardiac magnetic resonance (CMR) in obese patients (body mass index [BMI] ≥30 kg/m(2)). Current stress imaging methods remain limited in obese patients. Given the impact of the obesity epidemic on cardiovascular disease, alternative methods to effectively risk stratify obese patients are needed. Consecutive patients with a BMI ≥30 kg/m(2) referred for vasodilating stress CMR were followed for major adverse cardiovascular events (MACE), defined as cardiac death or nonfatal myocardial infarction. Univariable and multivariable Cox regressions for MACE were performed to determine the prognostic association of inducible ischemia or late gadolinium enhancement (LGE) by CMR beyond traditional clinical risk indexes. Of 285 obese patients, 272 (95%) completed the CMR protocol, and among these, 255(94%) achieved diagnostic imaging quality. Mean BMI was 35.4 ± 4.8 kg/m(2), with a maximum weight of 200 kg. Reasons for failure to complete CMR included claustrophobia (n= 4), intolerance to stress agent (n= 4), poor gating (n= 4), and declining participation (n= 1). Sedation was required in 19 patients(7%; 2 patients with intravenous sedation). Sixteen patients required scanning by a 70-cm-bore system (6%). Patients without inducible ischemia or LGE experienced a substantially lowerannual rate of MACE (0.3% vs. 6.3% for those with ischemia and 6.7% for those with ischemia and LGE). Median follow-up of the cohort was 2.1 years. In a multivariable stepwise Cox regression including clinical characteristics and CMR indexes, inducible ischemia (hazard ratio 7.5; 95% confidence interval: 2.0 to 28.0; p=0.002) remained independently associated with MACE. When patients with early coronary revascularization (within 90 days of CMR) were censored on the day of revascularization, both presence of inducible ischemia and ischemia extent per segment maintained a strong association with MACE. Stress CMR is feasible and effective in prognosticating obese patients, with a verylow negative event rate in patients without ischemia or infarction.