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Stress cardiac magnetic resonance feasible and prognostic in obese patients

Publish date: April 9, 2014
By
Bianca Nogrady
MDedge News

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CMR’s prognostic value affirmed

Stress SPECT imaging has been problematic in obese patients, often yielding poor quality images. This study by Dr. Shah and his coworkers clearly shows the prognostic value of stress cardiac magnetic resonance in obese individuals.

Those patients with absence of both ischemia and late gadolinium enhancement had an excellent prognosis during follow-up. It should be pointed out that PET myocardial perfusion imaging is also effective in obese patients with a similar event-free survival in those with normal studies. As the authors note, however, PET imaging is associated with some radiation exposure, whereas CMR imaging has no radiation exposure to the patient.

CMR use in this setting is limited, however, as some patients require sedation because of claustrophobia, and the technique is not readily available to all cardiac imaging laboratories.

Dr. George A. Beller is chief of the cardiovascular division at the University of Virginia Health System in Charlottesville. He has no financial conflicts of interest.


 

FROM JACC CARDIOVASCULAR IMAGING

Stress cardiac magnetic resonance is highly feasible and prognostically useful in obese patients, a population in which stress imaging methods are limited, according to a study of nearly 300 patients reported online in JACC: Cardiovascular Imaging on April 9.

Dr. Ravi V. Shah of Harvard Medical School, Boston, and his colleagues, said stress echocardiography and nuclear perfusion can be challenging in obese patients, and PET has issues around ionizing radiation and cost, but the use of stress cardiac magnetic resonance had also been limited by concerns about claustrophobia and safety monitoring.

In this feasibility study in 285 patients with a mean body mass index of 35.4 kg/m2, the primary outcome was a composite of cardiac death or MI (MACE). During a mean follow-up of 2.1 years, 19 patients died, 7 from cardiovascular causes.

The incidence of MACE increased with both inducible ischemia and late gadolinium enhancement (LGE). The patients with no evidence of inducible ischemia, infarction, or LGE had a very low annualized MACE rate of 0.3%, while those who had no inducible ischemia who did have LGE had a rate of 2.4%. The MACE rate jumped significantly, to 6.3%, in patients with inducible ischemia and no LGE, and further yet in patients with evidence of both to 6.7%.

Diabetes, age, prior MI, prior revascularization, and reduced left ventricular ejection fraction were all associated with MACE in the study.

The investigators noted that only 13 (5%) of patients failed to complete the study protocol because of claustrophobia, intolerance to the stress agent, or poor gating, and sedation was required in 19 (7%) of patients.

However diagnostic-quality imaging was achieved in more than 89% of patients (JACC Cardiovasc. Imaging 2014 [dx.doi.org/10.1016/j.jcmg.2013.11.011]).

These results "confirm, in an obese population, that inducible ischemia and LGE by stress perfusion CMR are robust markers of risk even in those patients without a clinical history of prior infarction," the authors concluded.

Researchers declared grants and awards from the American Heart Association, the National Institutes of Health and the Alberta Heritage Foundation for Medical Research, and one author declared research support from Astellas Pharma US.

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