Myocardial perfusion imaging has low yield for detecting ischemia in AF patients

An analysis of patients with atrial fibrillation at the Cleveland Clinic found the yield of using myocardial perfusion imaging (MPI) for detecting ischemia was low and did not significantly increase with increasing cardiovascular risk. Ischemia was not associated with mortality, either.

Lead researcher Paul C. Cremer, MD, of the Cleveland Clinic, and colleagues published their results in JAMA Internal Medicine on Sept. 14.

Although appropriate use criteria recommend MPI in asymptomatic atrial fibrillation patients, the researchers noted the recommendation was based on scant evidence.

In this analysis, they retrospectively analyzed 1,700 asymptomatic patients with atrial fibrillation who received rest-stress MPI at the Cleveland Clinic from October 2006 through December 2014. They defined asymptomatic as patients who did not have chest pain or dyspnea.

At baseline, the mean age of patients was 69.9, and 63.8 percent were males. Of the patients, 77.9 percent had hypertension, 68.3 percent had hyperlipidemia and 50 percent were obese.

The median 10-year global cardiovascular risk was 22.8 percent among patients with lipid values.

Further, 4.6 percent of patients had greater than 5 percent ischemic myocardium. Only seven of the 1,700 patients had obstructive coronary artery disease and underwent revascularization.

The yield of using MPI for detecting ischemia was 3.4 percent in patients with a 10-year global cardiovascular risk of less than 10 percent; 5.5 percent in patients with a 10-year global cardiovascular risk of between 10 percent and 20 percent; and 5.2 percent in patients with high global cardiovascular risk.

The researchers defined high global cardiovascular risk as a history of coronary artery disease or a 10-year global cardiovascular risk of more than 20 percent.

After a mean follow-up period of 2.6 years, 47 of the 841 patients with mortality data had died. A multivariable analysis found the following variables were associated with increased mortality: high global cardiovascular risk, pharmacologic test and ejection fraction of less than 45 percent.

The researchers mentioned a few limitations, including that they did not assess nonfatal MI and did not have mortality data for all patients, which weakened the strength of their conclusions on the prognostic value of ischemia.

However, they also noted this study’s data regarding the yield to detect ischemia was comparable to previous research.

“The yield was similar in our study, suggesting that the presence of atrial fibrillation does not identify asymptomatic patients that are more likely to have occult myocardial ischemia,” they wrote. “Instead, stress MPI should likely be reserved for patients with atrial fibrillation who have an intermediate to high likelihood of [coronary artery disease] based on their symptoms.”