Research presented at the Society of Nuclear Medicine and Molecular Imaging’s 2019 Annual Meeting draws a strong link between severe obstructive sleep apnea (OSA) and impaired coronary flow reserve, which is an early sign of the heart disease atherosclerosis. Using 13N-ammonia positron emission tomography/computed tomography (PET/CT), researchers were able to noninvasively evaluate coronary microvascular function in OSA patients and use their findings to predict cardiovascular disease risk.

To evaluate the cardiovascular disease risk factors in OSA patients, researchers conducted 13N-ammonia PET/CT imaging on 38 patients, who were divided into three groups based on the severity of their sleep apnea. During the PET/CT imaging, myocardial blood flow and coronary flow reserve—key indicators of coronary dysfunction—were automatically calculated using quantitative PET/CT software.

The mean rest myocardial blood flow was similar among patients in the three groups of mild, moderate, and severe OSA. The mean hyperemic myocardial blood flow was also similar, though researchers found that the blood flow decreased gradually as the severity of OSA increased. There were, however, significant differences in the mean coronary flow reserve among the three groups—those with severe OSA had a substantially lower coronary flow reserve.

“As we all know, impaired coronary flow reserve is an early sign of atherosclerosis,” says Ruonan Wang, MD, The First Hospital of Shanxi Medical University in Taiyuan, China, in a release. “Our study suggests that patients with OSA, especially severe OSA, should receive PET myocardial perfusion imaging as early as possible to exclude coronary microcirculatory dysfunction.”

The abstract (#163), “Evaluation of Myocardial Blood Flow and Coronary Flow Reserve with 13N-Ammonia PET/CT in Patients with Different Degrees of Obstructive Sleep Apnea,” is published in The Journal of Nuclear Medicine.

Image: Left grouping: Mild OSA in a 38-year-old male, untreated. Center: Moderate OSA in a 49-year-old male, untreated. Right: Severe OSA in a 63-year-old male, untreated. Credit: Wang R, Wu P, Li L, et al.