Byrne C, et al. - Researchers investigated if there is an additive negative impact of atrial fibrillation (AF) during scan on the myocardial perfusion in patients with non-ischemic systolic heart failure. They performed a Rubidium-82 positron emission tomography/computed tomography perfusion scan on 27 young healthy controls and 114 patients with non-ischemic systolic heart failure (23 with AF during scan). Findings revealed lower flow reserve in patients with systolic heart failure vs healthy controls. Also, if patients with systolic heart failure had AF during scan, they had even lower myocardial flow reserve.