Impact of macrovascular and microvascular cardiac disease assessed by 82-rubidium positron emission tomography in patients with chronic kidney disease

Background Patients with impaired renal function have higher mortality and risk of major cardiac events (MACE). Coronary microvascular dysfunction (CMD) is common in chronic kidney disease (CKD) and may worsen outcomes. The combined impact of CMD and obstructive coronary artery disease (CAD) remains unclear. Purpose To evaluate cardiac microvascular and macrovascular function, assessed by 82-Rb PET, in the risk stratification of patients with CKD. Methods and Results We included 4783 patients referred for at clinically indicated 82-rubidium positron emission tomography myocardial perfusion imaging (82-Rb PET) at three sites between January 2018 and August 2020. 995 (20.8%) patients had CKD defined as eGFR <60. Patients with CKD were older and more had hypertension and diabetes. More had a significant perfusion defect, lower MFR and lower left ventricular ejection fraction (LVEF). The 995 CKD patients were followed through registries until May 2024 with no loss to follow-up. Primary outcomes were MACE (myocardial infarction and stroke), hospitalization for heart failure, and all-cause mortality. CMD was defined as a myocardial flow reserve (MFR) <2 and obstructive CAD as a perfusion defect of ≥10%. 562 (56.5%) had MFR <2 and 183 (18.3%) had perfusion defect. During follow-up there were 128 MACE, 207 heart failure admissions, and 307 deaths. In unadjusted analysis stratified by four groups of perfusion defect and MFR, patients with reduced MFR, independent of perfusion defect, had higher risk of all outcomes (figure 1). Only 34 patients with ≥10% perfusion defect had MFR >2. This group had better outcomes, but conclusions are limited by the small group size. In multivariable adjusted Cox models, MFR <2, but not perfusion defects, was associated with higher risk of MACE, heart failure and mortality (figure 2). Conclusion In patients with CKD referred for 82-Rb PET, impaired MFR was a contributor to increased risk, independently of perfusion defect.