Coronary flow reserve does not correlate with coronary artery calcification in patients with end-stage renal disease

Objectives Chronic kidney disease (CKD) is a major risk factor for the development of coronary artery disease (CAD). Patients with CKD have an increased risk for myocardial infarction, heart failure and cardiac death, while particularly patients with end-stage renal disease (ESRD) are at high risk. Myocardial perfusion imaging (MPI) with PET is used for the detection of hemodynamically relevant CAD in CKD patients. Coronary flow reserve (CFR) and coronary artery calcification (CAC) have been shown to be prognostic markers for cardiovascular events. We herein questioned the relationship of these relevant morphological and functional parameters in kidney transplant waitlist patients with ESRD.

Methods 48 patients (32 male; mean age 52 ± 12.8 years) underwent list-mode driven, quantitative myocardial perfusion ¹³NH₃ PET/CT under hyperemic and resting conditions. Myocardial perfusion defects (summed stress score, SSS 蠅 4) were detected in the static PET images while absolute rest and hyperemic myocardial blood flow (MBF) and CFR were calculated from the dynamic PET images. A CFR ≤ 1.8 was considered as pathologic. CAC was derived from the non-ECG triggered, low-dose CT scan of the chest which was acquired for attenuation correction of the PET data and expressed as Agatston score.

Results CFR was impaired in six patients (12.5%);one patient presented with an additional perfusion defect. Static MPI showed stress perfusion defects in another five patients (10%) in which CFR was preserved. Mean Agatston score was 425 ± 893 (range 0 - 3957). While there was a moderate negative correlation between hyperemic MBF and CACB (r=-0.304; p=0.038), CFR did not significantly correlate with CAC (r=-0.111; p=0.46). Age was negatively correlated with hyperemic MBF (r=-0.518; p<0.001) and CFR (r=-0.39; p<0.01) but not significantly with CAC (r=0.27; p=0.071).

Conclusions Although established as markers for atherosclerosis and predictors for cardiovascular events in non-CKD patients, CFR and CAC do not correlate in patients with ESRD. While CAC was not correlated with age, hyperemic MBF and CFR decrease with increasing age of the patients. Notably, myocardial perfusion defects detected by static PET imaging in ESRD patients do not necessarily come along with an impaired CFR, which points towards the need for a differentiated cardio vascular risk assessment in these patients.