Prognostic value of coronary flow reserve in patients with dialysis-dependent ESRD

Abstract

Capillary rarefaction of the coronary microcirculation is a consistent phenotype in patients with dialysisdependent ESRD (dd-ESRD) and may help explain their excess mortality. Global coronary flow reserve (CFR) assessed by positron emission tomography (PET) is a noninvasive, quantitativemarker ofmyocardial perfusion and ischemia that integrates the hemodynamic effects of epicardial stenosis, diffuse atherosclerosis, and microvascular dysfunction. We tested whether global CFR provides risk stratification in patients with dd-ESRD. Consecutive patients with dd-ESRD clinically referred for myocardial perfusion PET imaging were retrospectively included, excluding patients with prior renal transplantation. Perpatient CFR was calculated as the ratio of stress to rest absolutemyocardial blood flow.Multivariable Cox proportional hazards models, including age, overt cardiovascular disease, and myocardial scar/ischemia burden, were used to assess the independent association of global CFR with all-cause and cardiovascular mortality. The incremental value of global CFR was assessed with relative integrated discrimination index and net reclassification improvement. In 168 patients included, median global CFR was 1.4 (interquartile range, 1.2-1.8). During follow-up (median of 3 years), 36 patients died, including 21 cardiovascular deaths. Log-transformed global CFR independently associated with all-cause mortality (hazard ratio, 0.01 per 0.5-unit increase; 95%confidence interval,,0.01 to 0.14; P,0.001) and cardiovascularmortality (hazard ratio, 0.01 per 0.5-unit increase; 95% confidence interval, ,0.01 to 0.15; P=0.002). For all-causemortality, addition of global CFR resulted in risk reclassification in 27% of patients. Thus, global CFR may provide independent and incremental risk stratification for all-cause and cardiovascular mortality in patients with dd-ESRD.