Prognostic Impact of Coronary Flow Reserve in Patients With CKD

Introduction: Both coronary flow reserve (CFR) and chronic kidney disease (CKD) are known to be associated with adverse cardiac events. However, it is unclear how these prognostic factors are interrelated. This study evaluated the association between intracoronary physiologic indexes and CKD and their prognostic implications.

Methods: A total of 351 patients without left ventricular systolic dysfunction (ejection fraction ≥ 40%) and not on dialysis whose revascularization was deferred based on fractional flow reserve (FFR) > 0.80 were analyzed. Depressed CFR was defined as CFR ≤ 2.0. The primary outcome was a composite of cardiac death or hospitalization for heart failure at 3 years.

Results: Patients with CKD showed lower CFR than the non-CKD population (3.28 ± 1.77 vs. 2.60 ± 1.09, P < 0.001), mainly driven by increased resting coronary flow. There was no significant difference in hyperemic coronary flow, FFR, and index of microvascular resistance between the 2 groups. CFR was significantly associated with estimated glomerular filtration rate (eGFR) (P = 0.045), and the proportion of depressed CFR was significantly increased with higher CKD stages (P = 0.011). The risk of cardiac death or hospitalization for heart failure was the lowest in the non-CKD and preserved CFR group (11.9%) and the highest in the CKD and depressed CFR group (60.0%, overall log rank P < 0.001). Both CKD (adjusted hazard ratio [HR_adj] 2.614, 95% confidence interval [CI] 1.505-4.539, P < 0.001) and depressed CFR (HR_adj 3.237, 95% CI 2.015-5.199, P < 0.001) were independently associated with the risk of the primary outcome.

Conclusion: There was a significant association between severity of CKD and CFR. Both CKD and depressed CFR showed independent association with higher risk of cardiac death or hospitalization for heart failure.