MRI Study of Kidney Blood Flow and Oxygenation in Heart Failure with Preserved and Reduced Ejection Fraction

Background: The pathophysiology of CKD in HFpEF has not been fully elucidated. It is unclear whether kidney cortical and medullary blood flow is altered in HFpEF compared to HFrEF. Methods: We recruited 19 HFpEF and 10 HFrEF participants as well as 5 CKD (eGFR < 60) and 3 healthy volunteer controls. HFpEF and HFrEF diagnoses were confirmed by EHR review including ejection fraction from echocardiographs and clinical assessments. All participants underwent a standardized study visit (including blood draws) and research kidney MRI protocols with a Siemens 3T scanner. Dynamic contrast enhanced imaging (DCE) for measuring kidney cortical and medullary blood flow as well as blood oxygen level dependent (BOLD) sequences were done. Results: As summarized in Table, HFrEF group had lower SBP, higher serum renin and renin/aldosterone ratio compared to HFpEF participants and controls indicating greater RAAS activation in HFrEF. Cortical and medullary blood flow seems consistent across controls and HFpEF, however, HFrEF had lower cortical and medullary blood flow rates. The ratio of cortical to medullary blood flow were similar across groups. Furthermore, tissue oxygenation indicated by T2* values were similar across groups. Conclusion: Reduced cortical and medullary blood flow with evidence of RAAS activation were present in HFrEF but not HFpEF. Reduced kidney blood flow might not be the cause of kidney dysfunction in HFpEF. - Healthy ControlN=3 CKD ControlN=5 HFrEFN=10 HFpEFN=19 Age, years 32 ± 9 76 ± 4 66 ± 16 68 ± 9 Female 1 (33) 3 (60) 5 (50) 11 (58) White Race 2 (67) 4 (80) 7 (70) 19 (100) BMI 29.3 ± 5.2 31.7 ± 6.0 30.6 ± 9.3 36.1 ± 7.1 eGFR 89 ± 25 40 ± 8 65 ± 20 59 ± 16 SBP, mmHg 119 ± 7 130 ± 13 102 ± 15 118 ± 20 Serum Aldosterone, ng/dL 10.0 ± 4.4 17.4 ± 10.5 21.0 ± 14.1 32.7 ± 21.4 Serum Renin, pg /dL ND 14.9 ± 16.7 241.0 ± 346.2 105.0 ± 146.9 Renin/Aldo ratio ND 1.4 ± 2.0 18.6 ± 26.8 3.7 ± 5.1 Cortical blood flow, mL blood/mL tissue/second 0.061 ± 0.0035 0.061 ± 0.0085 0.039 ± 0.0120 0.061 ± 0.0173 Medullary blood flow, mL blood/mL tissue/second 0.020 ± 0.001 0.0225 ± 0.0064 0.014 ± 0.0046 0.020 ± 0.0053 Cortex / Medulla QB ratio 3.11 ± 0.01 2.77 ± 0.37 2.81 ± 0.42 3.05 ± 0.59 T2* cortex, ms 66 ± 2.7 68.5 ± 8.2 69.5 ± 3.6 70.5 ± 6 T2* medulla, ms 42 ± 3.4 40 ± 2.7 43.5 ± 3.8 43.5 ± 3.8 Note. Renin was not done (ND) for Healthy Controls