Link of renal microcirculatory dysfunction to increased coronary microcirculatory resistance in hypertensive patients.

BACKGROUND: This study investigated the correlation between renal microcirculation and coronary microcirculation in hypertensive patients.
METHODS: Participants consisted of 231 consecutive candidates who were referred to the Second Affiliated Hospital of Wenzhou Medical University from March 2014 to May 2016 for elective coronary angiography due to suspected myocardial ischemia. All participants were evaluated for the index of microvascular resistance (IMR), coronary flow reserve (CFR), and fractional flow reserve (FFR) us¬ing a pressure wire. Blood and urine samples were collected for determination of the levels of urinary microalbuminuria (mALB), b2-microglobulin (b2-MG), serum cystatin C (CysC), and uric acid (UA). All participants were categorized into two groups according to the renal microcirculatory function.
RESULTS: Participants in the observation group had a higher IMR (31 ± 5 vs. 22 ± 6; p < 0.01) and a lower FFR (0.84 ± 0.10 vs. 0.87 ± 0.09 U; p < 0.05) during hyperemia than those in the control group. Linear regression tests revealed that mALB, b2-MG, CysC, and UA levels were positively cor¬related with IMR (r = 0.610, 0.553, 0.701, and 0.647, respectively, p < 0.01). The hs-CRP levels were positively correlated with IMR (r = 0.419, p < 0.01). Multiple regression analysis indicated that renal microcirculation was an independent predictor of IMR.
CONCLUSIONS: Renal microcirculatory dysfunction in hypertensive patients is characterized by higher IMR and lower FFR; in addition, it is closely correlated with an increased coronary microcirculatory resistance.