Relation of Impaired Coronary Microcirculation to Increased Urine Albumin Excretion in Patients With Systemic Hypertension and No Epicardial Coronary Arterial Narrowing

Coronary flow reserve (CFR) is impaired and urinary albumin excretion is increased in patients with essential hypertension. Our aim was to investigate the associations between CFR and cardiac and renal damage in hypertensives. For this purpose we studied 37 never-treated hypertensives (57.9 years old, 16 men) without chest pain but with a positive ischemia stress test result and normal coronary arteries on coronary angiogram. CFR was calculated by a 0.014-inch Doppler guidewire (Flowire, Volcano, San Diego) in the left anterior descending artery in response to bolus intracoronary administration of adenosine (60 μg) as the ratio of hyperemic to basal average peak velocity of the distal vessel. All participants underwent complete echocardiographic study including left ventricular diastolic function evaluation by tissue Doppler imaging (peak early diastolic velocity/peak atrial systolic velocity) and determination of the albumin-to-creatinine ratio (ACR). Hypertensives with low CFR (<2.5, n = 22) compared to those with high CFR (n = 15) exhibited a larger left ventricular mass index by 10.9 g/m2 (p = 0.045) and ACR values by 10 mg/g (p <0.001). CFR was negatively correlated with logACR (r = −0.511, p = 0.001). LogACR (beta −0.792, p <0.001), male gender (beta 0.313, p = 0.005), left ventricular mass index (beta −0.329, p = 0.007), and peak early diastolic velocity/peak atrial systolic velocity (beta 0.443, p <0.001) were the only independent predictors of CFR in linear regression analysis (adjusted R2 = 0.672). In conclusion, never-treated asymptomatic hypertensives who exhibit impaired CFR and angiographically normal epicardial arteries are characterized by intrarenal vascular damage as reflected by increased ACR. These findings suggest a plausible role of ACR estimation in the identification of hypertensive subjects with early coronary microvascular dysfunction.