Malik, A. Rauoof

Key Points We studied the link between brachial-ankle pulse wave velocity (baPWV) and CKD risk in adults undergoing cardiovascular disease screening. A higher baseline baPWV was predictive of an increased annualized rate of creatinine-based eGFR (eGFR Cr ) decline. Compared with normal baPWV, higher baseline baPWV was associated with increased risk of developing CKD and lower CKD-free survival time. Background CKD affects 35 million adults in the United States and is associated with high morbidity and mortality. We investigated whether brachial-ankle pulse wave velocity (baPWV), a noninvasive measure of arterial stiffness, was associated with kidney function decline in adults undergoing cardiovascular disease (CVD) screening. Methods In 1862 patients referred for an exercise electrocardiogram test between 2007 and 2009, baPWV was measured using an Omron Colin oscillometric device. Creatinine-based GFR was estimated (eGFR Cr ) for participants with available baseline and follow-up creatinine values using the CKD Epidemiology Collaboration formula. We performed multivariable linear regression analyses to assess whether baseline baPWV was associated with annualized change in eGFR Cr , after adjustment for age, sex, body mass index, baseline eGFR Cr , and traditional CVD risk factors, including mean arterial pressure, diabetes and hypertension diagnoses, nephroprotective medication use, smoking status, and total cholesterol. To determine risk of developing CKD and CKD-free survival time by arterial stiffness subgroups, we performed covariable-adjusted Cox proportional hazards modeling and a Kaplan-Meier survival analysis, respectively. Results After exclusion of participants with missing covariable data and adjustment for covariables, one SD increase in baPWV was associated with a 0.18 ml/min per 1.73 m 2 BSA greater yearly decrease in eGFR Cr ( P = 0.023) over a median follow-up time of 13.2 years. Participants with higher baseline baPWV had increased risk of CKD (hazard ratio [95% confidence interval], P value; elevated baPWV: 2.4 [1.1 to 5.4], P = 0.037; borderline-elevated baPWV: 1.8 [1.1 to 3.1], P = 0.028) and had a shorter CKD-free survival time (median CKD-free survival time [years]; normal baPWV: 16.2; borderline-elevated baPWV: 16.0; elevated baPWV: 15.6 [ P < 0.001]). Conclusions Elevated baPWV, a noninvasive measure of arterial stiffness that can be obtained in the office setting, was associated with decline in kidney function, risk of CKD development, and CKD-free survival in individuals undergoing CVD screening.

Vascular reactivity may affect the stiffness characteristics of the arterial wall. We investigated the association between forearm microcirculatory and conduit artery function and measures of arterial stiffness in 527 asymptomatic non-Hispanic white adults without known cardiovascular disease. High-resolution ultrasonography of the brachial artery (ba) was performed to assess forearm microcirculatory function (ba blood flow velocity, local shear stress, and forearm vascular resistance at rest and during reactive hyperemia) and conduit artery function (ba flow-mediated dilatation [baFMD] and ba nitroglycerin-mediated dilatation [baNMD]). Arterial stiffness was assessed by cuff-derived brachial pulse pressure and aortic pulse wave velocity (aPWV) measured by applanation tonometry. In regression analyses that adjusted for heart rate, mean arterial pressure, height, cardiovascular risk factors, and hypertension medication and statin use, higher baseline ba systolic velocity and systolic shear stress were associated with greater pulse pressure ( P =0.0002 and P =0.006, respectively) and higher aPWV (each P <0.0001). During hyperemia, lower ba mean velocity and lower mean shear stress were associated with higher pulse pressure ( P =0.045 and P =0.036, respectively), whereas both systolic and mean velocity ( P <0.0001 and P =0.002, respectively) and systolic and mean shear stress ( P <0.0001 and P =0.003, respectively) were inversely associated with aPWV. baFMD was not associated with pulse pressure but was inversely associated with aPWV ( P =0.011). baNMD was inversely associated with pulse pressure ( P =0.0002) and aPWV ( P =0.008). Our findings demonstrate that impaired forearm microvascular function (in the form of elevated resting blood flow velocity and impaired flow reserve) and impaired brachial artery reactivity are associated with increased arterial stiffness.

Resistin, a recently discovered proinflammatory cytokine, has been variably associated with insulin resistance, inflammation, and renal dysfunction. We investigated the association of plasma resistin with estimated glomerular filtration rate and albuminuria in 1575 hypertensive adults without known coronary heart disease or stroke (857 blacks and 718 non-Hispanic whites). Resistin was measured by a solid phase sandwich immunoassay, estimated glomerular filtration rate was estimated from serum creatinine, and albuminuria was expressed as urine albumin:creatinine ratio. After adjustment for coronary heart disease risk factors (age, sex, body mass index, smoking history, systolic blood pressure, diabetes, and total and high-density lipoprotein cholesterol) and use of renin-angiotensin blockers and statins, higher plasma resistin levels were associated with lower estimated glomerular filtration rate in both ethnic groups (each P <0.0001); the association remained significant after further adjustment for a marker of insulin resistance (homeostasis model assessment for insulin resistance) and a marker of inflammation (plasma C-reactive protein) and was seen in subjects with and without diabetes (each P <0.0001) in both ethnic groups. Higher plasma resistin levels were associated with a higher urine albumin:creatinine ratio in black subjects with diabetes ( P <0.0001) and non-Hispanic white subjects with diabetes ( P =0.032), independent of coronary heart disease risk factors, hypertension medication use, and statin use; the association remained significant after additional adjustment for homeostasis model assessment for insulin resistance and C-reactive protein. In adults with hypertension, higher circulating resistin levels were associated with a lower estimated glomerular filtration rate and with increased urine albumin:creatinine ratio in the presence of concomitant diabetes. This association was independent of coronary heart disease risk factors and markers of insulin resistance and inflammation.

In the present study, we investigated whether measures of brachial artery reactivity were associated with the presence and extent of subclinical coronary atherosclerosis in asymptomatic adults. Electron beam computed tomography was employed to assess the presence and quantity of CAC (coronary artery calcium) in 441 participants (mean age, 61 years; 49% men) without prior history of CHD (coronary heart disease) or stroke, and CAC score was calculated using the method described by Agatston and co-workers [(1990) J. Am. Coll. Cardiol. 15, 827–832] High-resolution ultrasound was employed to measure BAD (brachial artery diameter), FMD (flow-mediated dilatation) and NMD (nitroglycerine-mediated dilatation). CAC score and FMD were log-transformed after adding 1 to reduce skewness. Multivariable logistic and linear regression models based on generalized estimating equations were used to assess whether BAD, FMD and NMD were each independently associated with the presence and quantity of CAC after adjustment for CHD risk factors and use of statin and hypertension medication. CAC was detectable in 64% of participants. After adjustment for age and sex, FMD was not correlated (r=−0.06; P=0.27), BAD was positively correlated (r=0.16; P=0.004) and NMD was inversely correlated in a borderline significant manner (r=−0.10; P=0.084) with log(CAC+1). In multivariable logistic regression analyses, FMD was not associated, whereas higher BAD (P=0.021) and lower NMD (P=0.030) were independently associated with the presence of CAC. In multivariable linear regression analyses, higher BAD (P=0.004) and lower NMD (P=0.016), but not FMD, were independently associated with log(CAC+1). We conclude that greater diameter of the brachial artery and lower vasodilator response to nitroglycerine, but not FMD, are associated with subclinical coronary atherosclerosis.