Loss of nighttime blood pressure dipping as a risk factor for coronary artery calcification in nondialysis chronic kidney disease

Nocturnal Dipping and Kidney Function Decline: Findings From the CKD in Children Study

Introduction

Normally, blood pressure (BP) declines by at least 10% from daytime to nighttime. In adults, blunted nocturnal dipping has been associated with more rapid decline in kidney function. Nondipping is prevalent in children with chronic kidney disease (CKD). We sought to determine whether nondipping is associated with proteinuria and progression to kidney failure in children with CKD.

Methods

In the prospective CKD in children (CKiD) cohort, Cox proportional hazards models were used to evaluate the relationship between baseline nondipping and progression to kidney failure. Linear mixed effects models were used to evaluate the relationship between nondipping and changes in iohexol glomerular filtration rate (GFR) and urine protein-to-creatinine ratio (log-UPCR, mg/mg) over time.

Results

Among 620 participants, mean age was 11 (± 4) years, mean iohexol GFR was 52 (± 22) ml/min per 1.73 m2, and 40% were nondippers at baseline. There were 169 kidney failure events during 2.9 years (median) of follow-up. Dipping status was not significantly associated with kidney failure overall (hazard ratio [HR] 1.08; 95% confidence interval [CI] 0.77, 1.51) or in those with (HR 1.21; 95% CI 0.53, 2.77) or without (HR 1.05; 95% CI 0.71, 1.55) glomerular disease. Dipping status did not modify the relationship between time and change in iohexol GFR or log (UPCR) from baseline (interaction P values = 0.20 and 0.054, respectively).

Conclusion

Nondipping is not associated with end-stage kidney disease, GFR decline, or change in proteinuria within the CKiD cohort.

Association of ambulatory blood pressure with aortic valve and coronary artery calcification

OBJECTIVE

We aimed to investigate the effect of ambulatory blood pressure (BP) on aortic valve calcification (AVC) and coronary artery calcification (CAC), which are subclinical atherosclerotic diseases.

METHODS

In this population-based, cross-sectional study, we assessed office BP, mean ambulatory BP (24-h, awake, and asleep), and variability of ambulatory BP, as determined by the coefficient of variation (awake and asleep). AVC and CAC were quantified using an Agatston score (>0) based on computed tomography scanning. We calculated relative risks (RRs) and 95% confidence intervals (CIs) with a 1-standard deviation increment in each BP index for the presence of AVC and CAC using a multivariate-adjusted Poisson regression with robust error variance.

RESULTS

Of 483 participants (mean age: 66.8 years), 154 (31.9%) and 310 (64.2%) had AVC and CAC, respectively. The presence of AVC was associated with office systolic BP (SBP; RR, 1.15; 95% CI, 1.03-1.28), awake diastolic BP (DBP) variability (RR, 1.12; 95% CI, 1.01-1.25), and asleep SBP variability (RR, 1.14; 95% CI, 1.03-1.27). The presence of CAC was associated with office SBP (RR, 1.08; 95% CI, 1.01-1.15), mean 24-h SBP (RR, 1.10; 95% CI, 1.04-1.16), mean awake SBP (RR, 1.11; 95% CI, 1.04-1.17), mean asleep SBP (RR, 1.07; 95% CI, 1.01-1.13), and asleep SBP variability (RR, 1.07; 95% CI, 1.01-1.13).

CONCLUSION

These findings highlight the association of ambulatory BP indices with both AVC and CAC, but with different effects on their presences.

Association Between Ambulatory Blood Pressure and Coronary Artery Calcification: The JHS

[Figure: see text].

Nocturnal blood pressure is associated with sympathetic nerve activity in patients with chronic kidney disease

Elevated nocturnal blood pressure (BP) and nocturnal non-dipping are frequently observed in patients with chronic kidney disease (CKD) and are stronger predictors of cardiovascular complications and CKD progression than standard office BP. The sympathetic nervous system (SNS) is thought to modulate diurnal hemodynamic changes and the vascular endothelium plays a fundamental role in BP regulation. We hypothesized that SNS overactivity and endothelial dysfunction in CKD are linked to elevated nocturnal BP and non-dipping. In 32 CKD patients with hypertension (56 ± 7 years), office BP, 24-hr ambulatory BP, muscle sympathetic nerve activity (MSNA) and endothelial function via flow-mediated dilation (FMD) were measured. Participants were subsequently divided into dippers (nighttime average BP > 10% lower than the daytime average BP, n = 8) and non-dippers (n = 24). Non-dippers had higher nighttime BP (p < .05), but not office and daytime BP, compared to dippers. MSNA burst incidence (81 ± 13 versus 67 ± 13 bursts/100 HR, p = .019) was higher and brachial artery FMD (1.7 ± 1.5 versus 4.7 ± 1.9%, p < .001) was lower in non-dippers compared to dippers. MSNA and FMD each predicted nighttime systolic (β = 0.48,-0.46, p = .02, 0.07, respectively) and diastolic BP (β = 0.38,-0.47, p = .04, 0.03, respectively) in multivariate-adjusted analyses. Our novel findings demonstrate that unfavorable nocturnal BP profiles are associated with elevated SNS activity and endothelial dysfunction in CKD. Specifically, CKD patients with higher nighttime BP and the non-dipping pattern have higher MSNA and lower FMD. These support our hypothesis that SNS overactivation and endothelial dysfunction are linked to the dysregulation of nighttime BP as well as the magnitude of BP lowering at nighttime in CKD.

Different Relevance of Peripheral, Central or Nighttime Blood Pressure Measurements in the Prediction of Chronic Kidney Disease Progression in Patients with Mild or No-Proteinuria

BACKGROUND/AIMS

Arterial hypertension is one of the leading factors aggravating the course of chronic kidney disease (CKD). It seems that the novel parameters used in the assessment of the blood pressure (BP) load (i.e. central blood pressure, nighttime blood pressure) may be more precise in predicting the cardiovascular risk and the progression of CKD in comparison with the traditional peripheral blood pressure measurements in the office conditions. The aim of the study was to assess the impact of the central, or nighttime blood pressure on the progression of CKD in patients with mild or no-proteinuria (autosomal, dominant polycystic kidney disease or IgA nephropathy).

METHODS

In each of the enrolled 46 patients with CKD stage 3 or 4, serum creatinine concentration was assessed, eGFR (MDRD) was calculated, also central blood pressure and pulse wave velocity (PWV) was assessed and the 24-hour ambulatory blood pressure monitoring (ABPM) was conducted at the beginning of the study and then repeated after one-year observation period.

RESULTS

During the observation period mean eGFR decreased from 44.1 (33.2-50.6) mL/min to 36.7 (29.7-46.3) mL/min. No significant differences were observed in the peripheral blood pressure or central blood pressure parameters. After one-year observation period the values of diastolic blood pressure dipping during the night significantly decreased from 16 (13-19) mmHg to 12 (10-15) mmHg; p< 0.05. The values of systolic dipping during the night or the mean BP values recorded in ABPM did not change significantly. Additionally, no significant differences in the PWV values were found. In the multivariate regression model the change of serum creatinine concentration was explained by the initial diastolic dipping values.

CONCLUSION

1. In patients with CKD stages 3 or 4 and mild or no- proteinuria, peripheral and central blood pressure did not change significantly during a one-year observation period despite the significant decline of eGFR and seems not to participate in the CKD progression. 2. Reduced magnitude of the diastolic dipping, which reflects the increase of diastolic blood pressure load during the nighttime, may play an important role in the pathogenesis of deterioration of kidney function in these patients.