Arterial stiffness but not endothelial dysfunction is associated with multidrug antihypertensive therapy and nondipper blood pressure pattern in kidney transplant recipients

Role of hypertension in kidney transplant recipients

Cardiovascular events are one of the leading causes of mortality in kidney transplant recipients. Hypertension is the most common comorbidity accompanying chronic kidney disease, with prevalence remaining as high as 90% even after kidney transplantation. It is often poorly controlled. Abnormal blood pressure profiles, such as masked or white-coat hypertension, are also extremely common in these patients. The pathophysiology of blood pressure elevation in kidney transplant recipients is complex and includes transplantation-specific risk factors, which are added to the traditional or chronic kidney disease-related factors. Despite these observations, hypertension management has been an under-researched area in kidney transplantation. Thus, relevant evidence derives either from studies in the general population or from small trials in kidney transplant recipients. Based on the relevant guidelines in the general population, lifestyle modifications should probably be applied as the first step of hypertension management in kidney transplant recipients. The optimal pharmacological management of hypertension in kidney transplant recipients is also not clear. Dihydropyridine calcium channel blockers are commonly used as first line agents because of their lack of adverse effects on the kidney, while other antihypertensive drug classes are under-utilised due to fear of the possible haemodynamic consequences on renal function. This review summarizes the existing data on the pathophysiology, diagnosis, prognostic significance and management of hypertension in kidney transplantation.

Beneficial Effect of Successful Simultaneous Pancreas-Kidney Transplantation on Plasma Profile of Metalloproteinases in Type 1 Diabetes Mellitus Patients

It is not fully elucidated whether the restoring of normal glucose metabolism after successful simultaneous pancreas-kidney transplantation (SPK) improves vascular wall morphology and function in type 1 diabetic (T1D) patients. Therefore, we compared arterial stiffness, assessed by pulse wave velocity (PWV), carotid intima-media thickness (IMT), and biomarkers of arterial wall calcification in T1D patients after SPK or kidney transplantation alone (KTA). In 39 SPK and 39 KTA adult patients of similar age, PWV, IMT, circulating matrix metalloproteinases (MMPs) and calcification biomarkers were assessed at median 83 months post transplantation. Additionally, carotid plaques were visualized and semi-qualitatively classified. Although PWV and IMT values were similar, the occurrence of atherosclerotic plaques (51.3 vs. 70.3%, p < 0.01) and calcified lesions (35.9 vs. 64.9%, p < 0.05) was lower in SPK patients. There were significantly lower concentrations of MMP-1, MMP-2, MMP-3, and osteocalcin in SPK subjects. Among the analyzed biomarkers, only logMMP-1, logMMP-2, and logMMP-3 concentrations were associated with log HbA_1c. Multivariate stepwise backward regression analysis revealed that MMP-1 and MMP-3 variability were explained only by log HbA_1c. Normal glucose metabolism achieved by SPK is followed by the favorable profile of circulating matrix metalloproteinases, which may reflect the vasoprotective effect of pancreas transplantation.

Diagnostic Performance of Office versus Ambulatory Blood Pressure in Kidney Transplant Recipients

INTRODUCTION

Hypertension is the most prominent risk factor in kidney transplant recipients (KTRs). No study so far assessed in parallel the prevalence, control, and phenotypes of blood pressure (BP) or the accuracy of currently recommended office BP diagnostic thresholds in diagnosing elevated ambulatory BP in KTRs.

METHODS

205 stable KTRs underwent office BP measurements and 24-h ambulatory BP monitoring (ABPM). Hypertension was defined as follows: (1) office BP ≥140/90 mm Hg or use of antihypertensive agents following the current European Society of Cardiology/European Society of Hypertension (ESC/ESH) guidelines, (2) office BP ≥130/80 mm Hg or use of antihypertensive agents following the current American College of Cardiology/American Heart Association (ACC/AHA) guidelines, (3) ABPM ≥130/80 mm Hg or use of antihypertensive agents, and (4) ABPM ≥125/75 mm Hg or use of antihypertensive agents.

RESULTS

Hypertension prevalence by office BP was 88.3% with ESC/ESH and 92.7% with ACC/AHA definitions compared to 94.1 and 98.5% at relevant ABPM thresholds. Control rates among hypertensive patients were 69.6 and 43.7% with office BP compared to 38.3 and 21.3% with ABPM, respectively. Both for prevalence (κ-statistics = 0.52, p < 0.001 and 0.32, and p < 0.001) and control rates (κ-statistics = 0.21, p < 0.001 and 0.22, and p < 0.001, respectively), there was moderate or fair agreement of the 2 techniques. White-coat and masked hypertension were diagnosed in 6.7 and 39.5% of patients at the 140/90 threshold and 5.9 and 31.7% of patients at the 130/80 threshold. An office BP ≥140/90 mm Hg had 35.3% sensitivity and 84.9% specificity for the diagnosis of 24-h BP ≥130/80 mm Hg. An office BP ≥130/80 mm Hg had 59.7% sensitivity and 73.9% specificity for the diagnosis of 24-h BP ≥125/75 mm Hg. Receiver operating curve analyses confirmed this poor diagnostic performance.

CONCLUSIONS

At both corresponding thresholds studied, ABPM revealed particularly high hypertension prevalence and poor BP control in KTRs. Misclassification of KTRs by office BP is substantial, due to particularly high rates of masked hypertension. The diagnostic accuracy of office BP for identifying elevated ambulatory BP is poor. These findings call for a wider use of ABPM in KTRs.

Arterial Stiffness in Patients With Renal Transplantation; Associations With Co-morbid Conditions, Evolution, and Prognostic Importance for Cardiovascular and Renal Outcomes

Patients with chronic kidney disease (CKD), particularly those with end-stage renal disease (ESRD), are at increased risk of cardiovascular events and mortality. The spectrum of arterial remodeling in CKD and ESRD includes atheromatosis of middle-sized conduit arteries and, most importantly, the process of arteriosclerosis, characterized by increased arterial stiffness of aorta and the large arteries. Longitudinal studies showed that arterial stiffness and abnormal wave reflections are independent cardiovascular risk factors in several populations, including patients with CKD and ESRD. Kidney transplantation is the treatment of choice for patients with ESRD, associated with improved survival and better quality of life in relation to hemodialysis or peritoneal dialysis. However, cardiovascular mortality in transplanted patients remains much higher than that in general population, a finding that is at least partly attributed to adverse lesions in the vascular tree of these patients, generated during the progression of CKD, which do not fully reverse after renal transplantation. This article attempts to provide an overview of the field of arterial stiffness in renal transplantation, discussing in detail available studies on the degree and the associations of arterial stiffness with other co-morbidities in renal transplant recipients, the prognostic significance of arterial stiffness for cardiovascular events, renal events and mortality in these individuals, as well as studies examining the changes in arterial stiffness following renal transplantation.

The Risk of Stroke in Kidney Transplant Recipients with End-Stage Kidney Disease

Background: The incidence of stroke after kidney transplantation is poorly understood. Our study aimed to determine the incidence and predictors of stroke as well as mortality from stroke in kidney transplant recipients (KTRs). Methods: This retrospective cohort study used the National Health Insurance Research Database in Taiwan to study KTRs (N = 4635), patients with end-stage renal disease (ESRD; N = 69,297), and patients from the general population who were chronic kidney disease (CKD)-free and matched by comorbidities (N = 69,297) for the years 2000 through 2010. The risk of stroke was analyzed using univariate and multivariate Cox regression models and compared between study cohorts. Findings: Compared with the ESRD subgroup, KTRs had a significantly lower risk of overall stroke (adjusted hazard ratio (aHR) = 0.37, 95% confidence interval (CI) = 0.31⁻0.44), ischemic stroke (aHR = 0.45, 95% CI = 0.37⁻0.55), and hemorrhagic stroke (aHR = 0.20, 95% CI = 0.14⁻0.29). The risk patterns for each type of stroke in the KTR group were not significantly different than those of the CKD-free control subgroup. The predictors of stroke were age and diabetes in KTRs. All forms of stroke after transplantation independently predicted an increased risk of subsequent mortality, and the strongest risk was related to hemorrhagic events. Interpretation: KTRs had a lower risk of stroke than ESRD patients, but this risk was not significantly different from that of the CKD-free comorbidities-matched general population group. Although stroke was relatively uncommon among cardiovascular events, it predicted unfavorable outcome in KTRs.