LONG-TERM SYSTOLIC BLOOD PRESSURE VARIABILITY AS AN INDEPENDENT RISK FACTOR FOR CARDIOVASCULAR EVENTS IN KIDNEY TRANSPLANT RECIPIENTS

Abstract

Objective: Cardiovascular (CV) events represent the main cause of death in patients undergoing renal transplantation. Several studies have described the role of blood pressure variability (BPV) in predicting all-cause mortality and fatal and non-fatal CV events in the general population and in diabetic patients. Systolic blood pressure variability (SBPV) has recently been proposed as a predictor of clinical outcomes in patients with chronic kidney disease. However, evidence is still scarce about the prognostic role of BPV in the setting of renal transplantation. The aim of our study was to evaluate the role of long-term SBPV in the development of fatal and non-fatal CV events (myocardial infarction, unstable angina or revascularization, stroke and hospitalization for heart failure) in subjects undergoing kidney transplantation. Design and method: We performed a single-center retrospective observational analysis in a cohort of 272 kidney transplant patients (mean age 64±13 years, 66% men), with a transplant duration beyond 12 months and with at least 6 blood pressure measurements at defined intervals (3 months ± 15 days) over an assessment period of 18 months. BPV was expressed as standard deviation of ambulatory systolic blood pressure (SBP) and patients were accordingly classified in tertiles (low <9.3 mmHg, medium 9.3-13 mmHg, high >13 mmHg). The role of SBPV was analyzed by Kaplan-Meier (logrank) and its independent effect by Cox Regression. Results: Over a mean follow-up of 58.7±17.2 months, 27 subjects (9.9%) developed CV events. For each increase of 2.7 mmHg in SBP standard deviation, the risk for fatal or non-fatal CV events increased almost 3-folds (P=0.02) and patients in the highest tertile of SBP standard deviation showed a 4-fold increased risk (P= 0.01) (Figure 1). This relationship was maintained even after incremental adjustment for time-averaged pulse pressure, age, diabetes, prior CV event, and dialysis vintage (HR 3.2, 95% CI 1.1–10.0, p 0.04) (Table 1). Conclusions: Long-term BPV represents an independent risk factor for CV events in kidney transplant patients. It is therefore essential to seek for stable long-term blood pressure levels in this population in order to minimize the residual CV risk.