THE INFLUENCE OF AMBULATORY BLOOD PRESSURE ON THE ASSOCIATIONS OF INTRADIALYTIC HYPERTENSION WITH FUTURE CARDIOVASCULAR EVENTS AND MORTALITY IN HEMODIALYSIS PATIENTS

Abstract

Objective: Patients with intradialytic hypertension (IDH) have higher mean 44-hour ambulatory blood pressure (BP) levels than patients without the phenomenon. IDH is associated with an increased risk of cardiovascular and all-cause mortality. Whether the excess risk for mortality in patients with IDH depends on the BP rise during dialysis per se or on elevated 44-h ambulatory BP is not known. This is the first study evaluating the association of IDH with cardiovascular events and all-cause mortality before and after adjustment for ambulatory BP and other cardiovascular risk factors. Design and method: A total of 242 hemodialysis patients underwent 48-h ABPM with Mobil-O-Graph-NG and were followed for a median of 45.7 months. IDH was defined as: SBP rise greater than or equal to 10 mmHg from pre- to post-dialysis and post-dialysis SBP greater than or equal to 150 mmHg. The primary end-point was all-cause mortality; the secondary endpoint was a composite of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, resuscitation after cardiac arrest, ospitalisation for heart failure, coronary or peripheral revascularization procedure. Results: During follow-up, a total of 122 patients died; 69 due to cardiovascular causes. Cumulative freedom from both the primary and secondary endpoint was significantly lower for patients with IDH (logrank-p = 0.048/0.022, respectively). The risk for all-cause mortality was significantly higher for patients with IDH (HR = 1.566 95%CI [1.001, 2.450]); similarly, the risk for the combined cardiovascular endpoint was higher for these individuals (HR = 1.675 95%CI [1.071, 2.620]). The observed associations attenuated after adjustment for 44-h SBP (all-cause mortality: HR = 1.529 95%CI [0.952, 2.457] and combined cardiovascular endpoint: HR = 1.388 95%CI [0.866, 2.225]. After additional adjustment for age, interdialytic weight gain, dialysis vintage, 44-h pulse wave velocity, history of coronary artery disease, diabetes mellitus and heart failure the respective HRs were 1.409 (95%CI [0.851, 2.332]) and 1.435 (95%CI [0.879, 2.343]). Conclusions: Patients with IDH presented higher risk for death and cardiovascular outcomes. Sustained high BP levels during the 44-h interdialytic period and not only intradialytic BP rise per se may be participating in the excess risk of this condition.