MO743: The Influence of Ambulatory Blood Pressure on the Associations of Intradialytic Hypertension with Future Cardiovascular Events and Mortality in Haemodialysis Patients

Abstract BACKGROUND AND AIMS Patients with intradialytic hypertension (IDH) have higher mean 44-h 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. METHOD A total of 242 haemodialysis 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 ≥ 10 mmHg from pre- to post-dialysis and post-dialysis SBP ≥ 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, hospitalization for heart failure, coronary or peripheral revascularization procedures. RESULTS During follow-up, a total of 122 patients died; 69 due to cardiovascular causes. Cumulative freedom from both the primary and secondary endpoints was significantly lower for patients with IDH (log rank-P = 0.048/0.022, respectively). The risk for all-cause mortality was significantly higher for patients with IDH [HR = 1.566, 95% confidence interval (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)]. CONCLUSION 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.