Non‐dipping is a potent predictor of cardiovascular mortality and is associated with autonomic dysfunction in haemodialysis patients

Background. Lack of nocturnal blood pressure (BP) fall (non-dipping) is common among haemodialysis (HD) patients, but much less is known regarding its association with cardiovascular (CV) disease morbidity and mortality. Methods. Eighty HD patients initially underwent 24 h ambulatory BP monitoring (ABPM), and then they were defined as either ‘dippers’ (ns24, nocturnal BP fall P10%) or ‘non-dippers’ (ns56, fall -10%). Coronary angiography was performed in the patients who had signs anduor symptoms of coronary artery disease (CAD). Twenty-four hour ambulatory ECG was recorded in 20 dippers and 20 non-dipper HD patients, and in 20 normal subjects. All patients were followed for up to 5.8 years (33.0"19.1 months). The outcome events studied were the hospitalisations due to CV diseases and CV death. Results. Compared with dippers, non-dippers initially had a higher incidence of coronary artery stenosis (P-0.05) along with left ventricular asynergy (both Ps-0.01). The circadian rhythm of autonomic function was impaired in non-dippers. The incidences of CV events and CV deaths were 3.5 and 9 times higher in non-dippers than in dippers. The cumulative CV event-free survival and CV survival rates were lower in non-dippers than in dippers (Ps0.02 and Ps0.005, respectively). Based on Cox analysis, non-dipping was associated positively with CV events and CV mortality [hazard ratio (HR) 2.46, 95% CI 1.02‐5.92, Ps0.038 and HR 9.62, 95% CI 1.23‐75.42, Ps0.031, respectively]. Meanwhile, nocturnal systolic BP fall, diurnal systolic BP and diurnal pulse pressure were negatively associated with CV eventudeath. The clinic BP was not associated with CV eventudeath. Conclusions. The non-dipping phenomenon is closely related to a high incidence of CV diseases, a poor long-term survival and profound autonomic dysfunction. ABPM is useful in predicting long-term CV prognosis in HD patients.