P1447EARLY MORNING ACCELERATION AND NOCTURNAL DECELERATION IN HEART RATE ASSOCIATE WITH LVH AND THE RISK OF DEATH AND CARDIOVASCULAR EVENTS IN HEMODIALYSIS PATIENTS

Abstract

Abstract Background and Aims Cardiovascular deaths cluster in the early morning hours and studies in the general population documented that an exaggeration of the early morning increase in BP, a phenomenon accompanied by a parallel rise in heart rate (HR), is a marker of high cardiovascular risk. The circadian profile of BP and HR in hemodialysis patients is notoriously altered but the early morning changes in these parameters and the nocturnal profile of HR have not been investigated in this population. Method BP and HR were registered at 15 min intervals by ambulatory monitoring (24hABPM, Spacelab) during the day after hemodialysis in a series of 64 patients. We measured the early morning (the average of the 2 hours after awakening minus the average of the 2 hours pre-awakening) changes in BP and HR and the nocturnal decline in BP and HR and tested the relationship of these parameters with the left ventricular mass index (LVMI) and with the risk of all-cause and cardiovascular death over a median follow up of 40 months (Interquartile range 21-81) Results The rise in HR after awakening was strongly related in an inverse fashion with the LVMI (Spearman ρ=-0.61, P<001) suggesting that patients with a more pronounced increase in HR after awakening may be protected from LVH .Both, the decline in HR (ρ =-0.38, P=0.002) and in systolic BP (ρ =-0.31, P=0.01 ) during night-time associated inversely with LVMI. These associations remained significant also when they were reciprocally adjusted (P<0.01) in a model including also age, gender and simultaneous changes in BP. In contrast, the rise is systolic BP upon awakening had no relationship with the LVMI (ρ =0.18, P=0.18). Thirty-two deaths (16 cardiovascular) occurred during follow up. The early morning rise in HR was an inverse predictor of all cause death (HR=0.95; 95%CI 0.92-0.98 P=0.004 ) and of cardiovascular death (HR=0.95; 95%CI 0.91-0.98) in analyses adjusted for the simultaneous rise in systolic BP which per se failed to predict the same outcomes. Again, in similarity with analyses looking at LVMI, the nocturnal dipping in HR associated inversely with all cause and cardiovascular death (p=0.003). Conclusion The analysis of the nocturnal decline in HR and of the rise in HR increase upon awakening In hemodialysis patients reveals stronger links among these parameters and LVMI than the corresponding BP parameters. The protective effect on the left ventricle of a more pronounced HR rise upon awakening and of a more pronounced decline in HR during night time underscore the relevance of preserved autonomic function for cardiovascular protection in this population. These associations seem to go along with a reduced risk for all-cause and cardiovascular death. Analysis of the HR profile provides unique information for the risk of cardiomyopathy and cardiovascular events in the hemodialysis population.