Abstract 19948: Progressive Neurohumoral Dysregulation In Atrial Fibrillation
Background: As atrial fibrillation (AF) progresses, atrial natriuretic peptide (ANP) and Brain natriuretic peptide (BNP) secretion changes compared with healthy controls (HC) but studies have shown conflicting results regarding the pattern of natriuretic peptide (NP) secretion in AF.
Hypothesis: Atrial integrity is reflected by a rise in ANP but not BNP during exercise in HCs and that this regulatory mechanism is progressively reversed in persistent and permanent AF.
Methods: Eighty five patients were studied- 44 with persistent AF (Pers-AF), 21 with permanent AF (Perm-AF) and 20 HCs, all with normal left ventricular function. All subjects had baseline blood pressure (BP), heart rate (HR), 12 lead ECG recordings, 2D echocardiograms along with serial NT-pro ANP (ANP), NT-proBNP(BNP) measurements at rest, peak exercise and in recovery phase. Differences between groups were assessed using ANOVA and 2-tailed t-test.
Results: Baseline characteristics of the 3 groups were similar for age, hypertension and BMI. Mean resting HR was higher in the perm-AF and pers-AF group compared with HC (93.09±14.32 vs. 87.11±17.73 vs. 75.50±11.85, <0.05). Differences in NP secretion are shown in Table 1. Absolute ANP and BNP levels were higher in perm-AF than pers-AF patients which were higher than HCs. Mean ANP secretion in HC increased significantly with exercise (22%) compared with a modest 8% in pers-AF and 2% in perm-AF. There was a positive correlation between baseline ANP levels and the duration of AF. Mean BNP rose only slightly with exercise in HC (6%) and pers- AF (4%) compared with 22% rise in perm- AF patients adjusted for HR and BP amongst the 3 groups.
Conclusions: Absolute ANP and BNP levels rise as AF progresses but normal neurohumoral feedback mechanisms in response to haemodynamic changes are lost. This suggests that myocyte damage and structural remodelling alone is not the cause of NP secretion but also neurohumoral dysregulation.
- © 2010 by American Heart Association, Inc.