Heart endocrine studies concerning patients with chronic atrial fibrillation (AF) have become increasingly important. Atrial natriuretic peptide (ANP) is released from atrial myocytes. The increased level of ANP in patients with AF is probably caused by the hemodynamic effect of the arrhythmia. The aim of this study was to explore plasma ANP levels in patients with chronic AF and to describe plasma ANP concentration changes following sinus rhythm (SR) restoration. The study group was comprised of 42 patients, aged between 43 and 76 years with chronic AF (more than 1 month) and a relatively controlled ventricular response (85.8+/-11.3 beats/min). Plasma ANP levels were measured before and 24 h after AF cardioversion. The control group comprised of 11 subjects. All had normal SR without history of AF and were compatible in age, sex and concomitant diseases with the examined group. ANP level values were expressed as mean+/-standard deviation. The mean plasma ANP level in the AF group was significantly higher than in the control group (59.5+/-15.6 vs. 34.3+/-10.2 pg/ml, P<0,001). Electrical or pharmacological cardioversion was performed in 42 patients. SR was successfully restored in 35 patients. Plasma ANP concentrations decreased significantly from baseline values (from 59.4+/-16.6 to 31.4+/-15.0 pg/ml, P<0.001) 24 h after cardioversion in the successful group, while they remained unchanged (60.2+/-10.7 to 59.4+/-10.4 pg/ml, NS) in patients with an unsuccessful cardioversion.
Conclusion: The mean concentration of ANP in patients with chronic AF was nearly two-times higher than in the control group with sinus rhythm. Conversion to SR was associated with a significant decrease and normalization in plasma ANP concentrations.