Acute Effect of Atrial Fibrillation on Circulating Natriuretic Peptides: The Influence of Heart Rate, Rhythm Irregularity, and Left Atrial Pressure Overload

Plasma natriuretic peptides (NPs) are increased in patients with atrial fibrillation (AF)
 compared with the patients with sinus rhythm. This study investigated whether this phe
nomenon is intrinsic to heart rhythm irregularity and independent of the heart rate and
 left atrial pressure (LAP) overload. We investigated 46 patients (age: 59 § 10 years, male
 gender: 77%) with non-valvular paroxysmal AF who were scheduled for catheter ablation
 and had documented stable sinus rhythm for at least 18 hours before the procedure. All
 patients underwent direct measurement of right atrial pressure and LAP, simultaneously
 with assessment of plasma B-type NP, N-terminal pro-brain NP, and mid-regional pro
atrial NP. The baseline measurement was followed by induction of AF by rapid atrial
 pacing in the first 24 patients and by regular pacing from the coronary sinus at 100/min
 (corresponding to the mean heart rate during induced AF) in the latter 22 patients. Hemo
dynamic assessment and blood sampling were repeated after 20 min of the ongoing AF or
 fast regular paging. The baseline characteristics and hemodynamic measurements were
 comparable between study groups; however, patients in the regular atrial pacing group
 had a higher body mass index and a larger left atrial diameter compared with the induced
 AF group. Plasma levels of all 3 NPs increased significantly during induced AF but not
 during fast regular pacing, and the increase of NPs was independent of right atrial pres
sure and LAP. Baseline concentrations of NPs and heart rhythm irregularity were the
 only independent predictors of increased NPs