MP-453085-7 PROGESTERONE WITHDRAWAL ASSOCIATED WITH INCREASED ATRIAL FIBRILLATION SUSCEPTIBILITY IN FEMALES

Atrial Fibrillation (AF) is the most common cardiac arrythmia in adults with likely sex-specific risk factors. Specifically, increasing parity has been identified as a factor that contributes to development of atrial fibrillation females. This suggests female sex hormones may be important modulating for fibrillation. we hypothesize progesterone (P4), hormone found high levels during pregnancy abrupt withdrawal immediately after parturition, modulates AF susceptibility goats. Cardiac specific TGF-b1 transgenic goats and age-matched wild-type (WT) were utilized. Pacemakers implanted all animals continuous arrhythmia monitoring inducibility. inducibility was evaluated using 5 separate 10 s bursts pacing (160 - 200 ms). All bred (n=12) via natural service circulating monitored throughout gestation. Additionally, seven treated high-dose exogenous oral P4 supplementation over two-week period, assessed at baseline, 48-hours following supplementation. Serum measured chemiluminescent assay. During increased compared baseline sharp post-partum period. decrease post-parturition associated an increase both WT (p = 0.002, time). Furthermore, negative correlation between noted pregnancy/post-partum periods. < 0.001). Separately, below post Consistent our hypothesis observations from studies, when [196±93 vs 34±18 34±20 s, respectively 0.01, time)]. These data support modulator More specifically, reduction significantly increases risk. Future investigation currently underway identify key cellular molecular mechanisms explain these observations.