Reduced left atrial cardiomyocyte PITX2 and elevated circulating BMP10 predict atrial fibrillation after ablation
Background: Genomic and experimental studies suggest a role for PITX2 in atrial fibrillation (AF). To assess whether this association is relevant for recurrent AF in patients, we tested whether left atrial PITX2 affects recurrent AF after AF ablation. Methods: mRNA concentrations of PITX2 and its cardiac isoform, PITX2c, were quantified in left atrial appendages (LAA) from patients undergoing thoracoscopic AF ablation, either in whole LAA tissue (n=83) or in LAA cardiomyocytes (n=52), and combined with clinical parameters to predict AF recurrence. Literature suggests bone morphogenetic protein 10 (BMP10) as a PITX2-repressed, atrial-specific, secreted protein. BMP10 plasma concentrations were combined with eleven cardiovascular biomarkers and clinical parameters to predict recurrent AF after catheter ablation in 359 patients. Results: Reduced cardiomyocyte PITX2 concentrations, but not whole LAA tissue PITX2, were associated with AF recurrence after thoracoscopic AF ablation (16% decreased recurrence per 2-(??Ct) increase in PITX2). RNA sequencing, qPCR and Western blotting confirmed BMP10 as one of most PITX2-repressed atrial genes. Left atrial size (hazard ratio per mm increase, HR [95%CI] 1.055 [1.028, 1.082], non-paroxysmal AF (HR 1.672 [1.206, 2.318]) and elevated BMP10 (HR 1.339 [CI 1.159, 1.546] per quartile increase) were predictive of recurrent AF. BMP10 outperformed eleven other cardiovascular biomarkers in predicting recurrent AF. Conclusions: Reduced left atrial cardiomyocyte PITX2 and elevated plasma concentrations of the PITX2-repressed, secreted, atrial protein BMP10 identify patients at risk of recurrent AF after ablation. Overall design: Left atrial tissue samples from WT and Pitx2+/- mice