CAV3 and hydrops fetalis: The purpose of this study attempts to investigate serum Cav-3 levels in AF patients, to explore the associations of Cav-3 with AF and incident HF, to evaluate the correlation of Cav-3 with echocardiographic parameters (left atrial diameter, LAD), to evaluate the role of Cav-3 as a biomarker for AF and incident HF.