Background: Calcium plays important role in myocardial contractility and arrrhythmogenesis. There are very few studies about calcium handling process in HF atrial tissue and its relationship to atrial tachyarrhythmia. This study evaluated relation of calcium handling protein changes and subsequent AF development in HF. Methods: A rat myocardial infarction (MI) model was used. Two days after induction of MI, rats were randomized into 2 groups: the sham group, the MI+Iso group (isoproterenol 30 關g/kg/hr for 2 weeks, administrated 8 weeks after the MI). Echocardiography, AF induction, and atrial fibrous tissue content analysis were done. RT PCR and western blotting of SERCA, phospholamban(PLB), RyR2, and AF inducibility tests were done. Results: Ejection fractions were significantly decreased in MI+Iso group. Fibrosis quantification showed significantly increased left atrial fibrosis in MI+Iso. Duration and inducibility of AF were increased in MI+Iso group. Atrial calcium handling proteins mRNA expression and protein expression levels were decreased in MI+Iso group. SERCA2a/PLB mRNA ratio was increased in MI+Iso group. Conclusion: Changes of calcium handling proteins are important contributing factors for subsequent AF inducibility in HF.