ABSTRACT
<p><b>OBJECTIVE</b>To investigate the relationship between the protein expression of calpain-2 and calcineurin (CaN) and atrial fibrillation (AF) in patient with valvular heart disease (VHD).</p><p><b>METHODS</b>A total of 40 patients who underwent valve replacement surgery in our hospital from March 2013 to March 2014, right atrial appendages were excised during operation and patients were divided into sinus rhythm (SR) group (n = 17) and AF group (n = 23). The protein expression of calpain-2 and the α-isoform of CaN catalytic subunit (CnA) in the right atrial appendages were determined by Western blot.</p><p><b>RESULTS</b>The protein levels of the full-length CnAa (60,000), the 45,000 fragment of CnAa without autoinhibitory domain, and calpain-2 were significantly upregulated in the AF group compared to the SR group (1.25 ± 0.51 vs. 0.76 ± 0.37, 1.08 ± 0.37 vs. 0.76 ± 0.25, and 0.82 ± 0.44 vs. 0.51 ± 0.19, respectively, all P < 0.05).</p><p><b>CONCLUSION</b>Activated calpain-2-CaN signal pathway might be involved in the pathogenesis of AF.</p>