CAPN2 and atrial fibrillation: At the transcription level, the expressions of calpain 2 (128.37 ± 63.01% versus 100 ± 36.07%, P = 0.015), CnA α (154.90 ± 100.38% versus 100 ± 98.44%, P = 0.020), CnA β (159.16 ± 144.34% versus 100 ± 73.36%, P = 0.037), and NFAT-c3 (130.79 ± 100.00% versus 100 ± 85.48%, P = 0.028) were significantly increased in patients with AF compared to those with SR.