RYR2 and atrial fibrillation: Upon pacing, RyR2-S2808D+/+ mice exhibited a progressive, age-related augmented susceptibility to AF in response to atrial burst pacing measured as the percentage of mice with pacing induced AF: 9.7% (3/31) at 3 months; 45.8% (11/24) at 6 months; and 68.4% (13/19) at 9 months).