Sinus Node Function
Figure 1A shows Holter observed heart rate metrics including minimum, average and peak heart rate (in beats per minutes / bpm) as stratified by AF GRS quartiles (n = L: 22; LI: 21; HI 23; H: 20). Baseline demographics were similar between the four quartiles labeled: age (L: 51 ± 8 years; LI: 52 ± 9 years; HI: 51 ± 9 years; H: 50 ± 9 years), male gender percent (L: 50%; LI: 53%; HI 50%; H: 50%); Body mass index (kg/m2) (L: 24.9 ± 4.4 ; LI: 24.1 ± 5.0; HI: 24.1 ± 4.6; H: 25.0 ± 6.1); ejection fraction (L: 54 ± 6 %; LI: 53 ± 8; HI: 54 ± 7; H: 56 ± 7). There is an observed association of increased minimum and average heart rate with increased GRS (minimum L: 55 ± 5 bpm; LI: 56 ± 5 bpm; HI: 58 ± 6 bpm; H: 62 ± 5 bpm; p = 0.02; average L: 75 ± 6 bpm; LI: 74 ± 7 bpm; HI: 79 ± 8 bpm; H: 81 ± 8 bpm; p = 0.01). There is no association between peak heart rate and GRS (maximum L: 125 ± 9 bpm; LI: 123 ± 9 bpm; HI: 128 ± 9 bpm; H: 125 ± 8 bpm; p = 0.30). Figure 1B shows Holter observed heart rate variability metrics including SDNN and RMSDD as stratified by GRS quartiles. There is an observed trend of decreased HR variability with increased AF GRS (SDNN L: 121 ± 13 ms; LI: 120 ± 12 ms; HI: 114 ± 13 ms; H: 108 ± 14 ms; p = 0.01; RMSDD L: 25 ± 4 ms; LI: 24 ± 5 ms; HI: 22 ± 6 s; H: 21 ± 5 ms; p = 0.04).