Change from baseline in heart rate variability (mean ± SD SDNN) by visit in the transition safety population. HRV assessed by 2-hour Holter monitoring. Baseline mean ± SD SDNN was 91.96 ± 33.21 msec at the beginning of phase 1 (measured at study TKT023 week 25/26). Phase 2 began ~197–223 (mean 210) weeks after phase 1 baseline. Agalα, agalsidase alfa; HRV, heart rate variability; msec, milliseconds; SDNN, standard deviation of all filtered RR intervals for the length of the analysis.