Table 4. Comparison of heart rate and HRV parameters from RRI and PWI.

We calculated mean heart rate, SDNN, and RMSSD for (i) all RRI detected in the ECGs, (ii) all RRI associated with PWI (at an accuracy limit of 0.1 s, see Table 2), (iii) all PWI associated with RRI, and (iv) the total set of all detected PWI. Group averages over 351 subjects with detected PWIs are presented.

	mean heart rate	SDNN	RMSSD
all RRI	65.1 1/min	93 ms	52 ms
matched RRI	64.4 1/min	70 ms	45 ms
matched PWI	64.4 1/min	76 ms	65 ms
all PWI	64.4 1/min	115 ms	138 ms