Table 2.

Changes in HRV parameters in the 2 study groups:

HRV	AC group			ET group			P- Value
	Baseline	Follow-up	Change	Baseline	Follow-up	Change
SDNN	30.2 ± 17.7	32.6 ± 15.4	2.4 ± 2.13	31.6 ± 21.0	47.0 ± 36.5	15.5 ± 5.02	0.016
RMSSD	20.4 ± 15.5	22.1 ± 15.9	1.7 ± 2.62	24.7 ± 24.7	42.3 ± 48.3	17.5 ± 7.85	0.003

Data represent means ± SD. P-Values represent comparison of least squared means of the change in HRV following adjustment for age, gender, heart rate, pulse pressure, beta blockers usage, baseline exercise capacity (peak exercise oxygen uptake, peak work load, exercise time, and heart rate recovery during baseline exercise stress testing) baseline HRV values, and heart failure category (preserved vs reduced ejection fraction). AC =attention control; ET = exercise training; SDNN- the standard deviation of all normal RR intervals; RMSSD- the root mean square of successive differences in normal RR intervals.