A Hybrid Signal Processing of RR Intervals from QTc Variation Searching Arrhythmia and Improving Heart Rate Variability Assessment in Acute Large Artery Ischemic Stroke

Table 1

HRV comparison of long QTc-AF and normal QTc-nonAF using Kalman filter for better RR interval.

	LQTc-AF Kalman	NQTc-nonAF Kalman
Mean HR	100.30 ± 27.99	73.98 ± 12.18
Mean RRI	669.3 ± 134.0	845.6 ± 154.5
SDNN	114.3 ± 68.1	58.5 ± 41.3
RMSSD	93.4 ± 48.3	34.43 ± 26.68	NS
pNN50	44.36 ± 26.55	8.10 ± 11.88	NS
VLF (0–0.04 Hz)	3001 ± 4729	1266 ± 1300	NS
LF (0.04–0.15 Hz)	6404 ± 9715	1203 ± 1733	NS
HF (0.15–0.4 Hz)	3893 ± 4022	832 ± 1234
LF/HF ratio	1.459 ± 0.618	2.464 ± 2.501	NS
SD1	66.23 ± 34.23	24.45 ± 18.92	NS
SD2	146.9 ± 91.7	77.3 ± 54.8
SD2/SD1	2.249 ± 0.645	3.620 ± 2.443
SamEn	1.413 ± 0.655	0.756 ± 0.460

NS: not significantly different. : significant difference. HR: heart rate (beat/min). RRI: RR interval (msec). SDNN (ms): standard deviation of all NN intervals. RMSSD (ms): square root of the mean squared difference between adjacent NN intervals. PNN50 (%): number of adjacent NN intervals that differ by 50 ms/total number of NN intervals. VLF (ms², %): very low frequency range (<0.003 Hz). LF (ms², %): low frequency range (0.04–0.15 Hz). HF (ms², %): high frequency range (0.15–0.4 Hz). SD1: standard deviation of points perpendicular to the line of identity. SD2: standard deviation of points along to the line of identity. SamEn: sample entropy.