Cardiol Res

Cardiology Research, ISSN 1923-2829 print, 1923-2837 online, Open Access

Article copyright, the authors; Journal compilation copyright, Cardiol Res and Elmer Press Inc

Journal website https://www.cardiologyres.org

Original Article

Volume 14, Number 1, February 2023, pages 45-53

Is T-Wave Alternans a Repolarization Abnormality Marker in COVID-19? An Investigation on the Potentialities of Portable Electrocardiogram Device

**Table 1.** Baseline Characteristics of Study Population
	COVID-19 (n = 76)	Non-COVID-19 (n = 34)	P value
BMI: body mass index; Ca: calcium, CAD: coronary artery disease; CKD: chronic kidney disease; DBP: diastolic blood pressure; DM: diabetes mellitus; GFR: glomerular filtration rate; K: potassium; LOS: length of stay; Na: natrium; N/A: not applicable; SBP: systolic blood pressure; SD: standard deviation; COVID-19: coronavirus disease 2019.
Clinical variables
Age (mean ± SD)	41.70 ± 13.80	38.35 ± 13.30	0.236
Sex
Male (n, %)	33 (43.42)	11 (32.35)	0.274
Female (n, %)	43 (56.58)	23 (67.65)
BMI (mean ± SD)	24.35 ± 3.56	23.74 ± 4.54	0.5697
SBP (mm Hg)	122.17 ± 15.82	130.31 ± 25.84	0.0478
DBP (mm Hg)	77.79 ± 11.13	81.09 ± 11.76	0.1689
D-dimer (mean ± SD)	1.32 ± 2.22	1.18 ± 1.20	0.8109
CRP (mean ± SD)	43.39 ± 57.01	50.12 ± 51.99	0.7637
Na (mean ± SD)	140.02 ± 22.60	132.26 ± 28.33	0.2013
K (mean ± SD)	4.01 ± 0.73	4.33 ± 1.29	0.1661
Ca (mean ± SD)	8.52 ± 1.89	8.3 ± 1.08	0.6529
LOS (mean ± SD)	12.46 ± 6.76	8.77 ± 7.39	0.0151
Comorbidities
Hypertension	0 (0)	0 (0)	N/A
CAD	14 (18.42)	3 (8.82)	0.198
CKD (GFR < 60 mL/min/1.73 m²)	4 (5.26)	0 (0)	0.173
Type 2 DM	7 (9.21)	3 (8.82)	0.948
Medication
Favipiravir	10 (13.16)	5 (14.70)	0.827
Azithromycin	20 (26.31)	9 (26.47)	0.986
Levofloxacin	1 (1.32)	0 (0)	0.502

Table 1. Baseline Characteristics of Study Population

COVID-19 (n = 76)

Non-COVID-19 (n = 34)

P value

BMI: body mass index; Ca: calcium, CAD: coronary artery disease; CKD: chronic kidney disease; DBP: diastolic blood pressure; DM: diabetes mellitus; GFR: glomerular filtration rate; K: potassium; LOS: length of stay; Na: natrium; N/A: not applicable; SBP: systolic blood pressure; SD: standard deviation; COVID-19: coronavirus disease 2019.

Clinical variables

Age (mean ± SD)

41.70 ± 13.80

38.35 ± 13.30

0.236

Sex

Male (n, %)

33 (43.42)

11 (32.35)

0.274

Female (n, %)

43 (56.58)

23 (67.65)

BMI (mean ± SD)

24.35 ± 3.56

23.74 ± 4.54

0.5697

SBP (mm Hg)

122.17 ± 15.82

130.31 ± 25.84

0.0478

DBP (mm Hg)

77.79 ± 11.13

81.09 ± 11.76

0.1689

D-dimer (mean ± SD)

1.32 ± 2.22

1.18 ± 1.20

0.8109

CRP (mean ± SD)

43.39 ± 57.01

50.12 ± 51.99

0.7637

Na (mean ± SD)

140.02 ± 22.60

132.26 ± 28.33

0.2013

K (mean ± SD)

4.01 ± 0.73

4.33 ± 1.29

0.1661

Ca (mean ± SD)

8.52 ± 1.89

8.3 ± 1.08

0.6529

LOS (mean ± SD)

12.46 ± 6.76

8.77 ± 7.39

0.0151

Comorbidities

Hypertension

0 (0)

N/A

CAD

14 (18.42)

3 (8.82)

0.198

CKD (GFR < 60 mL/min/1.73 m²)

4 (5.26)

0 (0)

0.173

Type 2 DM

7 (9.21)

3 (8.82)

0.948

Medication

Favipiravir

10 (13.16)

5 (14.70)

0.827

Azithromycin

20 (26.31)

9 (26.47)

0.986

Levofloxacin

1 (1.32)

0 (0)

0.502

**Table 2.** TWA Profile on Admission and Discharge According to PCR Swab Result*
PCR result	Admission, mean ± SD (µV)	P value	Discharge, mean ± SD (µV)	P value
*Independent t-test. TWA: T-wave alternans; PCR: polymerase chain reaction; SD: standard deviation.
PCR-positive (n = 76)	42.47 ± 26.52	0.757	53.45 ± 34.42	0.030
PCR-negative (n = 34)	44.72 ± 38.21		25.15± 17.64

Table 2. TWA Profile on Admission and Discharge According to PCR Swab Result*

PCR result

Admission, mean ± SD (µV)

P value

Discharge, mean ± SD (µV)

P value

*Independent t-test. TWA: T-wave alternans; PCR: polymerase chain reaction; SD: standard deviation.

PCR-positive (n = 76)

42.47 ± 26.52

0.757

53.45 ± 34.42

0.030

PCR-negative (n = 34)

44.72 ± 38.21

25.15± 17.64

**Table 3.** COVID-19 Patients Disease Severity and TWA
Disease severity	n (%) admission, n = 62	Admission TWA (µV), mean ± SD	P value	n (%) discharge, n = 38	Discharge TWA (µV), mean ± SD	P value
COVID-19: coronavirus disease 2019; TWA: T-wave alternans; SD: standard deviation.
Mild illness	47 (75.80)	44.29 ± 27.14	0.3418	25 (65.79)	49.47 ± 33.62	0.3303
Moderate illness	15 (24.19)	36.75 ± 24.46		13 (34.21)	61.09 ± 35.99

Table 3. COVID-19 Patients Disease Severity and TWA

Disease severity

n (%) admission, n = 62

Admission TWA (µV), mean ± SD

P value

n (%) discharge, n = 38

Discharge TWA (µV), mean ± SD

P value

COVID-19: coronavirus disease 2019; TWA: T-wave alternans; SD: standard deviation.

Mild illness

47 (75.80)

44.29 ± 27.14

0.3418

25 (65.79)

49.47 ± 33.62

0.3303

Moderate illness

15 (24.19)

36.75 ± 24.46

13 (34.21)

61.09 ± 35.99

**Table 4.** Final Regression Model of TWA at Discharge and PCR Result
TWA (discharge)	Coefficient	Standard error	P>t	95% CI
TWA: T-wave alternans; PCR: polymerase chain reaction; CI: confidence interval.
PCR	18.298	8.234	0.030	1.802 - 34.793
Constants	35.152	6.667	0.000	21.800 - 48.504

Table 4. Final Regression Model of TWA at Discharge and PCR Result

TWA (discharge)

Coefficient

Standard error

P>t

95% CI

TWA: T-wave alternans; PCR: polymerase chain reaction; CI: confidence interval.

PCR

18.298

8.234

0.030

1.802 - 34.793

Constants

35.152

6.667

0.000

21.800 - 48.504