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://cr.elmerpub.com

Original Article

Volume 16, Number 2, April 2025, pages 120-129

Computer-Assisted Electrocardiogram Analysis Improves Risk Assessment of Underlying Atrial Fibrillation in Cryptogenic Stroke

Figure 1. Graphic example of some of the relevant ECG variables quantified by the Philips algorithm. ECG: electrocardiogram.

Figure 2. Flow diagram of the methods employed to obtain the final predictive model. CS: cryptogenic stroke; AF: atrial fibrillation; ECG: electrocardiogram.

**Table 1.** Clinical, Biochemical, Echocardiographic and Manually Assessed ECG Baseline Characteristics
	All patients (n = 67)	No AF (n = 46)	AF (n = 21)	P value
Quantitative variables are displayed as median (1Q; 3Q). BMI: body mass index; CAD: coronary artery disease; TNT: troponin T; NT-proBNP: N-terminal B-type natriuretic peptide; LADV: left atrium diastolic volume; iLADV: indexed LADV; LASV: left atrium systolic volume; LASr: left atrial reservoir strain; LAEF: left atrial ejection fraction; LVEF: left ventricular ejection fraction (calculated by Simpson biplane method); RBBB: right bundle branch block; LBBB: left bundle branch block; TIA: transitory ischemic attack.
Age (years)	80.0 (73.0; 84.0)	78.5 (71.0; 82.8)	83.0 (78.0; 86.0)	0.010
BMI (kg/m²)	25.7 (23.6; 28.0)	25.9 (23.6; 28.5)	24.8 (23.3; 26.8)	0.154
Sex				0.780
Female	35 (52.2%)	23 (50.0%)	12 (57.1%)
Hypertension	39 (58.2%)	22 (47.8%)	17 (81.0%)	0.022
Diabetes mellitus	16 (23.9%)	11 (23.9%)	5 (23.8%)	1.000
Dyslipidemia	39 (58.2%)	28 (60.9%)	11 (52.4%)	0.699
Tobacco				0.674
Never	51 (76.1%)	34 (73.9%)	17 (81.0%)
Current	7 (10.4%)	6 (13.0%)	1 (4.76%)
Former	9 (13.4%)	6 (13.0%)	3 (14.3%)
CAD	10 (14.9%)	6 (13.0%)	4 (19.0%)	0.713
TNT (ng/L)	14.0 (10.1; 24.1)	12.9 (9.87; 21.7)	17.1 (12.0; 29.0)	0.036
NT-proBNP (pg/mL)	245 (113; 463)	152 (66.0; 372)	420 (305; 1704)	< 0.001
LADV (mL)	51.0 (39.0; 68.2)	47.8 (36.8; 55.8)	65.0 (47.0; 77.0)	0.014
iLADV (mL/m²)	29.5 (22.8; 40.0)	27.5 (21.2; 33.8)	37.8 (27.7; 42.0)	0.014
LASV (mL)	25.0 (18.0; 37.0)	20.9 (16.2; 29.8)	33.0 (22.0; 38.0)	0.020
LASr (%)	27.1 (18.5; 34.1)	31.1 (26.9; 37.6)	16.9 (13.9; 21.8)	< 0.001
LAEF (%)	51.6 (37.2; 59.7)	52.6 (38.5; 64.0)	45.9 (37.0; 53.3)	0.105
Septal thickness (mm)	11.0 (10.0; 12.0)	11.0 (10.0; 12.0)	11.0 (10.0; 12.0)	0.606
LVEF (%)	63.0 (59.5; 73.0)	63.0 (59.0; 68.6)	66.0 (60.0; 75.0)	0.276
LVEDV (mL)	66.0 (51.0; 86.0)	69.5 (54.0; 87.0)	61.0 (46.0; 70.0)	0.229
LVESV (mL)	20.0 (15.5; 31.0)	22.5 (16.0; 33.0)	19.0 (15.0; 26.0)	0.433
Interatrial block				0.42
Type 1	4 (5.97%)	2 (4.35%)	2 (9.52%)
Type 2	6 (8.95%)	5 (10.9%)	1 (4.76%)
PR (ms)	177 (160; 190)	172 (160; 190)	180 (160; 190)	0.533
QRS morphology				0.258
RBBB	4 (5.97%)	2 (4.35%)	2 (9.52%)
LBBB	5 (7.46%)	5 (10.9%)	0 (0.00%)
QRS (ms)	100 (90.0; 110)	100 (90.0; 110)	98.0 (95.0; 110)	0.635
QTc (ms)	442 (430; 455)	440 (429; 457)	445 (440; 450)	0.583
TIA	17 (25.4%)	13 (28.3%)	4 (19.0%)	0.616

Table 1. Clinical, Biochemical, Echocardiographic and Manually Assessed ECG Baseline Characteristics

All patients (n = 67)

No AF (n = 46)

AF (n = 21)

P value

Quantitative variables are displayed as median (1Q; 3Q). BMI: body mass index; CAD: coronary artery disease; TNT: troponin T; NT-proBNP: N-terminal B-type natriuretic peptide; LADV: left atrium diastolic volume; iLADV: indexed LADV; LASV: left atrium systolic volume; LASr: left atrial reservoir strain; LAEF: left atrial ejection fraction; LVEF: left ventricular ejection fraction (calculated by Simpson biplane method); RBBB: right bundle branch block; LBBB: left bundle branch block; TIA: transitory ischemic attack.

Age (years)

80.0 (73.0; 84.0)

78.5 (71.0; 82.8)

83.0 (78.0; 86.0)

0.010

BMI (kg/m²)

25.7 (23.6; 28.0)

25.9 (23.6; 28.5)

24.8 (23.3; 26.8)

0.154

Sex

0.780

Female

35 (52.2%)

23 (50.0%)

12 (57.1%)

Hypertension

39 (58.2%)

22 (47.8%)

17 (81.0%)

0.022

Diabetes mellitus

16 (23.9%)

11 (23.9%)

5 (23.8%)

1.000

Dyslipidemia

39 (58.2%)

28 (60.9%)

11 (52.4%)

0.699

Tobacco

0.674

Never

51 (76.1%)

34 (73.9%)

17 (81.0%)

Current

7 (10.4%)

6 (13.0%)

1 (4.76%)

Former

9 (13.4%)

6 (13.0%)

3 (14.3%)

CAD

10 (14.9%)

6 (13.0%)

4 (19.0%)

0.713

TNT (ng/L)

14.0 (10.1; 24.1)

12.9 (9.87; 21.7)

17.1 (12.0; 29.0)

0.036

NT-proBNP (pg/mL)

245 (113; 463)

152 (66.0; 372)

420 (305; 1704)

< 0.001

LADV (mL)

51.0 (39.0; 68.2)

47.8 (36.8; 55.8)

65.0 (47.0; 77.0)

0.014

iLADV (mL/m²)

29.5 (22.8; 40.0)

27.5 (21.2; 33.8)

37.8 (27.7; 42.0)

0.014

LASV (mL)

25.0 (18.0; 37.0)

20.9 (16.2; 29.8)

33.0 (22.0; 38.0)

0.020

LASr (%)

27.1 (18.5; 34.1)

31.1 (26.9; 37.6)

16.9 (13.9; 21.8)

< 0.001

LAEF (%)

51.6 (37.2; 59.7)

52.6 (38.5; 64.0)

45.9 (37.0; 53.3)

0.105

Septal thickness (mm)

11.0 (10.0; 12.0)

0.606

LVEF (%)

63.0 (59.5; 73.0)

63.0 (59.0; 68.6)

66.0 (60.0; 75.0)

0.276

LVEDV (mL)

66.0 (51.0; 86.0)

69.5 (54.0; 87.0)

61.0 (46.0; 70.0)

0.229

LVESV (mL)

20.0 (15.5; 31.0)

22.5 (16.0; 33.0)

19.0 (15.0; 26.0)

0.433

Interatrial block

0.42

Type 1

4 (5.97%)

2 (4.35%)

2 (9.52%)

Type 2

6 (8.95%)

5 (10.9%)

1 (4.76%)

PR (ms)

177 (160; 190)

172 (160; 190)

180 (160; 190)

0.533

QRS morphology

0.258

RBBB

4 (5.97%)

2 (4.35%)

2 (9.52%)

LBBB

5 (7.46%)

5 (10.9%)

0 (0.00%)

QRS (ms)

100 (90.0; 110)

98.0 (95.0; 110)

0.635

QTc (ms)

442 (430; 455)

440 (429; 457)

445 (440; 450)

0.583

TIA

17 (25.4%)

13 (28.3%)

4 (19.0%)

0.616

**Table 2.** Predictive Model Including Clinical, Echocardiographic and Biochemical Variables
Variable (range)	OR	CI (2.5% - 97.5%)	P value
OR: odds ratio; CI: confidence interval; NT-proBNP: N-terminal B-type natriuretic peptide; LASr: left atrial reservoir strain.
Age (> 76 years)	4.69	0.59 - 51.50	0.163
NT-proBNP (> 203.5 pg/mL)	8.21	1.56 - 58.55	0.020
LASr (≤ 23.3%)	36.07	7.26 - 301.83	< 0.001

Table 2. Predictive Model Including Clinical, Echocardiographic and Biochemical Variables

Variable (range)

CI (2.5% - 97.5%)

P value

OR: odds ratio; CI: confidence interval; NT-proBNP: N-terminal B-type natriuretic peptide; LASr: left atrial reservoir strain.

Age (> 76 years)

4.69

0.59 - 51.50

0.163

NT-proBNP (> 203.5 pg/mL)

8.21

1.56 - 58.55

0.020

LASr (≤ 23.3%)

36.07

7.26 - 301.83

< 0.001

**Table 3.** Final Predictive Model Including Clinical, Echocardiographic Biochemical and ECG Variables
Variable (range)	OR	CI (2.5% - 97.5%)	P value
ECG: electrocardiogram; NT-proBNP: N-terminal B-type natriuretic peptide; LASr: left atrial reservoir strain; V1_ramp: amplitude of the R wave in lead V1.
Age (> 76 years)	12.51	0.47 - 845.03	0.17
NT-proBNP (> 203.5 pg/mL)	23.61	2.65 - 665.99	0.016
LASr (≤ 23.3%)	145.91	13.94 - 6,223.62	< 0.001
V1_ramp (> 137 µV)	33.04	3.38 - 1,167.86	0.013

Table 3. Final Predictive Model Including Clinical, Echocardiographic Biochemical and ECG Variables

Variable (range)

CI (2.5% - 97.5%)

P value

ECG: electrocardiogram; NT-proBNP: N-terminal B-type natriuretic peptide; LASr: left atrial reservoir strain; V1_ramp: amplitude of the R wave in lead V1.

Age (> 76 years)

12.51

0.47 - 845.03

0.17

NT-proBNP (> 203.5 pg/mL)

23.61

2.65 - 665.99

0.016

LASr (≤ 23.3%)

145.91

13.94 - 6,223.62

< 0.001

V1_ramp (> 137 µV)

33.04

3.38 - 1,167.86

0.013