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July2005 Vol.42 Issue:      2 Table of Contents
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Heart Rate Variability and QT Dispersion in Patients with Acute Stroke

Khaled Baraka1, Fahim Shaker3, Khaled Sayed1, Wail T. Soliman2, Alaa Rabiea1, Enjy Magdy
Departments of Cardiology1, Neurology2, El-Minya University, Al-Sahel Educational Hospital3

ABSTRACT

Fifty two first-stroke (infarction or hemorrhage) patients with a mean age ±SD of 58.6±6.4 years, as well as 20 control subjects with a mean age±SD of 56.1±4.4 were included in this study. All patients were subjected to full clinical evaluation, neurological assessment using Glasgow coma scale, NIH score, Barthel index & modified Rankin score, laboratory work-up, ECG, Holter, echocardiography, and brain CT scan. Results: ST-T changes were significantly higher in patients with hemorrhagic than infarction stroke. Incidence of arrhythmia was not different. Maximum QT & QTD were significantly higher in both thrombotic & hemorrhagic stroke patients than controls, and in hemorrhagic than infarction stroke patients. QTD had significant negative correlation with admission Glasgow coma scale, but significant positive correlation with NIH score on admission & at discharge and Modified Rankin scale at discharge. QTD was significantly higher in patients with severe functional impairment as evaluated by NIH score system at discharge, compared with patients with either mild or moderate functional impairment. Furthermore, we found a significant negative correlation between QTD and patient’s improvement as judged by change in the Barthel index but the correlation with the change in NIH score system did not reach statistical significance. QTD was significantly higher in patients who died during hospitalization due to stroke compared with those who survived. LF nu & LF/HF (low frequency/high frequency) ratio were significantly higher in patients with thrombotic & hemorrhagic stroke than controls. HF nu (normalized high frequency component) was significantly lower in both groups of patients compared with controls. Meanwhile, there was no significant difference between infarction and hemorrhagic stroke patients regarding heart rate variability parameters. There was no significant correlation between LF/HF ratio and any of the neurological scales either on admission or at discharge. Meanwhile, Both LF nu & LF/HF ratio correlated with patient’s improvement as judged by the change in NIH score. LF nu also correlated with the change in Barthel index. Ventricular ectopic beats (VEB)/h were significantly more frequent in patients with infarction & hemorrhagic stroke compared with controls. Furthermore, supraventricular ectopic beats (SVEB)/h were significantly more frequent in patients with infarction & hemorrhagic stroke versus controls. VEB/h & SVEB/h were significantly higher in patients with hemorrhagic than patients with infarction stroke. Conclusions: Patients with acute stroke have significant prolongation of QTD, impairment in heart rate variability & increased incidence of arrhythmia.

(Egypt J. Neurol. Psychiat. Neurosurg., 2005, 42(2): 441-451).

 




 

INTRODUCTION

 

The electrocardiographic (ECG) changes and cardiac arrhythmia frequently encountered after stroke are not solely explicable by concomitant ischemic cardiac disease. Excessive sympatho-adrenergic tone is contributory. Specifically, it is believed that augmentation of intracardiac sympathetic nerve activity occurs producing intracardiac myocyte damage and depolarizing ionic shift resulting in electrocardiographic repolarizing changes and arrhythmogenesis1.

 

Aim of the work:

The aim of this work was to study Heart rate variability and QT dispersion and electric cardiac changes that occur in the acute phase of infarction or hemorrhagic stroke, in patients without pre-existing organic heart disease.

 

PATIENTS AND METHODS

 

This study was carried out in the Departments of Cardiology & Neurology, Al-Minya University Hospital, from December 2003 to October 2004. It included 52 patients with a mean age±SD of 58.625±6.45 years, as well as 20 normal subjects with a mean age±SD of 56.15±4.45 as controls.

Based on admission computed tomography, 28 patients had cerebral hemisphere infarction and 24 had acute intracerebral hemorrhage.

Exclusion criteria: lacunar stroke, transient ischemic attacks, History or clinical or echocardiographic evidence of ischemic or valvular heart disease, or cardiomyopathy or any other structural heart disease, heart failure, prior stroke, medications such as: digoxin, antiarrhythmic agents, phenothiazines, theophylline, levodopa, tricyclic antidepressants, or lithium (within 5 half lives), basic ECG abnormalities such as bundle branch block, left ventricular hypertrophy, atrial flutter or fibrillation.

All patients were subjected to: full clinical assessment, Standard 12-lead ECG, Echocardiography to exclude the presence of structural heart disease, 24 hours Holter monitoring & laboratory work work-up.

Full neurological assessment was applied using Glasgow coma scale (eye opening, best verbal response & best motor response): higher scale indicating better status, Barthel index (Bowel control, Bladder control, Grooming, Toilet use, Feeding, Transfer, Mobility, Dressing, Climbing stairs, and Bathing): higher scale indicating better status2, National Institute of Health (NIH) score (Level of consciousness, Best Gaze, Visual Field, Facial palsy, Motor Arm, Motor Leg, Limb Ataxia, Sensory, Best Language, Dysarthria, and Extinction/Neglect): higher scale indicating worse status3, and modified Rankin score (degree of disability): higher scale indicating worse status4.

QT dispersion: is defined as the difference between the minimum and maximum QT intervals of the 12-lead ECG5.

Computed Tomography was performed on admission. It helped to detect: Nature of stroke: infarction or hemorrhagic, Extent of the insult: ventricular & insular involvement, mass effect, and Localization of stroke: right or left sided. If cerebral infarction does not appear in admission CT, follow up CT was done 48 hours later.

Holter monitoring: was done using cardioline, AD-35, TOP scanning systems, for detection of arrhythmias & evaluation of heart rate variability analyzed in the frequency-domain.

 

Statistical methods:

Data were tabulated and fed into a personal computer program of high statistical capabilities: SPSS version 10. Parametric data were expressed as means+SD, and analyzed using the student’s independent samples t-test. Non parametric data were expressed as percentages, and compared using the nonparametric percentage comparison z-test. Correlation studies were done using the Pearson’s correlation coefficient r. In all tests, p value < 0.05 was considered statistically significant.

 

RESULTS

 

The current study included 52 patients, with a mean age+SD of 58.7±6, presenting with first-ever acute stroke within the first 24 hours of symptom onset, as well as 20 normal subjects with a mean age+SD of 56.1±4.4 as controls. Based on admission CT findings, patients were classified into 28 patients with cerebral hemisphere infarction and 24 with acute intracerebral hemorrhage. Of patients with stroke: 20 had right-sided, and 32 had left-sided strokes (Table 1).

Comparing infarction and hemorrhagic groups regarding neurological assessment and CT data, the only statistically significant difference was regarding the mass effect on CT scan (Table 2).

LF nu, HF nu, LF/HF, VEB/h and SVEB/h were highly statistically different comparing infarction versus control groups and hemorrhagic versus control groups. While Comparing infarction and hemorrhagic groups, VEB/h and SVEB/h were statistically significant different (Table 3).

There were high statistically significant difference between patients who died and survivors regarding admission Glasgo coma scale and NIH scale and discharge MRS, Barthel index and NIH scale. Also, there were statistically significant difference between patients who died and survivors regarding maximum QT and QT depression and highly significant regarding VEB/hour (Table 4).

There was no statistically significant difference between patients with mild and moderate degrees of functional impairment on NIH  scala  at  discharge  regarding  QTD,  LF  nu,  HF  nu  or  LF / HF.  Comparing  patients with mild and sever impairment, QTD was statistically significant different. Also, QTD and LF nu were statistically significant different comparing patients with mild and sever impairment (Table 5).

In our study QTD had significant negative correlation with admission Glasgow coma scale (r=-0.30, p=0.02), but significant positive correlation with NIH score on admission (r=0.32, p=0.02) & at discharge (r=0.34, p=0.01) and Modified Rankin scale at discharge (r=0.34, p=0.01). QTD was significantly higher in patients with severe functional impairment as evaluated by NIH score at discharge, compared with patients with either mild (P =0.02), or moderate (0.007) functional impairment (Table 6).

Furthermore, we found a significant negative correlation between QTD and patient’s improvement as judged by change in the Barthel index (r= -0.28, p=04), but the correlation with the change in NIH score system did not reach statistical significance (r= -0.27, p=0.052). QTD was significantly higher in patients who died during hospitalization due to stroke compared with those who survived (p=0.017) (Table 6).


 

 

Table 1. Demographic and laboratory data of the study groups.

 

 

Data

Infarction

Hemorrhagic

Control

P

Infarc/ Cont

P Hem/ Cont

P Infarc/ Hem

Mean/no

SD

Mean/no

SD

Mean/no

SD

Males

16

57%

16

66.7%

9

45%

0.411

0.15

0.486

Age

58.85

5.78

58.6

6.44

56.15

4.45

0.086

0.15

0.892

RBS

139.14

53.9

146.8

63.06

103.15

17.04

0.006

0.00

0.638

Urea

37.10

13.8

37.37

13.91

35.25

7.72

0.591

0.54

0.945

Creatinine

1.01

0.30

0.983

0.322

0.94

0.22

0.356

0.61

0.722

K

3.97

0.30

4.029

0.470

4.08

0.41

0.312

0.68

0.756

DM

4

14. 3

6

25

-

-

-

-

0.333

HTN

7

25

13

54. 2

-

-

-

-

0.033

Death

6

21. 4

9

37. 5

-

-

-

-

 

0.265

Survival

22

78.6

15

62. 5

-

-

-

-

RBS: Random blood sugar, DM: Diabetes mellitus, HTN: Hypertension, Infarc: Infarction,

Hem: Hemorrhagic, Cont: Control

 

 

Table 2. Neurological assessment & CT data of infarction versus hemorrhagic stroke.

 

Parameter

Infarction (n.=28)

Hemorrhagic(n=24)

P value

Mean / n.

SD / %

Mean / n.

SD / %

Admission Glasgow scale

11.1071

1.6852

10.3750

1.3772

0.961

NIH score on admission

14.3214

3.7521

15.4167

4.52930

0.345

Barthel index on admission

2.3929

1.0306

2.2917

1.6545

0.789

NIH score prior to discharge

10.7857

9.2310

14.9583

10.0973

0.106

Barthel index prior to discharge

7.4286

4.4922

5.9583

5.6220

0.300

Modified Rankin scale on discharge

3.3214

1.1564

3.8333

1.1672

0.119

Deepening coma

9

32.1

10

41.7

0.481

Right-sided stroke

8

28.6%

12

50%

0.117

Left-sided stroke

20

71.4%

12

50%

Insular involvement

4

14.3%

9

37. 5%

0.056

Mass effect

8

28.6%

18

75.0%

0.001

 

 

Table 3. Heart rate variability & Holter 24-hour data in the study groups.

 

 

Infarction

Hemorrhagic

Control

P

Infarc/ Cont

P

Hem/ Cont

P

Infarc/ Hem

Mean / no

SD

Mean / no

SD

Mean / no

SD

Min HR

46.19

12.41

45.67

11.07

45.50

10.65

0.843

0.960

0.875

Aver HR

82.57

15. 33

80.21

17.88

79.50

10. 56

0.443

0.877

0.610

Max HR

132.00

33. 21

120.67

31.11

141.20

28. 83

0.323

0.030

0.213

LF nu

68.1107

12.0340

73.2833

13.4445

41.10

11.290

0.0001

0.0001

0.149

HF nu

30.6071

11.779

25.7917

14.300

58.30

10.9837

0.0001

0.0001

0.174

LF/HF

1.46675

0.84427

1.6802

0.8479

0.758

0.39592

0.001

0.0001

0.369

VEB/h

15.6082

7.7773

21.6417

8.9572

1.3100

0.6561

0.0001

0.0001

0.026

SVEB/h

22.2795

19.200

49.0867

48.0312

1.0998

0.74121

0.0001

0.0001

0.009

Aver: Average, LF: Low frequency band, HF: High frequency band, nu: Normalized units,

VEB: Ventricular ectopic beats, SVEB: Supraventricular ectopic beats

Table 4. Comparison between deaths & survivals.

 

Parameter

DEATH(n=15)

SURVIVAL(n=37)

P value

Mean / n.

SD/ %

Mean /n.

SD/%

Random blood sugar

132.400

45.5519

146.8649

62.27

0.420

Serum creatinine

1.06000

0.2501

0.9757

0.3286

0.376

Blood urea

41.4667

9.9345

38.5405

15.5806

0.505

Serum potassium

3.9933

0.4079

4.0054

0.3858

0.920

Admission Glasgow

9.2000

1.0823

11.4054

1.2793

0.0001

Admission Barthel

1.8667

0.7432

2.5405

1.4831

0.1010

Admission NIH

18.7333

2.5486

13.2432

3.5544

0.0001

Discharge Barthel

0.0000

0.0000

9.4865

3.0698

0.0001

Discharge NIH

27.333

1.1751

6.7838

3.0924

0.0001

Modified Rankin

5.000

0.0000

2.9730

0.8656

0.0001

NIH change

8.6000

2.1314

6.4595

3.5242

0.0001

ECG HR

81.7198

20.4285

78.5380

17.7618

0.578

Minimum QT

365.333

36.6190

264.3243

50.5821

0.944

Maximum QT

488.000

50.5964

445.4054

52.630

0.010

QT dispersion

122.667

23.7447

81.0811

62.8837

0.017

Minimum heart rate

42. 50

8.01

47.28

12.66

0.197

Average heart rate

58.73

17.90

79.76

15.73

0.238

Maximum heart rate

123.20

28. 36

128.22

34. 23

0.618

LF in normalized unit (nu)

75.2000

9.4218

68.5915

13.646

0.095

HF in normalized unit

23.5333

9.4557

29.378

14.028

0.078

LF/HF ratio

1.8490

0.9565

1.4502

0.7793

0.124

VEB/hour.

24.2615

7.9201

14.7250

7.2685

0.0001

SVEB /hour.

36.1983

32.1691

38.6676

35.658

0.765

 

 

Table 5. QTD & Holter data in patients with various degrees of functional impairment on NIH scale at discharge.

 

Data

Mild functional impairment

(n=26)

Moderate functional impairment (n=11)

Severe functional impairment

(n=25)

P mild/ mod

P mod/ severe

P mild/

severe

Mean

SD

Mean

SD

Mean

SD

QTD

98.4615

36.1875

90.9091

31.4498

122.667

23.7447

0.551

0.007

0.026

LF nu.

67.4576

0.6811

71.2727

71.2727

72.2000

9.4217

0.445

0.295

0.039

HF nu.

31.7307

14.787

27.0909

8.9157

23.5333

9.45566

0.341

0.341

0.083

LF/HF

1.30176

0.6811

1.80011

0.9133

1.84900

0.95650

0.074

0.899

0.061


Table 6. Correlation studies.

 

Parameter 1

Parameter 2

r

p

QT dispersion in msec.

Admission Glasgow coma scale

- 0.306

0.027

Admission Barthel index

-0.030

0.833

Admission NIH score

0.322

0.020

Barthel index at discharge

- 0.258

0.065

NIH score at discharge

0.346

0.012

Modified Rankin scale

0.348

0.011

Improvement judged by NIH change

-0.271

0.052

Improvement judged by Barthel change

-0.286

0.040

LF/HF ratio

Admission Glasgow coma scale

-0.015

0.917

Admission Barthel index

-0.029

0.837

Admission NIH score

-0.083

0.559

Barthel index at discharge

-0.217

0.123

NIH score at discharge

0.248

0.076

Modified Rankin scale

0.199

0.158

Improvement judged by NIH change

- 0.275

0.049

Improvement judged by Barthel change

0.257-

0.066

LF in nu.

Improvement judged by NIH change

-0.321

0.021

Improvement judged by Barthel change

-0.279

0.045

HF in nu.

Improvement judged by NIH change

0.336

0.015

Improvement judged by Barthel change

0.304

0.028

Average SVEB per hour

Admission Glasgow coma scale

-0.057

0.689

Admission Barthel index

0.066

0.643

Admission NIH score

0.020

0.889

Barthel index at discharge

0.091

0.523

NIH score at discharge

-0.044

0.757

Modified Rankin scale

0.040

0.779

Average VEB per hour.

Admission Glasgow coma scale

- 0.098

0.490

Admission Barthel index

0.059

0.679

Admission NIH score

0.153

0.280

Barthel index at discharge

0.137

0.333

NIH score at discharge

- 0.043

0.763

Modified Rankin scale

- 0.025

0.859

Random blood sugar on admission.

Admission Glasgow coma scale

0.128

0.366

Admission Barthel index

-0.189

0.179

Admission NIH score

0.011

0.937

Barthel index at discharge

0.004

0.979

NIH score at discharge

-0.104

0.463

Modified Rankin scale

-0.071

0.617

 



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