J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 5, Number 6, December 2013, pages 441-450

Unexplained Syncope and Diagnostic Yield of Tests in Syncope According to the ICD-10 Discharge Diagnosis

**Table 1.** Baseline Characteristics
Characteristics	Total (%)
Age is given in median and interquartile range (IQR). ACEi: angiotensin converting enzyme inhibitor; ARB: angiotensin receptor blocker; PCI: percutaneous coronary intervention; CABG: coronary artery bypass graft.
Number of patients	570 (100)
Men	297 (52)
Age years (IQR)	68.5 (53 - 81)
Previous syncope	130 (23)
Prodromal symptoms	249 (44)
Comorbidities
Ischemic heart disease	126 (22)
Peripheral vascular disease	78 (14)
Previous myocardial infarction	87 (15)
Systemic hypertension	288 (51)
Previous or current atrial fibrillation	77 (14)
Other arrhythmias	37 (6)
Previous stroke	72 (13)
Congestive heart failure	61 (11)
Previous or ongoing cancer	49 (9)
Chronic obstructive pulmonary disorder	46 (8)
Diabetes	56 (10)
Cardiac pacemaker or ICD unit	21 (4)
Epilepsy	7 (1)
Alcoholism	18 (3)
Dementia	29 (5)
Depression	25 (4)
Previous PCI or CABG	61 (11)
Previous or current smoker	223 (39)
Alcohol intake above recommended level	124 (22)
Pharmacotherapy
Beta blockers	140 (25)
ACEi/ARB	210 (37)
Digoxin	21 (4)
Nitrates	34 (6)
Calcium channel blockers	85 (15)
Spironolactone	21 (4)
Thiazide	111 (19)
Loop diuretics	85 (15)
Class Ic antiarrhythmic drugs	1 (0)
Class III antiarrhythmic drugs	13 (2)
Anxiolytics	56 (10)
Antipsychotics	27 (5)
Antidepressants	76 (13)
Glucose lowering drugs	51 (9)

Table 1. Baseline Characteristics

Characteristics

Total (%)

Age is given in median and interquartile range (IQR). ACEi: angiotensin converting enzyme inhibitor; ARB: angiotensin receptor blocker; PCI: percutaneous coronary intervention; CABG: coronary artery bypass graft.

Number of patients

570 (100)

Men

297 (52)

Age years (IQR)

68.5 (53 - 81)

Previous syncope

130 (23)

Prodromal symptoms

249 (44)

Comorbidities

Ischemic heart disease

126 (22)

Peripheral vascular disease

78 (14)

Previous myocardial infarction

87 (15)

Systemic hypertension

288 (51)

Previous or current atrial fibrillation

77 (14)

Other arrhythmias

37 (6)

Previous stroke

72 (13)

Congestive heart failure

61 (11)

Previous or ongoing cancer

49 (9)

Chronic obstructive pulmonary disorder

46 (8)

Diabetes

56 (10)

Cardiac pacemaker or ICD unit

21 (4)

Epilepsy

7 (1)

Alcoholism

18 (3)

Dementia

29 (5)

Depression

25 (4)

Previous PCI or CABG

61 (11)

Previous or current smoker

223 (39)

Alcohol intake above recommended level

124 (22)

Pharmacotherapy

Beta blockers

140 (25)

ACEi/ARB

210 (37)

Digoxin

21 (4)

Nitrates

34 (6)

Calcium channel blockers

85 (15)

Spironolactone

21 (4)

Thiazide

111 (19)

Loop diuretics

85 (15)

Class Ic antiarrhythmic drugs

1 (0)

Class III antiarrhythmic drugs

13 (2)

Anxiolytics

56 (10)

Antipsychotics

27 (5)

Antidepressants

76 (13)

Glucose lowering drugs

51 (9)

**Table 2.** The Total Number of Tests Used During First Admission and Workup
Test	Number (%)	Abnormal test (%)	Definite diagnosis Diagnostic yield of test (%)
ECG: electrocardiogram; MRI: magnetic resonance imaging; EP: electrophysiological; CT: computed tomography. *These 17 patients were all diagnosed with neurological disease during the workup, primarily epilepsy, thus the diagnostic yield was as counted, but the patients were probably ultimately classified wrongly as syncopal origin.
Total tests	2601	632 (24)	165 (6)
Laboratory and blood results	570 (100)	NA	NA
ECG	569 (100)	235 (41)	22 (4)
Telemetry	431 (76)	103 (24)	18 (4)
Echocardiogram	272 (48)	97 (36)	11 (4)
Long-term ECG monitoring	198 (35)	70 (35)	29 (15)
Stress ECG	43 (8)	6 (14)	2 (5)
Orthostatic hypotension test	114 (20)	31 (27)	23 (20)
Electrophysiological study	29 (5)	3 (10)	3 (10)
Tilt table	60 (11)	34 (57)	28 (47)
Carotid sinus massage	61 (11)	5 (8)	5 (8)
Implantable loop recorder	38 (7)	7 (18)	7 (18)
MRI cerebrum	25 (4)	6 (24)	3 (12)*
CT cerebrum	143 (25)	25 (17)	4 (3)*
Electroencephalogram	48 (8)	10 (21)	10 (21)*

Table 2. The Total Number of Tests Used During First Admission and Workup

Test

Number (%)

Abnormal test (%)

Definite diagnosis
Diagnostic yield of test (%)

ECG: electrocardiogram; MRI: magnetic resonance imaging; EP: electrophysiological; CT: computed tomography. *These 17 patients were all diagnosed with neurological disease during the workup, primarily epilepsy, thus the diagnostic yield was as counted, but the patients were probably ultimately classified wrongly as syncopal origin.

Total tests

2601

632 (24)

165 (6)

Laboratory and blood results

570 (100)

ECG

569 (100)

235 (41)

22 (4)

Telemetry

431 (76)

103 (24)

18 (4)

Echocardiogram

272 (48)

97 (36)

11 (4)

Long-term ECG monitoring

198 (35)

70 (35)

29 (15)

Stress ECG

43 (8)

6 (14)

2 (5)

Orthostatic hypotension test

114 (20)

31 (27)

23 (20)

Electrophysiological study

29 (5)

3 (10)

Tilt table

60 (11)

34 (57)

28 (47)

Carotid sinus massage

61 (11)

5 (8)

Implantable loop recorder

38 (7)

7 (18)

MRI cerebrum

25 (4)

6 (24)

3 (12)*

CT cerebrum

143 (25)

25 (17)

4 (3)*

Electroencephalogram

48 (8)

10 (21)

10 (21)*

**Table 3.** Number of Tests Performed During First Admission in the 207 (35%) Patients Where the Etiological Diagnosis was Made During Admission
Test	Number (%)	Abnormal test (%)	Definite diagnosis. Diagnostic yield of test during admission (%)
*These 3 patients received another definitive diagnosis than syncope and were ultimately classified wrongly by the physician.
Laboratory and blood results	207 (100)	NA	NA
ECG	207 (100)	83 (40)	17 (8)
Telemetry	144 (70)	44 (31)	16 (11)
Echocardiogram	72 (35)	33 (46)	7 (10)
Stress ECG	7 (3)	1 (14)	1 (14)
Orthostatic hypotension test	32 (16)	20 (63)	15 (47)
Electrophysiological study	5 (2)	1 (20)	1 (20)
Carotid sinus massage	10 (5)	2 (20)	2 (20)
CT cerebrum	29 (14)	9 (31)	3 (10)*

Table 3. Number of Tests Performed During First Admission in the 207 (35%) Patients Where the Etiological Diagnosis was Made During Admission

Test

Number (%)

Abnormal test (%)

Definite diagnosis.
Diagnostic yield of test during admission (%)

*These 3 patients received another definitive diagnosis than syncope and were ultimately classified wrongly by the physician.

Laboratory and blood results

207 (100)

ECG

207 (100)

83 (40)

17 (8)

Telemetry

144 (70)

44 (31)

16 (11)

Echocardiogram

72 (35)

33 (46)

7 (10)

Stress ECG

7 (3)

1 (14)

Orthostatic hypotension test

32 (16)

20 (63)

15 (47)

Electrophysiological study

5 (2)

1 (20)

Carotid sinus massage

10 (5)

2 (20)

CT cerebrum

29 (14)

9 (31)

3 (10)*

**Table 4.** Number of Tests Performed During Workup in 102 Patients Where the Etiological Diagnosis Was Unknown at Discharge but Apparent After Workup
Test	Number (%)	Abnormal test (%)	Definite diagnosis. Diagnostic yield of test (%)
*These 11 tests were performed in patients who received another definitive diagnosis than syncope and were initially classified wrongly by the discharging physician.
Echocardiogram	74 (73)	25 (34)	5 (7)
Long-term ECG monitoring	72 (71)	32 (44)	19 (26)
Stress ECG	13 (13)	1 (8)	1 (8)
Orthostatic hypotension test	30 (29)	8 (27)	7 (23)
Electrophysiological study	10 (10)	2 (20)	2 (20)
Tilt table	36 (35)	25 (69)	22 (61)
Carotid sinus massage	36 (35)	3 (8)	3 (8)
Implantable loop recorder	12 (12)	6 (50)	6 (50)
MRI cerebrum	10 (10)	4 (40)	3 (75)*
CT cerebrum	26 (25)	5 (19)	4 (15)*
Electroencephalogram	13 (13)	4 (31)	4 (31)*

Table 4. Number of Tests Performed During Workup in 102 Patients Where the Etiological Diagnosis Was Unknown at Discharge but Apparent After Workup

Test

Number (%)

Abnormal test (%)

Definite diagnosis.
Diagnostic yield of test (%)

*These 11 tests were performed in patients who received another definitive diagnosis than syncope and were initially classified wrongly by the discharging physician.

Echocardiogram

74 (73)

25 (34)

5 (7)

Long-term ECG monitoring

72 (71)

32 (44)

19 (26)

Stress ECG

13 (13)

1 (8)

Orthostatic hypotension test

30 (29)

8 (27)

7 (23)

Electrophysiological study

10 (10)

2 (20)

Tilt table

36 (35)

25 (69)

22 (61)

Carotid sinus massage

36 (35)

3 (8)

Implantable loop recorder

12 (12)

6 (50)

MRI cerebrum

10 (10)

4 (40)

3 (75)*

CT cerebrum

26 (25)

5 (19)

4 (15)*

Electroencephalogram

13 (13)

4 (31)

4 (31)*

**Table 5.** Etiology of Syncope After Discharge and After Workup
Etiology	Number (%) after discharge	Number (%) after workup	P value	Age < 65 years	Age ≥ 65 years	P-value between age groups
¹Vasovagal, situational and carotid sinus syncope; ²Primary autonomic failure, secondary autonomic failure, drug induced and volume depletion;³Pulmonary embolism, angina and left main stenosis, digoxin intoxication and pacemaker induced tachycardia;⁴Epilepsy, psychogenic pseudosyncope, stroke, intracerebral tumor, fatigue and collapse.
Reflex¹	87 (15)	117 (21)	< 0.001	80 (68)	37 (32)	< 0.001
Orthostatic hypotension²	41 (7)	55 (10)	< 0.001	15 (27)	40 (73)	0.022
Cardiac	72 (11)	102 (18)	< 0.001	19 (19)	83 (81)	< 0.001
Ventricular arrhythmias	15 (3)	18 (3)
Sick sinus syndrome	14 (2)	20 (4)
Advanced second- or third-degree AV block	27 (5)	44 (8)
Structural cardiac disease	8 (1)	12 (2)
Other cardiogenic³	8 (1)	8 (1)
Unknown	363 (64)	272 (48)	< 0.001	115 (42)	157 (58)	0.808
Non syncopal events⁴	7 (1)	24 (4)	< 0.001	9 (38)	15 (62)	0.666

Table 5. Etiology of Syncope After Discharge and After Workup

Etiology

Number (%) after discharge

Number (%) after workup

P value

Age < 65 years

Age ≥ 65 years

P-value between age groups

¹Vasovagal, situational and carotid sinus syncope; ²Primary autonomic failure, secondary autonomic failure, drug induced and volume depletion;³Pulmonary embolism, angina and left main stenosis, digoxin intoxication and pacemaker induced tachycardia;⁴Epilepsy, psychogenic pseudosyncope, stroke, intracerebral tumor, fatigue and collapse.

Reflex¹

87 (15)

117 (21)

< 0.001

80 (68)

37 (32)

< 0.001

Orthostatic hypotension²

41 (7)

55 (10)

< 0.001

15 (27)

40 (73)

0.022

Cardiac

72 (11)

102 (18)

< 0.001

19 (19)

83 (81)

< 0.001

Ventricular arrhythmias

15 (3)

18 (3)

Sick sinus syndrome

14 (2)

20 (4)

Advanced second- or third-degree AV block

27 (5)

44 (8)

Structural cardiac disease

8 (1)

12 (2)

Other cardiogenic³

8 (1)

Unknown

363 (64)

272 (48)

< 0.001

115 (42)

157 (58)

0.808

Non syncopal events⁴

7 (1)

24 (4)

< 0.001

9 (38)

15 (62)

0.666

**Table 6.** Selected Pharmacotherapy and Comorbidity According to Diagnosis After Workup
Pharmacotherapy and Comorbidity	Unknown N = 272	Cardiac N = 102	Orthostatic N = 55	Reflex N = 117	Other causes N = 24
CHF: congestive heart failure; IHD: ischemic heart disease; AMI: acute myocardial infarction; AF: atrial fibrillation; ACE: angiotensin converting enzyme; ARB: angiotensin receptor blocker.
Comorbidity (in %)
CHF	28 (10)	24 (23)	6 (11)	2 (2)	1 (4)
IHD	67 (24)	39 (38)	11 (20)	6 (5)	5 (20)
AMI	47 (17)	27 (28)	9 (16)	4 (3)	0 (0)
AF	39 (14)	25 (24)	5 (9)	7 (6)	2 (8)
Other arrhythmias	12 (4)	15 (14)	4 (7)	4 (3)	2 (8)
Stroke	34 (12)	19 (18)	12 (22)	3 (2)	4 (15)
Diabetes	21 (8)	15 (15)	12 (22)	5 (4)	2 (8)
Cardiac device	10 (4)	6 (6)	3 (5)	2 (2)	0 (0)
Depression	12 (4)	6 (6)	6 (11)	1 (1)	0 (0)
Pharmacotherapy (in %)
Beta blockers	67 (25)	41 (39)	18 (33)	14 (12)	1 (4)
ACE/ARB	104 (38)	53 (51)	27 (49)	20 (17)	8 (31)
Thiazide	54 (20)	18 (17)	14 (25)	18 (15)	7 (27)
Loop diuretics	40 (15)	30 (29)	11 (20)	3 (3)	2 (8)
Anxiolytics	33 (12)	9 (9)	8 (15)	3 (3)	3 (12)
Antipsycotics	14 (5)	3 (3)	6 (11)	2 (2)	2 (8)
Antidepressants	43 (16)	-12	11 (20)	8 (7)	3 (12)

Table 6. Selected Pharmacotherapy and Comorbidity According to Diagnosis After Workup

Pharmacotherapy and Comorbidity

Unknown
N = 272

Cardiac
N = 102

Orthostatic
N = 55

Reflex
N = 117

Other causes
N = 24

CHF: congestive heart failure; IHD: ischemic heart disease; AMI: acute myocardial infarction; AF: atrial fibrillation; ACE: angiotensin converting enzyme; ARB: angiotensin receptor blocker.

Comorbidity (in %)

CHF

28 (10)

24 (23)

6 (11)

2 (2)

1 (4)

IHD

67 (24)

39 (38)

11 (20)

6 (5)

5 (20)

AMI

47 (17)

27 (28)

9 (16)

4 (3)

0 (0)

39 (14)

25 (24)

5 (9)

7 (6)

2 (8)

Other arrhythmias

12 (4)

15 (14)

4 (7)

4 (3)

2 (8)

Stroke

34 (12)

19 (18)

12 (22)

3 (2)

4 (15)

Diabetes

21 (8)

15 (15)

12 (22)

5 (4)

2 (8)

Cardiac device

10 (4)

6 (6)

3 (5)

2 (2)

0 (0)

Depression

12 (4)

6 (6)

6 (11)

1 (1)

0 (0)

Pharmacotherapy (in %)

Beta blockers

67 (25)

41 (39)

18 (33)

14 (12)

1 (4)

ACE/ARB

104 (38)

53 (51)

27 (49)

20 (17)

8 (31)

Thiazide

54 (20)

18 (17)

14 (25)

18 (15)

7 (27)

Loop diuretics

40 (15)

30 (29)

11 (20)

3 (3)

2 (8)

Anxiolytics

33 (12)

9 (9)

8 (15)

3 (3)

3 (12)

Antipsycotics

14 (5)

3 (3)

6 (11)

2 (2)

2 (8)

Antidepressants

43 (16)

-12

11 (20)

8 (7)

3 (12)

**Table 7.** Predominant Prodromal Symptom and Final Etiological Diagnosis
Predominant prodrome	Etiology
Palpitations (%)	2 (2)	0	2 (2)	12 (4)	0.045
Light-headedness, nausea and sweating (%)	19 (19)	16 (29)	58 (50)	54 (20)	< 0.001
Chest pain (%)	1 (1)	3 (5)	0	5 (2)	0.330
During exercise (%)	3 (3)	0	0	9(3)	0.527

Table 7. Predominant Prodromal Symptom and Final Etiological Diagnosis

Predominant prodrome

Etiology

Cardiac

Orthostatic

Reflex

Unknown

P value

Palpitations (%)

2 (2)

12 (4)

0.045

Light-headedness, nausea and sweating (%)

19 (19)

16 (29)

58 (50)

54 (20)

< 0.001

Chest pain (%)

1 (1)

3 (5)

5 (2)

0.330

During exercise (%)

3 (3)

9(3)

0.527