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Diagnostic Patterns and Temporal Trends in the Evaluation of Adult Patients Hospitalized With Syncope
Luis A. Pires, MD;
Jangadeesh R. Ganji, MD;
Regina Jarandila, RN;
Robert Steele, MD
Arch Intern Med. 2001;161:1889-1895.
ABSTRACT
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Background Syncope is a common clinical problem that is often difficult and expensive
to diagnose. We examined diagnostic patterns and trends and use of specialty
consultations in the evaluation of syncope.
Methods We retrospectively reviewed the medical records of consecutive adult
patients hospitalized with the principal diagnosis of syncope (International Classification of Diseases, Ninth Revision, code 780.2)
during 1994 and 1998 at 2 community teaching hospitals.
Results A total of 649 patients (57% female) with a mean (±SD) age of
68 ± 15 years were identified in 1994 (n = 451) and 1998 (n = 198).
Three hundred forty-one patients (53%) underwent at least 1 neurologic test,
including brain computed tomographic (CT) scan (n = 283), electroencephalography
(n = 253), carotid Doppler echocardiography (n = 185), and brain magnetic
resonance imaging (n = 10). Only brain CT scan and electroencephalography
yielded diagnoses in 5 (2%) and 6 patients (2%), respectively with history
consistent with seizures or stroke. Cardiovascular tests providing the highest
diagnostic yields (postural blood pressure check in 52 [30%], head-up tilt-table
test in 32 [24%], and electrophysiologic study in 5 [16%]) were used in 176
(27%), 132 (20%), and 31 patients (5%), respectively. Differences in the use
of some tests were noted at the participating hospitals and over time (1994
vs 1998). The total number of diagnosed cases was similar for patients undergoing
evaluation by primary care physicians alone (65/103 [63%]), compared with
cardiology (48/85 [56%]), neurology (29/48 [60%]), or both (81/141 [57%]).
After a mean (±SD) length of stay of 5 ± 4 days, 320 (49%) of
649 cases remained undiagnosed.
Conclusions Despite a reduction in the use of some tests (eg, brain CT scan and
carotid Doppler) over time, lower-yield neurologic tests were overused and
higher-yield cardiovascular tests were likely underused. The untargeted, seemingly
random use of specialty evaluations did not seem to contribute to an increase
in the overall number of diagnosed cases. Increased use of specific tests
directed by history and results of physical examination may improve diagnostic
yield and decrease the cost of evaluating syncope.
INTRODUCTION
SYNCOPE, DEFINED as sudden loss of consciousness and postural tone from
which the patient recovers spontaneously, is common,1-2
often disabling,3 potentially life threatening,4 and difficult and expensive to diagnose.5-6
Data from the early 1980s showed that in nearly half of these patients, the
cause of syncope is not determined after initial, often extensive, investigations.1, 4-8
More recently, the use of the head-up tilt-table (HUTT) test and electrophysiologic
study (EPS) has reduced the proportion of undiagnosed cases to 10% to 26%.9-11 However, these tests
are useful only in properly selected cases and are best guided by a careful
history and results of physical examination.12-13
The undirected use of any of the available diagnostic tests is generally of
low yield and not cost-effective. For instance, for many years routine neurologic
testing has been a mainstay in the evaluation of syncope, although such tests
(eg, electroencephalography [EEG]) are rarely helpful in those without focal
neurologic signs or a history suggestive of seizure.1, 5, 14
Given the high prevalence of syncope1-2
and its economic impact,6, 15-16
a cost-effective evaluation is highly desirable. However, despite expert recommendations,6, 12-14 it
is unclear whether the diagnostic approach of patients with syncope has changed
significantly.
The goals of this study were to assess patterns, temporal trends, and
results of specialty consultations in the examination of consecutive adult
patients hospitalized with the diagnosis of syncope at 2 community teaching
hospitals during 1994 and 1998.
PATIENTS AND METHODS
PATIENT POPULATION
Included in this study were consecutive adult patients (aged  18
years) with the principal diagnosis of syncope admitted during two 12-month
periods (1994 and 1998) to 2 community teaching hospitals with separate staff
except for cardiac electrophysiology. Patients were identified through a retrospective
review of medical records of all patients who were assigned a principal diagnosis
of syncope (International Classification of Diseases, Ninth
Revision, code 780.2) at the time of admission. Patients undergoing
initial evaluation at another institution and transferred for a specific predetermined
diagnostic test (eg, EPS) were excluded.
DATA ANALYSIS
Diagnostic tests and procedures, including frequency of use and diagnostic
yields, and the use of specialty evaluations (cardiovascular and neurologic)
were obtained directly from the patients' medical records. A test or procedure
was considered diagnostic when the result, alone or combined with the history
of the patient's syncope, explained the cause of syncope. We used documented
details about the patients' history and results of physical examination with
the results of diagnostic tests to arrive at the final diagnoses, based on
previously described criteria1, 4
and presented in the following 4 broad categories8:
vasovagal/psychogenic, neurologic, cardiac (arrhythmic and mechanical), and
drug/metabolic. Vasovagal syncope was diagnosed in patients with typical prodromal
symptoms and/or a positive HUTT finding.17
A psychogenic diagnosis (eg, hysteria) required confirmation by a psychiatric
consultant. Neurologic causes of syncope required specific clinical presentations
plus confirmation by a staff neurologist. For seizure, the patient had to
have had witnessed seizurelike activities and/or postictal states, with or
without a positive EEG finding, and focal findings on examination in case
of stroke/transient ischemic attack. Arrhythmic syncope was based on documented
(eg, symptomatic arrhythmia recorded using telemetry monitoring) or presumed
(eg, induced sustained ventricular tachycardia during EPS) arrhythmic events.
Mechanical cardiac causes of syncope (eg, aortic stenosis) and acute myocardial
infarction required compatible clinical presentations plus supportive documentation,
eg, typical echocardiographic features and elevations in cardiac enzyme levels,
respectively. Drug/metabolic causes of syncope included, eg, severe hypoglycemia,
alcohol intoxication, or orthostatic hypotension. Orthostatic hypotension
was implicated as the cause of syncope when there was a decrease in systolic
blood pressure of greater than 20 mm Hg associated with dizziness or syncope,
at the patient's bedside or during HUTT.
To evaluate practice patterns between hospitals, we compared the results
among patients hospitalized in 1994 at Sinai-DMC and St John Hospital, Detroit,
Mich. In assessing practice trends, we compared the findings from patients
admitted in 1994 vs 1998 at St John Hospital only.
Numerical data were compared by t,  2, or Fisher exact test, and data are presented as mean ± SD. P<.05 was considered statistically significant.
RESULTS
PATIENT CHARACTERISTICS
A total of 649 patients were identified during the 1994 (n = 451) and
1998 (n = 198) periods. In 1994, 252 patients were admitted at Sinai-DMC and
199 at St John Hospital; in 1998, 198 patients were hospitalized at St John
Hospital. The patients' clinical characteristics are shown in Table 1. Patients undergoing evaluation at St John Hospital in 1994
and 1998 were older, on average, than those admitted at Sinai-DMC in 1994
(71 vs 62 years; P<.01) and had a higher incidence
of coronary artery disease (36% [1994] and 34% [1998] vs 20%; P<.01); otherwise the patient groups shared similar clinical characteristics
(Table 1).
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Table 1. Clinical Characteristics of the Study Patients*
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FREQUENCY AND RESULTS OF DIAGNOSTIC TESTS
Table 2 depicts the types,
frequency, and results of neurologic and cardiovascular diagnostic tests and
procedures used in the evaluations in all 649 patients. Three hundred forty-one
(53%) patients underwent at least 1 neurologic test, including brain CT scan,
EEG, carotid Doppler, and brain magnetic resonance imaging (MRI) in 283 (44%),
253 (39%), 185 (29%), and 10 patients (2%), respectively. These tests identified
some type of abnormalities in 31 (11%), 44 (17%), 19 (10%), and 3 cases (30%),
respectively. Abnormal findings on brain CT scan (atrophy in 11, old infarct
in 15, and acute infarct in 5), EEG (generalized or focal slowing in 38 and
epileptiform discharge in 6), carotid Doppler (70% arterial stenosis in
19), and brain MRI (nonspecific atrophy in 3) were not diagnostic in any of
the patients whose clinical presentations were inconsistent with stroke/transient
ischemic attack or seizure (Table 2).
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Table 2. Frequency and Results of Various Diagnostic Tests*
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When we included continuous telemetry (performed in all patients), all
of the 649 patients underwent at least 1 cardiovascular test, accounting for
an average of 2.2 tests per patient. Continuous telemetry (649 [100%]), Holter
monitoring (193 [30%]), and echocardiography (277 [43%]) yielded diagnoses
in only 7 (1%), 6 (3%) and 3 cases (1%), respectively (Table 2). Postural blood pressure (BP) check, HUTT, and EPS were
performed less frequently (in 27%, 20%, and 5% of patients, respectively),
but the findings were more often abnormal (and diagnostic), ie, in 43% (30%),
31% (24%), and 45% (16%) of patients, respectively (Table 2). Stress testing and cardiac catheterization, performed
generally to rule out ischemia in 10% and 2% of patients, respectively, yielded
no definitive diagnosis (Table 2).
Carotid sinus pressure, performed in 24 of 31 cases during EPS, was nondiagnostic
in all cases; in the remaining 625 patients (96%), the procedure was not performed
or the results were not recorded.
In addition, all 649 patients underwent routine blood tests, chest roentgenography,
and electrocardiography. Four patients received a diagnosis of acute myocardial
infarction on the basis of elevated cardiac enzyme levels and typical electrocardiographic
changes; and 2 patients received a diagnosis of pulmonary embolism on the
basis of findings of ventilation-perfusion scans and pulmonary angiography
performed in 17 (3%) and 2 patients (0.3%), respectively.
COMPARISON OF EVALUATION PATTERNS BETWEEN HOSPITALS
The results and diagnostic yield of the tests used in the assessment
of patients admitted in 1994 at Sinai-DMC (n = 252) and St John Hospital (n
= 199) are compared in Table 3.
Brain CT scan was used more frequently at St John Hospital than at Sinai-DMC
(61% vs 38%; P<.01); EEG was used more frequently
at Sinai-DMC (46% vs 32%; P = .01); but use of carotid
Doppler (33% vs 35%; P = .34) and brain MRI (0.4%
vs 0.5%; P = .43) was equivalent at both hospitals.
The diagnostic yields of neurologic tests were equally low at both hospitals
(Table 3). Among cardiovascular
tests, postural BP was determined less frequently (6% vs 41%; P<.001) but the findings were more often abnormal (60% vs 37%; P<.01) at Sinai-DMC than at St John Hospital; otherwise
all tests were equally used and identified comparable abnormal and diagnostic
findings among patients at both hospitals (Table 3). The hospital length of stay was longer for patients hospitalized
at St John Hospital compared with Sinai-DMC (5.8 ± 4.1 vs 4.5 ±
2.9 days; P<.01).
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Table 3. Comparison of Diagnostic Tests and Results*
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TRENDS IN EVALUATION
Comparisons of diagnostic evaluation and results among patients at St
John Hospital in 1994 vs 1998 are shown in Table 4. Fewer brain CT scans (33% vs 61%; P<.01)
and carotid Doppler (17% vs 35%; P<.01) were performed
in 1998 compared with 1994, but a similar proportion of patients underwent
EEG (37% vs 32%), and there was a trend toward an increase in the use of brain
MRI (4% vs 0.5%). These tests were of comparably low diagnostic yields in
patients undergoing evaluation in 1994 and 1998 (Table 4). A smaller proportion of patients underwent echocardiography
(23% vs 51%; P<.01) and more underwent Holter
monitoring (35% vs 24%; P<.01) in 1998 compared
with 1994. The other cardiovascular tests, including HUTT and EPS, were used
with equal frequencies during both periods, uncovering a comparable number
of nonspecific and diagnostic abnormal findings during 1994 and 1998 (Table 4). The length of stay was similar
for patients undergoing evaluation in 1994 and 1998 (5.8 ± 4.1 vs 5.2
± 2.9 days).
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Table 4. Comparison of Diagnostic Evaluation in Patients by Year*
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FINAL DIAGNOSIS AND USE OF SPECIALTY EVALUATIONS
After a mean length of stay of 5.1 ± 3.6 days (range, 1-28 days),
the cause of syncope was established or, in some cases, presumed, in only
329 cases (51%). Among the 329 diagnosed cases, 71 (22%) were vasovagal/psychogenic,
63 (19%) were cardiac (ventricular tachycardia [n = 24], supraventricular
tachycardia [n = 5], bradyarrhythmia [n = 21], myocardial infarction [n =
8], severe aortic stenosis [n = 2], hypertrophic cardiomyopathy [n = 1], pulmonary
embolism [n = 2]), 34 (10%) were neurologic (stroke/TIA [n = 20] and seizures
[n = 14]), and 161 (49%) were drug/metabolic (Table 5). The categorical breakdown of causes of syncope reflected
the types of specialty evaluations. There were more cardiac causes among those
patients seen by cardiologists (37%) compared with those undergoing evaluation
by other specialties (8%-18%) and, similarly, more neurologic causes (34%
vs 2%-13%) among patients seen by neurologists. Vasovagal/psychogenic (13%)
and drug/metabolic causes (69%), which are more readily determined using histories
and results of physical examinations, were generally identified by primary
care physicians. Specialty consultations from cardiology, neurology, or both
were obtained in 181 (28%), 92 (14%), and 151 patients (23%), respectively,
whereas 225 patients (35%) were examined and treated solely by primary care
physicians. Of the 424 patients (65%) seen by at least 1 specialty consultant,
the causes of syncope were established in 208 (49%) compared with 121 (54%)
of the 225 patients treated solely by primary care physicians.
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Table 5. Final Diagnosis and Subcategories Based on Specialty Consultations*
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The length of stay was longer (6 vs 5 days; P<.05)
for patients undergoing evaluation by neurologists compared with the other
groups (Table 5). During the 1994
period, 174 (69%) of 252 patients at Sinai-DMC compared with 116 (58%) of
199 at St John Hospital underwent at least 1 specialty evaluation. A smaller
proportion of patients treated at St John Hospital in 1998 was seen by consultants
compared with 1994 (98/198 [49%] vs 116/199 [58%]; P
= .04).
COMMENT
MAIN FINDINGS
In this select but relatively large adult patient population hospitalized
with syncope, we found that despite a reduction in the use of some low-yield
diagnostic tests (eg, brain CT scan and carotid Doppler) during the study
periods (1994 and 1998), the approach to patient evaluation did not change
appreciably. Neurologic testing, despite its traditionally low diagnostic
yield, was commonly used, whereas cardiovascular tests providing the highest
diagnostic yields were used relatively infrequently at both participating
hospitals.
HISTORICAL EVALUATION OF SYNCOPE
The evaluation and management of syncope have changed considerably in
the past 2 decades. In the early 1980s, several investigators showed that
the causes of syncope were often not identified, even after extensive testing.1, 4-8
Such findings in turn led to the use of other diagnostic modalities, such
as EPS and HUTT, which have had great impact in patient evaluation when used
in properly selected groups.9-11,13
Whereas in earlier investigations the cause of syncope remained unknown in
approximately 50% of cases, the use of EPS and HUTT have made it possible
to diagnose as many as 90% of cases.9-11
Unfortunately, despite the high cost of syncope evaluation,6, 15-16
our findings suggest insignificant changes in the pattern of evaluation. For
example, neurologic tests, most notably brain CT scan, EEG, and carotid Doppler,
which have been a mainstay in patient evaluation for many years, are still
commonly used, although they are of low diagnostic yield in unselected patients.1, 4-8,13-14,18-19
In patients without focal neurologic findings or history consistent with (primary)
seizures, these tests are of limited use.13-14
Among current patients, abnormal findings on brain CT scans (11%) and EEG
(17%) were rarely diagnostic (in 2% of cases for each modality). Similarly,
carotid Doppler, performed in 185 patients (29%), was not diagnostic in any
of the 19 patients (10%) with abnormal findings. To our knowledge, no study
has examined the usefulness of carotid Doppler in patients with syncope, although
in a study of syncope patients who had received permanent pacemakers, occlusive
disease of uncertain significance was found in 3 of 46 cases.18
Our findings regarding the pattern of use and the diagnostic yield of various
neurologic tests are similar to those of previous reports.19-20
In a study of 297 consecutive patients (mean age, 69 years) admitted in 1993-1994,
Blanck et al19 reported that 1 or more neurologic
tests, which accounted for 15% of the total diagnostic charges, were performed
in more than 50% of cases, yielding a possible diagnosis in only 3 cases.
Nyman et al16 also found a similarly high use
of low-yield neurologic tests in elderly patients with recurrent syncope undergoing
evaluation in 1993. In a later study involving patients admitted in 1995-1996,
Stetson and colleagues20 reported similar results,
ie, nearly half of 100 randomly selected patients (from a total of 901) underwent
some neurologic testing (brain CT scan, 40%), the results of which did not
identify any cause of syncope. Blanck and colleagues19
noted that neurology consultations were obtained in only 53 patients (18%),
indicating that most tests were requested by physicians other than neurologists.
We noted a similar pattern, especially with respect to the use of brain CT
scan (approximately 50% ordered by emergency department physicians) and carotid
Doppler. One would expect that having a neurologist, far more capable of uncovering
pertinent historical facts and focal neurologic abnormalities from a given
patient, would reduce unnecessary tests; unfortunately, current and past data19 suggest that this may not be the case. In addition
to being costly,15, 19 an overemphasis
on neurologic testing and diagnoses can lead to a delay in the identification
(and proper treatment) of previously unrecognized cardiovascular causes of
syncope.21 The length of stay was also longer
(6 vs 5 days; P<.05) among patients who underwent
neurologic evaluation, although other factors may have accounted for the difference.
Encouraging, however, is the fact that fewer patients underwent brain CT scans
(33% vs 61%; P<.01) and carotid Doppler (17% vs
35%; P<.01) in 1998 compared with 1994. On the
other hand, there was no change in frequency of use of EEG (37% vs 32%), and
there was a trend toward a greater use of brain MRI, probably reflecting its
more widespread availability.
Cardiovascular testing, in addition to providing a greater diagnostic
yield,1, 4-13,19-20
also helps to identify high-risk patients1, 4-5,7-8
who would benefit most from a more aggressive workup and appropriate treatment.22-23 Like neurologic testing, cardiovascular
testing is best guided by the findings of history and physical examination.12-13 Tests and procedures, especially
postural BP check, HUTT, and EPS, which have had the greatest impact in the
evaluation of syncope, are often underused.15-16,19-20
Our results show a similar pattern, ie, abnormal findings on postural BP check,
HUTT, and EPS were diagnostic in 30%, 24%, and 16% of cases, respectively,
but were performed in 27%, 20%, and 5%, respectively, of all patients (Table 2). Determination of orthostatic
hypotension is important, since it may account for approximately 15% of syncope
in elderly patients,1, 4 particularly
those taking certain drugs, as was the case with our patients (Table 1). Similarly, we encountered only rare instances (3%) in
which carotid sinus pressure was performed (or reported), yet the procedure
is fairly safe24 and often diagnostic,20 and carotid sinus hypersensitivity may be responsible
for a significant proportion of syncope (and unexplained falls) in older patients.25 On the other hand, Holter monitoring and echocardiography
were performed in 30% and 43% of our patients, respectively, although, as
with our patients (1% and 3%, respectively), they are rarely diagnostic.26-27 However, echocardiography may provide
important data about the presence or absence of structural heart disease,
which has an impact on the patient's prognosis and the selection of additional
diagnostic tests (notably, EPS).5-6,12-13
ETIOLOGY OF SYNCOPE
As in previous reports involving some patients undergoing evaluation
nearly 2 decades ago,1, 4-8
the present study did not identify the causes of syncope in 49% of the cases.
However, the distribution of causes is essentially unchanged, except for a
higher and lower proportion of drug/ metabolic (49%) and vasovagal/psychogenic-related
causes (22%), respectively, among our patients. These discrepancies likely
represent differences in patient population (older in our population) and
the inclusion, in our classification, of orthostatic hypotension under drug/metabolic
causes, largely because cardiovascular-active drugs (taken by 58% of our patients)
were often the causes of syncope. Cardiac (19%) and neurologic (10%) causes,
including their subcategories, were comparable to the results of previous
reports of 7% to 49% and 3% to 32%, respectively.1, 4-8
SPECIALTY EVALUATION
We found no difference in the total number of diagnosed cases among
patients undergoing evaluation solely by primary care physicians compared
with those seen by neurology and cardiovascular specialists (49% vs 54%).
Our findings are similar to those of Mascioli and colleagues,28
who found interdisciplinary cooperation useful in facilitating quicker evaluation
but not in increasing the number of diagnosed cases of syncope. On the other
hand, Vloka et al29 found patients seen by
specialists twice more likely to have a diagnosis of the causes of their syncope.
These discrepant results might reflect the limited role of untargeted specialty
evaluations or, in some cases, appropriate triaging by the referring physicians;
the retrospective nature of our study precluded a determination of which factor
played a greater role. Clearly, fewer of our patients required neurologic
testing and, since nearly half had some form of structural heart disease or
history suggestive of vasovagal syncope, more patients may have received a
diagnosis by means of specialized cardiovascular tests such as EPS and HUTT.12-13 However, in the absence of patient
outcome data, the relative merit of any specific test cannot be made with
certainty. In many cases in which the cause of syncope is readily determined
from results of history and physical examination, estimated at up to 50%,4-6,12 specialty
testing is required to confirm a suspected diagnosis (eg, the use of EPS to
establish suspected ventricular tachycardia).
STUDY LIMITATIONS
Aside from its retrospective nature, our results involved patients undergoing
evaluation at 2 centers only, and the findings may not reflect widespread
practice patterns. However, past data involving patients from different centers
indicated similar results, namely a reliance on the use of low-yield neurologic
tests and low use of higher-yield cardiovascular tests such as EPS and HUTT.18-21 Our
findings do not explain why these patterns persist. Since our data were collected
retrospectively, the established diagnoses or lack thereof, often dependent
on the quality of documented data, may have been biased or incorrect in some
cases. We also did not examine the value of newer diagnostic modalities30 that may have been used after hospital discharge
in some of our patients. Our evaluation was also restricted to hospitalized
patients, and considerable differences might exist in the diagnostic approach
to hospitalized vs nonhospitalized patients with syncope.
CONCLUSIONS
The present data indicate that, although there were some differences
in the pattern (between hospitals) and trend (different times) of evaluation
of syncope, assessment of such patients seems to remain largely unchanged.
Neurologic testing, which is rarely diagnostic, remains a common practice,
whereas more useful cardiovascular tests are used infrequently. A focused
evaluation guided by history, results of physical examination, and use of
specific tests in properly selected cases may improve diagnostic yield and
reduce cost. Elimination of routine neurologic testing in unselected patients
alone could lead to considerable cost savings.
AUTHOR INFORMATION
Accepted for publication January 18, 2001.
Corresponding author and reprints: Luis A. Pires, MD, Cardiac Electrophysiology,
St John Hospital and Medical Center, 22101 Moross, Detroit, MI 48236 (e-mail: luis.pires{at}stjohn.org).
From the Division of Cardiology, Department of Medicine, St John Hospital
and Medical Center, Sinai-DMC, and Wayne State University School of Medicine,
Detroit, Mich.
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