Age and Ageing 2006 35(2):183-185; doi:10.1093/ageing/afj043
© The Author 2006. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org
An early drop in systolic blood pressure predicts a positive tilt table test in elderly patients with unexplained falls or syncope
SIR—Syncope and unexplained falls are frequent reasons
for emergency room visits and hospital admissions in elderly
patients [
1]. Results from the Framingham study showed that
10.5% of the population experienced one or more syncopal events
during a 17-year period of observation. Although the overall
incidence was 6.2 events per 1000 person-years, rates were significantly
higher in elderly subjects (17 per 1000 person-years in males
and 19 per 1000 person-years in females aged
80 years) [
2].
Syncope has been reported to account for 3% of hospital emergency
visits and 1–6% of admissions [
3,
4].
The tilt table test (TTT) is a valuable diagnostic tool to evaluate patients with syncope and unexplained falls [5, 6]. The safety of TTT has been proven in a large number of elderly patients [7]. A positive TTT (TTT+) is defined by a drop in systolic blood pressure (SBP) 50 mmHg, with production of symptoms of pre-syncope or syncope (with or without changes in heart rate) [6, 8]. TTT is usually conducted over 30–45 minutes with a technician and physician in attendance. Shorter durations are often offset by pharmacologic challenge (e.g. glyceryl trinitrate) [6]. The time and staffing requirements make TTT relatively underutilised in most centres. Therefore, any strategy that will allow better case selection or a shortened testing regimen may improve patient care.
The predictors of TTT+ remain largely unknown. It is theoretically possible that global autonomic dysfunction in these patients leads to significant haemodynamic changes during the early phases of tilting, antedating the dramatic blood pressure fall later during the test. However, the co-existence of other factors potentially affecting these changes, such as age, co-morbidities and different drug classes, prompts the need for adequately powered studies to adjust for these variables.
The main aim of our study was to identify the predictors of TTT+. In particular, we speculated that abnormal early haemodynamic responses to tilting might predict the test outcome.
 |
Methods
|
|---|
We performed a TTT on 161 elderly patients (mean age 80.9 ±
5.9 years, mean ± SD), consecutively referred for tilt
table testing in our Institution, for investigation of unexplained
falls and/or syncope/pre-syncope. Exclusion criteria included
history of ventricular arrhythmia, acute coronary syndrome or
cerebrovascular accident within the last 3 months, documented
severe left ventricular outflow tract obstruction, critical
cardiac valvular lesions and Mini-Mental State Examination score
<20 of 30. In addition, 15 subjects declined enrolment because
of either physical inability to stand for the required time
or pain. The study was performed according to the Declaration
of Helsinki after being approved by the local research ethics
committee. Each subject gave written informed consent before
starting the study.
Tilt table test protocol
The tests were performed in a quiet room with dim lighting. Patients remained on their usual medications prior to testing. A qualified nurse and physician were present at all times. Blood pressure and heart rate were measured continuously using finger plethysmograph and surface electrocardiograph, respectively (TaskForce Monitor, CNSystems, Graz, Austria). After 10 minutes of resting supine, patients were tilted to 70° head-up. The tests were limited to 45 minutes. A drop in SBP 50 mmHg with production of any symptoms of pre-syncope or syncope was considered a positive test (with or without changes in heart rate).
|
Statistical analysis
|
|---|
Differences between groups were assessed using two-way ANOVA.
Predictors of TTT+ were identified by performing a backward
regression analysis including the following 16 variables into
the model: age, history of cardiac failure, ischaemic heart
disease, arrhythmia, hypertension, diabetes mellitus, epilepsy,
Parkinson’s disease, cerebrovascular disease, folate/vitamin
B
12 deficiency, current therapy with anti-psychotics, benzodiazepines,
ß-blockers, renin–angiotensin system blockers,
calcium channel blockers and diuretics (SPSS for Windows 11.0,
SPSS Inc, Chicago, IL, USA). Given that at least 10 subjects
per each variable are required for the analysis, a population
size of 161 subjects was considered adequate for the purposes
of the study. A
P value < 0.05 indicated statistical significance.
|
Results
|
|---|
The test was positive in 28 patients (17.4%). Demographic and
clinical characteristics were similar between TTT+ and TTT–
subjects (Table
1). However, patients with TTT+ had a significant
fall in SBP after 2 minutes of tilting compared with TTT–
patients (–13.8 ± 25.8 versus –3.2 ±
16.1 mmHg,
P = 0.006). Thirteen of 28 TTT+ patients (46.4%)
had an SBP fall >15 mmHg. A significantly smaller proportion
of patients (30 of 133, 22.6%,
P = 0.018) with TTT– had
SBP fall >15 mmHg at 2 minutes.
Backward regression analysis showed that the degree of SBP fall at 2 minutes of tilting strongly and independently predicted TTT+ (Table 2). However, the regression model only accounted for 5.8% of the overall variability. The rate of TTT+ in patients with unexplained falls without documented syncope and those with syncope or symptoms of pre-syncope was similar (17.6 and 17.2%).
|
Discussion
|
|---|
In this study, we sought to identify factors which might allow
the early prediction of TTT+. Of the factors we considered,
only the fall in SBP at 2 minutes after tilting had significant
predictive value (
P = 0.014), suggesting the presence of a global
deficit in autonomic function in TTT+ patients. When this fall
was considered as a percentage of baseline SBP, there was even
stronger predictive value (
P = 0.007).
Because it is a relatively simple and integral part of the clinical assessment of patients with falls/syncope, we postulated that the measurement of postural drop in SBP should influence the decision to perform a TTT. However, because it is not feasible to apply a complex mathematical model to every patient’s TTT results, as a practical solution, we applied an SBP drop at 2 minutes >15 mmHg as a cut-off and found that it retained predictive value (P = 0.018). Using a more familiar cut-off of 20 mmHg did not have predictive value, however.
We did not identify or exclude subjects with postural hypotension prior to testing. As postural hypotension is known to be associated with autonomic dysfunction, this may be a confounding variable.
Although these findings might be applied clinically to improve case selection, the fact that the regression model only accounted for a small proportion of the overall variability indicates that there are other factors that need to be considered, in addition to blood pressure changes, before prediction of a positive test may be achieved.
|
Key points
|
|---|
- The TTT is an important, well-tolerated, safe test to investigate syncope and falls in elderly people.
- In our series, 17.4% of tests were positive, which is consistent with previously published data.
- A fall in SBP, 2 minutes after 70° head-up tilt, is associated with a positive test result; however, this cannot be considered as a sole predictor of a positive TTT.
- In a clinical setting, a postural decrease in SBP of 15 mmHg may be a more useful predictor than the traditional cut-off of 20 mmHg.
|
Funding
|
|---|
The study was funded by the Flinders Medical Centre Foundation
and The Flinders Institute for Health and Medical Research.
Derek Yiu1,
Zbigniew Gieroba2,
Karen Hall1,
Sharon Mackintosh3,
Andrew Russell3 and
Arduino A. Mangoni1,*
1 Department of Clinical Pharmacology, Flinders Medical Centre, Bedford Park, South Australia 5042, Australia Tel: (+61) 8 8204 5202 Fax: (+61) 8 8204 5114 Email: arduino.mangoni{at}fmc.sa.gov.au
2 Department of Rehabilitation, Aged Care and Allied Health, Repatriation General Hospital, Daw Park, South Australia 5041, Australia
3 Department of Cardiology, Repatriation General Hospital, Daw Park, South Australia 5041, Australia
* To whom correspondence should be addressed
|
Acknowledgements
|
|---|
We are deeply indebted to Mrs Helen Wright for her superb technical
assistance.
|
References
|
|---|
- Chen-Scarabelli C, Scarabelli TM. Neurocardiogenic syncope. BMJ 2004; 329: 336–41.[Free Full Text]
- Soteriades ES, Evans JC, Larson MG et al. Incidence and prognosis of syncope. N Engl J Med 2002; 347: 878–85.[Abstract/Free Full Text]
- Day SC, Cook EF, Funkenstein H, Goldman L. Evaluation and outcome of emergency room patients with transient loss of consciousness. Am J Med 1982; 73: 15–23.[CrossRef][ISI][Medline]
- Silverstein MD, Singer DE, Mulley AG, Thibault GE, Barnett GO. Patients with syncope admitted to medical intensive care units. JAMA 1982; 248: 1185–9.[Abstract]
- Benditt DG, Ferguson DW, Grubb BP et al. Tilt table testing for assessing syncope. American College of Cardiology. J Am Coll Cardiol 1996; 28: 263–75.[CrossRef][ISI][Medline]
- Parry SW, Kenny RA. The role of tilt table testing in neurocardiocascular instability in older adults. Eur Heart J 2001; 22: 370–2.[Free Full Text]
- Gieroba ZJ, Newton JL, Parry SW, Norton M, Lawson J, Kenny RA. Unprovoked and glyceryl trinitrate-provoked head-up tilt table test is safe in older people: a review of 10 years’ experience. J Am Geriatr Soc 2004; 52: 1913–15.[Medline]
- Brignole M, Alboni P, Benditt DG et al. Guidelines on management (diagnosis and treatment) of syncope—update 2004. Europace 2004; 6: 467–537.[Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
Top
Methods
Statistical analysis