Responses to the prolonged head-up tilt followed by sublingual nitrate provocation in asymptomatic older adults

'Front-loaded' head-up tilt table testing: validation of a rapid first line nitrate-provoked tilt protocol for the diagnosis of vasovagal syncope

Head-up tilt testing is the investigation of choice in the diagnosis of vasovagal syncope. The test is time consuming and labour intensive, with conventional tilt testing taking up to 45 min. We compared a shortened 'front-loaded' 20-min glyceryl trinitrate-provoked head-up tilt (FLGTN-HUT) with the standard 40-min passive tilt (HUT) as first line investigations in patients with unexplained syncope and asymptomatic controls. In the study, 149 consecutive patients with unexplained syncope and 83 asymptomatic controls were enrolled. Subjects were randomly assigned to FLGTN-HUT (800 mcg, metred spray) or HUT, then the opposite tilt-test 1 week later. Seventeen (11.4%) patients had diagnostic haemodynamic changes and symptom reproduction during HUT and 54 (36.2%) during FLGTN-HUT. A total of 24.8% more patients had a positive test with FLGTN-HUT than with passive HUT (95% CI: 16.3%, 33.4%). Nine (10.8%) controls had significant haemodynamic changes during HUT and 23 (27.7%) during GTN provocation. Seven controls had haemodynamic changes on both HUT and FLGTN-HUT testing. The controls group had 16.8% more significant haemodynamic changes with FLGTN-HUT than with HUT (95% CI: 0.06, 27.4). The front-loaded GTN protocol provided a higher diagnostic rate than passive tilt testing, and provides a rapid alternative to conventional methods, though false positivity rates are higher.

Cardiovascular assessment of falls in older people

Falls in older people can be caused by underlying cardiovascular disorders, either because of balance instability in persons with background gait and balance disorders, or because of amnesia for loss of consciousness during unwitnessed syncope. Pertinent investigations include a detailed history, 12-lead electrocardiography, lying and standing blood pressure, carotid sinus massage (CSM), head-up tilt, cardiac electrophysiological tests, and ambulatory blood pressure and heart rate monitoring, which includes external and internal cardiac monitoring. The presence of structural heart disease predicts an underlying cardiac cause. Conversely, the absence of either indicates that neurally mediated etiology is likely. CSM and tilt-table testing should be considered in patients with unexplained and recurrent falls. Holter monitoring over 24 hours has a low diagnostic yield. Early use of an implantable loop recorder may be more cost-effective. A dedicated investigation unit increases the likelihood of achieving positive diagnoses and significantly reduces hospital stay and health expenditure.

Elderly patients with unexplained syncope: What should be considered a positive tilt test response?

INTRODUCTION

Syncope is a common problem and can lead to serious consequences in the elderly. Tilt test is useful to investigate recurrent syncope, but few studies have investigated the hemodynamic responses of this population to tilt test.

OBJECTIVE

To describe the tilt test responses of elderly patients with recurrent syncope of unknown origin and to determine the occurrence of altered cardiovascular autonomic function in a subset of those with the diagnosis of dysautonomic pattern to the tilt test.

METHODS

Elderly patients (n=165; >60 years old) who sought medical assistance because of recurrent syncope during 18 months were initially enrolled and submitted to a two-stage, nitroglycerin-potentiated tilt test. A subset of patients who presented with dysautonomic response to tilt test performed clinical autonomic tests.

RESULTS

The most frequent cause of syncope during tilt test was the dysautonomic pattern (43%), followed by mixed type neurocardiogenic syncope (35%). Most patients who remained asymptomatic during tilt test showed clear abnormal hemodynamic response during the exam.

CONCLUSION

Autonomic dysfunction, which can be found during tilt test, is probably an important cause of syncope in the elderly, regardless of the occurrence of symptoms during the tilt test.

Causes of syncope in patients with Alzheimer's disease treated with donepezil

INTRODUCTION

Treatment of Alzheimer's disease (AD) with cholinesterase inhibitors carries a theoretical risk of precipitating bradycardia. Though syncope occurs in patients with AD, its aetiology is unclear. The aim of this study was to determine the causes of syncope in patients with AD who were treated with donepezil and hospitalised for evaluation of syncope.

METHODS

We studied 16 consecutive patients (12 women, 4 men) with AD aged 80 +/- 4 years who were hospitalised for evaluation of syncope. All patients underwent staged evaluation, ranging from physical examination to electrophysiological testing.

RESULTS

The mean dose of donepezil administered was 7.8 mg/day, and the mean duration of donepezil treatment at the time of syncope was 12 +/- 8 months. A cause of syncope was identified in 69% of patients. Carotid sinus syndrome was observed in three patients, complete atrioventricular block in two patients, sinus node dysfunction in two patients, severe orthostatic hypotension in two patients and paroxysmal atrial fibrillation in one patient. A brain tumour was discovered in one patient. No cause of syncope was found in 31% of patients despite comprehensive investigation. Repetition of the investigations after discontinuation of donepezil was noncontributory.

CONCLUSION

In patients with AD treated with donepezil, a noninvasive evaluation identified a probable cause of syncope in over two-thirds of patients. Cardiovascular abnormalities were predominant. Noninvasive evaluation is recommended before discontinuing treatment with cholinesterase inhibitors in patients with AD and unexplained syncope.

Single-stage adenosine tilt testing in patients with unexplained syncope

INTRODUCTION

We previously have shown that a 3-minute single-stage adenosine tilt test has a diagnostic yield comparable to a two-stage protocol consisting of a 30-minute drug-free tilt followed by a 15-minute isoproterenol tilt. In this study, we sought to further define the clinical utility of adenosine tilt testing in patients with unexplained syncope by prospectively evaluating test specificity and determining predictors of a positive test response.

METHODS AND RESULTS

The specificity of single-stage adenosine tilt testing was determined using 30 control subjects. To determine the diagnostic yield of this protocol, adenosine tilts were performed in 129 patients with unexplained syncope. The adenosine tilt test protocol had high specificity (100%) but a low overall diagnostic yield (18%). However, the yield was affected significantly by age. In patients </=40 years of age, the tilt test was positive in 15 (41%) of 37 patients, which was significantly greater than the yield in patients between the ages of 41 and 64 years (6/41 patients [15%], P = 0.012) and those >/=65 years of age (2/41 patients [5%], P < 0.0001).

CONCLUSION

These data support single-stage adenosine tilt testing in patients </=40 years of age because the diagnostic yield of the test is maximal in this group and the test can be completed in </=3 minutes. Conversely, the diagnostic yield of adenosine tilt testing in patients >40 years of age is low, suggesting that the clinical utility of this protocol is limited in these patients.

Comparison between isoproterenol and nitroglycerin sensitized head-upright tilt in patients with unexplained syncope and negative or positive passive head-up tilt response

It is unknown if the head-upright tilt test in patients who receive isoproterenol and nitroglycerin can identify different populations with vasovagal syncope. The aim of this study was to compare the positive or negative responses to passive tilt between isoproterenol- and nitroglycerin-sensitized upright tilt. Ninety-six patients referred for unexplained recurrent syncope underwent passive tilt (45 minutes at 70 degrees angle), which was then systematically followed, within the same session and in a random order, by a 20-minute tilt at a 70 degrees angle after administration of nitroglycerin (NTG-tilt) and 10-minute tilt at a 70 degrees angle with a continuous infusion of isoproterenol (ISO-tilt). NTG-tilt led to significantly more positive responses than passive tilt or ISO-tilt (55% vs 34% vs 42%, respectively). In the subgroup of patients with a positive response during passive tilt, the percentage of positive responses with NTG-tilt was significantly higher than with ISO-tilt (94% vs 67%). The agreement between NTG-tilt and ISO-tilt was very weak (Kappa coefficient 0.06). In the subgroup of patients with a negative response during passive tilt, the percentage of positive responses between NTG-tilt and ISO-tilt was similar (35% vs 29%). The agreement between NTG-tilt and ISO-tilt was good (Kappa coefficient 0.34). NTG-tilt led to a higher number of positive responses than ISO-tilt, especially when passive tilt outcome was positive. These 2 pharmacologic agents may identify 2 different subpopulations of patients because of their specific pharmacologic actions.