Interventions aimed to increase average 24-h systolic blood pressure reduce blood pressure drops in patients with reflex syncope and orthostatic intolerance

AIMS

Systolic blood pressure (SBP) drops recorded by 24-h ambulatory blood pressure (BP) monitoring (ABPM) identify patients with susceptibility to reflex syncope and orthostatic intolerance. We tested the hypothesis that treatments aimed to increase BP (reassurance, education, and lifestyle measures plus pharmacological strategies) can reduce SBP drops.

METHODS AND RESULTS

This was a multicentre, observational proof-of-concept study performed in patients with reflex syncope and/or orthostatic intolerance and with SBP drops on a screening ABPM. Among 144 eligible patients, 111 underwent a second ABPM on average 2.5 months after start of treatment. Overall, mean 24-h SBP increased from 114.1 ± 12.1 to 121.4 ± 14.5 mmHg (P < 0.0001). The number of SBP drops <90 and <100 mmHg decreased by 61%, 46% during daytime, and by 48% and 37% during 24-h period, respectively (P < 0.0001 for all). The dose-response relationship between difference in 24-h average SBP increase and reduction in number of SBP drops reached a plateau around ∼15 mmHg increase of 24-h SBP. The reduction in SBP drop rate was consistent and significant in patients who underwent deprescription of hypotensive medications (n = 44) and in patients who received BP-rising drugs (n = 67).

CONCLUSION

In patients with reflex syncope and/or orthostatic intolerance, an increase in average 24-h SBP, regardless of the implemented strategy, significantly reduced the number of SBP drops and symptom burden. A 13 mmHg increase in 24-h SBP appears to represent the optimal goal for aborting the maximal number of SBP drops, representing a possible target for future interventions. ClincalTrials.gov identifier: NCT05729724.

Tests for the identification of reflex syncope mechanism

INTRODUCTION

Treatment efficacy of reflex syncope is mainly related to the mechanism underlying syncope rather than its etiology or clinical presentation. The predominant mechanism underlying reflex syncope can be assigned to hypotensive or to bradycardic phenotypes.

AREAS COVERED

Methodology and diagnostic criteria of the most useful tests for the identification of hypotensive and bradycardic phenotypes are discussed. Diagnostic tests for the hypotensive phenotype include office blood pressure measurement with active standing test, home, and wearable blood pressure monitoring, 24-h ambulatory blood pressure monitoring and tilt table test. Diagnostic tests for the bradycardic phenotype include carotid sinus massage, tilt table test and prolonged ECG monitoring.

EXPERT OPINION

In reflex syncope, the documentation of bradycardia/asystole during a syncopal episode does not rule out the possibility that a preceding or parallel hypotensive reflex plays an important role. Similarly, even when a hypotensive mechanism is established, the possibility of an associated cardioinhibitory reflex should be investigated. Investigating the mechanism of reflex syncope is mandatory in patients with severe recurrent episodes, with the final aim to develop a personalized treatment strategy. Recent trials have demonstrated the benefits of personalized mechanism-based therapy, thus highlighting the importance of a comprehensive assessment of the mechanisms underlying syncope.

Case report: Recurrent syncope as initial symptom in a patient with neck lymphoma

Syncope may have many different causes, requiring careful identification. Recurrent syncope is uncommon as an initial symptom of neck lymphoma. Head and neck tumors involving the carotid artery cause syncope associate with carotid sinus syndrome. We report the case of a 72-year-old man who suffered from recurrent syncope due to compression of the right carotid sinus by diffuse large B-cell lymphoma and was successfully treated with immunochemotherapy. Syncope may be an early or sole sign of a neck or head tumor. We should be aware of the possibility of an underlying malignancy in patients with unexplained syncope after initial evaluation.

Complementary effectiveness of carotid sinus massage and tilt testing for the diagnosis of reflex syncope in patients older than 40 years: a cohort study

AIMS

Indications, methodology, and diagnostic criteria for carotid sinus massage (CSM) and tilt testing (TT) have been standardized by the 2018 Guidelines on Syncope of the European Society of Cardiology. Aim of this study was to assess their effectiveness in a large cohort which reflects the performance under 'real-world' conditions.

METHODS AND RESULTS

We analysed all patients who had undergone CSM and TT in the years 2003-2019 for suspected reflex syncope. Carotid sinus massage was performed according to the 'Method of Symptoms'. Tilt testing was performed according to the 'Italian protocol' which consists of a passive phase followed by a sublingual nitroglycerine phase. For both tests, positive test was defined as reproduction of spontaneous symptoms in the presence of bradycardia and/or hypotension. Among 3293 patients (mean age 73 ± 12 years, 48% males), 2019 (61%) had at least one test positive. A bradycardic phenotype was found in 420 patients (13%); of these, 60% were identified by CSM, 37% by TT, and 3% had both test positive. A hypotensive phenotype was found in 1733 patients (53%); of these, 98% were identified by TT and 2% had both TT and CSM positive.

CONCLUSION

The overall diagnostic yield of the tests in patients >40-year-old with suspected reflex syncope was 61%. Both CSM and TT are useful for identifying those patients with a bradycardic phenotype, whereas CSM has a limited value for identifying the hypotensive phenotype. Since the overlap of responses between tests is minimal, both CSM and TT should be performed in every patient over 40 years receiving investigation for unexplained but possible reflex syncope.

Diagnostic Tools to Assess Dysfunction of Autonomic Control of the Heart

The most important diagnostic tool available in assessment of dysfunction of the autonomic control of the heart is the clinical history which must be taken in the greatest possible detail including from the patient and witnesses of the syncope/event. Correct history taking will make many diagnoses avoiding need for further testing and guide further investigation if needed and when appropriate. This paper focusses on the investigation of patients when required, the available tests, their indications, how to perform them for maximum yield and how to interpret the results. Tilt-testing, carotid sinus massage, active stand, cardiovascular autonomic nervous system tests, ambulatory blood pressure and insertable ECG loop recorder are covered.

Pacing in vasovagal syncope: Physiology, pacemaker sensors, and recent clinical trials-Precise patient selection and measurable benefit

The role of pacing in vasovagal syncope (VVS) is considered from a physiological basis. Most VVS patients lose consciousness due to hypotension before severe bradycardia/asystole occurs. Patients who benefit from dual-chamber pacing typically are older with highly symptomatic, late-onset, frequent and severe syncope with short/no prodrome and documented severe cardioinhibition. Tilt testing is of value in patients with recurrent unexplained syncope to identify important hypotensive susceptibility stemming from reduced venous return and stroke volume (SV). A negative tilt test in vasovagal patients with spontaneous asystole documented by an implantable/insertable loop recorder is associated with lower syncope recurrence rates after pacemaker implantation. Pacing may be more effective if triggered by sensor detection of a parameter changing earlier in the reflex than bradycardia when SV may still be relatively preserved. In this regard, detection of right ventricular impedance offers promise. Conservatism is recommended, limiting pacing in VVS to a small subset of symptomatic older patients with clearly documented cardioinhibition and paying particular attention to the timing of loss of consciousness in relation to asystole/bradycardia. Understanding VVS physiology permits application of well-timed, appropriate pacing that yields benefit for highly symptomatic patients.

Carotid Sinus Nerve: A Comprehensive Review of Its Anatomy, Variations, Pathology, and Clinical Applications

The carotid sinus nerve branches off the glossopharyngeal nerve just after its appearance from the jugular foramen, descends along the internal carotid artery, and enters the carotid sinus. There have been many studies of the pathway and the course of the carotid sinus nerve and its communications with surrounding nerves. The intercommunication is exceedingly complicated. Acknowledgment of its anatomic diversity can be important in specific operations dealing with this area. Herein we review the anatomy, variations, pathology, and clinical applications of the carotid sinus nerve.

Usefulness of Tilt Testing and Carotid Sinus Massage for Evaluating Reflex Syncope

Thirty years ago Tilt Testing (TT) was described as a tool in the diagnostic work-up of vasovagal syncope; after its initial success, some flaws have become evident. The concept of hypotensive susceptibility has provided the test a new relevance, shifting from diagnosis only, to therapeutic management. Carotid Sinus Massage (CSM) was introduced at the beginning of the XX century; the technique has evolved over years, whereas the concept of carotid sinus syndrome (CSS) has remained unchanged and uncontested for more than half a century. Nowadays, CSS is a matter of debate, with new classifications and criteria coming on the scene. Recently, a common central etiological mechanism has been hypothesized for reflex syncope, manifesting as CSS, vasovagal syncope or both. In this context, TT and CSM acquire an important role in clinical practice, being essential for a complete diagnosis and treatment. Recalling their historical background, the present paper illustrates an actual interpretation of TT and CSM.

Reflex syncope: Diagnosis and treatment

For the diagnosis of reflex syncope, diligent history-building with the patient and a witness is required. In the Emergency Department (ED), the assessment of syncope is a challenge which may be addressed by an ED Observation Unit or by a referral to a Syncope Unit. Hospital admission is necessary for those with life-threatening cardiac conditions although risk stratification remains an unsolved problem. Other patients may be investigated with less urgency by carotid sinus massage (>40 years), tilt testing, and electrocardiogram loop recorder insertion resulting in a clear cause for syncope. Management includes, in general terms, patient education, avoidance of circumstances in which syncope is likely, increase in fluid and salt consumption, and physical counter-pressure maneuvers. In older patients, those that will benefit from cardiac pacing are now well defined. In all patients, the benefit of drug therapy is often disappointing and there remains no ideal drug. A role for catheter ablation may emerge for the highly symptomatic reflex syncope patient.

Syncope in Patients with Pacemakers

Syncope in a pacemaker patient is a serious symptom but it is rarely due a pacemaker system malfunction. Syncope occurs in about 5 % of patients paced for atrioventricular (AV) block in 5 years, 18% in those paced for sinus node disease in 10 years, 20 % of those paced for carotid sinus syndrome in 5 years and 5-55 % of those older patients paced for vasovagal syncope in 2 years. The vastly different results in vasovagal syncope depend on the results of tilt testing, where those with negative tests approach results in pacing for AV block and those with a positive tilt test show no better results than with no pacemaker. The implication of tilt results is that a hypotensive tendency is clearly demonstrated by tilt positivity pointing to syncope recurrence with hypotension. This problem may be addressed by treatment with vasoconstrictor drugs in those who are suited or, more commonly, a reduction or cessation of hypotensive therapy in hypertensive patients. Other causes of syncope such as tachyarrhythmias are rare. The clinical approach to patients who report syncope is detailed.

The Association of Cardiovascular Disorders and Falls: A Systematic Review

OBJECTIVE

Cardiovascular disorders are recognized as risk factors for falls in older adults. The aim of this systematic review was to identify cardiovascular disorders that are associated with falls, thus providing angles for optimization of fall-preventive care.

DESIGN

Systematic review.

DATA SOURCES

Medline and Embase.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

studies addressing persons aged 50 years and older that described cardiovascular risk factors for falls. Key search terms for cardiovascular abnormalities included all synonyms for the following groups: structural cardiac abnormalities, cardiac arrhythmia, blood pressure abnormalities, carotid sinus hypersensitivity (CSH), orthostatic hypotension (OH), vasovagal syncope (VVS), postprandial hypotension (PPH), arterial stiffness, heart failure, and cardiovascular disease. Quality of studies was assed using the Newcastle-Ottawa Scale.

RESULTS

Eighty-six studies were included. Of studies that used a control group, most consistent associations with falls were observed for low blood pressure (BP) (4/5 studies showing a positive association), heart failure (4/5), and cardiac arrhythmia (4/6). Higher prevalences of CSH (4/6), VVS (2/2), and PPH (3/4) were reported in fallers compared with controls in most studies, but most of these studies failed to show clear association measures. Coronary artery disease (6/10), orthostatic hypotension (9/25), general cardiovascular disease (4/9), and hypertension (7/25) all showed inconsistent associations with falls. Arterial stiffness was identified as an independent predictor for falls in one study, as were several echocardiographic abnormalities.

CONCLUSION

Several cardiovascular associations with falls were identified, including low BP, heart failure, and arrhythmia. These results provide several angles for optimizing fall-preventive care, but further work on standard definitions, as well as the exact contribution of individual risk factors on fall incidence is now important to find potential areas for preventive interventions.

Cardiac Iodine-123-Meta-Iodo-Benzylguanidine Uptake in Carotid Sinus Hypersensitivity

Background

Carotid sinus syndrome is the association of carotid sinus hypersensitivity with syncope, unexplained falls and drop attacks in generally older people. We evaluated cardiac sympathetic innervation in this disorder in individuals with carotid sinus syndrome, asymptomatic carotid sinus hypersensitivity and controls without carotid sinus hypersensitivity.

Methods

Consecutive patients diagnosed with carotid sinus syndrome at a specialist falls and syncope unit were recruited. Asymptomatic carotid sinus hypersensitivity and non-carotid sinus hypersensitivity control participants recruited from a community-dwelling cohort. Cardiac sympathetic innervation was determined using Iodine-123-metaiodobenzylguanidine (123-I-MIBG) scanning. Heart to mediastinal uptake ratio (H:M) were determined for early and late uptake on planar scintigraphy at 20 minutes and 3 hours following intravenous injection of 123-I-MIBG.

Results

Forty-two subjects: carotid sinus syndrome (n = 21), asymptomatic carotid sinus hypersensitivity (n = 12) and no carotid sinus hypersensitivity (n = 9) were included. Compared to the non- carotid sinus hypersensitivity control group, the carotid sinus syndrome group had significantly higher early H:M (estimated mean difference, B = 0.40; 95% confidence interval, CI = 0.13 to 0.67, p = 0.005) and late H:M (B = 0.32; 95%CI = 0.03 to 0.62, p = 0.032). There was, however, no significant difference in early H:M (p = 0.326) or late H:M (p = 0.351) between the asymptomatic carotid sinus hypersensitivity group and non- carotid sinus hypersensitivity controls.

Conclusions

Cardiac sympathetic neuronal activity is increased relative to age-matched controls in individuals with carotid sinus syndrome but not those with asymptomatic carotid sinus hypersensitivity. Blood pressure and heart rate measurements alone may therefore represent an over simplification in the assessment for carotid sinus syndrome and the relative increase in cardiac sympathetic innervation provides additional clues to understanding the mechanisms behind the symptomatic presentation of carotid sinus hypersensitivity.

Assessment of a standardized algorithm for cardiac pacing in older patients affected by severe unpredictable reflex syncopes

AIMS

Opinions differ regarding the effectiveness of cardiac pacing in patients affected by reflex syncope. We assessed a standardized guideline-based algorithm in different forms of reflex syncope.

METHODS AND RESULTS

In this prospective, multi-centre, observational study, patients aged >40 years, affected by severe unpredictable recurrent reflex syncopes, underwent carotid sinus massage (CSM), followed by tilt testing (TT) if CSM was negative, followed by implantation of an implantable loop recorder (ILR) if TT was negative. Those who had an asystolic response to one of these tests received a dual-chamber pacemaker.

POPULATION

253 patients, mean age 70 ± 12 years, median 4 (3-6) syncopes, 89% without or with short prodromes. Of these patients, 120 (47%) received a pacemaker and 106 were followed up for a mean of 13 ± 7 months: syncope recurred in 10 (9%). The recurrence rate was similar in 61 CSM+ (11%), 30 TT+ (7%), and 15 ILR+ (7%) patients. The actuarial total syncope recurrence rate was 9% (95% confidence interval (CI), 6-12) at 1 year and 15% (95% CI, 10-20) at 2 years and was significantly lower than that observed in the group of 124 patients with non-diagnostic tests who had received an ILR: i.e. 22% (95% CI, 18-26) at 1 year and 37% (95% CI, 30-43) at 2 years (P = 0.004).

CONCLUSION

About half of older patients with severe recurrent syncopes without prodromes have an asystolic reflex for which cardiac pacing goes along with a low recurrence rate. The study supports the clinical utility of the algorithm for the selection of candidates to cardiac pacing in everyday clinical practice.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT01509534.

Carotid sinus syndrome: Progress in understanding and management

Carotid sinus syndrome (CSS) is a disease of the autonomic nervous system presenting with syncope, especially in older males who often have cardiovascular disease. The aetiology is unknown and epidemiological data is limited. Forty new patients/million population have been estimated to require pacing for CSS and these patients represent ∼9% of those presenting syncope to a specialist facility. CSS is defined as a response to carotid sinus massage (CSM) that includes reproduction of spontaneous symptoms. Cardioinhibitory CSS shows 3s asystole on CSM and vasodepressor CSS shows >50 mmHg fall in blood pressure (BP), there are mixed forms. The methodology of CSM requires correct massage in the supine and upright with continuous ECG and BP. Assessment of the vasodepressor component implies the ‘method of symptoms’ using atropine to prevent asystole. Carotid sinus hypersensitivity (CSH) is a related condition where CSM is positive in an asymptomatic patient. CSH cannot be assumed to respond to pacing. CSS patients present syncope with little or no warning. If no cause is revealed by the initial evaluation, CSM should be considered in all patients >40 years. CSM carries a small risk of thromboembolism. Therapy for cardioinhibitory CSS is dual chamber pacing, which is most effective in patients with a negative tilt test. Syncope recurrence is ∼20% in 5 years in paced patients. Therapy for the vasodepressor component of CSS, as pure vasodepression or mixed, where tilt testing will likely be positive, is often unrewarding: alternative therapeutic measures may be needed including discontinuation/reduction of hypotensive drugs.

Benefit of pacemaker therapy in patients with presumed neurally mediated syncope and documented asystole is greater when tilt test is negative: an analysis from the third International Study on Syncope of Uncertain Etiology (ISSUE-3)

BACKGROUND

In the Third International Study on Syncope of Uncertain Etiology (ISSUE-3), cardiac pacing was effective in reducing recurrence of syncope in patients with presumed neurally mediated syncope (NMS) and documented asystole but syncope still recurred in 25% of them at 2 years. We have investigated the role of tilt testing (TT) in predicting recurrences.

METHODS AND RESULTS

In 136 patients enrolled in the ISSUE-3, TT was positive in 76 and negative in 60. An asystolic response predicted a similar asystolic form during implantable loop recorder monitoring, with a positive predictive value of 86%. The corresponding values were 48% in patients with non-asystolic TT and 58% in patients with negative TT (P=0.001 versus asystolic TT). Fifty-two patients (26 TT+ and 26 TT-) with asystolic neurally mediated syncope received a pacemaker. Syncope recurred in 8 TT+ and in 1 TT- patients. At 21 months, the estimated product-limit syncope recurrence rates were 55% and 5%, respectively (P=0.004). The TT+ recurrence rate was similar to that seen in 45 untreated patients (control group), which was 64% (P=0.75). The recurrence rate was similar between 14 patients with asystolic and 12 with non-asystolic responses during TT (P=0.53).

CONCLUSIONS

Cardiac pacing was effective in neurally mediated syncope patients with documented asystolic episodes in whom TT was negative; conversely, there was insufficient evidence of efficacy from this data set in patients with a positive TT even when spontaneous asystole was documented. Present observations are unexpected and need to be confirmed by other studies. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT01463358.