Implantable loop recorder in unexplained syncope: classification, mechanism, transient loss of consciousness and role of major depressive disorder in patients with and without structural heart disease

ECG Smart Monitoring versus Implantable Loop Recorders for Atrial Fibrillation Detection after Cryptogenic Stroke-An Overview for Decision Making

Up to 20% of patients with ischemic stroke or transient ischemic attack have a prior history of known atrial fibrillation (AF). Additionally, unknown AF can be detected by different monitoring strategies in up to 23% of patients with cryptogenic or non-cardioembolic stroke. However, most studies had substantial gaps in monitoring time, especially early after the index event. Following this, AF rates would be higher if patients underwent continuous monitoring early after stroke, avoiding any gaps in monitoring. The few existing randomized studies focused on patients with cryptogenic stroke but did not focus otherwise specifically on prevention strategies in patients at high risk for AF (patients at higher age or with high CHA2DS2-VASC scores). Besides invasive implantable loop recorders (ILRs), external loop recorders (ELRs) and mobile cardiac outpatient telemetry (MCOT) are non-invasive tools that are commonly used for long-term ECG monitoring in cryptogenic-stroke patients in the ambulatory setting. The role of MCOT and hand-held devices within ECG smart monitoring in the detection of AF for the prevention of and after cryptogenic stroke is currently unclear. This intense review provides an overview of current evidence, techniques, and gaps in knowledge and aims to advise which patients benefit most from the current available devices.

Usefulness of insertable cardiac monitors for risk stratification: current indications and clinical evidence

INTRODUCTION

The 2018 ESC Syncope guidelines expanded the indications for an insertable cardiac monitor (ICM) to patients with unexplained syncope and primary cardiomyopathy or inheritable arrhythmogenic disorders.

AREAS COVERED

This review article discusses the clinical evidence for using an ICM for risk stratification in different patient populations including Brugada syndrome, long QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoidosis, and congenital heart disease.

EXPERT OPINION

Clinical data on the usefulness of ICMs in different patient populations is limited but most studies demonstrate early detection of clinically relevant arrhythmias, such as nonsustained ventricular tachycardia or atrial fibrillation. It is important to emphasize that the study populations usually comprise selected populations where conventional diagnostic methods fail to clarify the mechanism of symptoms. The effect of an ICM on prognosis by earlier detection of arrhythmias is difficult to demonstrate in populations with rare disease. Risk stratification in patients with cardiomyopathy or inheritable arrhythmogenic disorders remains a niche indication for ICMs. The most important indication for an ICM remains unexplained syncope in patients at low risk of SCD. Given the device costs and uncertain clinical value of device-detected arrhythmias, it is unclear whether it is also useful in non-syncopal patients.

Implantable loop recorders in patients with heart disease: comparison between patients with and without syncope

OBJECTIVE

Patients with heart disease are at increased risk for sudden cardiac death. Guidelines recommend an implantable loop recorder (ILR) for symptomatic patients when symptoms are sporadic and possibly arrhythmia-related. In clinical practice, an ILR is mainly used in patients with unexplained syncope. We aimed to compare the clinical value of an ILR in patients with heart disease and a history of syncope versus those with non-syncopal symptoms.

METHODS

In this observational single-centre study, we included symptomatic patients with heart disease who received an ILR. The primary endpoint was an actionable event which was defined as an arrhythmic event leading to a change in clinical management. The secondary endpoint was an event leading to device implantation.

RESULTS

One hundred and twenty patients (mean age 47±17 years, 49% men) were included. The underlying disease substrate was inherited cardiomyopathy (31%), congenital heart disease (28%), channelopathy (23%) and other (18%). Group A consisted of 43 patients with prior syncope and group B consisted of 77 patients with palpitations and/or near-syncope. The median follow-up duration was 19 months (IQR 8-36). The 3-year cumulative event rate was similar between groups with regard to the primary endpoint (38% vs 39% for group A and B, respectively, logrank p=0.54). There was also no difference in the 3-year cumulative rate of device implantation (21% vs 13% for group A and B, respectively, logrank p=0.65).

CONCLUSION

In symptomatic patients with heart disease, there is no difference in the yield of an ILR in patients presenting with or without syncope.

Clinical predictors for bradycardia and supraventricular tachycardia necessitating therapy in patients with unexplained syncope monitored by insertable cardiac monitor

Background

Insertable cardiac monitors (ICMs) improve diagnostic yield in patients with unexplained syncope. The most of cardiac syncope is arrhythmic causes include paroxysmal bradycardia and supraventricular tachycardia (SVT) in patients with unexplained syncope receiving ICM. Predictors for bradycardia and SVT that necessitate therapy in patients with unexplained syncope are not well known.

Hypothesis

This study aimed to investigate predictors of bradycardia and SVT necessitating therapy in patients with unexplained syncope receiving ICMs.

Methods

We retrospectively reviewed medical records of consecutive patients who received ICMs to monitor unexplained syncope. We performed Cox's stepwise logistic regression analysis to identify significant independent predictors for bradycardia and SVT.

Results

One hundred thirty‐two patients received ICMs to monitor unexplained syncope. During the 17‐month follow‐up period, 19 patients (14%) needed pacemaker therapy for bradycardia; 8 patients (6%) received catheter ablation for SVT. The total estimated diagnostic rates were 34% and 48% at 1 and 2 years, respectively. Stepwise logistic regression analysis indicated that syncope during effort (odds ratio [OR] = 3.41; 95% confidence interval [CI], 1.21 to 9.6; p = .02) was an independent predictor for bradycardia. Palpitation before syncope (OR = 9.46; 95% CI, 1.78 to 50.10; p = .008) and history of atrial fibrillation (OR = 10.1; 95% CI, 1.96 to 52.45; p = .006) were identified as significant independent predictors for SVT.

Conclusion

Syncope during effort, and palpitations or history of atrial fibrillation were independent predictors for bradycardia and for SVT. ICMs are useful devices for diagnosing unexplained syncope.

Incremental Value of an Insertable Cardiac Monitor in Patients with Hypertrophic Cardiomyopathy with Low or Intermediate Risk for Sudden Cardiac Death

AIMS

The aim of the present study was to compare the rate of actionable arrhythmic events between patients with hypertrophic cardiomyopathy (HCM) who are monitored with an insertable cardiac monitor (ICM) or Holter monitoring.

METHODS

We studied 50 patients (mean age 52 years, 72% men) with HCM at low or intermediate risk for sudden cardiac death (SCD), of whom 25 patients received an ICM between November 2014 and February 2019. We retrospectively identified a control group of 25 patients who were matched on age, sex, and HCM Risk-SCD score category. The mean HCM Risk-SCD score was 3.41 ± 1.31 and 3.31 ± 1.43 for the ICM and Holter groups, respectively. The primary endpoint was an actionable event which was defined as an arrhythmic event resulting in a change in patient management. The secondary endpoint was the occurrence of ventricular tachycardia (VT).

RESULTS

The cumulative actionable event rate at 30 months was higher in the ICM group (51 vs. 27%, log-rank p value <0.01). De novo atrial fibrillation requiring oral anticoagulation occurred only in the ICM group (n = 3). Overall, 4 implantable cardioverter-defibrillators were implanted for primary prevention (n = 2 in each group). The cumulative rate of VT episodes at 30 months was similar between groups (23% [ICM group] vs. 42% [Holter group], log-rank p value = 0.71). Furthermore, the characteristics of VT were similar between groups with regard to the number of beats and rate.

CONCLUSIONS

In adults with HCM, an ICM will detect more arrhythmic events requiring an intervention than a conventional Holter strategy. In contrast, the diagnostic yield of detecting VT seems similar for both groups.

Fitness to Drive After Syncope and/or in Cardiovascular Disease - An Overview and Practical Advice

The risk of syncope occurring while driving has implications for personal and public safety. Little is thought about the medical considerations related to the driving of motor vehicles. Physicians treating patients with cardiovascular disease need to acquire basic competences to be able to advise them about their fitness to drive. Current knowledge, governmental regulations, and recommendations concerning fitness to drive in patients with syncope and/or cardiovascular disease are presented. Narrative review with educational and clinical advice. Cardiovascular disease can make a driver lose control of a vehicle without warning and thereby lead to an accident. The main pathophysiological mechanisms of sudden loss of control are disturbances of brain perfusion (eg, syncope with or without cardiac arrhythmia, sudden cardiac death due to ventricular fibrillation or asystole, stroke, etc.) and marked general weakness (eg, after major surgery or in heart failure). Patients with syncope and/or cardiovascular disease should be properly advised by their physicians about their fitness to drive, and restrictions should be documented.

Value of implantable loop recorders in patients with structural or electrical heart disease

Purpose

In patients with structural heart disease (SHD) or inherited primary arrhythmia syndrome (IPAS), the occurrence of unexplained syncope or palpitations can be worrisome as they are at increased risk of sudden cardiac death. An implantable loop recorder (ILR) can be a useful diagnostic tool. Our purpose was to compare the diagnostic yield, arrhythmia mechanism, and management in patients with SHD, patients with IPAS, and those without heart disease.

Methods

Retrospective single-center study in consecutive patients who underwent an ILR implantation.

Results

Between March 2013 and December 2016, a total of 94 patients received an ILR (SHD, n = 20; IPAS, n = 14; no SHD/IPAS, n = 60). The type of symptoms at the time of implantation was similar between groups. During a median follow-up of 10 months, 45% had an ILR-guided diagnosis. Patients with IPAS had a lower diagnostic yield (14%) in comparison to the other groups (no SHD/IPAS 47%, P = 0.03; SHD 60%, P = 0.01, respectively). Furthermore, patients with SHD had a higher incidence of nonsustained VT in comparison to patients without SHD/IPAS (30 versus 3%, P < 0.01). ILR-guided therapy was comparable between groups. In the SHD group, a high proportion (10%) received an implantable cardioverter-defibrillator; however, this was not statistically significantly higher than the other groups (no SHD/IPAS 3%, IPAS 0%, P = 0.08).

Conclusions

In comparison to patients without heart disease, the diagnostic yield of an ILR was lower in patients with IPAS and the prevalence of ILR-diagnosed nonsustained VT was higher in patients with SHD.

The Role of the Syncope Management Unit

Syncope is a common symptom, experienced by 15% of persons less than 18 years old and up to 23% of elderly nursing home residents, so it is important to consider optimizing strategies for the management of these patients. The strategy selected will inevitably differ from place to place. However, an organized structure offers more cost-effective care. This article discusses possible health care delivery models for syncope management and reviews the current status of the organization of syncope care, to show the value of a multidisciplinary approach to the organized management of patients with syncope.

Syncope in the Elderly

A rapid change in ageing demographic is taking place worldwide such that healthcare professionals are increasingly treating old and very old patients. Syncope in the elderly is a challenging presentation that is under-recognised, particularly in the acute care setting. The reason for this is that presentation in the older person may be atypical: patients are less likely to have a prodrome, may have amnesia for loss of consciousness and events are frequently unwitnessed. The older patient thus may present with a fall rather than transient loss of consciousness. There is an increased susceptibility to syncope with advancing age attributed to age-related physiological impairments in heart rate and blood pressure, and alterations in cerebral blood flow. Multi-morbidity and polypharmacy in these complex patients increases susceptibility to syncope. Cardiac causes and more than one possible cause are also common. Syncope is a major cause of morbidity and mortality and is associated with enormous personal and wider health economic costs. In view of this, prompt assessment and early targeted intervention are recommended. The purpose of this article is to update the reader regarding the presentation and management of syncope in this rapidly changing demographic.

ECG monitoring in syncope

Electrocardiographic (ECG) monitoring is a well-established procedure in the work-up of patients with syncope or for diagnosing arrhythmias. The investigation of syncope remains, however, challenging and physicians have an increasing armamentarium of diagnostic tools available and with advances in technology the role of these tools has to be continuously evaluated. The gold standard for the diagnosis of syncope is a symptom-ECG correlation, and while many studies have investigated the use and indications of both short-term and long-term monitoring; there is still some uncertainty in their clinical utility and practical approach. The use of ECG monitoring and other diagnostic tools is often subject to a "shot-gun approach" rather than a strict guideline algorithm. A systematic approach and selection of ECG monitoring tools helps permit an effective usage of the limited health care resources available for the management of unexplained syncope. In this review we aim to focus and clarify the role of short-term (Holter and external loop recorders) and long-term (implantable loop recorders) ECG monitoring in the diagnosis and management of patients with unexplained syncope.

Selecting appropriate diagnostic tools for evaluating the patient with syncope/collapse

The investigation of syncope is challenging and physicians have an ever-increasing array of diagnostic tools at their disposal. There are two essential goals that drive investigation: risk stratification and identification of etiology. In this review, we outline our approach while providing a synopsis of the available supportive evidence. The key to syncope is in the story as told by the patient and a bystander, since this drives both risk assessment and diagnostic testing. All patients should initially be evaluated with a systematic history and physical examination as well as an ECG. The initial evaluation provides an estimation of risk and directs whether inpatient or outpatient evaluation is appropriate. In a substantial proportion of patients, the etiology will be evident after initial evaluation and no further investigation is required. In the remaining, targeted use of additional investigations in the form of cardiac imaging, provocative testing and/or ambulatory ECG monitoring should be performed. A thoughtful and systematic approach to the investigation of syncope optimizes the diagnostic yield but also ensures efficient usage of limited health care resources.

CURRENT RECOMMENDATIONS ON RISK STRATIFICATION AND SUDDEN CARDIAC DEATH PREVENTION IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY (BASED ON THE 2011 RECOMMENDATIONS BY THE AMERICAN COLLEGE OF CARDIOLOGY / AMERICAN HEART ASSOCIATION)

One of the clinical scenarios of hypertrophic cardiomyopathy (HCMP) is sudden cardiac death (SCD). The stratification of SCD risk is the key component of defining the therapeutic strategy in HCMP patients. Timely preventive treatment is the only life-saving intervention in patients with high SCD risk. The available clinical evidence suggests that SCD risk stratification is an effective algorithm for determining the need for preventive treatment. The latter should be individualised, based on the risk levels in each patient. 

[Long-term follow-up after implantable loop recorder in patients with syncope: results of a French general hospital survey]

BACKGROUND AND OBJECTIVE

Despite recent advances in diagnostic procedures, syncope remains unexplained in 15 to 35% of patients. If implantable loop recorder is a validated diagnostic tool for unexplained syncope, results of this strategy are largely issued from randomized studies. We lack the results of surveys. The aim of this study was to report a single center experience with implantable loop recorders, in patients with unexplained syncope.

METHODS AND RESULTS

A device (Medtronic Reveal DX or XT) was implanted in 31 patients between January 2009 and January 2012. During a mean follow-up of 10.5±8.5 months, loop recording definitively determined that an arrhythmia was the cause of symptoms in 10 patients (32%). Fourteen patients (45%) experienced syncope or pre-syncope. In eight of the 14 patients with syncope, during follow-up, no arrhythmic diagnosis could be made (one patient has been diagnosed as presenting epilepsy and seven as having hypotensive vasovagal syncope). In six patients, the ILR showed an arrhythmic aetiology. Four other patients presented an abnormal ILR result without symptoms. Diagnosis included sinusal arrest in four patients, bradycardia in one patient, advanced atrioventricular block in two patients, ventricular arrythmias in two patients, and supraventricular tachycardia of 180/min in one patient. Therapy was instituted in all patients, in whom an arrhythmic cause was found except one who refused the therapy (six pacemaker, two implantable cardioverter-defibrillator implantations, and one cryoablation of atrioventricular nodal reentrant tachycardia confirmed by an invasive exploration).

CONCLUSION

In this survey, implantable loop recorder implantation led to the diagnosis of an arrhythmic cause in 32% of patients and excluded an arrhythmic cause in 26% of patient with a mean follow-up of 10.5 months.

The Implantable Loop Recorder—An Important Addition to the Armentarium in the Management of Unexplained Syncope

Introduction: Unexplained syncope is a common condition with a significant impact both on the patient and on healthcare expenditure. Often, the diagnosis is hampered due to the temporary sporadic nature of the symptoms. Conventional monitoring methods have a low yield for identifying an abnormality during a spontaneous event. The implantable loop recorder (ILR), often underutilised, is an important diagnostic device that may fill this void in the early assessment of patients presenting with syncope. Materials and Methods: This article begins with 2 case vignettes which highlight the clinical utility of ILRs in making a definitive diagnosis and guiding subsequent management. This is followed by a review of the existing evidence for ILRs, including the recent international guidelines, underpinning the role of ILRs in the present management algorithm of patients presenting with unexplained syncope. The technical aspects and cost implications will also be reviewed. Results: Present evidence-based international guidelines have recommended the early use of ILRs in the management of patients with unexplained syncope. Furthermore, there may also be an important role for ILR use in patients with presumed epilepsy refractory to treatment and in the neurally mediated syncope cohort with recurrent symptoms. Cost benefit analysis also demonstrates advantages with early ILR use. Conclusion: The early use of ILR in selected patients remains an accurate, cost-effective, high yield tool for diagnosis and management of patients with unexplained syncope. However, its use should not detract from the importance of taking a detailed medical history and physical examination in the initial assessment to facilitate identification of the aetiology and risk stratification of patients. Key words: Electrophysiological study, Epilepsy, External loop recorder, Holter, Tilt testing

Syncope in adults: systematic review and proposal of a diagnostic and therapeutic algorithm

This review aims to provide a practical and up-to-date description on the relevance and classification of syncope in adults as well as a guidance on the optimal evaluation, management and treatment of this very common clinical and socioeconomic medical problem. We have summarized recent active research and emphasized the value for physicians to adhere current guidelines. A modern management of syncope should take into account 1) use of risk stratification algorithms and implementation of syncope management units to increase the diagnostic yield and reduce costs; 2) early implantable loop recorders rather than late in the evaluation of unexplained syncope; and 3) isometric physical counter-pressure maneuvers as first-line treatment for patients with neurally-mediated reflex syncope and prodromal symptoms.

[Significance of diagnostic methods in the work-up of syncope]

After the initial evaluation including detailed history, physical examination, electrocardiogram, and orthostatic blood pressure measurements, risk stratification should follow, if the cause of syncope is still unclear in order to define the acuteness and extensiveness of the further diagnostic evaluation. The documentation of arrhythmia during syncope is the gold standard for diagnosis of arrhythmic syncope. The implantable loop recorder should be integrated early in the diagnostic work-up. In patients >40 years with otherwise unexplained syncope, carotid sinus massage is recommended. In suspected reflex-mediated syncope, the tilt test is able to confirm the diagnosis and gives information about the underlying pathomechanisms, while electrophysiological studies have still a proven indication in patients with previous myocardial infarction and preserved left ventricular function. The adenosine triphophate test has no clinical relevance in the diagnostics of syncope. Echocardiography plays an important role in the risk stratification by diagnosing structural cardiac disease. In patients experiencing syncope associated with exertion, exercise stress testing is indicated. Finally, a coronary angiogram should be performed, if ischemia triggered syncope is suspected. A routinely performed neurological evaluation is not recommended.

Management and therapy of vasovagal syncope: A review

Vasovagal syncope is a common cause of recurrent syncope. Clinically, these episodes may present as an isolated event with an identifiable trigger, or manifest as a cluster of recurrent episodes warranting intensive evaluation. The mechanism of vasovagal syncope is incompletely understood. Diagnostic tools such as implantable loop recorders may facilitate the identification of patients with arrhythmia mimicking benign vasovagal syncope. This review focuses on the management of vasovagal syncope and discusses the non-pharmacological and pharmacological treatment options, especially the use of midodrine and selective serotonin reuptake inhibitors. The role of cardiac pacing may be meaningful for a subgroup of patients who manifest severe bradycardia or asystole but this still remains controversial.

Time to manual activation of implantable loop recorders--implications for programming recording period: a 10-year single-centre experience

AIM

A new generation of commercially available implantable loop recorders (ILRs) has improved arrhythmia detection algorithms but reduced manually activated ECG storage duration. We investigated the effect that this would have had on symptom-arrhythmia correlation in a retrospective patient cohort.

METHOD AND RESULTS

Retrospective review of all patients receiving a Medtronic Reveal 9525/9526 for the investigation of unexplained syncope or pre-syncope in our centre between 1998 and 2008. All ILRs were programmed for a single manual activation with 40 min retrospective ECG recording. We identified all patients who subsequently underwent permanent pacemaker implantation and analysed the time delay between bradycardia onset and manual ILR activation. Five hundred and sixty-four patients underwent implantation of an ILR during the study period. Of these, 57 (10%) subsequently underwent the implantation of a pacemaker (31 male, median age 66 years, range 9-86 years). In this group, 35 of 57 (61%) bradycardia diagnoses were made in patients (18 male, median age 65 years, range 9-86 years) after manual activation of the ILR. The median time from bradycardia onset to ILR activation was 136 s (0-488 s). Nineteen recordings showed high-grade atrio-ventricular block and 16 sinus node disease.

CONCLUSION

Ten-year experience with the ILR confirms its utility in establishing a pacemaker indication as the cause for syncope or pre-syncope in 6% (34 of 564) of recipients following manual activation. This requires a recording loop of sufficient duration to reliably include both symptoms and activation.

Predicting the cause of syncope from clinical history in patients undergoing prolonged monitoring

BACKGROUND

Syncope may be the result of primary bradycardia or tachycardia, vasovagal syncope, or noncardiac syncope. Risk factors and outcome scores to predict prognosis in patients with syncope have been developed. Although these correlate with morbidity and mortality in patients with syncope, their relationship with the mechanism of syncope has not been investigated.

OBJECTIVE

The purpose of this study was to identify clinical predictors of primary bradycardia in a cohort of patients undergoing prolonged monitoring for unexplained syncope.

METHODS

One hundred nineteen patients underwent prolonged monitoring with an implantable or external loop recorder after assessment at a single-center, tertiary care arrhythmia service. Fifty-two patients with recurrent syncope during monitoring were classified according to the mechanism of syncope (International Study on Syncope of Uncertain Etiology [ISSUE] classification). Clinical predictors of primary arrhythmic syncope were identified.

RESULTS

Twenty patients were classified with primary arrhythmia and 32 patients were classified with nonarrhythmic syncope. Five clinical variables were associated with primary arrhythmia: left bundle branch block, structural heart disease, and syncope without prodrome increased the likelihood of primary arrhythmia; a normal baseline ECG and history of syncope in childhood decreased the likelihood of primary arrhythmia. After multiple logistic regression, risk factors for the diagnosis of primary arrhythmia included syncope without warning symptoms and structural heart disease. The presence of left bundle branch block correlated perfectly with primary arrhythmia, whereas a normal ECG reduced the likelihood of primary arrhythmia.

CONCLUSION

Clinical predictors of primary arrhythmia in patients with recurrent syncope include normal ECG and structural heart disease. Left bundle branch block is an important finding in patients with unexplained syncope.

Experience with implantable loop recorders for recurrent unexplained syncope

Knowledge of what occurs during spontaneous syncope is the gold standard for evaluation. Initially, implantable loop recorders (ILRs) were used in patients with unexplained syncope at the end of unsuccessful full, conventional work-up. In pooled data regarding 247 patients, a correlation between syncope and electrocardiographic findings was found in 84 patients (34%); of these, 52% had a bradycardia or asystole at the time of the recorded event, 11% had tachycardia, and 37% had no arrhythmia. Presyncope-electrocardiography correlation was observed in another third of the patients; presyncope was much less likely to be associated with an arrhythmia than was syncope. The diagnostic yield was similar in patients with and without structural heart diseases and was higher in older than in younger patients. Recent studies showed that ILR implantation can be safely performed in an early phase of the diagnostic evaluation--provided that patients at risk for life-threatening events are carefully excluded--in the patients who have a severe presentation of syncope (because of high risk of trauma or high frequency of episodes) which can be a benefit of a mechanism-specific therapy.