Utility of implantable loop recorders for diagnosing unexplained syncope in clinical practice

Bradycardia risk stratification with implantable loop recorder after unexplained syncope

BACKGROUND

An implantable loop recorder is an effective tool for diagnosing unexplained syncope. However, after a first episode in non-high-risk patients, the usefulness of implantable loop recorder implantation remains unclear.

AIMS

To analyse relevant risk factors for significant bradycardia in order to identify patients who do or do not benefit from implantable loop recorder implantation. Also, to study whether implantable loop recorder implantation with remote monitoring is associated with less recurrence of traumatic syncope.

METHODS

This was a retrospective monocentric study including patients with implantable loop recorder implantation after unexplained syncope, using remote monitoring and iterative consultations.

RESULTS

Two hundred and thirty-seven patients were implanted for unexplained syncope. Significant bradycardia occurred in 53 patients (22.4%): 23 (43.4%) caused by paroxysmal atrioventricular block and 30 (56.6%) caused by sinus node dysfunction, leading to permanent pacemaker implantation in 48 patients. Compared with younger patients, there was a 3.46-fold increase (95% confidence interval 1.92-6.23; P<0.0001) in the risk of significant bradycardia in patients aged≥60 years. Based on multivariable analysis, only "typical syncope" was associated with significant bradycardia occurrence (hazard ratio 3.14, 95% confidence interval 1.75-5.65; P=0.0001). There was no recurrence of significant bradycardia with traumatic complications among patients implanted for traumatic syncope.

CONCLUSIONS

This study shows that: (1) implantable loop recorders identify more significant bradycardia in patients aged≥60 presenting with a first non-high-risk typical syncope, suggesting that an implantable loop recorder should be implanted after a first episode of unexplained syncope in such conditions; and (2) after traumatic syncope, implantable loop recorder implantation is safe, and is associated with little or no recurrence of traumatic syncope.

The future of cardioneuroablation in cardiovascular medicine

INTRODUCTION

Cardioneuroablation is increasingly being utilized to improve outcomes in patients with vagally mediated bradyarrhythmias. However, there are still controversial issues in the field including patient selection, safety and efficacy, and procedural end-points.

AREAS COVERED

In this review, the current role of cardioneuroablation is summarized, and controversial issues related to the modality are discussed.

EXPERT OPINION

According to small open-label cohort studies, overall freedom from syncope recurrence was higher than 90% after cardioneuroablation in patients with vasovagal syncope (VVS). Use of the electrogram-based strategy or high-frequency stimulation demonstrate similar success rate except in procedures limited to the right atrium. Based on a recently published randomized controlled trial and metanalysis, it may be possible now to make a strong recommendation for cardioneuroablation in patients <40 years of age, and those with the cardioinhibitory or mixed type of VVS who continue to experience frequent and/or burdensome syncope recurrences. Considering patients with VVS are prone to significant placebo/expectation effect, sham-controlled trials may help to quantify the placebo effect. In well-selected patients with functional atrioventricular block and sinus bradycardia, may result in encouraging medium-term outcomes. However, functional bradycardia is identified in a minority of patients presenting with high-grade atrioventricular block or sinus node dysfunction.

Diagnostic value of implantable loop recorders in patients with unexplained syncope or palpitations

Background

The implantable loop recorder (ILR) is a small cardiac rhythm‐monitoring device. Our aim was to determine ILR diagnostic value in patients with unexplained syncope, presyncope, or palpitations suggesting cardiac arrhythmias.

Methods

This has been a retrospective, observational, single‐center study. We included 181 patients in whom ILR was implanted at the Clinical Center of Serbia between January 2006 and July 2019. An event was marked as diagnostic if it led to a diagnosis and ILR was considered diagnostic if it verified or excluded an arrhythmia as the cause of syncope or palpitations.

Results

The mean age was 51.8 ± 17.8 years and 94 (51.9%) were male. The mean follow‐up period was 20.2 ± 15.8 months. ILR was diagnostic in 98 patients (54.1%). There was no significant difference in diagnostic value of ILR in regard to the baseline patients’ characteristics. The mean time to occurrence of the diagnostic event was 11.1 ± 9.6 months. The time to occurrence of a diagnostic event did not differ significantly between patients who underwent basic as compared to extended diagnostics before ILR implantation.

Conclusions

ILR was able to achieve an etiological diagnosis in 54.1% of patients with unexplained syncope, presyncope, or palpitations suggesting cardiac arrhythmias. In a subgroup of patients with recurrent palpitations, ILR was significantly less diagnostic than in patients with syncope or presyncope. ILR should be implanted beforehand in syncope evaluation process.

Usefulness of an Implantable Loop Recorder in Diagnosing Unexplained Syncope and Predictors for Pacemaker Implantation

BACKGROUND

An implantable loop recorder (ILR) is an effective tool for diagnosing unexplained syncope (US). We examined the diagnostic utility of an ILR in detecting arrhythmic causes of US and determining which clinical factors are associated with pacemaker (PM) implantation.

METHODS

This retrospective, multicenter, observational study was conducted from February 2006 to April 2018 at 11 hospitals in Korea. Eligible patients with recurrent US received an ILR to diagnose recurrent syncope and document arrhythmia.

RESULTS

A total of 173 US patients (mean age, 67.6 ± 16.5 years; 107 men [61.8%]) who received an ILR after a negative conventional workup were enrolled. During a mean follow-up of 9.4 ± 11.1 months, 52 patients (30.1%) had recurrent syncope, and syncope-correlated arrhythmia was confirmed in 34 patients (19.7%). The ILR analysis showed sinus node dysfunction in 24 patients (70.6%), supraventricular tachyarrhythmia in 4 (11.8%), ventricular arrhythmia in 4 (11.8%), and sudden atrioventricular block in 2 (5.9%). Overall, ILR detected significant arrhythmia in 99 patients (57.2%) irrespective of syncope. Among patients with clinically relevant arrhythmia detected by ILR, PM implantation was performed in 60 (34.7%), an intra-cardiac defibrillator in 5 (2.9%), and catheter ablation in 4 (2.3%). In a Cox regression analysis, history of paroxysmal atrial fibrillation (PAF) (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.33-4.12; P < 0.01) and any bundle branch block (BBB) (HR, 2.52; 95% CI, 1.09-5.85; P = 0.03) were significantly associated with PM implantation.

CONCLUSION

ILR is useful for detecting syncope-correlated arrhythmia in patients with US. The risk of PM is high in US patients with a history of PAF and any BBB.

Predictors of future arrhythmic events in patients with unexplained syncope

AIMS

The purpose of this study was to examine the usefulness of implantable loop recorders (ILRs) for symptom-rhythm correlation and to identify predictors of future arrhythmic events.

PATIENTS AND METHODS

In our dual-centre study, we analysed ILR data of 189 patients (mean age 67.4 ± 15.2 years, 114 male) with unexplained syncope (single syncope 21 patients, recurrent 168 patients, traumatic injury 43 patients). Patients had severe comorbidities such as hypertension (n = 127), coronary artery disease (n = 31), diabetes mellitus (n = 33) and chronic renal insufficiency (n = 18). The median ILR usage was 29 months (M), with a range between 1 and 46 M.

RESULTS

Forty-nine (26%) patients experienced syncope during the study, with a median of 8 M to first recurrence of syncope. In 43 patients, pacemaker implantation was performed because of sinus node disease (n = 29), high-degree AV-block (n = 6) or atrial fibrillation with slow ventricular rate (n = 8). In five patients, an ICD was implanted because of documented ventricular tachycardia (n = 4) or left ventricular ejection fraction <35% (n = 1). One patient received ablation of the cavotricuspid isthmus because of documented atrial flutter. Concerning the clinical course, in five patients explantation of the ILR was necessary due to pocket infection. Three patients died due to non-cardiac causes. Logistic regression analysis revealed that older patients had a significantly higher risk for future arrhythmic events (OR 1.3, p = .039).

CONCLUSIONS

ILR monitoring is effective in indicating causes of unexplained syncope by providing symptom-rhythm associations. Only age was a predictor of future arrhythmic events. The mortality in patients with unexplained syncope was very low.

Holding Area LINQ Trial (HALT)

Background

Recent studies have shown that insertable cardiac monitors (ICMs) can be implanted out of the traditional hospital setting and efforts are being made to explore the feasibility of implanting these devices in a specific standardized location other than the operating room or a cardiac catherization/electrophysiology lab.

Methods

This was a prospective, non-randomized, single center post-market clinical trial designed to occur in the holding area of a hospital operating room or cardiac catheterization/electrophysiology laboratory. The Medtronic Reveal LINQ ICM was implanted and patients were followed for 90 days post implant. This study was designed to observe any procedure related adverse events stemming from the holding area implantation.

Results

Twenty patients were implanted at our hospital in a holding room not traditionally associated with the electrophysiology/cardiac/operatory labs. One patient was lost to the 90-day follow up. In one case, ICM implantation led to diagnosis requiring removal of ICM before the 90 day follow up and insertion of a biventricular implantable cardioverter defibrillator (ICD). In the remaining 18 patients, there were no serious complications such as minor skin infections, systemic infections or procedure-related adverse events requiring device explant.

Conclusion

When following a standardized protocol with attention to sterile technique, it is feasible to implant ICMs in a holding area with no procedure related adverse events (AE).

Cost comparison of two implantable cardiac monitors in two different settings: Reveal XT in a catheterization laboratory vs. Reveal LINQ in a procedure room

AIMS

Implantable cardiac monitors (ICMs) are used for long-term heart rhythm monitoring, e.g. to diagnose unexplained syncope or for detection of suspected atrial and ventricular arrhythmias. The newest ICM, Reveal LINQ™ (Medtronic Inc.), is miniaturized and inserted with a specific insertion tool kit. The procedure is therefore minimally invasive and can be moved from catheterization laboratory (cath lab) to a less resource intensive setting. This study aims to assess the change in procedure costs when performed outside the cath lab.

METHODS AND RESULTS

A bottom-up costing methodology was used. Data were collected from interviews with physicians, cath lab managers, and financial controllers. Hospitals in the Netherlands, France, and the UK were included in this study. The cost comparison of a Reveal XT implantation in a cath lab setting vs. a Reveal LINQ insertion outside a cath lab resulted in an estimated reduction of €662 for the UK, €682 for the Netherlands, and €781 for France. These cost savings were primarily realized through fewer staff, less equipment, and overhead costs. The net effect on savings depends on the price differential between these two technologies. The patient care pathway can be improved due to the possibility to move the procedure out of the cath lab.

CONCLUSION

Inserting the miniaturized version of the ICM is simpler and faster, and the procedure can take place outside the cath lab in a less resource intensive environment. Hospitals save resources when the higher price of the Reveal LINQ does not outweigh these savings.

Self-terminated long-lasting ventricular fibrillation: What is the mechanism?

A 60-year-old woman with dilated cardiomyopathy was referred to our hospital due to recurrent syncope. The electrocardiogram recorded by an implantable loop recorder during a syncopal episode revealed an episode of ventricular fibrillation lasting almost 3 min that terminated spontaneously. A detailed analysis of the rhythm strip showed that the chaotic rhythm became an organized ventricular rhythm with a cycle length of 220 ms for the last 14 s before it terminated. <Learning objective: Ventricular tachyarrhythmias are one of the causes of syncope and have been observed in 1-3% of syncopal patients using an implantable loop recorder (ILR). However, long-lasting ventricular fibrillation (VF) as a cause of syncope is rare in clinical practice, because VF seldom terminates spontaneously. The long-lasting VF became an organized ventricular rhythm, and finally self-terminated as sinus rhythm was restored and this entire sequence of the arrhythmic events was recorded by an ILR.>.

Unexplained syncope: implications of age and gender on patient characteristics and evaluation, the diagnostic yield of an implantable loop recorder, and the subsequent treatment

BACKGROUND

Syncope is a common clinical problem with a variety of underlying mechanisms, some of which occur more frequently in 1 of the sexes or at a certain age.

HYPOTHESIS

There may be clinically significant age- and gender-related differences in patients with unexplained syncope.

METHODS

Five hundred seventy patients (54% women) with unexplained syncope received an implantable loop recorder (ILR) and were followed until diagnosis or for at least 1 year.

RESULTS

Women were older and more prone to severe trauma during syncope (40.8% vs 29.9%, P = 0.007), and hospitalization was more common at ≥65 years (P = 0.003) without gender difference. Muscle spasms or grand mal seizures were more common in men and at <65 years old. Carotid sinus pressure, exercise testing, coronary angiography and magnetic resonance imaging/computed tomography scans were more commonly performed in men, whereas no test was more common in women. Tilt testing, exercise test, electroencephalography, and neurological or psychiatric evaluation were more common at ≥65 years. There were no age- or gender-related differences in the diagnostic yield of the ILR, whereas patients ≥65 years old more often received specific treatment based on ILR data.

CONCLUSIONS

Gender and/or age had relevance for the clinical evaluation, rate of recurrence, and subsequent specific treatment but not for the diagnostic yield of the ILR.

Implant evaluation of an insertable cardiac monitor outside the electrophysiology lab setting

Background

To date, insertable cardiac monitors (ICM) have been implanted in the hospital without critical evaluation of other potential settings. Providing alternatives to in-hospital insertion may increase access to ICM, decrease waiting times for patients awaiting diagnosis, and reduce hospital resources.

Methods

This was a prospective, non-randomized, clinical trial involving nine clinical sites throughout the United States designed to assess the feasibility of ICM implants in a non-hospital setting. Other than the Reveal® ICM, implant supplies and techniques were left to physician discretion in patients who met indications. Patients were followed up to 90 days post-implant. The primary objective was to characterize the number of procedure-related adverse events that required surgical intervention within 90 days.

Results

Sixty-five patients were implanted at nine out-of-hospital sites. The insertion procedure was well tolerated by all patients. There were no deaths, systemic infections or endocarditis. There were two (3%) procedure-related adverse events requiring device explant and four (6%) adverse events not requiring explant. ICM use led to 16 diagnoses (24.6%) with 9 patients proceeding to alternate cardiac device implants during the course of the 90-day follow up.

Conclusion

Out-of-hospital ICM insertion can be accomplished with comparable procedural safety and represents a reasonable alternative to the in-hospital setting.

Clinicaltrials.gov registration number:NCT01168427

Holter monitoring in syncope: diagnostic yield in octogenarians

OBJECTIVES

To determine the diagnostic yield of Holter monitoring in very old adults (≥80) with syncope.

DESIGN

A Holter study was considered diagnostic if the arrhythmia explained syncope (atrioventricular (AV) block, sinus node dysfunction, atrial fibrillation with severe bradycardia or tachycardia, supraventricular or ventricular tachycardia).

SETTING

A tertiary care center in Switzerland over a period of 10 years.

PARTICIPANTS

Four hundred seventy-five Holter studies were performed in individuals aged 80 and older (median age 84, 65% female, mean left ventricular ejection fraction (LVEF) 0.56 ± 0.1%).

MEASUREMENTS AND RESULTS

Fifty-three Holter studies (11%) were diagnostic. The detected arrhythmias were AV block (n=13), sinus node dysfunction (n=13), binodal disease (n=2), atrial fibrillation with slow or rapid ventricular response (n=21), ventricular tachycardia (n=3) and supraventricular tachycardia (n=1). Forty participants (8%) received a pacemaker, and one received an implantable cardioverter-defibrillator because of the results of Holter monitoring. The yield of Holter monitoring was significantly greater (all P<.01) in the presence of heart disease (17%) and low LVEF (22%), in men (17%) and in participants aged 90 and older (20%). Heart disease (odds ratio (OR)=3.2, 95% confidence interval (CI)=1.7-6.1), male sex (OR=2.1, 95% CI=1.1-3.8), and aged 90 and older (OR=2.4, 95% CI=1.2-5.1) remained independent predictors for a high diagnostic yield of Holter monitoring. Furthermore, Holter monitoring was helpful in excluding arrhythmias as a cause of syncope in an additional 10% of cases.

CONCLUSION

The diagnostic value of Holter monitoring in participants aged 80 and older with syncope was 11.2%. Its yield was higher in men and in the presence of structural heart disease and was 20% in individuals aged 90 and older.

Self-terminated ventricular fibrillation and recurrent syncope

Ventricular fibrillation (VF) is a lethal arrhythmia that requires immediate cardioversion and is rarely self-terminating. Spontaneous termination is typically associated with more organized activation than sustained VF terminated by shock, but the precise mechanism is unclear. In the present case, we describe a patient with recurrent syncope and documented self-terminating VF, who ultimately underwent implantable cardioverter defibrillator insertion. Assessment of the rhythm strip revealed organization of a chaotic rhythm into monomorphic ventricular tachycardia before termination, in supportive of previous reports. In conclusion, self-terminating VF is a very rare condition that can cause syncope.