Loop recorders for syncope evaluation: what is the evidence?

Effectiveness and safety of implantable loop recorder and clinical utility of remote monitoring in patients with unexplained, recurrent, traumatic syncope

BACKGROUND

Implantable loop recorder (ILR) is still underutilized in clinical practice, especially in the setting of elderly patients with recurrent, traumatic, unexplained syncope. Data on the actual risk of traumatic syncopal recurrence during ILR monitoring in this specific patient setting are lacking.

RESEARCH DESIGN AND METHODS

Prospective, multicentre registry enrolling consecutive patients undergoing ILR insertion for unexplained, recurrent, traumatic syncope. In a proportion of enrolled patients, remote monitoring (RM) was used for device follow-up. The risk of traumatic and non-traumatic syncopal recurrences during ILR observation were prospectively assessed.

RESULTS

A total of 483 consecutive patients (68±14 years, 59% male) were enrolled. During a median follow-up of 18 months, a final diagnosis was reached in 270 patients (55.9%). The risk of syncopal and traumatic syncopal recurrence was of 26.5 and 9.3%, respectively. RM significantly reduced the time to diagnosis (19.7±10.3 vs. 22.1±10.8 months; p=0.015) and was associated with a significant reduction in the risk of syncope recurrence of 48% (p<0.001), and of traumatic syncope recurrence of 49% (p=0.018).

CONCLUSIONS

ILR monitoring is effective and safe in patients with unexplained, recurrent, traumatic syncope. RM reduces the time to diagnosis and significantly reduces the risk of traumatic and non-traumatic syncopal relapses.

Clinical predictors of cardiac syncope in patients with unexplained syncope after the implantation of an insertable cardiac monitor

Syncope prognosis is related to both its etiology and comorbidities, with cardiac syncope (CS) having higher risks for mortality and cardiovascular events than syncope of non-cardiac causes. Although a novel insertable cardiac monitor (ICM) is an effective diagnostic tool for unexplained syncope, decision regarding ICM implantation with a high pre-test likelihood of CS should contribute to economic cost reduction and avoidance of unnecessary complications. This study aimed to investigate clinical factors associated with CS after ICM implantation in patients with unexplained syncope. This retrospective observational study included 31 consecutive patients with ICM implantation for syncope between September 2016 and August 2021. The initial examinations for syncope included a detailed history, physical examination, blood tests, 12-lead electrocardiograms, and transthoracic echocardiography. Of the 31 patients, 13 (41.9%) experienced recurrent CS during follow-up (676 ± 469 days). Among several clinical factors, syncope-related minor injuries (p = 0.017) and higher brain natriuretic peptide (BNP; p = 0.043) levels were significantly associated with CS. Moreover, multivariable analysis showed that both syncope-related minor injuries (odds ratio, 11.2; 95% confidence interval, 1.4-88.4; p = 0.022) and BNP higher than 64.0 pg/mL (odds ratio, 7.0; 95% confidence interval, 1.1-44.2; p = 0.038) were independent predictors of CS after ICM implantation. In conclusion, a history of minor injury secondary to syncope and higher BNP levels were independent CS predictors in patients receiving ICM for syncope. These results emphasized the utility of ICM implantation early in the diagnostic journey of patients presenting with CS predictors requiring specific treatments.

Ambulatory External Electrocardiography Monitoring: Holter, Extended Holter, Mobile Cardiac Telemetry Monitoring

Ambulatory external electrocardiography (AECG) monitoring is effective as an evidence-based diagnostic tool when suspicion for cardiac arrhythmia is high. Multiple modalities of AECG monitoring exist, with unique advantages and limitations that predict effectiveness in a variety of clinical settings. Knowledge of these characteristics allows appropriate use of AECG, maximizing patient adherence, diagnostic yield, and cost-effectiveness. In addition, new technology has allowed the development of a modern generation of devices that offer increased efficacy and functionality compared with Holter monitors.

Implantable Loop Recorders-Syncope, Cryptogenic Stroke, Atrial Fibrillation

The implantable loop recorder (ILR) is a subcutaneous, single-lead, electrocardiographic (ECG) monitoring device used for diagnosis in patients with recurrent, unexplained episodes of palpitations or syncope, for long-term monitoring in patients at risk for atrial fibrillation (AF), and to guide clinical management in patients with known AF. These devices are capable of storing and transmitting ECG data automatically in response to a significant bradyarrhythmia or tachyarrhythmia or in response to patient activation. This document aims to review the clinical utility of ILRs for arrhythmia monitoring in common clinical situations such as syncope, cryptogenic stroke, and management of patients with known AF.