The utility of implantable loop recorders (ILR) in patient management: an age and indication stratified study in the outpatient-implant era

Introduction Implantable loop recorders (ILR) are now routinely implanted for long-term cardiac monitoring in the clinic setting. This study examined the real-world performance of these devices, focusing on the management decision changes made in response to ILR-recorded data. Methods and Results This was a single centre, prospective observational study of consecutive patients undergoing ILR implantation. All patients who underwent implantation of a Medtronic Reveal LINQ device from September 2017 to June 2019 at Barts Heart Centre were included. 501 patients were included. 302 (60%) patients underwent ILR implantation for an indication of pre-syncope/syncope, 96 (19%) for palpitations, 72 (14%) for atrial fibrillation (AF) detection with a history of cryptogenic stroke and 31 (6%) for patients deemed to be high risk of serious cardiac arrhythmia. The primary outcome of this study was that an ILR-derived diagnosis altered management in 110 (22%) of patients. Secondary outcomes concerned sub-group analyses by indication: in patients who presented with syncope/presyncope, a change in management resulting from ILR data was positively associated with age (HR: 1.04 [95%CI 1.02–1.06]; p < 0.001) and negatively associated with a normal ECG at baseline (HR 0.54 [0.31–0.93]; p = 0.03). Few patients (1/57, 2%) aged < 40 years in this group underwent device implantation, compared to 19/62 patients (31%) aged 75 years and over (p = 0.0024). 22/183 (12%) of patients in the 40–74 age range had a device implanted. In patients who underwent ILR insertion following cryptogenic stroke, 13/72 patients (18%) had AF detected leading to a decision to commence anticoagulation. Conclusion These results inform the utility of ILR in the clinical setting. Diagnoses provided by ILR that lead to changes in management are rare in patients under age 40, particularly following syncope, presyncope or palpitations. In older patients new diagnoses are frequently made and trigger important changes in treatment.

Arrhythmic risk stratification in patients with clinically-suspected left ventricular arrhythmogenic cardiomyopathy

Background Arrhythmic risk of patients with left ventricular arrhythmogenic cardiomyopathy (LVAC) is unpredictable. Purpose To identify risk facors associated with major ventricular tachyarrhythmias (VTA) in clinically-suspected LVAC patients. Methods We enrolled 127 consecutive patients (69% males, age 46±13 y, LVEF 54±7%) with clinically-suspected LVAC. All patients presented with either major (VT, VF) or minor VTA (NSVT, frequent VEB), and underwent extensive diagnostic workup to rule-out alternative diagnoses. Medical treatment and ICD implant were clinically-driven. Prospective follow-up was obtained via sequential 24h-Holter ECG (2–4/y) with or without continuous arrhythmia monitoring (ICD or implantable loop recorders, ILR). The primary endpoint was occurrence of major VTA (VT/VF/ICD therapy) by 24-month follow-up. Results At presentation, 56 (44%) and 71 patients (56%) had, respectively, major and minor VTA. Variants in desmosomal genes were identified in 7 of the 9 patients with clinically-indicated genetic test. Delayed gadolinium enhancement (DGE, average 23±12% of the LV mass) had anteroseptal distribution in 43 cases (34%). Monitoring strategy included ICD (n=64), ILR (n=33), or sequential Holer ECGs (n=30). By 24-month follow-up, major VTA occurred in 32 patients (25%). At univariable anlysis, major VTA onset (HR 16.8, 95% CI 5.4–52.2, p<0.001) and anteroseptal DGE (HR 3.0, 95% CI 1.3–6.9, p=0.010) were significantly associated with major VTA by 24-month follow-up. Among patients presenting with minor VTA, the only factor significantly associated with the primary endpoint was anteroseptal DGE (3/4 vs. 14/67, p=0.004). Conclusion Our preliminary experience suggests that, in patients with clinically-suspected LVAC, major VTA onset and anteroseptal DGE are relevant risk factors for major arrhythmic events by 24-month follow-up. FUNDunding Acknowledgement Type of funding sources: None.

Atrial fibrillation in unexplained syncope: observations from the Reveal LINQ registry

Background Implantable loop recorders (ILRs) have come to play an important role in the workup of patients with recurrent syncope of uncertain origin. In addition to detecting bradyarrhythmias related to syncope, which is the main diagnostic focus in these patients, ILRs are also capable of uncovering subclinical atrial fibrillation (AF). Purpose We sought to determine the percentage of patients monitored with an ILR for unexplained syncope who have AF detected and to describe clinical actions taken in these patients. Methods Patients enrolled in the Reveal LINQ Registry who received an ILR for unexplained syncope and had at least one follow-up form were included. The device automatically detects AF episodes lasting ≥2 minutes. Patients were considered to have AF based on an AF diagnosis made by the treating physician during follow-up or if device-detected AF was adjudicated as true AF by an external reviewer. AF detection rates were calculated using Kaplan-Meier methods. Results In total, 498 patients (aged 61.8±20.0 years, 49.6% female, CHA2DS2VASc score 2.2±1.7) were included and followed for 22±12 months. A history of AF was present in 97 (20%) patients, while 401 patients had no history. By 18 months, the incidence of AF was 70.9% (95% CI, 60.8%, 80.3%) in patients with a history of AF and 21.4% (95% CI, 17.4%, 26.1%) in patients without (Figure). AF detection in those with (30.4%) and without (30.1%) syncope during follow-up was similar. By the end of follow-up, and among patients with newly detected AF, 29/86 (33.7%) were on oral anticoagulation, 7 (8.1%) underwent AF ablation, 6 (7.0%) underwent other type of ablation, and 2 (2.3%) received cardioversion. Other actions among the whole cohort included implant of an IPG, ICD, or CRT in 98/498 (19.7%). Conclusion Among patients monitored with ILRs to determine the cause of recurrent syncope episodes, approximately 1 in 5 patients had new AF detected. In addition to improving the management of patients with syncope, ILR data served to support AF-related clinical decisions. FUNDunding Acknowledgement Type of funding sources: Private company. Main funding source(s): Medtronic Inc Incidence of AF according to baseline AF