Use of implantable and external loop recorders in syncope with unknown causes

Implantable loop recorder in unexplained palpitations or syncope: A randomised study among young patients with structurally normal heart

Background

The utility of an implantable loop recorder (ILR) in the evaluation of unexplained syncope or palpitations in young patients in the absence of structural heart disease or ventricular dysfunction is limited. To compare the diagnostic yield of ILR with conventional extended Holter evaluation in the detection of arrhythmias among young patients with a structurally normal heart presenting with unexplained palpitations or syncope.

Methods

Open-label randomised control trial was conducted in a tertiary cardiac care centre among young patients with recurrent unexplained palpitations (≥3 episodes/year) or syncope (≥2 episodes) with normal electrocardiogram and echocardiography, after excluding non-cardiac causes. Patients were block randomised to either ILR implantation or conventional extended Holter monitoring.

Results

Fourteen patients in the ILR group and 16 patients in the conventional group completed the study. The mean age of the patients was 31.9 ± 5.5 and 31.2 ± 5.4 years. Males constituted 78.5% and 75% in the two groups, respectively. Diagnosis was established in 10 (71.5%) patients in the ILR group as compared to only 3 (18.7%) in the conventional group (p = 0.01), with an RR of 0.26 (95% CI 0.089-0.76, p = 0.01). The arrhythmias diagnosed with ILR were narrow complex tachycardia (30%), atrial fibrillation (20%), VPCs (20%), severe bradycardia with asystole due to sinus arrest (10%), VPCs with bigeminy (10%), and ventricular tachycardia (10%).

Conclusion

In young patients with unexplained syncope or palpitations, ILR has a higher diagnostic yield in the accurate detection of arrhythmia compared with conventional Holter strategy, resulting in better management.

The diagnostic yield of implantable loop recorders stratified by indication: "real-world" use in a large academic hospital

PURPOSE

To report on the clinical utility of implantable loop recorders (ILRs) in a large academic hospital setting over a 4-year period.

METHODS

Retrospective study (2013-2016) of patients receiving ILRs for any indication including syncope, cryptogenic stroke (CrS), atrial fibrillation (AF) burden, palpitations, ventricular arrhythmias (VA), and other. Remote checks, symptomatic transmissions, and in-person checks were reviewed. Time to diagnosis was documented.

RESULTS

A total of 263 patients (54% male, mean age 63 ± 15 years, mean follow-up 601 (range 9-1714) days) received ILRs for 324 indications; multiple indications were noted in 53/263 (20.2%) patients. ILR indications were 126 (39%) syncope, 81 (25%) CrS, 46 (14%) AF, 37 (11%) palpitations, 10 (3%) VA, and 24 (7%) other. Diagnostic yield for each indication was compared to the overall yield for all other indications. Three indications showed a significantly higher yield: AF (65% vs. 22%, p < 0.002), palpitations (60% vs. 24%, p < 0.001), and VA (70% vs. 28%, p < 0.004). For all other indications, there were no significant differences. Syncope had nearly half the diagnostic yield of previously published trials (28% vs. 43-56%). We observed a fourfold increase in ILR implant rate over the study duration.

CONCLUSIONS

In a "real-world" academic hospital setting, the diagnostic rate of ILRs was highest for AF, palpitations, and VA; however, these high yield indications comprised only 29% of all indications. The diagnostic yield for the commonest indication (syncope) was approximately half that reported in the previously published trials. With increasing implantation rates, additional studies are required to refine guideline-based indications for ILR implantation to improve diagnostic yield.

Imaging features of leadless cardiovascular devices

Cardiovascular devices and hemodynamic monitoring systems continue to evolve with the goal of allowing for rapid clinical intervention and management. Cardiovascular devices including the CardioMicroelectromechanical (CardioMEMS) device, implantable loop recorder, and right ventricular (RV) leadless pacemaker are now widely used for treatment and monitoring of advanced cardiac conditions, as many of these devices have been shown to significantly improve patient outcomes. Additionally, hemodynamic monitoring devices have shown utility in monitoring patients with aortic aneurysms after endovascular aortic repair (EVAR) for early detection of Type I and Type II endoleaks. There is limited published data regarding the imaging features of these devices. As these devices become more widely used, it is important for radiologists to become familiar with the normal imaging features and potential complications. The goal of this review is to summarize the data regarding the use of leadless cardiovascular devices including the CardioMEMS device, implantable loop recorder, and RV leadless pacemaker, and to present cases demonstrating their utility and normal imaging features.