Cardiac Loop Research Articles

Implantable cardiac loop recorders in the setting of a daily hospital: opportunities and challenges

Implantable cardiac loop recorders in the setting of a daily hospital: opportunities and challenges

Creating new embryological models for teaching cardiac development in embryology.

Embryology is an essential component to understanding human anatomy. It requires an in-depth understanding of 3D knowledge but is primarily taught with 2-dimensional resources. In particular, the development of the human heart is a complex process and difficult to understand using traditional teaching methods. We present here a series of heart embryology models created to supplement embryology education and aid students in understanding this complex process. Using Polydoh moldable plastic, models representing six different critical steps in heart formation are described, including: the fusing of the heart tubes (days 21-23), beginning of the cardiac loop (early day 23), fully formed cardiac loop (late day 23), four-week heart, formation of the endocardial cushions and septi (late fourth week), and heart with fully formed septi with functioning foramen ovale (sixth week). These models not only improve embryology education but also the understanding of heart pathologies. This method provides an affordable option for embryology education and provides students with learning tools that assist with the comprehension of the development of a complex organ.

Cardiac Development and Factors Influencing the Development of Congenital Heart Defects (CHDs): Part I.

The traditional description of cardiac development involves progression from a cardiac crescent to a linear heart tube, which in the phase of transformation into a mature heart forms a cardiac loop and is divided with the septa into individual cavities. Cardiac morphogenesis involves numerous types of cells originating outside the initial cardiac crescent, including neural crest cells, cells of the second heart field origin, and epicardial progenitor cells. The development of the fetal heart and circulatory system is subject to regulatation by both genetic and environmental processes. The etiology for cases with congenital heart defects (CHDs) is largely unknown, but several genetic anomalies, some maternal illnesses, and prenatal exposures to specific therapeutic and non-therapeutic drugs are generally accepted as risk factors. New techniques for studying heart development have revealed many aspects of cardiac morphogenesis that are important in the development of CHDs, in particular transposition of the great arteries.

Machine Learning Modeling to Predict Atrial Fibrillation Detection in Embolic Stroke of Undetermined Source Patients.

In patients with embolic stroke of undetermined source (ESUS), occult atrial fibrillation (AF) has been implicated as a key source of cardioembolism. However, only a minority acquire implantable cardiac loop recorders (ILRs) to detect occult paroxysmal AF, partly due to financial cost and procedural inconvenience. Without the initiation of appropriate anticoagulation, these patients are at risk of increased ischemic stroke recurrence. Hence, cost-effective and accurate methods of predicting AF in ESUS patients are highly sought after. We aimed to incorporate clinical and echocardiography data into machine learning (ML) algorithms for AF prediction on ILRs in ESUS. This was a single-center cohort study that included 157 consecutive patients diagnosed with ESUS from October 2014 to October 2017 who had ILR evaluation. We developed four ML models, with hyperparameters tuned, to predict AF detection on an ILR. The median age of the cohort was 67 (IQR 59-74) years old and the median monitoring duration was 1051 (IQR 478-1287) days. Of the 157 patients, 32 (20.4%) had occult AF detected on the ILR. Support vector machine predicted for AF with a 95% confidence interval area under the receiver operating characteristic curve (AUC) of 0.736-0.737, multilayer perceptron with an AUC of 0.697-0.708, XGBoost with an AUC of 0.697-0.697, and random forest with an AUC of 0.663-0.674. ML feature importance found that age, HDL-C, and admitting heart rate were important non-echocardiography variables, while peak mitral A-wave velocity and left atrial volume were important echocardiography parameters aiding this prediction. Machine learning modeling incorporating clinical and echocardiographic variables predicted AF in ESUS patients with moderate accuracy.

Three-dimensional assessment of image distortion induced by active cardiac implants in 3.0T CMR

CMR at 3.0T in the presence of active cardiac implants remains a challenge due to susceptibility artifacts. Beyond a signal void that cancels image information, magnetic field inhomogeneities may cause distorted appearances of anatomical structures. Understanding influencing factors and the extent of distortion are a first step towards optimizing the image quality of CMR with active implants at 3.0T. All measurements were obtained at a clinical 3.0T scanner. An in-house designed phantom with a 3D cartesian grid of water filled spheres was used to analyze the distortion caused by four representative active cardiac devices (cardiac loop recorder, pacemaker, 2 ICDs). For imaging a gradient echo (3D-TFE) sequence and a turbo spin echo (2D-TSE) sequence were used. The work defines metrics to quantify the different features of distortion such as changes in size, location and signal intensity. It introduces a specialized segmentation technique based on a reaction–diffusion-equation. The distortion features are dependent on the amount of magnetic material in the active implants and showed a significant increase when measured with the 3D TFE compared to the 2D TSE. This work presents a quantitative approach for the evaluation of image distortion at 3.0T caused by active cardiac implants and serves as foundation for both further optimization of sequences and devices but also for planning of imaging procedures.

Comparing the outcomes and costs of cardiac monitoring with implantable loop recorders and mobile cardiac outpatient telemetry following stroke using real-world evidence.

Aim: Patients with ischemic stroke (IS) commonly undergo monitoring to identify atrial fibrillation with mobile cardiac outpatient telemetry (MCOT) or implantable loop recorders (ILRs). The authors compared readmission, healthcare cost and survival in patients monitored post-stroke with either MCOT or ILR. Materials & methods: The authors used claims data from Optum's de-identified Clinformatics® Data Mart Database to identify patients with IS hospitalized from January 2017 to December 2020 who were prescribed ambulatory cardiac monitoring via MCOT or ILR. They compared the costs associated with the initial inpatient visit as well as the rate and causes of readmission, survival and healthcare costs over the following 18months. Datasets were balanced using patient baseline and hospitalization characteristics. Multivariable generalized linear gamma regression was used for cost comparisons. Cox proportional hazard regression was used for survival and readmission analysis. Sub-cohorts were analyzed based on the severity of the index IS. Results: In 2244 patients, readmissions were significantly lower in the MCOT monitored group (30.2%) compared with the ILR group (35.4%) (hazard ratio [HR] 1.23; 95% CI: 1.04-1.46). Average cost over 18months starting with the index IS was $27,429 (USD) lower in the MCOT group (95% CI: $22,353-$32,633). Survival difference bordered on statistical significance and trended to lower mortality in MCOT (8.9%) versus ILR (11.3%) (HR 1.30; 95% CI: 1:00-1.69), led by significance in patients with complications or comorbidities with the index event (MCOT 7.5%, ILR 11.5%; HR 1.62; 95% CI: 1.11-2.36). Conclusion: The use of MCOT versus ILR as the primary monitor following IS was associated with significant decreases in readmission, lower costs for the initial IS and total care over the next 18months, significantly lower mortality for patients with complications and comorbidities at the index stroke, and a trend toward improved survival across all patients.

Abstract NS8: Interventional Nurse Practitioner-Led Loop Recorder Implantation Program: Impact on Quality of Etiopathogenic Diagnosis of Ischemic Stroke

Background: Extended cardiac rhythm monitoring increases the odds of detecting paroxysmal atrial fibrillation (PAF), an important finding in the etiopathogenic evaluation of patients with ischemic stroke. The development of a systematic approach to extended cardiac monitoring in this population is bound to positively influence the quality of diagnostic evaluation and, by extension, the application of tailored protocols for secondary stroke prevention. Methods: We retrospectively analyzed our experience with a cardiac loop recorder implantation program specifically designed for ischemic stroke patients suspected of having cardiogenic embolism, led and implemented by an interventional nurse practitioner in our team. We specifically queried its diagnostic yield as it relates to the quality of etiopathogenic diagnosis of this population. Results: The program has been currently in operation for 21 months, during which, 103 patients have undergone successful implantation of a cardiac loop recorder. The cohort includes 54 women and 49 men, their ages ranging 39-89 years (Mean = 67), 90 (87.38%) of whom had suffered an ischemic stroke, while the remainder had transient ischemic attacks. A total of 12 (11.65%) patients had newly detected PAF during the monitoring period, which varied 12-612 days (Mean = 316). The interval from implantation to PAF detection varied 3-202 days (mean = 90). Only one (0.97%) procedural complication (i.e., site infection) occurred, requiring device explantation without any long-term effects. All instances (100%) of PAF detection resulted in a change in from antiplatelet to anticoagulant agents for secondary stroke prevention. Conclusions: Programmatic implantation of cardiac loop recorders can successfully be carried out by interventional nurse practitioners, and it effectively enhances the etiopathogenic evaluation of ischemic stroke patients. Moreover, its yield for detection of PAF is considerable, and it translates in measurable changes in preventive antithrombotic regimens.

Abstract 14603: Post-Myocardial Infarction Secondary Mitral Regurgitation Elevates Circumferential Strain in the Remote Zone and Contractile Dyssynchronicity in a Swine Model

Introduction: Post-myocardial infarction (MI) secondary mitral regurgitation (SMR) worsens left ventricular function and mortality, due to the volume overload it imposes on the ventricle. In this study, we sought to investigate the effects of the volume load from SMR on regional myocardial mechanics and dyssynchrony. Methods: Ten Yorkshire swine were induced with MI by occluding the left circumflex branch. Cardiac MRI and PV loop were performed at baseline (prior to MI), and at termination (3 months after MI). SMR was quantified using epicardial echo. Pigs were divided into 2 groups: no/mild MR (nmMR, n=4) and moderate/severe MR (msMR, n=6). MRI images were analyzed to measure infarction size, end-diastolic (EDV) and end-systolic volume (ESV), circumferential strain (CS), and standard deviation of time to peak of CS as systolic dyssynchrony index (SDI) to evaluate the dyssynchrony. The myocardial region was divided into the infarction, border, and remote zone, based on the LCx-supplied region (Fig. A and B1) . Results: There were no differences in infarction size between the two groups. The changes (Δ) of EDV and ESV from baseline to 3M were greater in msMR compared to nmMR (63.8±24.6mL vs 33.5±9.2 mL, p<0.05, and 48.1±18.9 mL vs 23.0±4.9 mL, p<0.05, respectively) (Fig. B) . Group-wise comparison of CS between baseline and 3M for each zone demonstrated that CS in the infarction zone decreased in both groups. However, CS in the remote zone was elevated at 3M only in msMR (-12.07±3.65 % vs -16.36±3.07 %, p<0.01) and there was a strong correlation between EDV and CS in the remote zone (Pearson r=-0.6614, p=0.01) (Fig. C) . Also, SDI of CS was significantly elevated at 3M in msMR (0.09741 vs 0.1255, p=0.015) (Fig. D) . Conclusions: Elevated CS in the remote zone and dyssynchrony due to volume load could impair LV function, potentially increasing oxygen demand and reducing pumping efficiency.

Point-of-Care Chemistry-Guided Dialysate Adjustment to Reduce Arrhythmias: A Pilot Trial

Excessive dialytic potassium (K) and acid removal are risk factors for arrhythmias; however, treatment-to-treatment dialysate modification is rarely performed. We conducted a multicenter, pilot randomized study to test the safety, feasibility, and efficacy of 4 point-of-care (POC) chemistry-guided protocols to adjust dialysate K and bicarbonate (HCO3) in outpatient hemodialysis (HD) clinics. Participants received implantable cardiac loop monitors and crossed over to four 4-week periods with adjustment of dialysate K or HCO3 at each treatment according to pre-HD POC values: (i) K-removal minimization, (ii) K-removal maximization, (iii) Acidosis avoidance, and (iv) Alkalosis avoidance. The primary end point was percentage of treatments adhering to the intervention algorithm. Secondary endpoints included pre-HD K and HCO variability, adverse events, and rates of clinically significant arrhythmias(CSAs). Nineteen subjects were enrolled in the study. HD staff completed POC testing and correctly adjusted the dialysate in 604 of 708 (85%) of available HD treatments. There was 1 K≤3, 29 HCO3<20 and 2 HCO3 >32 mEq/l and no serious adverse events related to study interventions. Although there were no significant differences between POC results and conventional laboratory measures drawn concurrently, intertreatment K and HCO3 variability was high. There were 45 CSA events; most were transient atrial fibrillation (AF), with numerically fewer events during the alkalosis avoidance period (8) and K-removal maximization period (3) compared to other intervention periods (17). There were no significant differences in CSA duration among interventions. Algorithm-guided K/HCO3 adjustment based on POC testing is feasible. The variability of intertreatment K and HCO3 suggests that a POC-laboratory-guided algorithm could markedly alter dialysate-serum chemistry gradients. Definitive end point-powered trials should be considered.

Real-life data on the workload of cardiac implantable electronic device remote monitoring in a large tertiary center.

Cardiac implantable electronic devices (CIED) and implantable loop recorders (ILR) are increasingly monitored by systems allowing remote transmission of data from the patient to the hospital. Remote monitoring (RM) has been shown to increase patient satisfaction and safety. However, real-life data on the number and causes of the RM transmissions, and actions initiated by them are scarce. A total of 3446 patients with CIED and 92 patients with ILR were included in the study. Data on the number of alerts, scheduled and patient-initiated transmissions as well as the causes and actions initiated by the transmissions were systematically collected from March 1 to December 30, 2022. The data was subdivided by the device type. During the study period 7087 remote CIED and 1212 ILR transmissions were generated, (0.2 and 1.3 per patient per month), respectively. Of these transmissions 49% (4084) were automatic alerts, and 29% (2434) and 22% (1781) were scheduled and patient initiated, respectively. Most of the CIED alerts (73%) and the scheduled transmissions (90%) were nonactionable, and only 7% and 5% led to in-office follow-up, respectively. Off all ILR alerts (1011) PM implantation was scheduled to 11 patients. RM transmissions were common, but most of them were nonactionable. These real-life findings indicate that detailed analysis of the causes of the RM transmissions is important for optimization of the remote follow-up workload.

Twin reversed arterial perfusion sequence with a cardiac loop

Twin reversed arterial perfusion sequence with a cardiac loop

Characterization of cardiac involvement in children with LMNA-related muscular dystrophy.

Introduction: LMNA-related muscular dystrophy is a rare entity that produce "laminopathies" such as Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B (LGMD1B), and LMNA-related congenital muscular dystrophy (L-CMD). Heart failure, malignant arrhythmias, and sudden death may occur. No consensus exists on cardiovascular management in pediatric laminopathies. The aim was to perform an exhaustive cardiologic follow-up in pediatric patients diagnosed with LMNA-related muscular dystrophy. Methods: Baseline cardiac work-up consisted of clinical assessment, transthoracic Doppler echocardiography, 12-lead electrocardiogram, electrophysiological study, and implantation of a long-term implantable cardiac loop recorder (ILR). Results: We enrolled twenty-eight pediatric patients diagnosed with EDMD (13 patients), L-CMD (11 patients), LGMD1B (2 patients), and LMNA-related mild weakness (2 patients). Follow-up showed dilated cardiomyopathy (DCM) in six patients and malignant arrhythmias in five (four concomitant with DCM) detected by the ILR that required implantable cardioverter defibrillator (ICD) implantation. Malignant arrhythmias were detected in 20% of our cohort and early-onset EDMD showed worse cardiac prognosis. Discussion: Patients diagnosed with early-onset EDMD are at higher risk of DCM, while potentially life-threatening arrhythmias without DCM appear earlier in L-CMD patients. Early onset neurologic symptoms could be related with worse cardiac prognosis. Specific clinical guidelines for children are needed to prevent sudden death.

Surgical placement of implantable cardiac loop recorders in great apes.

Cardiovascular diseaseis the leading cause of morbidity and mortality in zoologically managed adult great apes, accounting for 29%-77% of adult deaths in the North American population depending on the species. In an effort to better understand the underlying causes of heart disease, implantable loop recorders (ILRs) have been used in some cases to monitor great apes with suspected or known cases of arrhythmia. This is a 10-year review of the Great Ape Heart Project's experience of implanting 21 ILRs in 7 gorillas (Gorilla gorilla gorilla; 9 total ILR devices), 5 chimpanzees (Pan troglodytes, 11 total ILR devices), and 1 orangutan (Pongo abelii, 1 ILR device) in an effort to develop effective methods for surgical implantation and remote collection of the data for analysis.

Comparative Effectiveness and Safety of Cryoablation Versus Radiofrequency Ablation Treatments for Persistent Atrial Fibrillation

The purpose of this study was to compare the effectiveness and safety of 2 strategies for catheter treatment of patients with persistent atrial fibrillation in the long-term period, using cardiac implantable loop recorders. The research is a prospective, randomized, controlled study designed to compare the results of modern catheter technologies in patients with persistent atrial fibrillation. The study included 127 patients with persistent atrial fibrillation in the last 6months before inclusion in the study, for whom at least 2 antiarrhythmic drugs of class I to III were not effective. By random distribution, 50 patients were included in group 1; they underwent cryoballoon ablation, using a cryoballoon of the second generation. Group 2 also included 50 patients who underwent radiofrequency ablation, where a catheter was used to control the contact force. Cardiac implantable loop electrocardiogram recorders were implanted in all patients after surgery. The average duration of follow-up was 36months. The primary end point of efficacy occurred in 15 patients in the group with cryoballoon ablation and 14 patients in the group with radiofrequency ablation. In conclusion, the primary effectiveness was relatively the same in the groups; yet, in the long-term period, the superiority of radiofrequency ablation using catheters with pressure control was noted, but the difference in results was statistically insignificant (p <0.672) and there was no significant difference between the 2 methods in terms of overall safety.

C19 REMOTE MONITORING OF IMPLANTABLE CARDIAC DEVICES: ANALYSIS AND CHARACTERISATION OF ONE CENTRE‘S ACTIVITY SINCE THE START OF THE COVID–19 PANDEMIC

IntroductionThe COVID–19 outbreak has accelerated the diffusion of remote monitoring (RM) in patients with Cardiac Implantable Electronic Devices (CIEDs). The primary objective of this analysis was to characterize the number of remotely monitored CIEDs in our centre since the start of the programme (November 2017) by comparing the number of patients monitored before and after the beginning of the pandemic (1 March 2020). The secondary objective was to quantify the number of scheduled hospital visits following the introduction of RM as an alternative to traditional outpatient monitoring from the first scheduled remote follow–up (1 November 2020) to the end the observation period (30 November 2021).Materials and MethodsAll patients with CIED compatible with RM technology (860 patients) were included. Information regarding CIED was obtained from CardioRef software (3A Sistemi, Castel San Pietro Terme, BO) and from the informative system in use in our Cardiology Department Log80 (Log80, Forlì, FC). All data were collected and analysed using Microsoft Excel software (Office 365 version).ResultsSeven hundred sixty–eight patients were provided with RM devices, which represent the 89.3% of monitorable CIEDs. Fig. 1 shows the number of RM patients characterised by type: pacemaker (PM), implantable cardiac defibrillator (ICD) and loop recorder (LR). The number of RM patients has substantially increased in the months following the start of the pandemic. Moreover, during the 13 months observation period, hospital visits decreased by an average of 42%, excluding the period July–August 2021, during which no scheduled follow–up visits in our centre are performed (Fig. 2). DiscussionOur RM activity, which started only for ICD and LR patients, was extended since March 2020 to PM patients, increasing from 125 to 768 MR patients. This has reduced the time spent by the patient and the caregiver in travelling to the hospital, attending for the visit. As a consequence, also the consumption of healthcare resources accordingly decreased, as documented by the 42% reduction in hospital visits. This result was achieved through the setting up of a multi–professional working group (doctor, nurses, biomedical engineer) dedicated to the daily management of incoming transmissions and phone interviews.

Catheter ablation for persistent atrial fibrillation: A multicenter randomized trial of pulmonary vein isolation (PVI) versus PVI with posterior left atrial wall isolation (PWI) - The CAPLA study

The success of pulmonary vein isolation (PVI) is reduced in persistent AF (PsAF) compared to paroxysmal AF. Adjunctive ablation strategies have failed to show consistent incremental benefit over PVI alone in randomized studies. The left atrial posterior wall is a potential source of non-PV triggers and atrial substrate which may promote the initiation and maintenance of PsAF. Adding posterior wall isolation (PWI) to PVI had shown conflicting outcomes, with earlier studies confounded by methodological limitations. To determine whether combining PWI with PVI significantly improves freedom from AF recurrence, compared to PVI alone, in patients with PsAF. This is a multi-center, prospective, international randomized clinical trial. 338 patients with symptomatic PsAF refractory to anti-arrhythmic therapy (AAD) will be randomized to either PVI alone or PVI with PWI in a 1:1 ratio. PVI involves wide antral circumferential pulmonary vein (PV) isolation, utilizing contact force sensing ablation catheters. PWI involves the creation of a floor line connecting the inferior aspect of the PVs, and a roof line connecting the superior aspect of the PVs. Follow up is for a minimum of 12 months with rhythm monitoring via implantable cardiac device and/or loop monitor, or frequent intermittent monitoring with an ECG device. The primary outcome is freedom from any documented atrial arrhythmia of > 30 seconds off AAD at 12 months, after a single ablation procedure. This randomized study aims to determine the success and safety of adjunctive PWI to PVI in patients with persistent AF.

Cardiac Response to &amp;#946;-Adrenergic Stimulation Determined by Pressure-Volume Loop Analysis

Here we describe a cardiac pressure-volume loop analysis under increasing doses of intravenously infused isoproterenol to determine the intrinsic cardiac function and the β-adrenergic reserve in mice. We use a modified open-chest approach for the pressure-volume loop measurements, in which we include ventilation with positive end-expiratory pressure.

Closed Chest Biventricular Pressure-Volume Loop Recordings with Admittance Catheters in a Porcine Model.

Pressure-volume (PV) loop recording enables the state-of-the-art investigation of load-independent variables of ventricular performance. Uni-ventricular evaluation is often performed in preclinical research. However, the right and left ventricles exert functional interdependence due to their parallel and serial connections, encouraging simultaneous evaluation of both ventricles. Furthermore, various pharmacological interventions may affect the ventricles and their preloads and afterloads differently. We describe our closed chest approach to admittance-based bi-ventricular PV loop recordings in a porcine model of acute right ventricular (RV) overload. We utilize minimally invasive techniques with all vascular accesses guided by ultrasound. PV catheters are positioned, under fluoroscopic guidance, to avoid thoracotomy in animals, as the closed chest approach maintains the relevant cardiopulmonary physiology. The admittance technology provides real-time PV loop recordings without the need for post-hoc processing. Furthermore, we explain some essential troubleshooting steps during critical timepoints of the presented procedure. The presented protocol is a reproducible and physiologically relevant approach to obtain a bi-ventricular cardiac PV loop recording in a large animal model. This can be applied to a large variety of cardiovascular animal research.

Investigating the effect of trigger delay on cardiac 31P MRS signals

The heart’s geometry and its metabolic activity vary over the cardiac cycle. The effect of these fluctuations on phosphorus (31P) magnetic resonance spectroscopy (MRS) data quality and metabolite ratios was investigated. 12 healthy volunteers were measured using a 7 T MR scanner and a cardiac 31P-1H loop coil. 31P chemical shift imaging data were acquired untriggered and at four different times during the cardiac cycle using acoustic triggering. Signals of adenosine-triphosphate (ATP), phosphocreatine (PCr), inorganic phosphate (Pi) and 2,3-diphosphoglycerate (2,3-DPG) and their fit quality as Cramér-Rao lower bounds (CRLB) were quantified including corrections for contamination by 31P signals from blood, flip angle, saturation and total acquisition time. The myocardial filling factor was estimated from cine short axis views. The corrected signals of PCr and gamma-ATP were higher during end-systole and lower during diastasis than in untriggered acquisitions (P<0.05). Signal intensities of untriggered scans were between those with triggering to end-systole and diastasis. Fit quality of PCr and gamma-ATP peaks was best during end-systole when blood contamination of ATP and Pi signals was lowest. While metabolite ratios and pH remained stable over the cardiac cycle, signal amplitudes correlated strongly with myocardial voxel filling. Triggering of cardiac 31P MRS acquisitions improves signal amplitudes and fit quality if the trigger delay is set to end-systole. We conclude that triggering to end-systole is superior to triggering to diastasis.

External Cardiac Loop Recorders: Functionalities, Diagnostic Efficacy, Challenges and Opportunities.

According to the World Health Organization's (WHO) report of 2016, cardiovascular diseases (CVDs) accounted for mortality of an estimated 17.9 million people globally. Of these deaths, 85% were due to myocardial infarction and stroke. Further, the pre-dominant atrial fibrillation (AF) arrhythmia has been the most suspected underlying cause of transient ischemic attack or stroke. Thus, the etiologies of early symptoms like syncope and palpitations in patients needs to be evaluated by employing proper diagnostic tests to make early treatment decisions. The most widely referred 24 to 48 hour Holter electrocardiographic (ECG) monitoring tests have not been proved to be much effective in recognizing infrequent intermittent arrhythmic episodes. These drawbacks have led to the development of long-term ambulatory ECG (AECG) monitoring devices. This review reports the state-of-the-art existing AECG monitoring devices and their role of long-term ECG recording in patients suspected with cardiac syncope and palpitations to understand the underlying arrhythmic cause, as well as in the diagnosis and management of AF. Primarily, the utility and diagnostic yield of external cardiac recorders or event loop recorders (ELRs) in capturing the symptom-rhythm correlation which constitutes a clinically useful recordings of heart's electrical activity during infrequent arrhythmic conditions was critically reviewed. Furthermore, a brief case study on challenges involved in clinical data acquisition at a cardiac care unit using ambulatory external monitoring device has been presented. Finally, improvements in design engineering and algorithmic developments to enhance the diagnostic yield and usability of ELRs in clinical settings have been proposed.