Reveal LINQ Insertable Cardiac Monitor Research Articles

PO-03-050 INCIDENCE OF INAPPROPRIATE ATRIAL FIBRILLATION DETECTION WITH REMOTE CARDIAC MONITORING BY INSERTABLE CARDIAC MONITOR

An increasing number of patients are receiving long-term cardiac monitoring to detect and manage atrial fibrillation (AF). The Reveal LINQ insertable cardiac monitor (ICM) (Medtronic, Minneapolis, MN, U.S.A.), is a miniaturized, leadless, subcutaneous, long-term cardiac monitoring that is widely used to manage arrhythmias. To study the inaccurate (false-positive (FP)) detection of AF during remote cardiac monitoring with the Reveal LINQ ICM. In this non-randomized retrospective study, all clinic patients with a Reveal LINQ ICM implanted between March 2014 and January 2021 were included. The record of the last reported AF for each patient was reviewed. Of 294 consecutive patients, 127 patients (average age= 67.8, Female = 52 (40.9%)) had at least one report of AF. The main reason for implanting cardiac monitoring was AF management (38.6%). There were 34 true AF and 93 inappropriate AF detections. The percentage of FP-reported AF was 73.2%. There was not a significant association between the rate of FP and reasons for cardiac monitoring (P-value = 0.516 by Fisher's exact test). Our findings based on the reason for monitoring are summarized in Table 1. The true diagnosis of reported inappropriate AF were: premature atrial contractions (44.9%) , premature ventricular contractions (11.8%), atrial flutter ( 10.2%) , atrial tachycardia ( 0.8%), premature atrial contractions / ventricular tachycardia (0.8%), noise (4.7%). There is a high rate of inappropriate AF detection by the Reveal LINQ ICM, requiring reviewing the tracing by an expert. More robust algorithms need to be developed for the Reveal LINQ ICM to reduce the rate of FP.

PO-03-055 INCIDENCE OF INAPPROPRIATE PAUSE DETECTION WITH REMOTE CARDIAC MONITORING BY INSERTABLE CARDIAC MONITOR, A REAL-WORLD STUDY

An increasing number of people receive long-term cardiac monitoring with implantable devices due to the growing prevalence of cardiac arrhythmias. The LINQ II is Medtronic’s latest generation insertable cardiac monitor (ICM) (Medtronic, Minneapolis, MN, U.S.A.) Compared to its previous generation, Reveal LINQ ICM, the LINQ II ICM employs artificial intelligence (AI) to reduce the false positive (FP) detection of pause. We previously showed that the rate of FP pause among our patients with Reveal LINQ ICM was 52%, but some researchers showed this rate could be as high as 76%. To detect the incidence of inappropriate (FP) diagnoses of pause during remote cardiac monitoring with the LINQ II ICM. This is a non-randomized retrospective study. All our clinic patients with LINQ II ICM between May 2021 and November 2022 were included. We excluded the patients with incomplete data. The record of all pauses for each patient was reviewed. Of 73 consecutive patients (average age 64.9, Female = 35 (48%)), 10 patients had at least one report of pause, and the total number of reported pauses was 43 (average 4.3 per patient, min = 1, max = 12). There were 15 true pause episodes and 28 inappropriate pause detections. The device’s accuracy in detecting a true pause was 35%. The rate of reported FP pauses was 65%. Five patients had at least one episode of true pause. The specificity of LINQ II ICM to find patients with pause was 50%. Despite using AI, there is a high rate of inappropriate pause detection by the LINQ II ICM, and tracing examination by an expert is essential to confirm the validity of the device report. AI didn’t improve the accuracy of pause detection in our patients. More robust algorithms are required to be developed for the LINQ II ICM to reduce the rate of FP.

Risk stratification parameters as assessed by continuous long-term cardiac monitoring in pulmonary hypertension – heart rate variability, heart rate, and physical activity

Abstract Background Pulmonary hypertension (PH) is a progressive disease affecting both the pulmonary vasculature and the heart. In the current ESC/ERS guidelines nine variables are used in PH risk assessment, and have been proven to be independent predictors of survival in PH. The risk assessment parameters include clinical symptoms, exercise capacity and imaging. The present study is the first to assess continuous 24/7 heart rate variability (HRV), heart rate (HR) and physical activity monitoring in patients with PH. Purpose To identify risk stratification parameters by continuous cardiac monitoring in PH. Methods Patients diagnosed with PH were included in this prospective single-centre study. Patients had a Reveal LINQ insertable cardiac monitor implanted to continuously monitor heart rate variability (HRV), heart rate at day and night and physical activity. HRV was expressed as the mean HRV in sinus rhythm during each full day (SDANN method). Pearson and Spearman correlations between the loop recorder variables and ESC/ERS risk stratification variables were calculated and compared with the loop recorder data in 30-days intervals. Results A total of 41 patients were prospectively enrolled, 27 patients with pulmonary arterial hypertension (PAH) and 14 patients with chronic thromboembolic pulmonary hypertension (CTPEH). The patients were monitored continuously in a total of 82 patient-years, had a mean age of 58 years and were primarily in a stable disease phase with a mean WHO functional class (FC) of 2.2. HRV and physical activity divided by heart rate at daytime showed the highest correlations respectively with current risk parameters. In particular, high correlations were found between HRV and NT-proBNP (R=−0,69 p≤2.2e-16), WHO FC (R=−0,65 p=2.4e-5), RVEF (R=0,61 p=0,00012) and right atrial pressure (RAP) (R=−0.67 p=0.0023) (Figure 1). Conclusion This study demonstrates the potential of HRV, and physical activity divided by heart rate daytime as risk parameters in pulmonary hypertension. Progression of symptoms in PH are often delayed compared with pathophysiological changes, and continuous monitoring offers a potential to early recognition of disease progression and optimization of PAH therapy. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): The study was supported by the Heart Centre Research Council,Rigshospitalet and an investigator initiated study research grant fromJansson Pharmaceuticals.

Safety of in-hospital insertable cardiac monitor procedures performed outside the traditional settings: results from the Reveal LINQ in-office 2 international study

BackgroundHistorically, the majority of insertable cardiac monitor (ICM) procedures were performed in the cardiac catheterization (cath) lab, electrophysiology (EP) lab, or operating room (OR). The miniaturization of ICMs allows the procedure to be relocated within the hospital without compromising patient safety. We sought to estimate the rate of untoward events associated with procedures performed within the hospital but outside the traditional settings and to characterize resource utilization, procedure time intervals, and physician experience.MethodsThe Reveal LINQ in-Office 2 (RIO 2) International study was a single arm, multicenter, prospective study. Patients indicated for an ICM and willing to undergo device insertion outside the cath/EP lab or OR were eligible and followed for 90 days after insertion.ResultsA total of 191 patients (45.5% female aged 63.8 ± 26.9 years) underwent successful Reveal LINQ ICM insertion at 17 centers in Europe, Canada and Australia. The median total visit duration was 106 min (interquartile range [IQR]: 55–61). Patient preparation and patient education accounted for 10 min (IQR: 5–20) and 10 min (IQR: 8–15) of total visit duration, respectively. Preparation and education occurred in the procedure room for 90.6 and 60.2% of patients, respectively. There were no untoward events (0.0, 95% CI: 0.0–2.1%) though four patients presented with procedure-related adverse events that did not require invasive intervention. Physicians rated procedure location as convenient or very convenient.ConclusionsThe Reveal LINQ™ ICM insertion can be safely and efficiently performed in the hospital outside the cath/EP lab or OR.Trial registrationClinicalTrials.gov identifier NCT02412488; registered on April 9, 2015.

Abstract WP257: Occurrence and Imaging Patterns of Recurrent Strokes iIn a Cohort of Cryptogenic Stroke Patients on Long Term Cardiac Monitoring

Introduction: Cryptogenic strokes account for one third of all strokes. Atrial fibrillation has been described as a leading cause in this population but occurrence of atrial fibrillation and imaging charecteristics amongst recurrent strokes in this population have not been characterized well. Methods: We reviewed electronic medical charts of a cohort of cryptogenic patients from February 2014 to September 2017 who underwent REVEAL LINQ insertable cardiac monitor. All patients met ESUS( Embolic Stroke of Unknown Source) criteria prior to implantation and were enrolled in the atrial fibrillation clinic with structured remote follow-up. All newly diagnosed atrial fibrillation was confirmed by electrophysiologists and recurrent strokes were confirmed by vascular neurologist after reviewing presentation, electronic medical record and brain imaging studies. Results: Atrial fibrillation was detected in 108 out of a total of 429 patients ( 25%) . Time to atrial fibrillation detection was average 79.8 days with a range of 13-430 days . All but one patient were started on anticoagulation. Within the entire cohort 55 patients had recurrent strokes with 7 of them having more than 1 recurrence.. 15 recurrent strokes occurred in patients in whom atrial fibrillation was detected during monitoring and 40 in patients without atrial fibrillation detected . Imaging pattern of recurrent strokes in patients with atrial fibrillation was cortical in 81.8% with 10 patients showing multiple infarcts and subcortical in 18.2% patients with one showing multiple infarcts. Strokes in patients without atrial fibrillation were cortical in location in 60% with 10 being multiple and subcortical in 40% with 3 patient having multiple infarcts.4 patients who did not have atrial fibrillation had more than 1 recurrent stroke and 3 patients who were detected to have atrial fibrillation had more than 1 recurrent stroke Conclusion majority of recurrent strokes in cryptogenic population did not have atrial fibrillation( 72.7%) Incidence of recurrent stroke was similar in patients with atrial fibrillation (13.8%) detected versus (12.4% %)not detected group . Imaging patterns showed more cortical strokes in A. fib patients ( 80%) and more subcortical strokes in patients without A. fib( 40%)

Abstract WMP69: Differential Risk Factor Profile in Cryptogenic Stroke Patients May Help Identify High Yield Candidates for Long-term Cardiac Monitoring in Detection of Paroxysmal Atrial Fibrillation

Introduction: Paroxysmal afib is the most common cause of cryptogenic strokes. Long-term insertable cardiac monitor (ICM) has been increasingly used for ongoing evaluation of afib in these patients. Due to financial affordability, it is important to identify appropriate candidates for its routine use. Methods: We reviewed EMRs of a cohort of cryptogenic stroke patients from February 2014 to May 2017 who received REVEAL LINQ ICMs. All patients met ESUS criteria prior to insertion and were enrolled in remote follow-up. At least one year monitoring was conducted if no afib was recorded. Patient demographics, stroke characteristics and risk factors were compared between patients with and without afib. Results: Among total 348 patients enrolled, 99 (28.5%) were found to have afib with median time to afib detection of 128 days. For patients without afib, the median length of follow up was 566 days. Patients with afib were significantly older (mean ± SD, 73.0 ± 9.42 vs. 64.4 ± 11.5, p<0.00001) and their left atrium size (mm) were significantly larger (37.9 ± 7.26 vs. 35.4 ± 5.81, p<0.005) than those patients without afib. Non-afib patients had statistically more frequent association with ongoing smoking or LDL ≥ 120 comparing with afib patients (p<0.05). Although not statistically significant, there was tendency that posterior circulation only strokes occurred less in afib group (p=0.08). However, intra- and extracranial atherosclerosis were comparable between afib and non-afib groups. Within the afib group, afib was detected within 30 days in 25 patients with median time to detection of 14 days. These patients had significant higher rate of intracranial stenosis (p=0.01) comparing with those patients with afib detected beyond 30 days. Conclusion: Paroxysmal afib related strokes account for about one-fourth of cryptogenic strokes in our cohort. Long term ICM may benefit more in older patients with enlarged left atrium and lack of risk factors such as smoking and high LDL. It likely has low yield in patients with posterior infarcts only. Noninvasive ambulatory ECG monitoring for 30 days may be considered first in patients with intracranial stenosis.

Real-world comparison of in-hospital Reveal LINQ insertable cardiac monitor insertion inside and outside of the cardiac catheterization or electrophysiology laboratory

Traditionally, insertable cardiac monitor (ICM) procedures have been performed in the cardiac catheterization (CATH) or electrophysiology (EP) laboratory. The introduction of the miniaturized Reveal LINQ ICM has led to simplified and less invasive procedures, affording hospitals flexibility in planning where these procedures occur without compromising patient safety or outcomes. The present analysis of the ongoing, prospective, observational, multicenter Reveal LINQ Registry sought to provide real-world feasibility and safety data regarding the ICM procedure performed in the CATH/EP lab or operating room and to compare it with insertions performed outside of these traditional hospital settings. Patients included had at least a 30-day period after the procedure to account for any adverse events. We analyzed 1222 patients (58.1% male, age 61.0 ± 17.1 years) enrolled at 18 centers in the US, 17 centers in Middle East/Asia, and 15 centers in Europe. Patients were categorized into 2 cohorts according to the location of the procedure: in-lab (CATH lab, EP lab, or operating room) (n = 820, 67.1%) and out-of-lab (n = 402, 32.9%). Several differences were observed regarding baseline and procedure characteristics. However, no significant differences in the occurrence of procedure-related adverse events (AEs) were found; of 19 ICM/procedure-related AEs reported in 17 patients (1.4%), 11 occurred in the in-lab group (1.3%) and 6 in the out-of-lab group (1.5%) (P = .80). This real-world analysis demonstrates the feasibility of performing Reveal LINQ ICM insertion procedures outside of the traditional hospital settings without increasing the risk of infection or other adverse events.

Effectiveness and accuracy of arrhythmia detection algorithm with the Reveal LINQ insertable cardiac monitor

Objective: To investigate the accuracy of arrhythmia detection algorithm and the effectiveness of Reveal LINQ insertable cardiac monitor (ICM). Methods: This single-center, descriptive, non-controlled clinical study was designed to enroll consecutive patients who were implanted with Reveal LINQ ICM in Minneapolis Veterans Affairs Medical Center from June 19, 2014 to April 18, 2017. The safety of implant procedure, the accuracy of automatic arrhythmia detection algorithm and the clinical effectiveness were evaluated and validated independently by two physicians. Results: Sixty patients with average age of (65±13) years (30-89 years) were enrolled and the follow-up duration was 466 days (30-1 072 days). Of these, 57 patients are male. The indications of ICM implantation were unexplained syncope in 35 cases, cryptogenic stroke in 13 cases, atrial fibrillation (AF) management in 5 cases, and palpitations in 7 cases. The implantation procedure was safe and successful in all patients without complications. The detection accuracy of arrhythmia algorithm was 86% (620/723), 82% (2 369/2 876), and 30% (411/1 380) for tachycardia, bradycardia, and pause events, respectively. The detection accuracy of arrhythmia algorithm for AF was 17% (5/30), 60% (1 569/2 632) and 69% (172/251) for cryptogenic stroke, unexplained syncope, and AF management, respectively. Important clinical findings were observed in 15% (9/60) patients. Only 5% (3/60) patients had important findings based on the intended clinical indications. Conclusion: The Reveal LINQ ICM is a safe, simple, and effective procedure for the detection of tachycardia and bradycardia events. However, the automatic AF and pause events detection algorithm had high false positive rate which requires further improvement.

Abstract WP199: Left Atrial Volume Index and PR Interval Are Independent Predictors of Atrial Fibrillation in Embolic Stroke Patients With Insertable Cardiac Monitor

Introduction: The use of insertable cardiac monitors (ICM) improved the detection rate of atrial fibrillation (AF) in patients with embolic strokes (ES). However, given cost of the device, current indications and availability of implant procedure, the optimal patient population that would benefit from the device remains unknown. Objectives: We sought to determine 1) the incidence of AF in patients with ES in our population and 2) whether certain variables are predictive of AF in patients with ES. Methods: A case control study was conducted from January 1, 2015 to June 23, 2017. Patients admitted to the Gates Vascular Institute with ES on MRI and CT angiogram but no evidence of AF on telemetry underwent Reveal LINQ ICM implant prior to discharge. Demographics, EKG and echocardiographic variables were assessed. Statistical analysis was conducted using SPSS version 22 and R v.1.0.44. Independent T tests were applied for continuous variables and Chi Square or Fisher’s exact test for categorical variables. Cox proportional hazard model was used to analyze whether certain variables were associated with increased odds of AF. A p-value of <0.05 was considered statistically significant. Results: A total of 177 patients were enrolled and followed for 478 ± 179 days. AF was detected in 31% (n=55). Mean age ± SD (positive vs. negative AF on ICM) was 71.1 ± 12.0 vs. 68.6 ± 11.8, p=0.20. Age, gender, race, BMI, systolic, diastolic blood pressures, cholesterol and HBA1c were not significantly different between the two groups. Significant univariate predictors of AF included PR interval (hazard ratio [HR] 1.19 per 10 milliseconds, p < 0.001) and Left Atrial Volume Index (LAVI) (HR 1.04 per 1 mL/m 2 , p = 0.01). In multivariate analysis, both PR interval and LAVI remained significant predictors of AF (HR 1.3, p < 0.001; HR 1.05, p < 0.001, respectively). Using a risk-score formulated from these predictors, we found that patients in the top quartile had a five fold higher rate of AF detection compared to the lowest quartile. Conclusion: In summary, our atrial fibrillation detection rate was 31%. PR interval and Left Atrial Volume Index were found to be both independent and multivariate predictors of atrial fibrillation in embolic stroke patients with insertable cardiac monitor.

Adapting detection sensitivity based on evidence of irregular sinus arrhythmia to improve atrial fibrillation detection in insertable cardiac monitors.

AimsIntermittent change in p-wave discernibility during periods of ectopy and sinus arrhythmia is a cause of inappropriate atrial fibrillation (AF) detection in insertable cardiac monitors (ICM). To address this, we developed and validated an enhanced AF detection algorithm.Methods and resultsAtrial fibrillation detection in Reveal LINQ ICM uses patterns of incoherence in RR intervals and absence of P-wave evidence over a 2-min period. The enhanced algorithm includes P-wave evidence during RR irregularity as evidence of sinus arrhythmia or ectopy to adaptively optimize sensitivity for AF detection. The algorithm was developed and validated using Holter data from the XPECT and LINQ Usability studies which collected surface electrocardiogram (ECG) and continuous ICM ECG over a 24–48 h period. The algorithm detections were compared with Holter annotations, performed by multiple reviewers, to compute episode and duration detection performance. The validation dataset comprised of 3187 h of valid Holter and LINQ recordings from 138 patients, with true AF in 37 patients yielding 108 true AF episodes ≥2-min and 449 h of AF. The enhanced algorithm reduced inappropriately detected episodes by 49% and duration by 66% with <1% loss in true episodes or duration. The algorithm correctly identified 98.9% of total AF duration and 99.8% of total sinus or non-AF rhythm duration. The algorithm detected 97.2% (99.7% per-patient average) of all AF episodes ≥2-min, and 84.9% (95.3% per-patient average) of detected episodes involved AF.ConclusionAn enhancement that adapts sensitivity for AF detection reduced inappropriately detected episodes and duration with minimal reduction in sensitivity.

Holding Area LINQ Trial (HALT)

BackgroundRecent 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. MethodsThis 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. ResultsTwenty 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. ConclusionWhen 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).

Insertion of miniaturized cardiac monitors outside the catheter operating room: experience and practical advice.

Minor surgical procedures are increasingly being performed as outpatient procedures in settings outside hospital operating rooms (ORs). In electrophysiology, the recent miniaturization of insertable cardiac monitors (ICMs) has enabled the routine insertion of the device as a minimally invasive procedure without the need of a catheter OR. However, a shift to office-based environments for minor surgical procedures is associated with some concerns, particularly with respect to patient- and procedure-related safety in the new setting. In the present document, the authors provide practical advice on facilities, practices, and adaptations necessary when performing ICM insertions in office settings, based on available recommendations as well as their own experience with the use of the novel Reveal LINQ ICM. The main differences from in-hospital implant settings are simplified requirements of room, equipment, and insertion procedures, while ensuring and maintaining an adequate, sterile environment. Patient selection is important: certain groups of patients are recommended to be treated in the catheter OR (e.g. those at increased risk for bleeding or very frail elderly individuals). Insertion in alternative positions, as is sometimes performed for cosmetic reasons, should be referred to dedicated hospitals. Quality assurance and internal quality control are critical in the new procedural landscape, and it is important not to trivialize minor surgical procedures. Operators' sharing of experiences and lessons learned, e.g. in the form of registries, should be encouraged.

Abstract WMP63: Prevalence of Occult Paroxysmal Atrial Fibrillation in Non-Cryptogenic Ischemic Stroke Patients

Background: Paroxysmal atrial fibrillation (PAF) is often asymptomatic and is more prevalent than persistent AF in patients with ischemic stroke (IS). Long-term monitoring with insertable cardiac monitors (ICM) yields an up to 30% PAF detection rate in cryptogenic IS patients. Yet, the prevalence of PAF in patients with a presumed stroke etiology other than AF remains unknown. Methods: Prospective cohort study of non-cryptogenic IS patients implanted within 10 days of stroke onset with the Reveal LINQ ICM (n=47 enrolled, 45/47 (95.7%) implanted). Patients were monitored until PAF detection (adjudicated by study cardiologist) or minimum of 12 months. Inclusion required a defined stroke etiology other than AF based on standard stroke evaluation (including ≥24 hour cardiac telemetry), age≥40, and either a virtual CHADS2 score ≥3, or ≥2 PAF related comorbidities (COPD, hyperthyroidism, obesity, prior MI, PR interval &gt;175ms, or renal impairment). Patients with high-risk cardiac sources, recent MI or cardiac bypass surgery, pacemaker or defibrillator, permanent anticoagulation indication or contraindication, and pregnancy were excluded. Results: Mean age 64.8 years (range 40-88 years), 15/47 (31.9%) female, mean virtual CHADS2 score 3.5 (range 3 to 5), mean CHA2DS2-VASc score 4.5 (range 3 to 8), and 8/47 (17.0%) had ≥2 PAF comorbidities. Lacunar stroke etiology predominated (n=33), followed by extracranial atherosclerotic stenosis (n=4), cardioembolic (n=3), arch atheroembolic (n=3), intracranial atherosclerosis (n=4), and extracranial dissection (n=2). Five had multiple potential sources. Interim analysis (mean monitoring 264 days, range 0 to 642 days) demonstrates 3/45 (6.7%) implanted patients have PAF (range of longest AF episode: 0.3 to 18.7 hours). Mean time to PAF diagnosis 162.7 days (range 9-356 days). All were started on anticoagulation. There was 1 device related complication (skin erosion) and 1 patient had recurrent stroke. Conclusions: Occult PAF in non-cryptogenic IS patients is infrequent and may reflect the background prevalence of PAF in this demographic. Despite this, long-term cardiac monitoring may promote optimization of stroke prevention therapy for a small but unanticipated proportion of these patients.

Baseline Demographics, Safety, and Patient Acceptance of an Insertable Cardiac Monitor for Atrial Fibrillation Screening: The REVEAL-AF Study

Given the high prevalence and risk of stroke associated with atrial fibrillation (AF), detection strategies have important public health implications. The ongoing prospective, single-arm, open-label, multicenter REVEAL AF trial is evaluating the incidence of previously undetected AF using an insertable cardiac monitor (ICM) in patients without prior AF or device implantation, but who could be at risk for AF due to their demographic characteristics, +/- non-specific but compatible symptoms. Enrollment required an elevated AF risk profile defined as CHADS2≥3 or CHADS2=2 plus one or more of the following: coronary artery disease, renal impairment, sleep apnea or chronic obstructive pulmonary disease. Exclusions included stroke or transient ischemic attack occurring in the previous year. Of 450 subjects screened, 399 underwent a device insertion attempt, and 395 were included in the final analysis (Reveal XT: n=122; Reveal LINQ: n=273; excluded: n=4). Participants were primarily identified by demographic characteristics and the presence of nonspecific symptoms, but without prior documentation of "overt" AF. The most common symptoms were palpitations (51%), dizziness/lightheadedness/pre-syncope (36%), and shortness of breath (36%). Over 100 subjects were enrolled in each pre-defined CHADS2 subgroup (2, 3 and ≥4). AF risk factors not included in the CHADS2 score were well represented (prevalence≥15%). Procedure and/or device related serious adverse events were low, with the miniaturized Reveal LINQ ICM having a more favorable safety profile than the predicate Reveal XT (all: n=13 [3.3%]; LINQ: n=6 [2.2%]; XT: n=7 [5.7%]). These data demonstrate that REVEAL AF was successful in enrolling its target population, high risk patients were willing to undergo ICM monitoring for AF screening, and ICM use in this group is becoming increasingly safe with advancements in technology. A clinically meaningful incidence of device detected AF in this study will inform clinical decisions regarding ICM use for AF screening in patients at risk.

In-office insertion of a miniaturized insertable cardiac monitor: Results from the Reveal LINQ In-Office 2 randomized study

Recent miniaturization of an insertable cardiac monitor (ICM) may make it possible to move device insertion from a hospital to office setting. However, the safety of this strategy is unknown. The primary objective was to compare the safety of inserting the Reveal LINQ ICM in an office vs a hospital environment. Ancillary objectives included summarizing device- and procedure-related adverse events and responses to a physician questionnaire. Five hundred twenty-one patients indicated for an ICM were randomized (1:1 ratio) to undergo ICM insertion in a hospital or office environment at 26 centers in the United States in the Reveal LINQ In-Office 2 study (ClinicalTrials.gov identifier NCT02395536). Patients were followed for 90 days. ICM insertion was successful in all 482 attempted patients (office: 251; hospital: 231). The untoward event rate (composite of unsuccessful insertion and ICM- or insertion-related complications) was 0.8% (2 of 244) in the office and 0.9% (2 of 227) in the hospital (95% confidence interval, -3.0% to 2.9%; 5% noninferiority: P < .001). In addition, adverse events occurred during 2.5% (6 of 244) of office and 4.4% (10 of 227) of hospital insertions (95% confidence interval [office minus inhospital rates], -5.8% to 1.9%; 5% noninferiority: P < .001). Physicians indicated that for procedures performed in an office vs a hospital, there were fewer delays >15 minutes (16% vs 35%; P < .001) and patient response was more often "very positive." Physicians considered the office location "very convenient" more frequently than the hospital location (85% vs 27%; P < .001). The safety profile for the insertion of the Reveal LINQ ICM is excellent irrespective of insertion environment. These results may expand site of service options for LINQ insertion.

56-77: Adapting the threshold for atrial fibrillation detection in insertable cardiac monitors based on evidence of irregular sinus rhythm

Background: Frequent premature atrial contractions and sick sinus syndrome are primary causes of inappropriate atrial fibrillation (AF) detection in insertable cardiac monitors (ICM). An algorithm was developed to reduce inappropriate AF detection based on adapting the threshold for detection in the presence of irregular RR intervals and p-wave evidence. Methods: The AF detection algorithm in Reveal LINQ ICM looks for evidence of AF based on differences in the pattern of RR intervals over a 2-minute period. The p-wave evidence based algorithm (P-SENSE) reduces evidence for AF detection if p-waves are detected. The adaptive P-SENSE enhancement uses the presence of p-wave evidence during periods of RR irregularity as evidence of the presence of sick sinus or ectopy to adaptively increase the threshold for AF detection. The algorithm was developed using Holter data from the XPECT study which collected two leads of surface ECG and continuously uplinked ICM ECG over a 46 hour period. ICM detections were compared with Holter annotations to compute episode and duration detection performance. Results: Valid Holter recordings were analyzed from the first 56 patients in the XPECT study with a total follow-up duration of 2168 hours (39 hours per patient). True AF was observed in 16 patients, yielding 89 true AF episodes ≥2 minutes and 201 hours of AF. In the nominal (and aggressive) mode of operation, the algorithm correctly identified 97.9% (97.8%) of total AF duration and 99.5% (99.6%) of total sinus or non-AF rhythm duration. The algorithm detected 89% (89%) of all AF episodes ≥2 minutes, and 60% (74%) of detected episodes had AF in the nominal mode of operation. The adaptive P-SENSE algorithm in nominal (or aggressive) mode was able to reduce false detects by 76% (87%) compared to an algorithm without P-SENSE and 56% (63%) compared to the nominal (aggressive) P-SENSE without any loss in true episode detection (Figure).

Real-world performance of an enhanced atrial fibrillation detection algorithm in an insertable cardiac monitor

Insertable cardiac monitors (ICMs) are used for long-term ECG monitoring. The Reveal LINQ ICM has an improved atrial fibrillation (AF) detection algorithm. The purpose of this study was to investigate the algorithm's real-world performance in patients with syncope, cryptogenic stroke, and known AF. Consecutive patients with implanted ICM and AF detection parameters automatically set and maintained depending on the indication for monitoring were included. A single reviewer annotated all stored episodes after ICM implant. A second reviewer annotated a random sample of 10% of all detected AF episodes. The episode detection positive predictive value as well as true and false detection rates were determined for AF episodes of different durations. The study enrolled 3759 patients (1604 [43%] with syncope, 1049 [28%] with known AF, 1106 [29%] with cryptogenic stroke). Overall, 20,659 AF episodes were detected in 1020 patients. The gross episode detection positive predictive value was 84%, 73%, and 26% for all episodes (≥2 minutes) and improved to 97%, 95%, and 91% for detected AF episodes ≥1 hour in the syncope, known-AF, and cryptogenic stroke patient cohorts, respectively. The true (and false) detection rate was 0.23 (0.05), 3.8 (1.4), and 0.23 (0.65) per patient-month of monitoring for the syncope, known-AF, and cryptogenic stroke patient cohorts, respectively. Limiting ECG storage to the longest detected AF episode significantly reduced the burden of episode adjudication without significantly compromising the identification of patients with true AF. The performance of LINQ ICM is dependent on the AF incidence rate in the population being monitored, the programmed sensitivity of AF algorithm, and the duration of detected AF episodes.

Performance of a new atrial fibrillation detection algorithm in a miniaturized insertable cardiac monitor: Results from the Reveal LINQ Usability Study

For clinicians, confidence in atrial fibrillation (AF) episode classification is an important consideration when electing to use insertable cardiac monitors (ICMs). The purpose of this study was to report on the improved AF detection algorithm in the Reveal LINQ ICM. The Reveal LINQ Usability Study is a nonrandomized, prospective, multicenter trial. The ICM has been miniaturized, uses wireless telemetry for remote patient monitoring, and its AF algorithm includes a new p-wave filter. At 1 month post-device insertion, Holter monitor data were collected and annotated for true AF episodes ≥2 minutes, and performance metrics were evaluated by comparing Holter annotations with ICM detections. The study enrolled 151 patients (age 56.6 ± 12.1, male 67%). Reasons for monitoring included AF ablation or AF management in 81.5% (n = 123), syncope in 12.6% (n = 19), and other indications in 5.9% (n = 9) of patients. Of the 138 patients with an analyzable Holter recording, a total of 112 true AF episodes were identified in 38 patients (27.5%). The overall accuracy of the ICM to detect durations of AF or non-AF episodes was 99.4%, and the AF burden measured by the ICM was highly correlated with the Holter (Pearson coefficient 0.995). The new AF detection algorithm in the Reveal LINQ ICM accurately detects the presence or absence of AF. Additionally, it showed high sensitivity in detecting AF duration in patients with a history of intermittent and symptomatic AF.

Abstract 209: High Yield of Long-Term Implantable Cardiac Monitoring Following Cryptogenic Ischemic Stroke

Introduction: Long-term post-hospitalization cardiac monitoring has detected occult paroxysmal atrial fibrillation and atrial flutter (PAF) in a substantial minority of cryptogenic ischemic stroke (CIS) patients. Herein, we aim to better define the frequency and clinical significance of PAF detection using the Reveal LINQ insertable cardiac monitor in a population of CIS patients treated at a comprehensive stroke center. Methods: A retrospective consecutive series of CIS patients (n=95; mean age 65.9 years; 56.8% female) with no prior history of PAF had a LINQ placed during the index hospitalization, or soon thereafter, following a negative stroke evaluation. The study cardiac electrophysiologist confirmed the presence of PAF, and other potentially relevant cardiac arrhythmias, and the characteristics of the episodes and any changes in management were recorded. Results: PAF was detected in 22/95 patients (23.2%; atrial fibrillation (AF) 13; atrial flutter (A-flutter) 6; both 3). Median time to first episode was 26 days (range less than 1 day to 398 days). Median longest episode duration for AF was 2.4 hours (range 6 minutes to greater than 99 hours) and for A-flutter was 49 seconds (range 5 to 174 seconds). Antiplatelet therapy was switched to anticoagulation in 20/21 (95.2%) patients with known follow-up, including all newly diagnosed AF patients. Additional potentially relevant arrhythmias included sinus bradycardia (5/95; 5.3%), sinus pauses (5/95; 5.3%) and bigeminy (7/95; 7.4%). Conclusions: LINQ insertion during, or soon after, in-hospital stroke evaluation detected PAF in a substantial proportion of CIS patients with a higher frequency and earlier detection than previous studies. Most episodes were deemed clinically relevant, resulting in anticoagulation initiation in almost all patients. Long-term invasive cardiac monitoring following CIS may have important implications in terms of secondary stroke prevention and the detection of other potentially relevant arrhythmias.

Abstract WP231: Risk Factors for Paroxysmal Atrial Fibrillation and Atrial Flutter Detection Following Cryptogenic Ischemic Stroke

Introduction: Long-term post-stroke insertable cardiac monitor (ICM) implantation has resulted in increasing frequencies of paroxysmal atrial fibrillation and atrial flutter (PAF) detection in a significant proportion of cryptogenic ischemic stroke (CIS) patients. Determining risk factors for PAF detection specific to the CIS population could allow for better selection of patients for ICM implantation. Methods: A retrospective study of CIS patients (n=95; mean age 65.9 years; 56.8% female) implanted with the Reveal LINQ ICM between September 2013 to July 2015. Device implantation was performed during, or soon after, index stroke admission. The study cardiac electrophysiologist confirmed PAF diagnosis. Univariate and multivariate logistic regression analyses compared clinical, laboratory, ECG and echocardiographic variables between patients with and without PAF. Results: PAF was detected in 22/95 (23.2%) patients. Factors associated with PAF detection include older age (mean (yr) 74.0 vs. 63.4; p=0.003), prolonged PR-interval (PR&gt;175 ms; OR 3.88, 95% CI 1.28-11.7), mitral regurgitation (MR; OR 3.36, 95% CI 1.24-9.08), left atrial diameter (LA diameter mean (cm) 3.80 vs. 3.51; p=0.039), and left atrial volume index (LAVI mean (cc/m2); 32.8 vs. 25.0; p=0.037). Controlling for age in the multivariate logistic regression model, obesity (BMI&gt;30; OR 4.80, 95% CI 3.50-9.60) and MR (OR 4.47, 95% CI 3.15-5.79) are independently associated with PAF detection. Conclusion: Long-term cardiac monitoring identified PAF in a substantial number of CIS patients. Older age, prolonged PR, MR, and larger LA diameter and LAVI are significantly associated with PAF diagnosis. Controlling for age, significant independent risk factors include obesity and MR. A larger prospective study is warranted to confirm these findings and to identify other possible risk factors. Ultimately, a risk factor based algorithm could enable better selection of CIS patients for ICM implantation.