Accuracy of the Apple Watch for Detection of AF: A Multi-Center Experience

BACKGROUND

The Apple Watch (AW) Irregular Rhythm Notification (IRN) feature uses photoplethysmography to identify prolonged episodes of irregular rhythm suggestive of atrial fibrillation (AF). IRN is FDA cleared for those with no previous history of AF, however, these devices are increasingly being used for AF management.

OBJECTIVE

To determine the accuracy of the IRN in subjects with a previous diagnosis of non-permanent AF.

METHODS

Subjects with a history of non-permanent AF and either an insertable cardiac monitor (ICM) or cardiac implanted electronic device (CIED) with < 5% ventricular pacing were fitted with an AW Series 5 for 6 months. AF episodes were compared between the ICM/CIED and IRN. The primary endpoints were sensitivity, specificity, PPV, and NPV of the IRN by subject for AF ≥ 1 hour. Secondary endpoints were sensitivity and PPV by AF episode ≥ 1 hour. Analysis was limited to a maximum of 10 ICM/CIED episodes per subject and included only those AF episodes occurring during active AW use confirmed by activity data.

RESULTS

Thirty participants, mean age was 65.4y ± 12.2y, 40% female, were enrolled. There were 10 ICMs and 20 CIEDs. 11 subjects had AF on ICM/CIED while the AW was worn, of whom 8 were detected by IRN. There were no false positive IRN detections by subject ("by subject" 72% sensitivity, 100% specificity, 100% PPV, and 90% NPV). 5 subjects had AF only when the AW was not worn. There were a total of 70 AF episodes on ICM/CIED, 35 of which occurred while the AW was being worn. Of these, 21 were detected by IRN with 1 false positive ("by episode" sensitivity = 60.0%, PPV = 95.5%).

CONCLUSION

In a population with known AF, the AW IRN had a low rate of false positive detections and high specificity. Sensitivity for detection by subject and by AF episode was lower. The current IRN algorithm appears accurate for AF screening as currently cleared, but increased sensitivity and wear times would be necessary for disease management. This article is protected by copyright. All rights reserved.

Prospective evaluation of the effect of smartphone electrocardiogram usage on anticoagulant medication compliance

PURPOSE

Compliance with anticoagulation treatment for atrial fibrillation is highly variable. Smartphone electrocardiograms that allow patients to have greater insight into their arrhythmia burden may improve anticoagulant compliance.

METHODS

Patients were enrolled if they had atrial fibrillation with a CHA₂DS₂-VASc score of 2 or more, were eligible for anticoagulation and had a smartphone. Participants were randomly assigned to receive a smartphone electrocardiogram (AliveCor Kardia) to record their electrocardiograms 5 times/week or to the control group. All patients received 6 months of anticoagulant (apixaban) dispensed as 1-month pre-loaded pill boxes.

RESULTS

A total of 100 patients were enrolled from July 2017 to August 2019, but 5 patients in the monitor arm and 1 in the control arm withdrew prematurely. The monitor and control groups did not differ in age, gender, CHA₂DS₂-VASc score, or comorbidities. Median medication compliance was 99.7%, with nonsignificantly greater compliance in the monitor group (100%) than in the control group (99.7%) (p-value = 0.247). There was also no significant difference between missing any dose and use/nonuse of the smartphone monitor (48.9% vs. 55.1%; p-value = 0.692). Mean monitor compliance was 86.8% ± 14.0% with an average of 4.34 recorded electrocardiograms per week. Monitor group patients with perfect medication compliance had significantly higher monitor compliance than those patients who missed doses (median 95.3% vs 86.7%; p-value = 0.02).

CONCLUSIONS

In a study population with higher-than-expected medication compliance, the use of smartphone electrocardiogram did not demonstrate an improvement in medication compliance as compared to usual care. Greater monitor compliance was associated with greater medication compliance.

CLINICAL TRIAL REGISTRATION

BOAT-OAR ClinicalTrials.gov number, NCT03515083.

Comparative outcomes of vascular access closure methods following atrial fibrillation/flutter catheter ablation: insights from VAscular Closure for Cardiac Ablation Registry

PURPOSE

This registry compared the safety and efficacy of vascular closure device Perclose (PC) with figure-of-eight stitch (Fo8) and manual compression (MC) following catheter ablation of atrial fibrillation/flutter.

METHODS

VAscular Closure for Cardiac Ablation Registry (VACCAR) is a prospective, observational registry that assessed the time to hemostasis (TTH), time to ambulation (TTA), length of stay (LOS), complications, patient-reported outcomes, and pain medication use.

RESULTS

A total of 434 patients (mean age 64.0±11.0 years; 38% female; 94.9% white) were enrolled between October 2017 and May 2019: 156 in MC, 203 in Fo8, and 75 in the PC group. Median TTH was significantly reduced in the PC and Fo8 group at 7 and 9 min respectively vs. the MC group at 20 min (p<0.001). Median TTA was significantly reduced in both the PC and Fo8 group at 2.2 h vs. the MC group at 6.5 h (p<0.001 for both). Median LOS for the PC group was significantly reduced at 27.5 h compared to the MC and Fo8 group at 29 h (p<0.01). A higher proportion of same-day discharges were noted in the PC and Fo8 groups at 14 (18.7%) and 25 (12.3%), respectively, compared to 5 (3.2%) in the MC group (p<0.01 for all). There was no significant difference in complications between the three groups.

CONCLUSIONS

Both PC and Fo8 are safe with improved TTH, TTA, LOS, and a higher number of same-day discharges compared to MC.

Outcomes using a single tapered dilator for Micra leadless pacemaker implant

Objectives

Comparison of outcomes, device deployment time (DT), and total time (TT) using a single tapered Coons dilator versus sequential serial dilation for implantation of the Micra leadless pacemaker.

Background

Micra leadless pacemaker placement requires a 23 French Micra introducer sheath (MIS) for percutaneous delivery. We sought to evaluate outcomes with use of a single tapered Coons dilator (CD) versus sequential serial dilatation (SD) method to facilitate insertion of the Micra introducer sheath.

Methods

35 patients were included in the SD arm and 49 in the CD arm. DT and TT were recorded in minutes and cost in dollars. Analysis was performed using independent t-test between two groups and one-way ANOVA to evaluate inter-operator variability in the CD arm.

Results

Both DT and TT were significantly lower for the CD arm (15.1 ± 5.1 vs 23.5 ± 9.3, p < 0.0005 and 29.9 ± 14 vs 39.3 ± 13.5 min, p = 0.000374; respectively). The cost was also significantly lower using a CD versus SD. There was no inter-operator variability in the CD arm between 6 operators (p = 0.177 for DT and p = 0.304 for TT). No complications occurred in the SD arm. There were 3 vascular access site complications in the CD arm, all of which occurred early in the operator’s experience.

Conclusion

Coons dilator is an efficient and cost-effective method for vascular dilatation to facilitate Micra leadless pacemaker insertion. Rate of complications is low and expected to improve with greater experience.

Exercise Interventions in Patients With Implantable Cardioverter-Defibrillators and Cardiac Resynchronization Therapy: A SYSTEMATIC REVIEW AND META-ANALYSIS

PURPOSE

Physical activity improves outcomes across a broad spectrum of cardiovascular disease. The safety and effectiveness of exercise-based interventions in patients with implantable cardioverter-defibrillators (ICDs) including cardiac resynchronization therapy defibrillators (CRT-Ds) remain poorly understood.

METHODS

We identified clinical studies using the following search terms: "implantable cardioverter-defibrillators"; "ICD"; "cardiac resynchronization therapy"; "CRT"; and any one of the following: "activity"; "exercise"; "training"; or "rehabilitation"; from January 1, 2000 to October 1, 2015. Eligible studies were evaluated for design and clinical endpoints.

RESULTS

A total of 16 studies were included: 8 randomized controlled trials, 5 single-arm trials, 2 observational cohort trials, and 1 randomized crossover trial. A total of 2547 patients were included (intervention groups = 1215 patients, control groups = 1332 patients). Exercise interventions varied widely in character, duration (median 84 d, range: 23-168 d), and follow-up time (median 109 d, range: 23 d to 48 mo). Exercise performance measures were the most common primary endpoints (87.5%), with most studies (81%) demonstrating significant improvement. Implantable cardioverter-defibrillator shocks were uncommon during active exercise intervention, with 6 shocks in 635 patients (0.9%). Implantable cardioverter-defibrillator shocks in follow-up were less common in patients receiving any exercise intervention (15.6% vs 23%, OR = 0.68; 95% CI, 0.48-0.80, P < .001). (Equation is included in full-text article.)O2 peak improved significantly in patients receiving exercise intervention (1.98 vs 0.36 mL/kg/min, P < .001).

CONCLUSION

In conclusion, exercise interventions in patients with ICDs and CRT-Ds appear safe and effective. Lack of consensus on design and endpoints remains a barrier to broader application to this important patient population.

Cost Effectiveness of Implantable Cardiac Monitor-Guided Intermittent Anticoagulation for Atrial Fibrillation: An Analysis of the REACT.COM Pilot Study

INTRODUCTION

Anticoagulation guidelines for patients with atrial fibrillation (AF) disregard AF burden. A strategy of targeted anticoagulation with novel oral anticoagulants (NOACs) based on continuous rhythm assessment with an implantable cardiac monitor (ICM) has recently been explored. We evaluated the potential cost-effectiveness of this strategy versus projected outcomes with continuous anticoagulation.

METHODS AND RESULTS

We developed a Markov model using data from the Rhythm Evaluation for AntiCoagulaTion With COntinuous Monitoring (REACT.COM) pilot study (N = 59) and prior NOAC trials to calculate the costs and quality-adjusted life years (QALYs) associated with ICM-guided intermittent anticoagulation for AF versus standard care during a 3-year time horizon. Health state utilities were estimated from the pilot study population using the SF-12. Costs were based on current Medicare reimbursement. Over 14 ± 4 months of follow-up, 18 of 59 patients had 35 AF episodes. The ICM-guided strategy resulted in a 94% reduction in anticoagulant use relative to continuous treatment. There were no strokes, 3 (5.1%) TIAs, 2 major bleeding events (on aspirin) and 3 minor bleeding events with the ICM-guided strategy. The projected total 3-year costs were $12,535 for the ICM-guided strategy versus $13,340 for continuous anticoagulation. Projected QALYs were 2.45 for both groups.

CONCLUSION

Based on a pilot study, a strategy of ICM-guided anticoagulation with NOACs may be cost-saving relative to expected outcomes with continuous anticoagulation, with similar quality-adjusted survival. This strategy could be attractive from a health economic perspective if shown to be safe and effective in a rigorous clinical trial.

Magnitude of increase in QTc interval after initiation of dofetilide in patients with persistent atrial fibrillation is associated with increased rates of pharmacological cardioversion and long-term freedom from recurrent atrial fibrillation

BACKGROUND

Dofetilide is a class III antiarrhythmic drug approved for the treatment of atrial fibrillation (AF). Dofetilide-induced corrected QT (QTc) interval prolongation is a surrogate for the degree of drug effect, but the relationships between drug-induced QTc interval prolongation, pharmacological cardioversion (PCV), and freedom from recurrent AF are unclear.

OBJECTIVE

The purpose of this study was to assess associations between QTc interval change during dofetilide initiation and PCV and long-term AF recurrence.

METHODS

We performed retrospective analyses of a prospective cohort of patients with AF admitted for dofetilide initiation between 2001 and 2014. Clinical characteristics and electrocardiographic variables were assessed. We evaluated outcomes of successful PCV in patients with persistent AF and time to recurrence of AF in patients with paroxysmal and persistent AF.

RESULTS

During the study, 243 patients with persistent AF and 176 patients with paroxysmal AF initiated dofetilide. PCV occurred in 93/243 (41.7%) patients with persistent AF. After multivariable adjustment, QTc interval change was associated with PCV (adjusted odds ratio 1.21; P = .003 per 10-ms QTc increase). Inhospital QTc interval change was associated with long-term freedom from AF in patients with persistent AF (adjusted hazard ratio 0.92; P = .011 at 4 years per 10-ms QTc increase), but not in patients with paroxysmal AF. In patients with persistent AF, PCV was also associated with long-term freedom from recurrent AF (adjusted hazard ratio 0.62; P = .009 at 4 years).

CONCLUSION

The magnitude of QTc interval prolongation during dofetilide initiation is an independent predictor of successful PCV and long-term freedom from arrhythmia in patients with persistent AF. QTc interval change had no association with AF recurrence in patients with paroxysmal AF, suggesting that different mechanisms of arrhythmogenesis may be operant in different AF types.

Effect of Smaller Left Ventricular Capture Threshold Safety Margins to Improve Device Longevity in Recipients of Cardiac Resynchronization-Defibrillation Therapy

Device longevity in cardiac resynchronization therapy (CRT) is affected by the pacing capture threshold (PCT) and programmed pacing amplitude of the left ventricular (LV) pacing lead. The aims of this study were to evaluate the stability of LV pacing thresholds in a nationwide sample of CRT defibrillator recipients and to determine potential longevity improvements associated with a decrease in the LV safety margin while maintaining effective delivery of CRT. CRT defibrillator patients in the Medtronic CareLink database were eligible for inclusion. LV PCT stability was evaluated using ≥2 measurements over a 14-day period. Separately, a random sample of 7,250 patients with programmed right atrial and right ventricular amplitudes ≤2.5 V, LV thresholds ≤ 2.5 V, and LV pacing ≥90% were evaluated to estimate theoretical battery longevity improvement using LV safety margins of 0.5 and 1.5 V. Threshold stability analysis in 43,256 patients demonstrated LV PCT stability of <0.5 V in 77% of patients and <1 V in 95%. Device longevity analysis showed that the use of a 0.5-V safety margin increased average battery longevity by 0.62 years (95% confidence interval 0.61 to 0.63) compared with a safety margin of 1.5 V. Patients with LV PCTs >1 V had the greatest increases in battery life (mean increase 0.86 years, 95% confidence interval 0.85 to 0.87). In conclusion, nearly all CRT defibrillator patients had LV PCT stability <1.0 V. Decreasing the LV safety margin from 1.5 to 0.5 V provided consistent delivery of CRT for most patients and significantly improved battery longevity.

Abstract 336: Cost-effectiveness of Implantable Cardiac Monitor-guided Intermittent Anticoagulation for Paroxysmal Atrial Fibrillation

Background: Patients with atrial fibrillation (AF) and stroke risk factors are recommended for treatment with long-term anticoagulation, even when rhythm control interventions result in a low AF burden. A strategy of guiding anticoagulation with novel oral anticoagulants (NOACs) based on daily transmissions from an implantable cardiac monitor (ICM) in CHADS 2 1 or 2 AF patients has recently been explored in a single-arm pilot study. The aim of our study was to evaluate the cost-effectiveness of this strategy versus projected outcomes with the current standard of continuous anticoagulation.

Methods: We developed a Markov model using data from the Rhythm Evaluation for AntiCoagulaTion With COntinuous Monitoring (REACT.COM) pilot study (N=59) and previously completed anticoagulant trials to calculate the costs and quality-adjusted life years (QALYs) associated with ICM-guided intermittent anticoagulation for AF vs. standard care. The model time horizon was 3 years (the battery life of an ICM). Health state utilities were estimated from the pilot study population using the SF-12. Costs were based on current Medicare reimbursement.

Results: In the pilot study, over 14±4 months of follow-up 18/59 patients were observed to have 35 AF episodes, 60% of which spontaneously terminated and 63% were asymptomatic. The protocol resulted in a >90% reduction in anticoagulant use relative to standard continuous treatment. There were no strokes, 2 (3.4%) TIAs, 2 major bleeding events (on aspirin) and 3 minor bleeding events with the ICM-guided strategy. The model projected total 3-year costs of $10,558 for the ICM-guided strategy vs. $12,898 for literature-based expected outcomes with continuous anticoagulation. Projected QALYs were 2.46 for both groups. Detailed sensitivity and scenario analyses are ongoing.

Conclusions: Based on the REACT.COM pilot study, a strategy of intermittent, ICM-guided oral anticoagulation with NOACs was cost-saving relative to expected outcomes with continuous anticoagulation, with equivalent quality-adjusted survival. This strategy requires validation in a larger, randomized study.

Survival in a case of diffuse alveolar hemorrhage due to Strongyloides stercoralis hyperinfection

Strongyloides stercoralis is an intestinal nematode endemic to tropical and sub-tropical regions. Although infection is typically asymptomatic or self-limited, immunocompromised individuals can develop a severe form of disease marked by hyperinfection. Pulmonary involvement accompanies hyperinfection in a majority of cases, though manifestations range from asymptomatic infiltrates to diffuse alveolar hemorrhage (DAH) and respiratory failure. When complicated by DAH, the hyperinfection syndrome is usually fatal. We report a case of a 65-year-old Guatemalan woman with chronic inflammatory demyelinating polyneuropathy (CIDP) treated with chronic steroids who presented with Escherichia coli urosepsis. She was initially treated with antibiotics and corticosteroids. She subsequently developed DAH due to disseminated strongyloidiasis. She was treated with oral and subcutaneous ivermectin and had complete recovery.

Characteristics of sudden arrhythmic death in a diverse, urban community

BACKGROUND

Sudden cardiac death (SCD) remains a major public health problem; however, its true burden remains unknown with widely variable estimates of its incidence. We aimed to examine the contemporary epidemiology and autopsy characteristics of SCD in an ethnically diverse community.

METHODS

Three physicians reviewed all deaths of individuals aged ≥20 years reported to the San Francisco medical examiner in 2007 for presentations fitting World Health Organization (WHO) SCD criteria-within 1 hour of symptom onset (witnessed) or within 24 hours of being observed alive and symptom free (unwitnessed). After comprehensive review of medical examiner investigation, WHO SCDs were classified as sudden arrhythmic death (SAD) or nonarrhythmic death. Coronary artery disease (CAD) and cardiac mass were evaluated in all SADs undergoing autopsy and compared with demographically similar accidental trauma control deaths.

RESULTS

We identified 252 WHO SCDs; 145 were SADs. Men had a 2.2-fold higher SAD rate (P < .0005). Blacks had a 3.15-fold higher SAD rate compared with whites (P = .003). Significant CAD was present in 38.9% of SADs and associated with higher SAD risk compared with control deaths (OR 2.58, 95% CI 1.12-5.97, P = .026). Mean cardiac mass was linearly associated with risk for SAD in cases without significant CAD (OR 2.06 per 100 g, 95% CI 1.43-2.98, P < .0005).

CONCLUSIONS

In a diverse, urban population, SAD incidence varied substantially by gender and race. Significant CAD accounted for far fewer SADs than previous studies but remained associated with a 2.6-fold higher risk as compared with control deaths. These findings may reflect the evolving contemporary epidemiology of SCD.