Six-month Electrical Performance of the First Dual-Chamber Leadless Pacemaker

BACKGROUND

The first dual-chamber leadless pacemaker (DC-LP) system consists of two separate atrial and ventricular devices that communicate to maintain synchronous atrioventricular pacing and sensing. The initial safety and efficacy were previously reported.

OBJECTIVE

Evaluate the chronic electrical performance of the DC-LP system.

METHODS

Patients meeting standard dual-chamber pacing indications were enrolled and implanted with the DC-LP system (Aveir DR, Abbott), including right atrial and ventricular helix-fixation LPs (ALP, VLP). Pacing capture threshold, sensed amplitude, and pacing impedance were collected using the device programmer at prespecified time points from 0-6 months post-implant.

RESULTS

De novo devices were successfully implanted in 381 patients with complete 6M data (62% male; age 69±14 years; weight 82±20 kg; 65% sinus node dysfunction, 30% AV block). ALPs were implanted predominantly in the right atrial appendage anterior base; VLPs primarily at the mid-to-apical right ventricular septum. From implant to 1 month, pacing capture thresholds (0.4 ms pulse width) improved in both ALPs (2.4±1.5 to 0.8±0.8 V, P<0.001) and VLPs (0.8±0.6 to 0.6±0.4 V, P<0.001). Sensed amplitudes improved in both ALPs (1.8±1.3 to 3.4±1.9 mV, P<0.001) and VLPs (8.8±4.0 to 11.7±4.2 mV, P<0.001). Impedances were stable in ALPs (334±68 to 329±52 Ω, P=0.17) and reduced in VLPs (789±351 to 646±190 Ω, P<0.001). Electrical measurements remained relatively stable from 1-6 months post-implant. No differences in electrical metrics were observed among ALP or VLP implant locations.

CONCLUSION

This first in-human evaluation of the new dual-chamber leadless pacemaker system demonstrated reliable electrical performance throughout the initial 6-month evaluation period.

Revolutionizing Atrial Fibrillation Treatment: The Robotic Convergent Plus Procedure

Atrial fibrillation (AF) is widely accepted to be the most common sustained arrhythmia, with an increasing incidence over time. This is thought to be due to the aging population across the world. AF occurs when abnormal electrical foci result in disorganization of atrial depolarization, though the exact pathophysiology leading to these abnormal foci is not well understood. A range of interventions exist for AF - pharmacological therapies (anti-arrhythmic or negative chronotropic medications), cardioversion, or ablations to interrupt the abnormal conduction pathways. Ablation may be via a catheter-based approach, via a surgical approach using the "Maze" procedure (Cox-Maze IV), or more recently, via a hybrid approach. This first involves a surgical epicardial ablation, with catheter-based endocardial ablation following a few weeks later to ensure durable transmural lesion sets via the "Convergent" procedure. We describe the use of the Da Vinci Xi™ robotic platform to improve the procedure, allowing continuous and improved visualization of the anatomy without the need for potentially harmful retraction of the atrial appendage or the back of the left atrium, as well as increased precision with our mapping tools and more complete ablation. Here, we highlight the advantages over a non-robotic (subxiphoid) Convergent procedure, while outlining the key operative steps in undertaking the "Robotic Convergent Plus" procedure using the Da Vinci Xi™ robotic surgical system.

Design and rationale of the MODULAR ATP global clinical trial: A novel intercommunicative leadless pacing system and the subcutaneous implantable cardioverter-defibrillator

Background

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has demonstrated safety and efficacy for the treatment of malignant ventricular arrhythmias. However, a limitation of the S-ICD lies in the inability to either pace-terminate ventricular tachycardia or provide prolonged bradycardia pacing support.

Objective

The rationale and design of a prospective, single-arm, multinational trial of an intercommunicative leadless pacing system integrated with the S-ICD will be presented.

Methods

A technical description of the modular cardiac rhythm management (mCRM) system (EMPOWER leadless pacemaker and EMBLEM S-ICD) and the implantation procedure is provided. MODULAR ATP (Effectiveness of the EMPOWER™ Modular Pacing System and EMBLEM™ Subcutaneous ICD to Communicate Antitachycardia Pacing) is a multicenter, international trial enrolling up to 300 patients at risk of sudden cardiac death at up to 60 centers trial design. The safety endpoint of freedom from major complications related to the mCRM system or implantation procedure at 6 months and 2 years are significantly higher than 86% and 81%, respectively, and all-cause survival is significantly >85% at 2 years.

Results

Efficacy endpoints are that at 6 months mCRM communication success is significantly higher than 88% and the percentage of subjects with low and stable thresholds is significantly higher than 80%. Substudies to evaluate rate-responsive features and performance of the pacing module are also described.

Conclusion

The MODULAR ATP global clinical trial will prospectively test the safety and efficacy of the first intercommunicating leadless pacing system with the S-ICD. This trial will allow for robust validation of device-device communication, pacing performance, rate responsiveness, and system safety.

A Dual-Chamber Leadless Pacemaker

BACKGROUND

Single-chamber ventricular leadless pacemakers do not support atrial pacing or consistent atrioventricular synchrony. A dual-chamber leadless pacemaker system consisting of two devices implanted percutaneously, one in the right atrium and one in the right ventricle, would make leadless pacemaker therapy a treatment option for a wider range of indications.

METHODS

We conducted a prospective, multicenter, single-group study to evaluate the safety and performance of a dual-chamber leadless pacemaker system. Patients with a conventional indication for dual-chamber pacing were eligible for participation. The primary safety end point was freedom from complications (i.e., device- or procedure-related serious adverse events) at 90 days. The first primary performance end point was a combination of adequate atrial capture threshold and sensing amplitude at 3 months. The second primary performance end point was at least 70% atrioventricular synchrony at 3 months while the patient was sitting.

RESULTS

Among the 300 patients enrolled, 190 (63.3%) had sinus-node dysfunction and 100 (33.3%) had atrioventricular block as the primary pacing indication. The implantation procedure was successful (i.e., two functioning leadless pacemakers were implanted and had established implant-to-implant communication) in 295 patients (98.3%). A total of 35 device- or procedure-related serious adverse events occurred in 29 patients. The primary safety end point was met in 271 patients (90.3%; 95% confidence interval [CI], 87.0 to 93.7), which exceeded the performance goal of 78% (P<0.001). The first primary performance end point was met in 90.2% of the patients (95% CI, 86.8 to 93.6), which exceeded the performance goal of 82.5% (P<0.001). The mean (±SD) atrial capture threshold was 0.82±0.70 V, and the mean P-wave amplitude was 3.58±1.88 mV. Of the 21 patients (7%) with a P-wave amplitude of less than 1.0 mV, none required device revision for inadequate sensing. At least 70% atrioventricular synchrony was achieved in 97.3% of the patients (95% CI, 95.4 to 99.3), which exceeded the performance goal of 83% (P<0.001).

CONCLUSIONS

The dual-chamber leadless pacemaker system met the primary safety end point and provided atrial pacing and reliable atrioventricular synchrony for 3 months after implantation. (Funded by Abbott Medical; Aveir DR i2i ClinicalTrials.gov number, NCT05252702.).

Tuberculosis Monitoring Encouragement Adherence Drive (TMEAD): Toward improving the adherence of the patients with drug-sensitive tuberculosis in Nashik, Maharashtra

Introduction

Adherence to tuberculosis (TB) medication is one of the critical challenges to tuberculosis elimination in India. Digital adherence technologies (DAT) have the potential to facilitate medication adherence and monitor it remotely. Tuberculosis Monitoring Encouragement Adherence Drive (TMEAD) is one such DAT piloted in Nasik, Maharashtra, from April 2020 to December 2021. The study aims to assess the adherence and cost-effectiveness of TMEAD compared to the standard of care among patients with drug-sensitive tuberculosis (DSTB) residing in the urban areas of Nasik, Maharashtra, India.

Methods

A quasi-experimental study was conducted among new cases of TB as per the National TB Elimination Programme (NTEP) residing in the urban geography of Nasik. The intervention and control arms were purposively selected from non-contaminating TB units (TUs). A total of 400 DSTB patients (200 in the intervention group and 200 in the control group) were enrolled. After enrolment, patients in the intervention arm were provided with the TMEAD device and followed for 24 weeks to assess treatment outcomes. Adherence was measured as those patients who have completed 80% of prescribed doses, as reported during patient follow-up, and further validated by analyzing the trace of rifampicin in urine among 20% of patients from both arms. A budget impact analysis was done to assess the impact of the TMEAD program on the overall state health budget.

Results

Out of 400 enrolled DSTB patients, 261 patients completed treatment, 108 patients were on treatment, 15 patients died, and 16 patients were defaulters over the study period. The study reported overall treatment adherence of 94% among those who completed treatment. Patient reports indicated high levels of treatment adherence in the intervention group (99%) as compared to the control group (90%). Adherence assessed through analyzing trace of rifampicin in the urine sample for the intervention arm was 84% compared to the control arm (80%). Per beneficiary (discounted) cost for TMEAD was Indian rupees (INR) 6,573 (USD 83). The incremental cost-effectiveness ratio of the intervention is INR 11,599 (USD 146), which shows that the intervention is highly cost-effective.

Conclusion

This study revealed that patient-reported treatment adherence was high in TMEAD when compared to standard therapy of care for DSTB patients and the intervention is cost-effective. TMEAD could complement the national strategy to end TB by improving adherence to the treatment regimen in India.

P172 First report of Aspergillus tamarii producing influenza associated invasive pulmonary Aspergillosis

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PM

 

Objective

Multiple infections can occur after 2009, pandemic influenza, including fungal and bacterial infections, but data from India are limited. To our knowledge, this is the first reported case of influenza-associated invasive pulmonary aspergillosis (IAPA), caused by Aspergillus tamarii, after infection with pandemic (H1N1) 2009 which was preceded by COVID-19, 20 months before.

Methods and Results

A 33-year-old male, known asthmatic, had been hospitalized elsewhere in August 2020 with COVID-19 pneumonia for 50 days and had been on mechanical ventilation for 37 days. He had no residual respiratory symptoms 3 months after recovery from COVID-19. He was admitted to Jupiter Hospital in April 2022 with fever, cough, and dyspnea for 8 days, which developed after a cold bath in a temple. HRCT (chest) showed ground glass opacities (GGOs), crazy paving, nodules, and traction bronchiectasis. Review of previous HRCT showed that only GGOs were present (Fig. 1).

At admission, the nasopharyngeal swab was positive for pandemic (H1N1) 2009 in the filmarray respiratory panel and no other pathogen was detected. He was treated with oseltamivir. Expectorated sputum examination showed a heavy load of thin septate hyphae, with acute angle branching, resembling Aspergilllus species (Fig. 2). Serum galactomannan was positive (1.8). Based on these features he was diagnosed as a case of probable IAPA and initiated posaconazole (PCZ) treatment. Sputum fungal culture was positive and was identified by MALDI TOF MS as A. tamarii. A. tamarii has been rarely encountered as a human pathogen. Case reports of its involvement in eyelid infection, keratitis, invasive sinonasal infection, and onychomycosis exist. Sensititre MICs were 0.0625 mcg/ml, 0.125 mcg/ml, 0.0625 mcg/ml, and 0.125 mcg/mL for itraconazole, voriconazole, PCZ, and for isavuconazole (ISVCZ) respectively.

The usually obtained PCZ trough level with standard dose is 1.2 mg/l which generates AUC of 200R. The usually obtained ISVC) trough level with standard dose is 3 mg/l which generates AUC of 100R. The PKPD index, AUC/MIC of 100, is needed with both these azoles for a therapeutic effectR. Therefore, it would be possible to treat this infection with any of these azoles.

PCZ was continued in view of the easy availability of therapeutic drug monitoring (TDM) to assure adequate drug exposure, lower cost, and clinical improvement which had already occurred.

Conclusion

An infection due to a rare Aspergillus species needs correct identification, MIC determination, and PKPD consideration for appropriate drug selection and management.

Comparison of anticoagulation with left atrial appendage closure after atrial fibrillation ablation: Rationale and design of the OPTION randomized trial

BACKGROUND

For patients with symptomatic atrial fibrillation (AF), physicians typically offer AF ablation for symptom relief; however, patients often anticipate/expect a life free from anticoagulation. This belief puts patients at increased risk of stroke due to the potential for asymptomatic AF postablation if anticoagulation is ceased contrary to clinical guidelines. Although the WATCHMAN device has been FDA-approved to decrease the risk of thromboembolism from the left atrial appendage (LAA) in patients with an appropriate rationale to avoid oral anticoagulation, it has not been well-studied following AF ablation. Additionally, there are limited data comparing the WATCHMAN device to direct oral anticoagulants. The OPTION study will investigate whether LAA closure with the WATCHMAN FLX device is a reasonable alternative to oral anticoagulation following percutaneous catheter ablation for nonvalvular AF.

TRIAL DESIGN

OPTION is a multinational, multicenter, prospective randomized clinical trial. Patients with a CHA₂DS₂-VASc of ≥2 in men or ≥3 in women and who underwent a AF catheter ablation procedure between 90 and 180 days prior to randomization (sequential) or are planning to have catheter ablation within 10 days of randomization (concomitant) will be randomized in a 1:1 allocation of WATCHMAN FLX vs control. Control patients will start or continue market-approved oral anticoagulation for the duration of the trial. A total of 1600 patients were randomized from 130 global investigational sites. Follow-up for both device and control patients will occur at 3, 12, 24, and 36 months. The primary effectiveness noninferiority endpoint is stroke (ischemic or hemorrhagic), all-cause death, or systemic embolism at 36 months. The primary safety superiority endpoint is nonprocedural bleeding through 36 months (International Society on Thrombosis and Haemostasis [ISTH] major bleeding or clinically relevant nonmajor bleeding). The secondary noninferiority endpoint is ISTH major bleeding through 36 months (including procedural bleeding).

CONCLUSIONS

This trial will assess the safety and efficacy of WATCHMAN FLX in a postablation contemporary clinical AF patient population at risk of stroke.

Wireless Communication Between Paired Leadless Pacemakers for Dual-Chamber Synchrony

BACKGROUND

Leadless pacemakers (LPs) can mitigate conventional pacemaker complications related to the transvenous leads and subcutaneous pocket surrounding the pulse generator. Although single-chamber leadless pacing has been established, multichamber pacing requires wireless bidirectional communication across multiple LPs to maintain synchrony. This preclinical study demonstrates the chronic performance of implant-to-implant (i2i) communication that achieves synchronous, dual-chamber pacing with 2 LPs.

METHODS

The i2i communication modality employs subthreshold electrical signals conducted between implanted LPs through the blood and myocardial tissue on a beat-by-beat basis. Right atrial and right ventricular LPs were implanted in 9 ovine subjects. The i2i transmission performance was evaluated 13 weeks after implant.

RESULTS

Right atrial and right ventricular LPs were implanted successfully and without complication in 9 ovine subjects. A total of 8715±457 right atrial-to-right ventricular and right ventricular-to-right atrial transmissions were sent per hour, with a success rate of 99.2±0.9%. Of periods with i2i communication failure when DDD pacing was not possible, 97.3±1.8% were resolved within 6 s.

CONCLUSIONS

For the first time, synchronized, dual-chamber pacing has been demonstrated in a chronic preclinical feasibility study by 2 leadless pacemakers using beat-to-beat, wireless communication, achieving a success rate of 99.2%.

Cardiovascular disease risk factors and outcomes of acute myocardial infarction in young adults in two nationwide cohorts in the united states

Funding Acknowledgements

Type of funding sources: None.

Background

Acute myocardial infarction (AMI) can have considerable morbidity and devastating socioeconomic and psychological consequences in young adults. Previous studies reveal that the decline in mortality in AMI has mainly been in the older population while being comparatively less significant in younger patients. This study compares young adults (18 to 44 years) hospitalized with AMI across two nationwide cohorts, 2007 and 2017, in the United States (US). It examines the burden of AMI hospitalizations, the prevalence of comorbidities, and in-hospital outcomes in young adults a decade apart. It highlights the rise in AMI hospitalizations, lack of decrease in mortality, sex-based and racial disparities, the surge in post-MI complications, and the decline in reperfusion interventions in young AMI patients over a decade.

Purpose

Coronary heart disease prevalence is challenging to ascertain in younger adults because of limited data and frequent silent clinical presentations. AMI and its complications can cause considerable morbidity, psychological trauma, and socioeconomic burden in the young.

Methods

We identified hospitalizations for AMI in young adults in 2007 and 2017 using the weighted data from the National Inpatient Sample (NIS), which covers 20% of stratified data of all non-federal community hospitals in the US. We compared the following data between the two cohorts: admission rates, sociodemographic features, in-hospital morbidity, complications, mortality, rate of coronary interventions, and healthcare utilization between the two cohorts. We used Pearson’s Chi-square test and Mann-Whitney U test to compare categorical and continuous variables, respectively. We also applied multivariable regression analyses to assess and compare the risk of cardiovascular complications and in-hospital mortality while controlling for confounders, including age, sex, race, median household income quartile, primary insurance enrolment, and pre-existing comorbidities.

Results

AMI’s incidence was higher in males in both the cohorts, although with a decline (71.1% vs 66.1%), whereas it rose from 28.9% to 33.9% in females. Hypertension (47.8% vs 60.7%), smoking (49.7% vs 55.8%), obesity (14.8% vs 26.8%), and diabetes mellitus (22.0% vs 25.6%) increased in the 2017 cohort (Table 1). We found no significant difference in all-cause mortality (aOR = 1.01 (0.93-1.10), p=0.749). Post-AMI complications, cardiogenic shock (aOR = 1.16 (1.06-1.27), p=0.001), and fatal arrhythmias increased. Reperfusion interventions decreased in the 2017 cohort (PCI; aOR=0.95 (0.91-0.98), p&lt;0.001; CABG; aOR=0.66 (0.61-0.71), p&lt;0.001) (Table 2).

Conclusion

Our study highlights the rise in AMI hospitalizations, plateauing of mortality, gender disparity, the surge in post-MI complications, and a reassuring decline in the requirement of reperfusion interventions in young AMI patients over a decade.

Oral anticoagulant monotherapy compared to oral anticoagulant plus single anti-platelet therapy in stable ischemic heart disease with atrial fibrillation: a meta-analysis

Introduction

Evidence for antithrombotic therapy regimen in patients with concurrent stable ischemic heart disease (SIHD) and atrial fibrillation (AF) is not well established. The ideal regimen needs to been balanced to prevent thrombotic and embolic events, without increasing the risk of bleeding tendencies. Two randomized control trials have been published studying oral anticoagulant monotherapy (OAC) as compared to oral anticoagulant plus single antiplatelet therapy (OAC+SAPT), of which one trial was terminated prematurely and was underpowered.

Purpose

We performed a meta-analysis of RCTs and observational studies comparing OAC monotherapy to OAC+ SAPT in SIDH patients with AF.

Methods

We performed a systematic search of the PubMed, EMBASE and Cochrane databases to identify relevant articles. The database search was performed from the inception of the databases to January 2020. Inclusion criteria were RCTs and observation studies comparing OAC to OAC+SAPT in SIDH patients with AF and reporting time to event outcomes of major bleeding or cardiovascular mortality. The definition of major bleeding as per the definition provided by individual studies. Two authors independently performed data extraction to check for reproducibility. We used inverse variance method with random effect model to calculate hazard ratio (HR) with 95% confidence interval (CI). Statistical heterogeneity was calculated using Higgins I2 statistics. All statistical analysis was performed using RevMan Version 5.3 (Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014).

Results

Seven studies (2 RCTs and 5 observational studies) were included in the final analysis. OAC+ SAPT as compared to OAC monotherapy in patients with SIHD and AF was associated with a higher incidence of major bleeding [HR: 1.59, 95% CI: 1.36–1.85, P value&lt;0.05, I2: 0%] [Figure 1, Panel A]. OAC+SPT as compared to OAC monotherapy was associated with similar incidence of cardiovascular mortality [HR: 1.07, 95% CI: 0.86–1.33, P value= 0.55, I2: 32%] [Figure 1, Panel B]. There was no statistical heterogeneity associated with either pooled estimates.

Conclusion

OAC monotherapy as compared to OAC+SAPT in patients with SIHD and AF was associated with a lower incidence of major bleeding and similar incidence of cardiovascular mortality.

Figure 1

Funding Acknowledgement

Type of funding source: None

Impella versus intra-aortic balloon pump in cardiogenic shock: a meta-analysis assessing 30-days mortality

Introduction

Cardiogenic shock is linked with eminent morbidity and mortality despite advances in treatment modality. Adjuvant treatment modalities to provide mechanical haemodynamic support in the form of intra-aortic balloon pump (IABP) or Impella are being used among patients with cardiogenic shock. The Impella prunes left ventricular preload, whereas, IABP persuades after load reduction and both contribute to improved cardiac output. A few underpowered randomised control trials (RCTs) and observational studies compared short term mortality benefit of Impella juxtaposed to IABP among patients with cardiogenic shock.

Purpose

A meta-analysis of RCTs and observational studies researching the short-term mortality in cardiogenic shock comparing Impella to IABP was executed.

Methods

The databases PubMed, EMBASE and Cochrane were searched systematically to identify relevant RCTs and observational studies contrasting Impella to IABP and reporting 30-days mortality as outcomes. The search terms used were “Impella”, “IAPB”, “intra-aortic balloon pump” and all word variations were utilised. The search was conducted from the debut of the databases up to January 2020. Two reviewers independently and in tandem performed data screening and extraction from identified articles. Inverse variance method with Paule-Mandel estimator for tau2 and Hartung-Knapp adjustment was used to calculate Risk Ratio with 95% confidence interval. Heterogeneity was assessed using I2 statistics. Furthermore, we calculated the 95% predictive interval for the pooled estimate. All statistical analysis for this meta-analysis was carried out using R statistical software version 3.6.2 using the package meta ( ). Additionally, Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria were used to assess the certainty of evidence.

Results

Five studies constituting 728 patients were included in the final analysis. Two were RCTs (ISAR-SHOCK trial and IMPRESS in Severe Shock trial), one study was a propensity score matched observational study and two were unmatched observational studies. There was no difference in the risk of 30-days mortality in patients treated with Impella as compared to IABP [Risk Ratio: 0.97, 95% confidence interval: 0.66–1.41, I2: 32%]. To account for the heterogeneity, we calculated 95% predictive interval: 0.46–2.02. Thus, very low certainty of evidence concluded no difference in the risk of 30-days mortality among cardiogenic shock patients treated with Impella in opposition to IABP.

Conclusion

This meta-analysis comparing Impella juxtaposed with IABP demonstrated no difference in the risk of 30-days mortality among patients with cardiogenic shock.

30-days Mortality

Funding Acknowledgement

Type of funding source: None

Mortality benefit with remote ischemic preconditioning in STEMI: a frequentist and Bayesian meta-analysis of randomized controlled trials

Introduction

Myocardial infarction related morbidity and mortality remains substantial despite perpetual improvement in patient care. Remote ischemic preconditioning among patients with myocardial infarction has exhibited to improve surrogate markers of ischemia. However, its effect on all-cause mortality is not well established.

Purpose

An updated frequentist and Bayesian meta-analysis of randomised control trials [RCTs] investigating remote ischemic preconditioning among patients with ST segment elevation myocardial infarction [STEMI] and its effect on all-cause mortality.

Methods

A systematic search across PubMed, EMBASE and Cochrane databases was performed. The inclusion criteria was RCTs comparing remote ischemic preconditioning with standard treatment juxtaposed to standard treatment alone among patients with STEMI and reporting all-cause mortality. Data extraction was carried out by two independent authors and looked for reproducibility. Inverse variance method with Paule-Mandel estimator for tau2 and Hartung-Knapp adjustment was used to calculate Risk Ratio with 95% confidence interval. Heterogeneity was assessed using I2 statistics. We estimated the robustness of our pooled effect size using Bayesian meta-analysis. A weakly informative prior [normal (0, 1) for intercept and uniform (0, 2) for standard deviation] and 20000 iterations [10000 warm-up + 10000 sampling] were used for Bayesian meta-analysis. We used meta ( ) and brm ( ) package in R for frequentist and Bayesian meta-analysis, respectively. All statistical analysis was carried out using R statistical software version 3.6.2. The certainty of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluations (GRADE).

Results

Five RCTs comprising a total of 6043 patients [3010 intervention and 3033 controls] were included in the final analysis. The largest included RCT was the CONDI-2/ERIC-PPCI 2019 trial. Remote ischemic preconditioning among patients with STEMI had no effect on all-cause mortality at follow-up [RR=0.70, 95% confidence interval = 0.26–1.87, I2=60%] [Figure 1, Panel A]. Similar results were obtained from hierarchical Bayesian meta-analysis [RR=0.55, 95% credibility interval = 0.23–1.38] [Figure 1, Panel B]. Low certainty of evidence as per GARDE, reports no benefit of remote ischemic preconditioning in reducing the risk of all-cause mortality in STEMI.

Conclusion

Remote ischemic preconditioning among patients with STEMI has no effect on all-cause mortality at follow-up.

Figure 1

Funding Acknowledgement

Type of funding source: None

Use of a Plasmodium vivax genetic barcode for genomic surveillance and parasite tracking in Sri Lanka

Background

Sri Lanka was certified as a malaria-free nation in 2016; however, imported malaria cases continue to be reported. Evidence-based information on the genetic structure/diversity of the parasite populations is useful to understand the population history, assess the trends in transmission patterns, as well as to predict threatening phenotypes that may be introduced and spread in parasite populations disrupting elimination programmes. This study used a previously developed Plasmodium vivax single nucleotide polymorphism (SNP) barcode to evaluate the population dynamics of P. vivax parasite isolates from Sri Lanka and to assess the ability of the SNP barcode for tracking the parasites to its origin.

Methods

A total of 51 P. vivax samples collected during 2005–2011, mainly from three provinces of the country, were genotyped for 40 previously identified P. vivax SNPs using a high-resolution melting (HRM), single-nucleotide barcode method. Minor allele frequencies, linkage disequilibrium, pair-wise F_ST values, and complexity of infection (COI) were evaluated to determine the genetic diversity. Structure analysis was carried out using STRUCTURE software (Version 2.3.4) and SNP barcode was used to identify the genetic diversity of the local parasite populations collected from different years. Principal component analysis (PCA) was used to determine the clustering according to global geographic regions.

Results

The proportion of multi-clone infections was significantly higher in isolates collected during an infection outbreak in year 2007. The minor allele frequencies of the SNPs changed dramatically from year to year. Significant linkage was observed in sample sub-sets from years 2005 and 2007. The majority of the isolates from 2007 consisted of at least two genetically distinct parasite strains. The overall percentage of multi-clone infections for the entire parasite sample was 39.21%. Analysis using STRUCTURE software (Version 2.3.4) revealed the high genetic diversity of the sample sub-set from year 2007. In-silico analysis of these data with those available from other global geographical regions using PCA showed distinct clustering of parasite isolates according to geography, demonstrating the usefulness of the barcode in determining an isolate to be indigenous.

Conclusions

Plasmodium vivax parasite isolates collected during a disease outbreak in year 2007 were more genetically diverse compared to those collected from other years. In-silico analysis using the 40 SNP barcode is a useful tool to track the origin of an isolate of uncertain origin, especially to differentiate indigenous from imported cases. However, an extended barcode with more SNPs may be needed to distinguish highly clonal populations within the country.

P4415Long obstructive sleep apneas as a biomarker of atrial fibrillation

Background

Even though obstructive sleep apnea (OSA) is strongly associated with atrial fibrillation (AF), the use of traditional OSA scoring by apnea hypopnea index (AHI) did not result in improved arrhythmia outcomes in recent randomized trials. Longer OSA episodes lead to stronger pro-arrhythmic changes, and whether very long OSA episodes are more prevalent in AF patients remains unknown.

Purpose

We hypothesized that AF patients with mild-moderate OSA manifest greater percentage of long (>20s), very long (>30s), and extremely long (>40s) OSA episodes, compared to control OSA patients matched to AHI, age and sex.

Methods

From patients studied with diagnostic polysomnography in our laboratory between 2016 and 2018, we selected 22 patients with mild-moderate untreated OSA of which 11 patients had history of paroxysmal AF and 11 patients did not have any cardiac history. The length, oxygen desaturation, and relationship to neighboring events was manually re-measured in all recorded apnea and hypopnea events.

Results

In the 22 included patients (age 62.5±9.1 years, AHI 12.8±6.1, 40% female) we recorded 1021 apneas: 508 in the AF group and 513 in the control group. AF patients had longer apneas compared to the patients without AF history (mean length 28.7±11.7s vs. 23.3±9.9s; p<0.0001). The proportion of apneas that were long (>20s), very long (>30s), and extremely long (>40s) was greater in the AF group as compared to the control (p=0.0039, p=0.0215, p=0.0104, respectively; see figure). The acute oxygen saturation drops (>2%) during apneas were comparable between the AF group and control groups (p=0.13), but the long (>20s) apneas were prone to greater oxygen desaturations.

Length of Apneas

Conclusions

While traditional scoring of OSA focuses on episodes lasting >10s, our data newly show that longer durations of OSA events are particularly prevalent in AF patients. These results, combined with recent mechanistic studies showing that longer apneas exert greater pro-arrhythmic effect on atrial conduction, suggest that novel scoring of OSA placing more weight on longer apneas should be explored, especially when screening and titrating OSA therapy in patients at risk of AF.

Ventricular asystole in a CRT-D device. What is the mechanism?

We present a case of an 89-year-old man with a left ventricular assist device and cardiac resynchronization therapy device (CRT-D) who presented with multiple presyncopal events. On the night of admission, telemetry revealed a 13-s pause with appropriately timed pacing spikes but with failure to capture, followed by intermittent ventricular contraction with different QRS morphology. What was the mechanism for his ventricular asystole?

A Case of Myocarditis and Near-Lethal Arrhythmia Associated With Interleukin-2 Therapy

We present a case of a 48-year-old female who developed myocarditis and near fatal arrhythmias during high dose Il-2 therapy for metastatic renal cancer. On day 5 of therapy, the patient developed sudden onset chest pain, elevated cardiac enzymes and ST segment changes on EKG. Coronary angiogram was normal, however echocardiogram showed reduced ejection fraction and hemodynamic measurements showed elevated bilateral elevated filling pressures. The patient then developed episodes of recurrent ventricular arrhythmia, precipitated by bradycardia and PVC, requiring defibrillation and temporary pacemaker placement. Endomycardial biopsy was nonspecific showing fibrosis with subsequent cardiac MRI showed evidence of myocardial edema, consistent with Il-2 induced myocarditis in the setting of no prior cardiac history. After the discontinuation of Il-2 therapy, the patient displayed clinical improvement as well as improved ejection fraction. This case brings attention to the cardiac toxicities associated with high dose Il-2 therapy including potentially lethal arrhythmias and highlights the importance of careful cardiac screening prior to initiation of treatment.

Chronic obstructive pulmonary disease as a risk factor for ventricular arrhythmias independent of left ventricular function

BACKGROUND

The association between chronic obstructive pulmonary disease (COPD) and sudden cardiac death has not been fully elucidated.

OBJECTIVE

The purpose of this study was to investigate whether decreased left ventricular ejection fraction (LVEF) can explain the increased rate of ventricular tachycardia (VT) in COPD.

METHODS

This retrospective study included consecutive adult patients who underwent pulmonary function testing (PFT), Holter monitoring, and transthoracic echocardiography. COPD was correlated with the frequency of VT in a multivariate analysis that adjusted for known confounders including LVEF. Long-term all-cause mortality of patients with COPD and VT was examined.

RESULTS

Of the 6351 patients included in this study (age 66 ± 15 years; 48% woman; 92% Caucasian, LVEF 59% ± 12%), 2800 (44%) had PFT indicative of COPD. VT was nearly twice as likely to occur during Holter monitoring in COPD patients (13% vs 23%; P <.001), and the severity of COPD correlated with the risk of VT (21% vs 28% vs 37% for mild-moderate, severe, and very severe COPD; P <.001). COPD and VT remained independently associated (P <.001) even after adjusting for LVEF, demographics, and comorbidities (age, sex, body mass index, hypertension, chronic kidney disease, coronary artery disease, cancer history, diabetes mellitus). COPD was associated with all-cause mortality independently of LVEF (P <.001).

CONCLUSION

COPD patients are at higher risk for VT and mortality. This may not be fully attributed to the confounding effect of systolic heart failure measured by LVEF. Further studies are needed to explore the mechanistic interactions between VT and COPD in order to determine whether antiarrhythmic strategies would apply especially to patients with severe COPD.

Effects of pressure variation and atrial fibrillation on CardioMEMS™ HF measured pulmonary artery diastolic pressure: comparison of device-averaged and visually inspected waveforms

OBJECTIVE

Heart failure (HF) management guided by implantable hemodynamic monitoring reduces hospitalization rates. Hemodynamic data from the CardioMEMS^™ HF system includes device-averaged pulmonary artery pressures (PAP) and heart rate. Agreement of device-averaged values compared to the standard method of visual inspection of pressure waveforms at end-expiration is unknown. We evaluated the agreement between device-averaged and visually inspected end-expiratory PAP.

APPROACH

Twenty-one patients implanted with the CardioMEMS^™ HF system were evaluated. Eight-hundred twenty-three PAP waveforms from the Merlin remote monitoring website were visually inspected and pulmonary artery systolic pressure (PASP) and pulmonary artery diastolic pressure (PADP) at end-expiration were recorded. Waveforms were evaluated for pressure variation (PV), defined as the difference between highest and lowest PASP measurement of  ⩾20 mmHg. Bland-Altman analysis quantified differences between device-averaged and visually inspected waveforms.

MAIN RESULTS

All patients were NYHA functional class III, mean age was 67  ±  15 years and 15 (71%) had AF. Bland-Altman analysis of all waveforms revealed a mean-difference in PADP of  -1.4 mmHg, indicating that visually inspected values were higher than device-averaged values. For PV  ⩾20 mmHg, this value increased to  -2.8 mmHg. The mean-difference comparing waveforms from patients with or without AF was  -1.3 and  -1.6 mmHg, respectively. The 95% limits of agreement were  >50% wider for waveforms from patients with versus without AF (10.3 versus 6.7 mmHg).

SIGNIFICANCE

There is good agreement between device-averaged and visually inspected waveforms when pressure variation is  <20 mmHg and for patients without atrial fibrillation.

Retrieval of the Leadless Cardiac Pacemaker

Background—

Leadless cardiac pacemakers have emerged as a safe and effective alternative to conventional transvenous single-chamber ventricular pacemakers. Herein, we report a multicenter experience on the feasibility and safety of acute retrieval (<6 weeks) and chronic retrieval (>6 weeks) of the leadless cardiac pacemaker in humans.

Methods and Results—

This study included patients enrolled in 3 multicenter trials, who received a leadless cardiac pacemaker implant and who subsequently underwent a device removal attempt. The overall leadless pacemaker retrieval success rate was 94%: for patients whose leadless cardiac pacemaker had been implanted for <6 weeks (acute retrieval cohort), complete retrieval was achieved in 100% (n=5/5); for those implanted for ≥ 6 weeks (chronic retrieval cohort), retrieval was achieved in 91% (n=10/11) of patients. The mean duration of time from implant to retrieval attempt was 346 days (range, 88–1188 days) in the chronic retrieval cohort, and nearly two thirds (n=7; 63%) had been implanted for >6 months before the retrieval attempt. There were no procedure-related adverse events at 30 days post retrieval procedure.

Conclusions—

This multicenter experience demonstrated the feasibility and safety of retrieving a chronically implanted single-chamber (right ventricle) active fixation leadless pacemaker.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov . Unique identifiers: NCT02051972, NCT02030418, and NCT01700244.

Percutaneous Implantation of an Entirely Intracardiac Leadless Pacemaker

BACKGROUND

Cardiac pacemakers are limited by device-related complications, notably infection and problems related to pacemaker leads. We studied a miniaturized, fully self-contained leadless pacemaker that is nonsurgically implanted in the right ventricle with the use of a catheter.

METHODS

In this multicenter study, we implanted an active-fixation leadless cardiac pacemaker in patients who required permanent single-chamber ventricular pacing. The primary efficacy end point was both an acceptable pacing threshold (≤2.0 V at 0.4 msec) and an acceptable sensing amplitude (R wave ≥5.0 mV, or a value equal to or greater than the value at implantation) through 6 months. The primary safety end point was freedom from device-related serious adverse events through 6 months. In this ongoing study, the prespecified analysis of the primary end points was performed on data from the first 300 patients who completed 6 months of follow-up (primary cohort). The rates of the efficacy end point and safety end point were compared with performance goals (based on historical data) of 85% and 86%, respectively. Additional outcomes were assessed in all 526 patients who were enrolled as of June 2015 (the total cohort).

RESULTS

The leadless pacemaker was successfully implanted in 504 of the 526 patients in the total cohort (95.8%). The intention-to-treat primary efficacy end point was met in 270 of the 300 patients in the primary cohort (90.0%; 95% confidence interval [CI], 86.0 to 93.2, P=0.007), and the primary safety end point was met in 280 of the 300 patients (93.3%; 95% CI, 89.9 to 95.9; P<0.001). At 6 months, device-related serious adverse events were observed in 6.7% of the patients; events included device dislodgement with percutaneous retrieval (in 1.7%), cardiac perforation (in 1.3%), and pacing-threshold elevation requiring percutaneous retrieval and device replacement (in 1.3%).

CONCLUSIONS

The leadless cardiac pacemaker met prespecified pacing and sensing requirements in the large majority of patients. Device-related serious adverse events occurred in approximately 1 in 15 patients. (Funded by St. Jude Medical; LEADLESS II ClinicalTrials.gov number, NCT02030418.).

HIV infection and risk factors among the armed forces personnel stationed in Kinshasa, Democratic Republic of Congo

Despite recent declines in HIV incidence, sub-Saharan Africa remains the most heavily affected region in the global HIV/AIDS epidemic. Estimates of HIV prevalence in African military personnel are scarce and inconsistent. We conducted a serosurvey between June and September 2007 among 4043 Armed Forces personnel of the Democratic Republic of Congo (FARDC) stationed in Kinshasa, Democratic Republic of Congo (DRC) to determine the prevalence of HIV and syphilis infections and describe associated risk behaviours. Participants provided blood for HIV and syphilis testing and responded to a demographic and risk factor questionnaire. The prevalence of HIV was 3.8% and the prevalence of syphilis was 11.9%. Women were more likely than men to be HIV positive, (7.5% vs. 3.6% respectively, aOR: 1.66, 95% C.I: 1.21-2.28, p < 0.05). Factors significantly associated with HIV infection included gender and self-reported genital ulcers in the 12 months before date of enrollment. The prevalence of HIV in the military appears to be higher than the general population in DRC (3.8% vs. 1.3%, respectively), with women at increased risk of infection.

Improving recognition and management of acute kidney injury

Acute kidney injury (AKI) is currently suboptimally recognised and managed in the UK, despite its association with significant patient morbidity, mortality and consequent implications for healthcare economics. Our prospective study, performed in a large urban London hospital, demonstrated that the introduction of a specially designed care bundle can significantly improve documentation of baseline creatinine, assessment and optimisation of fluid status, performance of urine dip, withholding of nephrotoxic drugs, appropriate monitoring of urine output, prescription of renal drug doses, and appropriate consideration of a renal ultrasound and urinary protein-creatinine ratio. Improved compliance of appropriate investigations and initial treatments translated to decreased requirement for intensive care admission and a trend towards shorter length of stays.

Range of Alcohol-Induced Damage in the Developing Central Nervous System

Fourteen previously reported cases of the fetal alcohol syndrome (FAS) showed anomalies of brain structure varying in severity from microscopic disorganization of tissue structure, or abnormalities in neuronal or glial migration only visible microscopically, to complete or partial agenesis of regions such as the corpus callosum or cerebellum and large neuronal heteropias. The difficulty is illustrated of differentiating this type of damage, lacking in specificity and uniformity, from other syndromes of uncertain aetiology, such as De Lange, DiGeorge and Dubowitz, in at least one of which (DiGeorge syndrome) maternal alcoholism has been implicated. Similar brain damage is also seen in other conditions with known causes. In FAS and syndromes with this type of brain damage, most of the non-CNS features which make the conditions clinically recognizable may well be determined by timing or ancillary factors. Alcohol-related antenatal effects should not be identified to restrictively with FAS but should be considered in any condition of unknown aetiology with disorganization of brain structure and mental retardation.

Efficient nonviral transfection of dendritic cells and their use for in vivo immunization

Immunization with dendritic cells (DCs) transfected with genes encoding tumor-associated antigens (TAAs) is a highly promising approach to cancer immunotherapy. We have developed a system, using complexes of plasmid DNA expression constructs with the cationic peptide CL22, that transfects human monocyte-derived DCs much more efficiently than alternative nonviral agents. After CL22 transfection, DCs expressing antigens stimulated autologous T cells in vitro and elicited primary immune responses in syngeneic mice, in an antigen-specific manner. Injection of CL22-transfected DCs expressing a TAA, but not DCs pulsed with a TAA-derived peptide, protected mice from lethal challenge with tumor cells in an aggressive model of melanoma. The CL22 system is a fast and efficient alternative to viral vectors for engineering DCs for use in immunotherapy and research.

A case of Miller-Dieker syndrome in a family with neurofibromatosis type I

The Miller-Dieker syndrome (type I lissencephaly) is a neuronal migration disorder which is associated with microdeletions in the short arm of chromosome 17. Neurofibromatosis type I (NF1) is an autosomal dominant condition associated with mutations in the long arm of chromosome 17, and characterised by neurofibromas, café-au-lait spots and axillary freckling. The neonatal period for a female infant born at 39 weeks gestation by emergency Caesarean section was complicated by frequent epileptic seizures as well as hypotonia. A computed tomography scan revealed evidence of lissencephaly, and chromosomal analysis showed a microdeletion on the short arm of chromosome 17 (17p13.3), confirming the diagnosis as Miller-Dieker syndrome. The child died at the age of 4 years and examination of the brain confirmed lissencephaly with a thickened cortex, deficient white matter, and grey matter heteropias. The mother had café-au-lait spots, and axillary freckling. In addition, the mother's and maternal grandmother's genetic analysis showed identical mutations in the neurofibromatosis I gene on the long arm of chromosome 17, confirming the diagnosis of NF1. The child did not possess the mutation. This case illustrates a rare neuronal migration disorder appearing in a child from a family with a history of NF1.