Rates of pulmonary vein reconnection at repeat ablation for recurrent atrial fibrillation and its impact on outcomes among females and males

BACKGROUND

Several studies have demonstrated that females have a higher risk of arrhythmia recurrence after pulmonary vein (PV) isolation for atrial fibrillation (AF). There are limited data on sex-based differences in PV reconnection rates at repeat ablation. We aimed to investigate sex-based differences in electrophysiological findings and atrial arrhythmia recurrence after repeat AF ablation METHODS: We conducted a retrospective study of 161 consecutive patients (32% female, age 65 ± 10 years) who underwent repeat AF ablation after index PV isolation between 2010 and 2022. Demographics, procedural characteristics and follow-up data were collected. Recurrent atrial tachycardia (AT)/AF was defined as any atrial arrhythmia ≥30 s in duration.

RESULTS

Compared to males, females tended to be older and had a significantly higher prevalence of prior valve surgery (10 vs. 2%; P = .03). At repeat ablation, PV reconnection was found in 119 (74%) patients. Males were more likely to have PV reconnection at repeat ablation compared to females (81 vs. 59%; P = .004). Excluding repeat PV isolation, there were no significant differences in adjunctive ablation strategies performed at repeat ablation between females and males. During follow-up, there were no significant differences in freedom from AT/AF recurrence between females and males after repeat ablation (63 vs. 59% at 2 years, respectively; P = .48).

CONCLUSIONS

After initial PV isolation, significantly fewer females have evidence of PV reconnection at the time of repeat ablation for recurrent AF. Despite this difference, long-term freedom from AT/AF was similar between females and males after repeat ablation.

Rationale and design of the NODE-303 study: evaluating the safety of symptom-prompted, self-administered etripamil for paroxysmal supraventricular tachycardia episodes in real-world settings

BACKGROUND

Paroxysmal supraventricular tachycardia (PSVT) is a common episodic arrhythmia characterized by unpredictable onset and burdensome symptoms including palpitations, dizziness, chest pain, distress, and shortness of breath. Treatment of acute episodes of PSVT in the clinical setting consists of intravenous adenosine, beta-blockers, and calcium channel blockers (CCBs). Etripamil is an intranasally self-administered L-type CCB in development for acute treatment of AV-nodal dependent PSVT in a nonmedical supervised setting.

METHODS

This paper summarizes the rationale and study design of NODE-303 that will assess the efficacy and safety of etripamil. In the randomized, double-blinded, placebo-controlled, Phase 3 RAPID trial, etripamil was superior to placebo in the conversion of single PSVT episodes by 30 minutes post initial dose when administered in the nonhealthcare setting; this study required a mandatory and observed test dosing prior to randomization. The primary objective of NODE-303 is to evaluate the safety of symptom-prompted, self-administered etripamil for multiple PSVT episodes in real-world settings, without the need for test dosing prior to first use during PSVT. Secondary endpoints include efficacy and disease burden. Upon perceiving a PSVT episode, the patient applies an electrocardiographic monitor, performs a vagal maneuver, and, if the vagal maneuver is unsuccessful, self-administers etripamil 70 mg, with an optional repeat dose if symptoms do not resolve within 10 minutes after the first dose. A patient may treat up to four PSVT episodes during the study. Adverse events are recorded as treatment-emergent if they occur within 24 hours after the administration of etripamil.

RESULTS

Efficacy endpoints include time to conversion to sinus rhythm within 30 and 60 minutes after etripamil administration, and the proportion of patients who convert at 3, 5, 10, 20, 30, and 60 minutes. Patient-reported outcomes are captured by the Brief Illness Perception Questionnaire, the Cardiac Anxiety Questionnaire, the Short Form Health Survey 36, the Treatment Satisfaction Questionnaire for Medication and a PSVT survey.

CONCLUSIONS

Overall, these data will support the development of a potentially paradigm-changing long-term management strategy for recurrent PSVT.

Pharmacokinetics and Pharmacodynamics of Etripamil, an Intranasally Administered, Fast-Acting, Nondihydropyridine Calcium Channel Blocker

Etripamil, a fast-acting nondihydropyridine L-type calcium channel blocker, is under investigation for potential self-administration for the acute treatment of supraventricular tachyarrhythmias in a medically unsupervised setting. We report detailed pharmacokinetics and pharmacodynamics of intranasally administered etripamil in healthy adults from 2 Phase 1, randomized, double-blind studies: Study MSP-2017-1096 (sequential dose-escalation, crossover study design, n = 64) and NODE-102 (single dose, 4-way crossover study, n = 24). Validated bioanalytical assays determined plasma concentrations of etripamil and its inactive metabolite. Noncompartmental pharmacokinetic parameters were calculated. Pharmacodynamic parameters were determined for PR interval, blood pressure, and heart rate. Etripamil was rapidly absorbed intranasally, with time to maximal plasma concentration of 5-8.5 minutes, corresponding to a rapid greater than 10% increase in mean maximum PR interval from baseline within 4-7 minutes of doses of 60 mg or greater. Following peak plasma concentrations, systemic etripamil levels declined rapidly within the first 15 minutes following dosing and decreased more gradually thereafter. PR interval prolongation greater than 10% from baseline was generally sustained for about 45 minutes at doses of 60 mg or greater. The mean terminal half-life ranged from about 1.5 hours with 60 mg to about 2.5-3 hours for the 70- and 105-mg doses. Etripamil was generally well tolerated without symptomatic hypotension. Adverse events were primarily mild to moderate and related to the administration site; no serious adverse events or episodes of atrioventricular block occurred. Intranasal etripamil administration, at doses of 60 mg or greater, produced rapidly occurring slowing of atrioventricular nodal conduction with a limited duration of effect without hemodynamic or electrocardiographic safety signals in healthy volunteers.

Ventricular Tachycardia Due to Triggered Activity: Role of Early and Delayed Afterdepolarizations

Most forms of sustained ventricular tachycardia (VT) are caused by re-entry, resulting from altered myocardial conduction and refractoriness secondary to underlying structural heart disease. In contrast, VT caused by triggered activity (TA) is unrelated to an abnormal structural substrate and is often caused by molecular defects affecting ion channel function or regulation of intracellular calcium cycling. This review summarizes the cellular and molecular bases underlying TA and exemplifies their clinical relevance with selective representative scenarios. The underlying basis of TA caused by delayed afterdepolarizations is related to sarcoplasmic reticulum calcium overload, calcium waves, and diastolic sarcoplasmic reticulum calcium leak. Clinical examples of TA caused by delayed afterdepolarizations include sustained right and left ventricular outflow tract tachycardia and catecholaminergic polymorphic VT. The other form of afterpotentials, early afterdepolarizations, are systolic events and inscribe early afterdepolarizations during phase 2 or phase 3 of the action potential. The fundamental defect is a decrease in repolarization reserve with associated increases in late plateau inward currents. Malignant ventricular arrhythmias in the long QT syndromes are initiated by early afterdepolarization-mediated TA. An understanding of the molecular and cellular bases of these arrhythmias has resulted in generally effective pharmacologic-based therapies, but these are nonspecific agents that have off-target effects. Therapeutic efficacy may need to be augmented with an implantable defibrillator. Next-generation therapies will include novel agents that rescue arrhythmogenic abnormalities in cellular signaling pathways and gene therapy approaches that transfer or edit pathogenic gene variants or silence mutant messenger ribonucleic acid.

Localized Re-Entry Is a Frequent Mechanism of De Novo Atypical Flutter

BACKGROUND

Limited data exist about the origins and mechanisms of atypical atrial flutter that occurs in the absence of prior ablation or surgery.

OBJECTIVES

The aims of this study were to report a large cohort of patients who presented for catheter ablation of de novo atypical flutters, to identify the most common locations and mechanisms of arrhythmia, and to describe outcomes after ablation.

METHODS

Demographic, electrophysiological, and outcome data were collected for patients who underwent ablation of de novo atypical flutter.

RESULTS

The mechanisms of 85 atypical flutters were identified in 62 patients and localized to the left atrium (LA) in 58 and right atrium (RA) in 27. In the LA, mechanisms were classified as macro-re-entry in 29 (50%) and localized re-entry in 29 (50%), whereas in the RA, mechanisms were macro-re-entry in 8 (30%) and localized re-entry in 19 (70%) (proportion of localized re-entry in the LA vs. RA, P = 0.08). Nine patients had both localized and macro-re-entrant atypical flutters. In the LA, localized re-entry was commonly found in the anterior LA, followed by the pulmonary veins and septum. In the RA, localized re-entry was found at various sites, including the lateral or posterior RA, septum, and coronary sinus ostium. During 39.4 months (Q1-Q3: 18.2-65.8 months) of follow-up, atrial arrhythmias occurred in 66% of patients after a single ablation and in 50% after >1 ablation. Among patients who underwent repeat ablation, compared with the index arrhythmia, different tachycardia circuits or arrhythmias were documented in 13 of 18 cases (72%).

CONCLUSIONS

Atypical atrial flutters in patients without prior surgery or complex ablation are often due to localized re-entry (approximately 50% in the LA and a higher frequency in the RA). Other atrial tachycardias commonly occur during long-term follow-up following ablation, suggesting progressive atrial myopathy in these patients.

Plain language summary of the safety and effectiveness of etripamil for atrioventricular-nodal-dependent supraventricular tachycardia: the RAPID study

WHAT IS THIS SUMMARY ABOUT?

This is a plain language summary of a clinical research study called RAPID. The study looked at the potential for how safe and effective etripamil was at stopping an episode of rapid heartbeats in people with atrioventricularnodal-dependent supraventricular tachycardia (AV-node-dependent SVT). An episode is used to describe the period of time when a person experiences an abnormally very fast heartbeat. This was done by comparing an investigational drug called etripamil with a placebo, each administered via a rapidly acting nasal spray. AV-node-dependent SVT affects the rhythm of the heart, causing it to suddenly beat rapidly. The condition often requires medical treatment to help return the heart to its normal, healthy heartbeat pattern and speed, called 'sinus rhythm'. Researchers are looking at ways of improving the management of supraventricular tachycardias (SVT) by reducing the need for patients to attend an urgent care clinic, emergency ward or hospital for treatment. In the RAPID study, participants used a nasal spray containing either 70 mg etripamil or a placebo solution when they experienced an episode of SVT. The researchers wanted to know how long it took for each participant's rapid heartbeat to return to sinus rhythm after administering the etripamil or placebo nasal spray. Participants in the study were considered successfully treated if their heartbeats returned to sinus rhythm for at least 30 seconds within 30 minutes of using the nasal spray. Although 30 seconds may seem brief, it's medically important because it shows that a person's heartbeat has been temporarily stabilized and returned to normal functioning.

WHAT WERE THE RESULTS?

Out of 99 people who used etripamil during an SVT episode, 63 participants (64%) experienced a return to sinus rhythm for at least 30 seconds within 30 minutes after using the nasal spray. In contrast, 26 out of 85 participants (31%) who used the placebo nasal spray experienced a return to sinus rhythm for at least 30 seconds within 30 minutes after use. Furthermore, the average time taken for the return to sinus rhythm was 17 minutes for the etripamil group which was 3-times faster than the placebo group at 53 minutes. Also, in the study no serious side effects occurred that were related to etripamil.

WHAT DO THE RESULTS OF THE STUDY MEAN?

The RAPID study supports the potential that etripamil may be safe and well tolerated by participants as a treatment for episodes of rapid heartbeat in people with AV-node-dependent SVT. The results also showed a significant improvement in symptoms following treatment with etripamil.

Podcast on Self-administered Intranasal Etripamil for Symptomatic Paroxysmal Supraventricular Tachycardia: The RAPID Trial

Paroxysmal supraventricular tachycardia (PSVT) is commonly seen in clinical practice and represents a significant burden to the healthcare system and to patients. First-line treatments include calcium channel blockers (CCB), although they are intravenous and require medical supervision. Etripamil is an investigational self-administered intranasal L-type CCB for unsupervised treatment of PSVT. In this podcast, we discuss the RAPID trial (NCT03464019), which was a phase 3 study that evaluated the safety and efficacy of etripamil in terminating PSVT episodes using a repeat-dosing regimen. RAPID was a multicenter, randomized trial that enrolled adults with electrocardiograph (ECG)-documented PSVT episodes lasting ≥ 20 min. Patients who tolerated test doses of etripamil were randomized 1:1 to receive either etripamil or placebo. Upon perceiving PSVT symptoms, patients began ECG monitoring and performed a vagal maneuver. If arrhythmia termination was unsuccessful, they self-administered 70 mg of etripamil or placebo, followed by an optional second dose after 10 min. The primary endpoint was time to conversion of PSVT to sinus rhythm within 30 min of the initial dose and sustained for ≥ 30 s. The safety group included all patients who self-administered the study treatment. Of 692 enrollees, 184 self-administered the study drug (99 etripamil, 85 placebo) for ECG-confirmed PSVT. Conversion of PSVT to sinus rhythm within 30 min was achieved in 64.3% of etripamil-treated subjects versus 31.2% of placebo-treated subjects. A significant threefold reduction in the median time to conversion of 17.2 min was observed in the etripamil group versus 53.5 min in the placebo group. Treatment-emergent adverse events were mild or moderate and primarily included transient nasal discomfort, nasal congestion, and rhinorrhea. If etripamil is approved by the US FDA, it can potentially address a significant unmet need for PSVT treatment outside a clinical setting, reducing the need for intravenous treatments that require medical supervision.Podcast available for this article.

Multicenter, Phase 2, Randomized Controlled Study of the Efficacy and Safety of Etripamil Nasal Spray for the Acute Reduction of Rapid Ventricular Rate in Patients With Symptomatic Atrial Fibrillation (ReVeRA-201)

BACKGROUND

Despite chronic therapies, atrial fibrillation (AF) leads to rapid ventricular rates (RVR) often requiring intravenous treatments. Etripamil is a fast-acting, calcium-channel blocker administered intranasally affecting the atrioventricular node within minutes.

METHODS

Reduction of Ventricular Rate in Patients with Atrial Fibrillation evaluated the efficacy and safety of etripamil for the reduction of ventricular rate (VR) in patients presenting urgently with AF-RVR (VR ≥110 beats per minute [bpm]), was randomized, double-blind, placebo-controlled, and conducted in Canada and the Netherlands. Patients presenting urgently with AF-RVR were randomized (1:1, etripamil nasal spray 70 mg: placebo nasal spray). The primary objective was to demonstrate the effectiveness of etripamil in reducing VR in AF-RVR within 60 minutes of treatment. Secondary objectives assessed achievement of VR <100 bpm, reduction by ≥10% and ≥20%, relief of symptoms and treatment effectiveness; adverse events; and additional measures to 360 minutes.

RESULTS

Sixty-nine patients were randomized, 56 dosed with etripamil (n=27) or placebo (n=29). The median age was 65 years; 39% were female patients; proportions of AF types were similar between groups. The difference of mean maximum reductions in VR over 60 minutes, etripamil versus placebo, adjusting for baseline VR, was -29.91 bpm (95% CI, -40.31 to -19.52; P<0.0001). VR reductions persisted up to 150 minutes. Significantly greater proportions of patients receiving etripamil achieved VR reductions <100 bpm (with longer median duration <100 bpm), or VR reduction by ≥10% or ≥20%, versus placebo. VR reduction ≥20% occurred in 66.7% of patients in the etripamil arm and no patients in placebo. Using the Treatment Satisfaction Questionnaire for Medication-9, there was significant improvement in satisfaction on symptom relief and treatment effectiveness with etripamil versus placebo. Serious adverse events were rare; 1 patient in the etripamil arm experienced transient severe bradycardia and syncope, assessed as due to hypervagotonia.

CONCLUSIONS

Intranasal etripamil 70 mg reduced VR and improved symptom relief and treatment satisfaction. These data support further development of self-administered etripamil for the treatment of AF-RVR.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique Identifier: NCT04467905.

Etripamil Nasal Spray for Conversion of Repeated Spontaneous Episodes of Paroxysmal Supraventricular Tachycardia During Long-Term Follow-Up: Results From the NODE-302 Study

Background Self-administration of investigational intranasal L-type calcium channel blocker etripamil during paroxysmal supraventricular tachycardia (PSVT) appeared safe and well-tolerated in the phase 3 NODE-301 (Multi-Centre, Randomized, Double-Blind, Placebo-Controlled, Efficacy, and Safety Study of Etripamil Nasal Spray for the Termination of Spontaneous Episodes of Paroxysmal Supraventricular Tachycardia) trial of adults with sustained atrioventricular nodal-dependent PSVT. The NODE-302 open-label extension further characterized etripamil safety and efficacy. Methods and Results Eligible patients were monitored via self-applied cardiac monitoring system for 5 hours after etripamil self-administration. The primary end point was time-to-conversion of positively adjudicated PSVT to sinus rhythm after etripamil treatment. Probability of conversion to sinus rhythm was reported via Kaplan-Meier plot. Adverse events were based on self-reported symptoms and clinical evaluations. Among 169 patients enrolled, 105 self-administered etripamil ≥1 time for perceived PSVT (median [range], 232 [8-584] days' follow-up). Probability of conversion within 30 minutes of etripamil was 60.2% (median time to conversion, 15.5 minutes) among 188 PSVT episodes (92 patients) positively adjudicated as atrioventricular nodal dependent by independent ECG analysis. Among 40 patients who self-treated 2 episodes, 75% had a significantly consistent response by 30 minutes; 9 did not convert on either episode, and 21 converted on both episodes (χ2=8.09; P=0.0045). Forty-five of 105 patients (42.9%) had ≥1 treatment-emergent adverse event, generally transient and mild-to-moderate, including nasal congestion (14.3%), nasal discomfort (14.3%), or rhinorrhea (12.4%). No serious cardiac safety events were observed within 24 hours of etripamil. Conclusions In this extension study, investigational etripamil nasal spray was well tolerated for self-treating recurrent episodes of PSVT without medical supervision. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03635996.

Retrieval of Chronically Implanted Dual-chamber Leadless Pacemakers in an Ovine Model

BACKGROUND

The clinical utilization of leadless pacemakers (LPs) as an alternative to traditional transvenous pacemakers is likely to increase with the advent of dual-chamber LP systems. Since device retrieval to allow LP upgrade or replacement will become an important capability, the first such dual-chamber, helix-fixation LP system (Aveir DR; Abbott, Abbott Park, IL) was specifically designed to allow catheter-based retrieval. In this study, the preclinical performance and safety of retrieving chronically implanted dual-chamber LPs was evaluated.

METHODS

Atrial and ventricular LPs were implanted in the right atrial appendage and right ventricular apex of 9 healthy ovine subjects. After ≈2 years, the LPs were retrieved using a dedicated transvenous retrieval catheter (Aveir Retrieval Catheter; Abbott) by snaring, docking, and unscrewing from the myocardium. Comprehensive necropsy/histopathology studies were conducted to evaluate device- and procedure-related outcomes.

RESULTS

At a median of 1.9 years postimplant (range, 1.8-2.6), all 18 of 18 (100%) LPs were retrieved from 9 ovine subjects without complications. The median retrieval procedure duration for both LPs, from first-catheter-in to last-catheter-out, was 13.3 minutes (range, 2.5-36.4). Postretrieval, all right atrial, and right ventricular implant sites demonstrated minimal tissue disruption, with intact fibrous tissue limited to the distal device body. No significant device-related trauma, perforation, pericardial effusion, right heart or tricuspid valve injury, or chronic pulmonary thromboembolism were observed at necropsy.

CONCLUSIONS

This preclinical study demonstrated the safe and effective retrieval of chronically implanted, helix-fixation, dual-chamber LP systems, paving the way for clinical studies of LP retrieval.

Self-administered intranasal etripamil using a symptom-prompted, repeat-dose regimen for atrioventricular-nodal-dependent supraventricular tachycardia (RAPID): a multicentre, randomised trial

BACKGROUND

Etripamil is a fast-acting, intranasally administered calcium-channel blocker in development for on-demand therapy outside a health-care setting for paroxysmal supraventricular tachycardia. We aimed to evaluate the efficacy and safety of etripamil 70 mg nasal spray using a symptom-prompted, repeat-dose regimen for acute conversion of atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia to sinus rhythm within 30 min.

METHODS

RAPID was a multicentre, randomised, placebo-controlled, event-driven trial, conducted at 160 sites in North America and Europe as part 2 of the NODE-301 study. Eligible patients were aged at least 18 years and had a history of paroxysmal supraventricular tachycardia with sustained, symptomatic episodes (≥20 min) as documented by electrocardiogram. Patients were administered two test doses of intranasal etripamil (each 70 mg, 10 min apart) during sinus rhythm; those who tolerated the test doses were randomly assigned (1:1) using an interactive response technology system to receive either etripamil or placebo. Prompted by symptoms of paroxysmal supraventricular tachycardia, patients self-administered a first dose of intranasal 70 mg etripamil or placebo and, if symptoms persisted beyond 10 min, a repeat dose. Continuously recorded electrocardiographic data were adjudicated, by individuals masked to patient assignment, for the primary endpoint of time to conversion of paroxysmal supraventricular tachycardia to sinus rhythm for at least 30 s within 30 min after the first dose, which was measured in all patients who administered blinded study drug for a confirmed atrioventricular-nodal-dependent event. Safety outcomes were assessed in all patients who self-administered blinded study drug for an episode of perceived paroxysmal supraventricular tachycardia. This trial is registered at ClinicalTrials.gov, NCT03464019, and is complete.

FINDINGS

Between Oct 13, 2020, and July 20, 2022, among 692 patients randomly assigned, 184 (99 from the etripamil group and 85 from the placebo group) self-administered study drug for atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia, with diagnosis and timing confirmed. Kaplan-Meier estimates of conversion rates by 30 min were 64% (63/99) with etripamil and 31% (26/85) with placebo (hazard ratio 2·62; 95% CI 1·66-4·15; p<0·0001). Median time to conversion was 17·2 min (95% CI 13·4-26·5) with the etripamil regimen versus 53·5 min (38·7-87·3) with placebo. Prespecified sensitivity analyses of the primary assessment were conducted to test robustness, yielding supporting results. Treatment-emergent adverse events occurred in 68 (50%) of 99 patients treated with etripamil and 12 (11%) of 85 patients in the placebo group, most of which were located at the administration site and were mild or moderate, and all of which were transient and resolved without intervention. Adverse events occurring in at least 5% of patients treated with etripamil were nasal discomfort (23%), nasal congestion (13%), and rhinorrhea (9%). No serious etripamil-related adverse events or deaths were reported.

INTERPRETATION

Using a symptom-prompted, self-administered, initial and optional-repeat-dosing regimen, intranasal etripamil was well tolerated, safe, and superior to placebo for the rapid conversion of atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia to sinus rhythm. This approach could empower patients to treat paroxysmal supraventricular tachycardia themselves outside of a health-care setting, and has the potential to reduce the need for additional medical interventions, such as intravenous medications given in an acute-care setting.

FUNDING

Milestone Pharmaceuticals.

Population-Level Prevalence of Rare Variants Associated With Atrial Fibrillation and its Impact on Patient Outcomes

BACKGROUND

Whole exome sequencing may identify rare pathogenic/likely pathogenic variants (LPVs) that are linked to atrial fibrillation (AF). The impact of LPVs associated with AF on a population level on outcomes is unclear.

OBJECTIVES

This study sought to examine the association of LPVs with AF and their impact on clinical outcomes using the UK Biobank, a national repository of participants with available whole exome sequencing data.

METHODS

A total of 200,631 individuals in the UK Biobank were studied. Incident and prevalent AF, comorbidities, and outcomes were identified using self-reported assessments and hospital stay operative, and death registry records. LPVs were determined using arrhythmia and cardiomyopathy gene panels with LOFTEE and ClinVar to predict variants of functional significance.

RESULTS

Compared with control subjects, there was a modestly increased prevalence of LPVs among 9,585 patients with AF (2.0% vs 1.7%, respectively; P = 0.01). Among those with prevalent AF at <45 years of age, 4.2% were LPV carriers. LPVs in TTN and PKP2 were associated with AF with adjusted odds ratios of 2.69 (95% CI: 1.57-4.61) and 2.69 (95% CI: 1.54-4.68), respectively. There was no significant difference in combined ischemic stroke, heart failure hospitalization, and mortality among patients who have AF with and without LPVs (25.1% vs 23.8%; P = 0.49). Among participants with AF and available cardiac magnetic resonance imaging data, LPV carriers had lower left ventricular ejection fractions than non-LPV carriers (42% vs 52%; P = 0.027).

CONCLUSIONS

Patients with AF had a modestly increased prevalence of LPVs. Among reference arrhythmia and cardiomyopathy genes, the contribution of rare variants to AF risk at a population level is modest and its impact on outcomes appears to be limited, despite an association of LPVs with reduced left ventricular ejection fraction among patients with AF.

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.).

Low Utilization of Lead Extraction Among Patients With Infective Endocarditis and Implanted Cardiac Electronic Devices

BACKGROUND

Cardiac implantable electronic device (CIED)-associated infections are associated with substantial morbidity, mortality, and costs. Guidelines have cited endocarditis as a Class I indication for transvenous lead removal/extraction (TLE) among patients with CIEDs.

OBJECTIVES

The authors sought to study utilization of TLE among hospital admissions with infective endocarditis using a nationally representative database.

METHODS

Using the Nationwide Readmissions Database (NRD), 25,303 admissions for patients with CIEDs and endocarditis between 2016 and 2019 were evaluated on the basis of International Classification of Diseases-10th Revision, Clinical-Modification (ICD-10-CM) codes.

RESULTS

Among admissions for patients with CIEDs and endocarditis, 11.5% were managed with TLE. The proportion undergoing TLE increased significantly from 2016 to 2019 (7.6% vs 14.9%; P trend < 0.001). Procedural complications were identified in 2.7%. Index mortality was significantly lower among patients managed with TLE (6.0% vs 9.5%; P < 0.001). Presence of Staphylococcus aureus infection, implantable cardioverter-defibrillator, and large hospital size were independently associated with TLE management. TLE management was less likely with older age, female sex, dementia, and kidney disease. After adjustment for comorbidities, TLE was independently associated with significantly lower odds of mortality (adjusted OR: 0.47; 95% CI: 0.37-0.60 by multivariable logistic regression, and adjusted OR: 0.51; 95% CI: 0.40-0.66 by propensity score matching).

CONCLUSIONS

Utilization of lead extraction among patients with CIEDs and endocarditis is low, even in the presence of low rates of procedural complications. Lead extraction management is associated with significantly lower mortality, and its use has trended upward between 2016 and 2019. Barriers to TLE for patients with CIEDs and endocarditis require investigation.

Advanced helix-fixation leadless cardiac pacemaker implantation techniques to improve success and reduce complications

INTRODUCTION

Leadless cardiac pacemakers (LCPs) are becoming more commonly utilized because of their potential advantages (i.e., reduced short and long-term complications, improved patient comfort) and may be the preferred option for patients with venous access problems, high-risk for infection, previous lead fractures, or skin erosion. There are currently two types of LCP fixation mechanisms that have been FDA approved-Medtronic's Micra system has a tine-based fixation and Abbott's Aveir system has a helix-fixation design. This article highlights important tips and tricks for a successful implant of a helix-fixation LCP, particularly when difficulties are encountered, and provides precautions to avoid potential complications.

METHODS

Cases of single chamber Aveir LCP implantation were reviewed to highlight examples of procedural pitfalls and suggested methods to circumnavigate them.

RESULTS

There are unique procedural considerations regarding the Aveir LCP implant as well as challenges that that may be occasionally encountered. Techniques to address these-such as avoiding air embolism, maneuvering difficult entry into the right ventricle, handling complicated positioning/repositioning, evaluating proper fixation, and releasing difficult tethers-are illustrated in detail. Advice to reduce risks of perforation and to position optimally for potential retrieval and communication for dual chamber pacing are also described.

CONCLUSIONS

The advanced teaching concepts described and emphasized in this article may help improve success and prevent procedural complications, especially when physicians are learning how implant these novel helix-fixation LCPs.

Dual-Chamber Leadless Pacing: Atrioventricular Synchrony in Preclinical Models of Normal or Blocked Atrioventricular Conduction

BACKGROUND

Dual-chamber leadless pacemakers (LP) require robust communication between distinct right atrial (RA) and right ventricular (RV) LPs to achieve atrioventricular (AV) synchrony.

OBJECTIVE

This preclinical study evaluated a novel, continuous implant-to-implant (i2i™) communication methodology for maintaining AV-synchronous, dual-chamber DDD(R) pacing by the 2 LPs.

METHODS

RA and RV LPs were implanted and paired in 7 ovine subjects, 4 of 7 with induced complete heart block. AV synchrony (% AV intervals <300 ms) and i2i communication success (% successful i2i transmissions between LPs) were evaluated acutely and chronically. During acute testing, 12-lead ECG and LP diagnostic data were collected from 5-minute recordings, in 4 postures and 2 rhythms (AP-VP and AS-VP or AP-VS and AS-VS) per subject. Chronic i2i performance was evaluated through 23 weeks post-implant (final i2i evaluation period: week 16-23).

RESULTS

Acute AV synchrony and i2i communication success across multiple postures and rhythms were 100.0% [100.0-100.0] (median [interquartile range]) and 99.9% [99.9-99.9], respectively. AV synchrony and i2i success rates did not differ across postures (P=0.59, P=0.11) or rhythms (P=1.00, P=0.82). During the final i2i evaluation period, the overall i2i success was 98.9% [98.1-99.0].

CONCLUSION

Successful AV-synchronous, dual-chamber DDD(R) leadless pacing using a novel, continuous, wireless communication modality was demonstrated across variations in posture and rhythm in a preclinical model.

Early Stroke and Mortality After Percutaneous Left Atrial Appendage Occlusion in Patients With Atrial Fibrillation

BACKGROUND

Percutaneous endocardial left atrial appendage occlusion (LAAO) is an alternative therapy for stroke prevention in patients with atrial fibrillation who are poor candidates for oral anticoagulants. Oral anticoagulation is generally discontinued 45 days following successful LAAO. Real-world data on early stroke and mortality following LAAO are lacking.

METHODS

Using International Classification of Diseases, Tenth Revision, Clinical-Modification codes, we performed a retrospective observational registry analysis to examine the rates and predictors of stroke, mortality, and procedural complications during index hospitalization and 90-day readmission among 42 114 admissions in the Nationwide Readmissions Database for LAAO between 2016 and 2019. Early stroke and mortality were defined as events occurring during index admission or 90-day readmission. Data on timing of early strokes post-LAAO were collected. Multivariable logistic regression modeling was used to ascertain predictors of early stroke and major adverse events.

RESULTS

LAAO was associated with low rates of early stroke (0.63%), early mortality (0.53%), and procedural complications (2.59%). Among patients who had readmissions with strokes after LAAO, the median time from implant to readmission was 35 days (interquartile range, 9-57 days); 67% of readmissions with strokes occurred <45 days postimplant. Between 2016 and 2019, the rates of early stroke after LAAO significantly decreased (0.64% versus 0.46% P-for-trend <0.001), while early mortality and major adverse event rates were unchanged. Peripheral vascular disease and a history of prior stroke were independently associated with early stroke after LAAO. Early post-LAAO stroke rates were similar between low, medium, and high LAAO volume tertile centers.

CONCLUSIONS

In this contemporary real-world analysis, the early stroke rate after LAAO was low, with the majority occurring within 45 days of device implantation. Despite an increase in LAAO procedures between 2016 and 2019, there with a significant decline in early strokes after LAAO during that period.

Initial experience with stylet-driven versus lumenless lead delivery systems for left bundle branch area pacing

INTRODUCTION

Left bundle branch area pacing (LBBP) has emerged as an alternative method for conduction system pacing. While initial experience with delivery systems for stylet-driven and lumenless lead implantation for LBBP has been described, data comparing outcomes of stylet-driven versus lumenless lead implantation for LBBP are limited. In this study, we compare success rates and outcomes of LBBP with stylet-driven versus lumenless lead delivery systems.

METHODS

Eighty-three consecutive patients (mean age 74.1 ± 11.2 years; 56 [68%] male) undergoing attempted LBBP at a single institution were identified. Cases were grouped by lead delivery systems used: stylet-driven (n = 53) or lumenless (n = 30). Baseline characteristics and procedural findings were recorded and compared between the cohorts. Intermediate term follow-up data on ventricular lead parameters were also compared.

RESULTS

Baseline characteristics were similar between groups. Successful LBBP was achieved in 77% of patients, with similar success rates between groups (76% in stylet-driven, 80% in lumenless, p = 0.79), and rates of adjudicated LBB capture and other paced QRS parameters were also similar. Compared with the lumenless group, the stylet-driven group had significantly shorter procedure times (90 ± 4 vs. 112 ± 31 min, p = 0.004) and fluoroscopy times (10 ± 5 vs. 15 ± 6 min, p = 0.003). Ventricular lead parameters at follow-up were similar, and rates of procedural complications and need for lead revision were low in both groups.

CONCLUSION

Delivery systems for stylet-driven and for lumenless leads for LBBP have comparable acute success rates. Long-term follow-up of lead performance following use of the various delivery systems is warranted.

First Randomized, Multicenter, Placebo-Controlled Study of Self-Administered Intranasal Etripamil for Acute Conversion of Spontaneous Paroxysmal Supraventricular Tachycardia (NODE-301)

Background:

Pharmacologic termination of paroxysmal supraventricular tachycardia (PSVT) often requires medically supervised intervention. Intranasal etripamil, is an investigational fast-acting, nondihydropyridine, L-type calcium channel blocker, designed for unsupervised self-administration to terminate atrioventricular nodal–dependent PSVT. Phase 2 results showed potential safety and efficacy of etripamil in 104 patients with PSVT.

Methods:

NODE-301, a phase 3, multicenter, double-blind, placebo-controlled study evaluated the efficacy and safety of etripamil nasal spray administered, unsupervised in patients with symptomatic sustained PSVT. After a medically supervised etripamil test dose while in sinus rhythm, patients were randomized 2:1 to receive etripamil 70 mg or placebo. When PSVT symptoms developed, patients applied a cardiac monitor and attempted a vagal maneuver; if symptoms persisted, they self-administered blinded treatment. An independent Adjudication Committee reviewed continuous electrocardiogram recordings. The primary efficacy endpoint was termination of adjudicated PSVT within 5 hours after study drug administration.

Results:

NODE-301 accrued 156 positively adjudicated PSVT events treated with etripamil (n=107) or placebo (n=49). The hazard ratio for the primary endpoint, time-to-conversion to sinus rhythm during the 5-hour observation period, was 1.086 (95% CI, 0.726–1.623; P =0.12). In predefined sensitivity analyses, etripamil effects (compared with placebo) occurred at 3, 5, 10, 20, and 30 minutes ( P <0.05). For example, at 30 minutes, there was a 53.7% of SVT conversion in the treatment arm compared to 34.7% in the placebo arm (hazard ratio, 1.87 [95% CI, 1.09–3.22]; P =0.02). Etripamil was well tolerated; adverse events were mainly related to transient nasal discomfort and congestion (19.6% and 8.0%, respectively, of randomized treatment-emergent adverse events.

Conclusions:

Although the primary 5-hour efficacy endpoint was not met, analyses at earlier time points indicated an etripamil treatment effect in terminating PSVT. Etripamil self-administration during PSVT was safe and well tolerated. These results support continued clinical development of etripamil nasal spray for self-administration during PSVT in a medically unsupervised setting.

REGISTRATION:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03464019.

Safety and Efficacy of a Novel Approach to Pulmonary Vein Isolation Using Prolonged Apneic Oxygenation

BACKGROUND

Improved ablation catheter-tissue contact results in more effective ablation lesions. Respiratory motion causes catheter instability, which impacts durable pulmonary vein isolation (PVI).

OBJECTIVES

This study sought to evaluate the safety and efficacy of a novel ablation strategy involving prolonged periods of apneic oxygenation during PVI.

METHODS

We conducted a multicenter, prospective controlled study of 128 patients (mean age 63 ± 11 years; 37% women) with paroxysmal atrial fibrillation undergoing PVI. Patients underwent PVI under general anesthesia using serial 4-minute runs of apneic oxygenation (apnea group; n = 64) or using standard ventilation settings (control group; n = 64). Procedural data, arterial blood gas samples, catheter position coordinates, and ablation lesion characteristics were collected.

RESULTS

Baseline characteristics between the 2 groups were similar. Catheter stability was significantly improved in the apnea group, as reflected by a decreased mean catheter displacement (1.55 ± 0.97 mm vs 2.25 ± 1.13 mm; P < 0.001) and contact force SD (4.9 ± 1.1 g vs 5.2 ± 1.5 g; P = 0.046). The percentage of lesions with a mean catheter displacement >2 mm was significantly lower in the apnea group (22% vs 44%; P < 0.001). Compared with the control group, the total ablation time to achieve PVI was reduced in the apnea group (18.8 ± 6.9 minutes vs 23.4 ± 7.8 minutes; P = 0.001). There were similar rates of first-pass PVI, acute PV reconnections and dormant PV reconnections between the two groups.

CONCLUSIONS

A novel strategy of performing complete PVI during apneic oxygenation results in improved catheter stability and decreased ablation times without adverse events. (Radiofrequency Ablation of Atrial Fibrillation Under Apnea; NCT04170894).

Atrioventricular Nodal Reentrant Tachycardia: Are there unknown long-term consequences of ablating the (incompletely) known?

Although atrioventricular nodal re-entrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia This article is protected by copyright. All rights reserved.

Constitutively Activating GNAS Somatic Mutation in Right Ventricular Outflow Tract Tachycardia

[Figure: see text].

Reappraisal of electrocardiographic criteria for localization of idiopathic outflow region ventricular arrhythmias

BACKGROUND

Electrocardiographic (ECG) criteria have been proposed to localize the site of origin of outflow region ventricular arrhythmias (VAs). Many factors influence the QRS morphology of VAs and may limit the accuracy of these criteria.

OBJECTIVE

The purpose of this study was to assess the accuracy of ECG criteria that differentiate right from left outflow region VAs and localize VAs within the aortic sinus of Valsalva (ASV).

METHODS

One hundred one patients (mean age 52 ± 16 years; 55 [54%] women) undergoing catheter ablation of right ventricular outflow tract (RVOT) or ASV VAs with a left bundle branch block, inferior axis morphology were studied. ECG measurements including V₂ transition ratio, transition zone index, R-wave duration index, R/S amplitude index, V₂S/V₃R index, V_1-3 QRS morphology, R-wave amplitude in the inferior leads were tabulated for all VAs. Comparisons were made between the predicted site of origin using these criteria and the successful ablation site.

RESULTS

Patients had successful ablation of 71 RVOT and 38 ASV VAs. For the differentiation of RVOT from ASV VAs, the positive predictive values and negative predictive values for all tested ECG criteria ranged from 42% to 75% and from 71% to 82%, respectively, with the V₂S/V₃R index having the largest area under the curve of 0.852. Morphological QRS criteria in leads V₁ through V₃ did not localize ASV VAs. The maximum R-wave amplitude in the inferior leads was the sole criterion demonstrating a significant difference between right ASV, right-left ASV commissure, and left ASV sites.

CONCLUSION

ECG criteria for differentiating right from left ventricular outflow region VAs and for localizing ASV VAs have a limited accuracy.

Premature battery depletion of EMBLEM subcutaneous implantable cardioverter-defibrillators

The EMBLEM subcutaneous implantable cardioverter defibrillator (S-ICD) has an expected longevity of 7 years. In August 2019, Boston Scientific released an advisory regarding a limited subset of ~400 S-ICDs that exhibited an increased likelihood of an electrical component malfunction causing accelerated battery depletion. We observed several cases of nonadvisory S-ICD early battery depletion and sought to systematically evaluate the cohort of EMBLEM devices implanted and followed in our medical center. Out of 118 nonadvisory EMBLEM S-ICDs with a median time to most recent follow-up after implant of 735 days (interquartile range 375-1219 days), there were four premature battery failures identified. Serial device interrogations showed a sudden reduction in battery life at 1 195, 1 205, 1 300, and 678 days after implant. The number of shocks delivered during the lifetime of the devices did not explain the premature depletion. There was a sudden departure from the gradual linear decrease in battery longevity observed over time. We are the first to report a signal of premature battery depletion among S-ICD EMBLEM devices that were not among the initial advisory devices. The prevalence of premature battery failure in our cohort was 3.4%, occurring at an average of 1 095 days. Following these reports, Boston Scientific issued an advisory on EMBLEM devices in December 2020 extending beyond the initial advisory subset. The current projected occurrence rate for hydrogen-induced accelerated battery depletion is 3.7% at 5 years. Increased surveillance of this potential device issue and mitigation to identify patients at risk for this is warranted.

A hybrid endocardial-epicardial biventricular implantable cardioverter-defibrillator to circumvent the tricuspid valve

The development of pacing and defibrillator systems that do not involve hardware traversing the tricuspid annulus can be desirable in order to minimize lead-related complications such as tricuspid regurgitation. Occasionally, primary tricuspid valve pathology (ie, infectious endocarditis, nonbacterial thrombotic endocarditis, and carcinoid disease) or congenital heart disease prohibits use of transvenous leads and alternative strategies are required to provide pacing or defibrillation. We describe such a case in which a biventricular implantable cardioverter defibrillator was implanted using a hybrid system involving endocardial and epicardial components.

Outcomes and mortality associated with atrial arrhythmias among patients hospitalized with COVID-19

INTRODUCTION

The impact of atrial arrhythmias on coronavirus disease 2019 (COVID-19)-associated outcomes are unclear. We sought to identify prevalence, risk factors and outcomes associated with atrial arrhythmias among patients hospitalized with COVID-19.

METHODS

An observational cohort study of 1053 patients with severe acute respiratory syndrome coronavirus 2 infection admitted to a quaternary care hospital and a community hospital was conducted. Data from electrocardiographic and telemetry were collected to identify atrial fibrillation (AF) or atrial flutter/tachycardia (AFL). The association between atrial arrhythmias and 30-day mortality was assessed with multivariable analysis.

RESULTS

Mean age of patients was 62 ± 17 years and 62% were men. Atrial arrhythmias were identified in 166 (15.8%) patients, with AF in 154 (14.6%) patients and AFL in 40 (3.8%) patients. Newly detected atrial arrhythmias occurred in 101 (9.6%) patients. Age, male sex, prior AF, renal disease, and hypoxia on presentation were independently associated with AF/AFL occurrence. Compared with patients without AF/AFL, patients with AF/AFL had significantly higher levels of troponin, B-type natriuretic peptide, C-reactive protein, ferritin and d-dimer. Mortality was significantly higher among patients with AF/AFL (39.2%) compared to patients without (13.4%; p < .001). After adjustment for age and co-morbidities, AF/AFL (adjusted odds ratio [OR]: 1.93; p = .007) and newly detected AF/AFL (adjusted OR: 2.87; p < .001) were independently associated with 30-day mortality.

CONCLUSION

Atrial arrhythmias are common among patients hospitalized with COVID-19. The presence of AF/AFL tracked with markers of inflammation and cardiac injury. Atrial arrhythmias were independently associated with increased mortality.

Differences between cardiac implantable electronic device envelopes evaluated in an animal model

INTRODUCTION

Cardiac implantable electronic device (CIED) pocket related problems such as infection, hematoma, and device erosion cause significant morbidity and the clinical consequences are substantial. Bioabsorbable materials have been developed to assist in the prevention of these complications but there has not been any direct comparison of these adjunctive devices to reduce these complications. We sought to directly compare the TYRX absorbable antibacterial and CanGaroo extracellular matrix (ECM) envelopes in an animal model susceptible to these specific CIED-related complications (i.e., skin erosion and infection).

METHODS AND RESULTS

Sixteen mice undergoing implantation with biopotential transmitters were divided into three groups (no envelope = 4, TYRX = 5, and CanGaroo = 7) and monitored for device-related complications. Following 12 weeks of implantation, gross and histological analysis of the remaining capsules was performed. Three animals in the CanGaroo group (43%) had device erosion compared to none in the TYRX group. The remaining capsules excised at 12 weeks were qualitatively thicker following CanGaroo compared to TYRX and no envelope and histological evaluation demonstrated increased connective tissue with CanGaroo.

CONCLUSION

CanGaroo ECM envelopes did not reduce the incidence of device erosion and were associated with qualitatively thicker capsules and connective tissue staining at 12 weeks compared to no envelope or TYRX. Further studies regarding the use of these envelopes to prevent device erosion and their subsequent impact on capsule formation are warranted.

Sex-based differences in outcomes, 30-day readmissions, and costs following catheter ablation of atrial fibrillation: the United States Nationwide Readmissions Database 2010-14

AIMS

Although catheter ablation has emerged as an important therapy for patients with symptomatic atrial fibrillation (AF), there are limited data on sex-based differences in outcomes. We sought to compare in-hospital outcomes and 30-day readmissions of women and men undergoing AF ablation.

METHODS AND RESULTS

Using the United States Nationwide Readmissions Database, we analysed patients undergoing AF ablation between 2010 and 2014. Based on ICD-9-CM codes, we identified co-morbidities and outcomes. Multivariable logistic regression and inverse probability-weighting analysis were performed to assess female sex as a predictor of endpoints. Of 54 597 study patients, 20 623 (37.7%) were female. After adjustment for age, co-morbidities, and hospital factors, women had higher rates of any complication [adjusted odds ratio (aOR) 1.39; P < 0.0001], cardiac perforation (aOR 1.39; P = 0.006), and bleeding/vascular complications (aOR 1.49; P < 0.0001). Thirty-day all-cause readmission rates were higher for women compared to men (13.4% vs. 9.4%; P < 0.0001). Female sex was independently associated with readmission for AF/atrial tachycardia (aOR 1.48; P < 0.0001), cardiac causes (aOR 1.40; P < 0.0001), and all causes (aOR 1.25; P < 0.0001). Similar findings were confirmed with inverse probability-weighting analysis. Despite increased complications and readmissions, total costs for AF ablation were lower for women than men due to decreased resource utilization.

CONCLUSIONS

Independent of age, co-morbidities, and hospital factors, women have higher rates of complications and readmissions following AF ablation. Sex-based differences and disparities in the management of AF need to be explored to address these gaps in outcomes.

Insertable cardiac monitor extraction technique: hook and reel

The use of insertable cardiac monitors (ICM) has been increasing because of their ability to provide long-term electrocardiographic monitoring and symptom correlation. Indications for implantation include evaluation of cryptogenic stroke, unexplained syncope, intermittent palpitations, and atrial fibrillation. When the ICM needs to be removed because of battery depletion and/or diagnostic revelation, its removal can be challenging because of its small size and the capsule that forms around the proximal end of the device. A simple technique is described that takes advantage of the ICM design to facilitate its successful extraction.

Inpatient hospital procedural volume and outcomes following catheter ablation of atrial fibrillation

INTRODUCTION

The real-world distribution of hospital atrial fibrillation (AF) ablation volume and its impact on outcomes are not well-established. We sought to examine patient characteristics, complications, and readmissions after AF ablation stratified by hospital procedural volume.

METHODS AND RESULTS

Using the nationally representative inpatient Nationwide Readmissions Database, we evaluated 54 597 admissions for AF ablation between 2010 and 2014. Hospitals were categorized according to tertiles of annual AF ablation volume. Index complications, 30-day readmissions, and early mortality were examined. Multivariable logistic regression was performed to assess the predictors of adverse outcomes. Between 2010 and 2014, low volume tertile hospitals accounted for 79.3% of hospitals performing AF ablations. When stratified by first, second, and third volume tertiles, complication and early mortality rates were higher in low volume centers (8.9% and 0.67% vs 6.1% and 0.33%, vs 4.5% and 0.16%, respectively; P < .001). Patients undergoing AF ablation at low volume centers were older and had a higher prevalence of congestive heart failure, coronary artery disease, and other comorbidities. Low volume hospitals were associated with increased cardiac perforation (adjusted odds ratio [aOR], 4.79; P < .001), vascular complications (aOR 1.49; P < .001), and any complication (aOR 2.06; P < .001) during index admission as well as increased early mortality (aOR 2.43; P = .039).

CONCLUSIONS

Among patients hospitalized for AF ablation, low inpatient AF ablation hospital volume was associated with worse outcomes following ablation, which was exacerbated by a greater comorbidity burden among patients at these centers.

Risk of Mortality Following Catheter Ablation of Atrial Fibrillation

BACKGROUND

Although procedure-related deaths during index admission following catheter ablation of AF have been reported to be low, adverse outcomes can occur after discharge. There are limited data on mortality early after AF ablation.

OBJECTIVES

This study aimed to identify rates, trends, and predictors of early mortality post-atrial fibrillation (AF) ablation.

METHODS

Using the all-payer, nationally representative Nationwide Readmissions Database, we evaluated 60,203 admissions of patients 18 years of age or older for AF ablation between 2010 and 2015. Early mortality was defined as death during initial admission or 30-day readmission. Based on International Classification of Diseases-9th Revision, Clinical Modification codes, we identified comorbidities, procedural complications, and causes of readmission following AF ablation. Multivariable logistic regression was performed to assess predictors of early mortality.

RESULTS

Early mortality following AF ablation occurred in 0.46% cases, with 54.3% of deaths occurring during readmission. From 2010 to 2015, quarterly rates of early mortality post-ablation increased from 0.25% to 1.35% (p < 0.001). Median time from ablation to death was 11.6 (interquartile range [IQR]: 4.2 to 22.7) days. After adjustment for age and comorbidities, procedural complications (adjusted odds ratio [aOR]: 4.06; p < 0.001), congestive heart failure (CHF) (aOR: 2.20; p = 0.011) and low AF ablation hospital volume (aOR: 2.35; p = 0.003) were associated with early mortality. Complications due to cardiac perforation (aOR: 2.98; p = 0.007), other cardiac (aOR: 12.8; p < 0.001), and neurologic etiologies (aOR: 8.72; p < 0.001) were also associated with early mortality.

CONCLUSIONS

In a nationally representative cohort, early mortality following AF ablation affected nearly 1 in 200 patients, with the majority of deaths occurring during 30-day readmission. Procedural complications, congestive heart failure, and low hospital AF ablation volume were predictors of early mortality. Prompt management of post-procedure complications and CHF may be critical for reducing mortality rates following AF ablation.

Outcomes, Costs, and 30-Day Readmissions After Catheter Ablation of Myocardial Infarct-Associated Ventricular Tachycardia in the Real World: Nationwide Readmissions Database 2010 to 2015

BACKGROUND

Patients undergoing catheter ablation of myocardial infarction-associated ventricular tachycardia (VT) have significant comorbidities that can increase the risks of adverse outcomes. The rates of readmissions after VT ablation are unknown. We sought to examine in-hospital outcomes, costs, and 30-day readmissions after catheter ablation of myocardial infarction-associated VT.

METHODS

Using the Nationwide Readmissions Database, we evaluated 4109 admissions for catheter ablation of myocardial infarction-associated VT occurring between 2010 and 2015. On the basis of International Classification of Diseases, Ninth Revision, Clinical Modification and Clinical Classification Software codes, we identified comorbidities, procedural complications, 30-day readmissions, and costs associated with VT ablation.

RESULTS

The index admission in-hospital mortality rate and procedural complication rate after VT ablation were 2.7% and 11.5%, respectively. Independent predictors of mortality included pulmonary hypertension, lung disease, obesity, and coagulopathy. Following discharge after VT ablation, the 30-day readmission rate was 19.2% with a median time to readmission of 10.0 days (IQR, 3.8-17.6 days) and an in-hospital mortality rate of 2.9%. Cardiac causes accounted for 74% of readmissions, with VT and congestive heart failure constituting 41% and 14% of all readmissions, respectively. Pulmonary hypertension, congestive heart failure, smoking, chronic pulmonary disease, and prolonged index hospitalization were significant independent predictors of 30-day readmission. After adjustment, 30-day readmissions were associated with a 38.9% increase in cumulative hospitalization costs.

CONCLUSIONS

Thirty-day readmissions after catheter ablation of VT occur in nearly 1 out of 5 cases, with the majority of readmissions being caused by recurrent VT or congestive heart failure. Baseline comorbidities are significant predictors of procedural mortality, complications, and readmissions. Strategies to reduce recurrent VT postablation by improving procedural success, optimizing postablation heart failure treatment, and ensuring close postdischarge follow-up may help reduce readmissions and healthcare costs.

Regional isolation in the right atrium with disruption of intra-atrial conduction after catheter ablation of atrial tachycardia

BACKGROUND

Ablation of atrial tachycardia (AT) that occurs after cardiac surgery or prior ablation often requires complex lesion sets. In combination with the pre-existing atrial scar, these lesion sets may result in inadvertent intra-atrial conduction block. This study reports the phenomenon of incidental isolation of right atrial (RA) regions that occurs secondary to AT ablation, which in some cases results in profound bradycardia due to sinus exit block.

METHODS AND RESULTS

Intracardiac electrograms were examined in consecutive patients who underwent AT ablation in the RA. Cases of localized isolation of the RA were defined as areas that developed electrical dissociation during ablation. Of 132 patients having ablation in both the RA free wall and the cavotricuspid isthmus (CTI), 10 (7.6%) developed unintentional isolation of the lateral RA. Five of these patients had prior mitral valve surgery, comprising 12.2% of all 41 patients with mitral surgery who underwent ablation in the CTI and the RA free wall. All patients with regional isolation had a pre-existing scar in the lateral wall of the RA. In six patients, isolation of the lateral RA resulted in profound bradycardia due to exit block from the peri-sinus node myocardium.

CONCLUSIONS

Complex ablation lesions in patients with prior valve surgery, prior ablation, or atrial myopathy may result in unintended localized conduction block in the RA. In some cases, isolation of the lateral RA can result in complete sinus exit block with profound bradycardia requiring pacemaker implantation.