Recurrence of new-onset post-operative AF after cardiac surgery: detected by implantable loop recorders: A systematic review and Meta-analysis

BACKGROUND

Atrial fibrillation (AF) is one of the most common complications after cardiac surgery. New-onset post-operative AF may signal an elevated risk of AF and associated outcomes in long-term follow-up. We aimed to estimate the rate of AF recurrence as detected by an implantable loop recorder (ILR) in patients experiencing post-operative AF within 30 days after cardiac surgery.

METHODS

We searched MEDLINE, Embase and Cochrane CENTRAL to April 2023 for studies of adults who did not have known AF, experienced new-onset AF within 30 days of cardiac surgery and received an ILR. We pooled individual participant data on timing of AF recurrence using a random-effects model with a frailty model applied to a Cox proportional hazard analysis.

RESULTS

From 8671 citations, 8 single-centre prospective cohort studies met eligibility criteria. Data were available from 185 participants in 7 studies, with a median follow-up of 1.7 (IQR: 1.3-2.8) years. All included studies were at a low risk of bias. Pooled AF recurrence rates following 30 post-operative days were 17.8% (95% CI 11.9%-23.2%) at 3 months, 24.4% (17.7%-30.6%) at 6 months, 30.1% (22.8%-36.7%) at 12 months and 35.3% (27.6%-42.2%) at 18 months.

CONCLUSIONS

In patients who experience new-onset post-operative AF after cardiac surgery, AF recurrence lasting at least 30 s occurs in approximately 1 in 3 in the first year after surgery. The optimal frequency and modality to use for monitoring for AF recurrence in this population remain uncertain.

Outcomes of tricuspid regurgitation after lead extraction

INTRODUCTION

Transvenous leads have been implicated in tricuspid valve (TV) dysfunction, but limited data are available regarding the effect of extracting leads across the TV on valve regurgitation. The aim of this study is to quantify tricuspid regurgitation (TR) before and after lead extraction and identify predictors of worsening TR.

METHODS

We studied 321 patients who had echocardiographic data before and after lead extraction. TR was graded on a scale (0 = none/trivial, 1 = mild, 2 = moderate, 3 = severe). A change of >1 grade following extraction was considered significant.

RESULTS

A total of 321 patients underwent extraction of a total of 338 leads across the TV (1.05 ± 0.31 leads across the TV per patient). There was no significant difference on average TR grade pre- and postextraction (1.18 ± 0.91 vs. 1.15 ± 0.87; p = 0.79). TR severity increased after extraction in 84 patients, but was classified as significantly worse (i.e., >1 grade change in severity) in only 8 patients (2.5%). Use of laser lead extraction was associated with a higher rate of worsening TR postextraction (44.0% vs. 31.6%, p = 0.04).

CONCLUSION

In our single-center analysis, extraction of leads across the TV did not significantly affect the extent of TR in most patients. Laser lead extraction was associated with a higher rate of worsening TR after extraction.

Impact of omitting the intravenous heparin bolus on outcomes of leadless pacemaker implantation

BACKGROUND

Early guidance recommended a bolus of intravenous heparin at the beginning of leadless pacemaker (LP) implantation procedures. However, due to concern about bleeding complications, more recent practice has tended toward omitting the bolus and only running a continuous heparin infusion through the introducer sheath. The impact of omitting the heparin bolus on procedural outcomes is not clear.

METHODS

We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. The decision to bolus with heparin was at operator discretion.

RESULTS

Among 621 LP implants, 326 received an intravenous heparin bolus, 243 did not, and 52 patients were excluded because heparin bolus status could not be confirmed. There was a trend toward more frequent omission of the heparin bolus with more recent implants. Median follow-up after LP implant was 14.3 (interquartile range [IQR]: 8.4-27.9) months. There was no difference between heparin bolus and no bolus groups in the number of device deployments/recaptures (1.42 ± 0.81 vs. 1.31 ± 0.66, p = .15). Implant-related adverse events were also similar between heparin bolus and no bolus groups: access-site hematoma requiring intervention (7 vs. 5, p = .99), pseudoaneurysm (1 vs. 1, p = .99), cardiac perforation (1 vs. 1, p = .99), intraprocedural device thrombus formation (2 vs. 4, p = .41), 30-day rehospitalization (21 vs. 15, p = .98), and 30-day all-cause mortality (16 vs. 14, p = .70). There was one additional nonfatal cardiac perforation in a patient who was excluded due to unknown heparin bolus status. Regarding device electrical parameters between heparin bolus and no bolus groups, there were no significant differences at the time of implant: pacing capture threshold 0.5 ± 0.4 vs. 0.5 ± 0.3, p = .10; pacing impedance 739.9 ± 226.4 vs. 719.1 ± 215.4, p = .52; R wave sensing 11.7 ± 5.7 vs. 12.0 ± 5.4, p = .34). Long-term device performance was also similar between groups.

CONCLUSION

Omission of the systemic heparin bolus at the time of LP implantation appears safe in appropriately selected patients. Heparin bolus may still be considered in long cases requiring multiple device deployments or in patients at high risk for thrombotic complications.

Leadless pacemakers at 5-year follow-up: the Micra transcatheter pacing system post-approval registry

BACKGROUND AND AIMS

Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed.

METHODS

All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models.

RESULTS

1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001).

CONCLUSIONS

Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection.

Accurate detection of lead malfunction from ECG-derived bipolar pacing stimulus amplitude

BACKGROUND

One common mode of lead failure is insulation breach, which may result in myopotential noise and device malfunction. "Pseudo-unipolarization" of bipolar pacing stimuli, as observed from a routine 12-lead electrocardiogram (ECG) due to stimulus current leak, has been observed with insulation breaches.

OBJECTIVE

We sought to characterize this electrocardiographic finding to detect this type of lead malfunction.

METHODS

A total of 138 transvenous leads were analyzed, including 88 with known malfunction and 50 normal leads. The amplitude of a bipolar pacing stimulus on the ECG was recorded and compared with a control data set of newly implanted leads with bipolar stimuli normalized for output.

RESULTS

The malfunction group consisted of 61% right atrium and 39% right ventricle leads with mean pacing output of 2.74 V at 0.5 ms. There was a significant difference in ECG bipolar stimulus amplitudes at time of identification of failure (7.89 ± 7.56 mm/V; P < .001) compared with those of normal leads (0.86 ± 0.41 mm/V). Receiver operating characteristic curve for the prediction of lead malfunction based on absolute ECG amplitude displayed an area under the curve of 0.93 (95% CI, 0.891-0.969). When normalized for programmed stimulus output, a cutoff of 5 mm/V demonstrated a sensitivity of 91% and a specificity of 92% (area under the curve, 0.967; 95% CI, 0.938-0.996).

CONCLUSION

The maximum amplitude of a bipolar pacing stimulus on the ECG is significantly lower in normal functioning leads compared with those with known malfunction. This simply derived variable demonstrated good accuracy at identifying lead failure due to insulation breach.

Pacing and Defibrillation Consideration in the Era of Transcatheter Tricuspid Valve Replacement

PURPOSE OF REVIEW

Tricuspid regurgitation is a commonly encountered valvular pathology in patients with trans-tricuspid pacing or implantable cardioverter-defibrillator leads. Transcatheter tricuspid valve interventions are increasingly performed in patients at high surgical risk. Implantation of these valves can lead to the "jailing" of a trans-tricuspid lead. This practice carries both short- and long-term risks of lead failure and subsequent infection without the ability to perform traditional transvenous lead extraction. Herein, this manuscript reviews available therapeutic options for lead management in patients undergoing transcatheter tricuspid valve interventions.

RECENT FINDINGS

The decision to jail a lead may be appropriate in certain high-risk cases, though extraction may be a better option in most cases given the variety of options for re-implant, including leadless pacemakers, valve-sparing systems, epicardial leads, leads placed directly through prosthetic valves, and the completely subcutaneous implantable-defibrillator. A growing number of patients meet the requirement for CIED implantation in the United States. A significant proportion of these patients will have tricuspid valve dysfunction, either related to or independent of their transvenous lead. As with any percutaneous intervention that has shown efficacy, the role of TTVI is also likely to increase as this therapy advances beyond the investigational phase. As such, the role of the heart team in the management of these patients will be increasingly critical in the years to come, and in those patients that have pre-existing CIED leads, we advocate for the involvement of an electrophysiologist in the heart team.

Electrocardiographic predictors of atrial mechanical sensing in leadless pacemakers

BACKGROUND

Leadless pacemakers (LPs) capable of VDD pacing allow for atrioventricular synchrony through mechanical sensing of atrial contraction. However, mechanical sensing is less reliable and less predictable than electrical sensing.

OBJECTIVE

The purpose of this study was to evaluate P-wave amplitude during sinus rhythm from preoperative 12-lead electrocardiograms (ECGs) as a predictor for atrial mechanical sensing in patients undergoing VDD LP implantation.

METHODS

Consecutive patients undergoing VDD LP implantation were included in this 2-center prospective cohort study. ECG parameters were evaluated separately and in combination for association with the signal amplitude of atrial mechanical contraction (A4).

RESULTS

Eighty patients (median age 82 years; female 55%; mean body mass index [BMI] 25.8 kg/m2) were included in the study and 61 patients in the A4 signal analysis (19 patients in VVI mode during follow-up). Absolute (aVL, aVF, V1, V2) and BMI-adjusted (I, II, aVL, aVF, aVR, V1, V2) P-wave amplitudes from baseline ECGs demonstrated a statistically significant positive correlation with A4 signal amplitude (all P <.05). A combined P-wave signal amplitude of at least 0.2 mV in V1 and aVL was predictive, with specificity of 83% (95% confidence interval 67%-100%) for A4 signal ≥1 m/s2. We found a significant correlation of A4 signal amplitude and overall atrioventricular synchrony (P = .013).

CONCLUSION

P-wave amplitudes in ECG leads aVL and V1 can predict A4 signal amplitude in patients with VDD LP and therefore the probability of successful AV synchronous pacing.

Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial

BACKGROUND

The PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events.

OBJECTIVE

This prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias.

METHODS

This multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm.

RESULTS

In total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13-279.95; P < .001).

CONCLUSION

A PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure.

Update on Cardiovascular Implantable Electronic Device Infections and Their Prevention, Diagnosis, and Management: A Scientific Statement From the American Heart Association: Endorsed by the International Society for Cardiovascular Infectious Diseases

The American Heart Association sponsored the first iteration of a scientific statement that addressed all aspects of cardiovascular implantable electronic device infection in 2010. Major advances in the prevention, diagnosis, and management of these infections have occurred since then, necessitating a scientific statement update. An 11-member writing group was identified and included recognized experts in cardiology and infectious diseases, with a career focus on cardiovascular infections. The group initially met in October 2022 to develop a scientific statement that was drafted with front-line clinicians in mind and focused on providing updated clinical information to enhance outcomes of patients with cardiovascular implantable electronic device infection. The current scientific statement highlights recent advances in prevention, diagnosis, and management, and how they may be incorporated in the complex care of patients with cardiovascular implantable electronic device infection.

Outcomes of patients implanted with an atrioventricular synchronous leadless ventricular pacemaker in the Medicare population

BACKGROUND

The Micra AV Coverage with Evidence Development study is a novel analysis of utilization and outcomes associated with Micra AV leadless pacing in US Medicare patients.

OBJECTIVE

The purpose of this study was to describe patient characteristics, complications, and outcomes of patients implanted with a Micra AV leadless pacemaker compared with a contemporaneous cohort of patients implanted with a dual chamber transvenous pacemaker.

METHODS

Patients implanted with Micra AV (n = 7471) or a dual chamber transvenous pacemaker (n = 107,800) from February 5, 2020, through December 1, 2021, were identified using device registry-linked Medicare claims data. Acute complications were assessed at 30 days, and chronic complications, reinterventions, and all-cause mortality were assessed at 6 months.

RESULTS

Patients implanted with Micra AV had higher rates of end-stage renal disease (14.9% vs 2.0%; P < .0001) and overall comorbidity burden (mean Charlson Comorbidity Index 4.9 vs 3.8; P < .0001). There was no difference in the unadjusted rate of complications at 30 days (9.1% vs 8.7%; P = .61), and patients implanted with Micra AV had a significantly lower adjusted rate of complications (8.6% vs 11.0%; P < .0001). At 6 months, patients implanted with Micra AV had significantly lower rates of complications (adjusted hazard ratio 0.50; 95% confidence interval 0.43-0.57; P < .0001) and reinterventions (adjusted hazard ratio 0.46; 95% confidence interval 0.36-0.58; P < .0001). Patients implanted with Micra AV had higher all-cause mortality at 30 days and 6 months, likely because of differences in the underlying risk of mortality.

CONCLUSION

Patients implanted with Micra AV had similar rates of complications at 30 days and significantly lower rates of complications and reinterventions at 6 months, despite being sicker than patients implanted with a transvenous pacemaker.

Complex repolarization dynamics in ex vivo human ventricles are independent of the restitution properties

AIMS

The mechanisms of transition from regular rhythms to ventricular fibrillation (VF) are poorly understood. The concordant to discordant repolarization alternans pathway is extensively studied; however, despite its theoretical centrality, cannot guide ablation. We hypothesize that complex repolarization dynamics, i.e. oscillations in the repolarization phase of action potentials with periods over two of classic alternans, is a marker of electrically unstable substrate, and ablation of these areas has a stabilizing effect and may reduce the risk of VF. To prove the existence of higher-order periodicities in human hearts.

METHODS AND RESULTS

We performed optical mapping of explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Signals recorded from the right ventricle endocardial surface were processed to detect global and local repolarization dynamics during rapid pacing. A statistically significant global 1:4 peak was seen in three of six hearts. Local (pixel-wise) analysis revealed the spatially heterogeneous distribution of Periods 4, 6, and 8, with the regional presence of periods greater than two in all the hearts. There was no significant correlation between the underlying restitution properties and the period of each pixel.

CONCLUSION

We present evidence of complex higher-order periodicities and the co-existence of such regions with stable non-chaotic areas in ex vivo human hearts. We infer that the oscillation of the calcium cycling machinery is the primary mechanism of higher-order dynamics. These higher-order regions may act as niduses of instability and may provide targets for substrate-based ablation of VF.

Long-term performance of single-connector (DF4) implantable defibrillator leads

AIMS

Single-connector (DF4) defibrillator leads have become the predominantly implanted transvenous implantable cardioverter-defibrillator lead. However, data on their long-term performance are derived predominantly from manufacturer product performance reports.

METHODS AND RESULTS

We reviewed medical records in 5289 patients with DF4 leads between 2011 and 2023 to determine the frequency of lead-related abnormalities. We defined malfunction as any single or combination of electrical abnormalities requiring revision including a sudden increase (≥2×) in stimulation threshold, a discrete jump in high-voltage impedance, or sensing of non-physiologic intervals or noise. We documented time to failure, predictors of failure, and management strategies. Mean follow-up after implant was 4.15 ± 3.6 years (median = 3.63), with 37% of leads followed for >5 years. A total of 80 (1.5%) leads demonstrated electrical abnormalities requiring revision with an average time to failure of 4 ± 2.8 years (median = 3.5). Of the leads that malfunctioned, 62/80 (78%) were extracted and replaced with a new lead and in the other 18 cases, malfunctioned DF4 leads were abandoned, and a new lead implanted. In multivariable models, younger age at implant (OR 1.03 per year; P < 0.001) and the presence of Abbott/St. Jude leads increased the risk of malfunction.

CONCLUSION

DF4 defibrillator leads demonstrate excellent longevity with >98.3% of leads followed for at least 5 years still functioning normally. Younger age at implant and lead manufacturer are associated with an increased risk of DF4 lead malfunction. The differences in lead survival between manufacturers require further investigation.

Safety of same-day discharge after lead extraction procedures

BACKGROUND

Same-day discharge (SDD) after cardiovascular procedures is rapidly gaining ground.

OBJECTIVE

We sought to evaluate the safety of SDD after transvenous lead extraction (TLE).

METHODS

We performed a retrospective chart review of patients who underwent elective TLE between January 2020 and October 2021 at our institution. The primary outcome was SDD, and major procedural complications and readmissions within 30 days of the procedure were secondary outcomes.

RESULTS

In this analysis of 111 patients who underwent elective TLE, 80 patients (72%) were discharged on the same day (SDD group) while 31 patients (28%) stayed overnight (overnight group). Lead malfunction was the most common indication for TLE in both groups. Patients in the overnight group were more likely to have a lead dwell time of ≤10 years than those in the SDD group (38.7% vs 20% of all leads in each group; P = .042), have laser sheaths used for extraction and a higher number of leads extracted. No major complications were reported in both groups. In a multivariate analysis, lower body mass index and the use of laser sheath during TLE were predictors of overnight stay. Patients who underwent a procedure using advanced extraction techniques were 3.5 times more likely to stay overnight (95% confidence interval 1.27-9.78; P = .016).

CONCLUSION

In appropriately selected patients undergoing elective lead extraction, SDD is feasible and safe. Higher body mass index, fewer extracted leads, shorter lead dwell times (<10 years), and less frequent use of laser-powered extraction sheaths were associated with an increased likelihood of SDD.

Outcomes of leadless pacemaker implantation after cardiac surgery and transcatheter structural valve interventions

INTRODUCTION

Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions.

METHODS

This retrospective study included patients who received a Micra VR (MicraTM MC1VR01) or Micra AV (MicraTM MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up.

RESULTS

A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 ± 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 ± 1.1 years: 1.6 ± 1.3 years for the Micra VR group and 0.8 ± 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% ± 37.2% postprocedure vs. 47.7% ± 40.6% at last follow-up, p < .001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% ± 10.6% vs. 51.5% ± 11.2% p < .001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% ± 11.9% vs. 48.8% ± 11.9%, p = .003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% ± 9.0% vs. 54.6% ± 9.7%, p = .06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction.

CONCLUSION

Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort.

Adaptive versus conventional cardiac resynchronisation therapy in patients with heart failure (AdaptResponse): a global, prospective, randomised controlled trial

BACKGROUND

Continuous automatic optimisation of cardiac resynchronisation therapy (CRT), stimulating only the left ventricle to fuse with intrinsic right bundle conduction (synchronised left ventricular stimulation), might offer better outcomes than conventional CRT in patients with heart failure, left bundle branch block, and normal atrioventricular conduction. This study aimed to compare clinical outcomes of adaptive CRT versus conventional CRT in patients with heart failure with intact atrioventricular conduction and left bundle branch block.

METHODS

This global, prospective, randomised controlled trial was done in 227 hospitals in 27 countries across Asia, Australia, Europe, and North America. Eligible patients were aged 18 years or older with class 2-4 heart failure, an ejection fraction of 35% or less, left bundle branch block with QRS duration of 140 ms or more (male patients) or 130 ms or more (female patients), and a baseline PR interval 200 ms or less. Patients were randomly assigned (1:1) via block permutation to adaptive CRT (an algorithm providing synchronised left ventricular stimulation) or conventional biventricular CRT using a device programmer. All patients received device programming but were masked until procedures were completed. Site staff were not masked to group assignment. The primary outcome was a composite of all-cause death or intervention for heart failure decompensation and was assessed in the intention-to-treat population. Safety events were collected and reported in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT02205359, and is closed to accrual.

FINDINGS

Between Aug 5, 2014, and Jan 31, 2019, of 3797 patients enrolled, 3617 (95·3%) were randomly assigned (1810 to adaptive CRT and 1807 to conventional CRT). The futility boundary was crossed at the third interim analysis on June 23, 2022, when the decision was made to stop the trial early. 1568 (43·4%) of 3617 patients were female and 2049 (56·6%) were male. Median follow-up was 59·0 months (IQR 45-72). A primary outcome event occurred in 430 of 1810 patients (Kaplan-Meier occurrence rate 23·5% [95% CI 21·3-25·5] at 60 months) in the adaptive CRT group and in 470 of 1807 patients (25·7% [23·5-27·8] at 60 months) in the conventional CRT group (hazard ratio 0·89, 95% CI 0·78-1·01; p=0·077). System-related adverse events were reported in 452 (25·0%) of 1810 patients in the adaptive CRT group and 440 (24·3%) of 1807 patients in the conventional CRT group.

INTERPRETATION

Compared with conventional CRT, adaptive CRT did not significantly reduce the incidence of all-cause death or intervention for heart failure decompensation in the included population of patients with heart failure, left bundle branch block, and intact AV conduction. Death and heart failure decompensation rates were low with both CRT therapies, suggesting a greater response to CRT occurred in this population than in patients in previous trials.

FUNDING

Medtronic.

Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System

BACKGROUND

The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up.

OBJECTIVES

The S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers.

METHODS

Patients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals.

RESULTS

A total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD-related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%.

CONCLUSIONS

In the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618).

Novel use of an irrigated ablation catheter to monitor real-time hemodynamics during ablation

INTRODUCTION

Hemodynamic decompensation during catheter ablation occurs due to prolonged procedure time and irrigant delivery directly into the cardiac chambers. Real-time hemodynamic monitoring of patients undergoing catheter ablation procedures may identify patients at risk of decompensation; we set out to assess the feasibility of a novel, real-time, intracardiac pressure monitoring system using a standard irrigated ablation catheter.

METHODS

We studied 13 consecutive who underwent pressure measurement of the left atrium (LA) and left ventricle (LV) via transeptal access with a Swan Ganz (SG) catheter followed by two commercially available irrigated ablation catheters. Pressure waveform data was extracted to compare LA peak pressure, LV peak systolic pressure, LV end-diastolic pressure, and waveform analysis.

RESULTS

Comparison between the SG and ablation catheters (AblA; AblB) demonstrated that LV systolic pressure (0.61-16.8 mmHg; 1.32-18.2 mmHg), and LV end-diastolic pressure (-3.4 to 2.8 mmHg; -3.0 to 3.35 mmHg) were well correlated and had accepted repeatability. Ablation waveforms demonstrated an 89.9 ± 6.4% correlation compared to SG waveforms.

CONCLUSION

Pressure measurements derived from an irrigated ablation catheter are accurate and reliable when compared to an SG catheter. Further studies are needed to determine how real-time pressure monitoring can improve outcomes during ablation procedures.

The Feasibility and Safety of Flecainide Use Among Patients With Varying Degrees of Coronary Disease

BACKGROUND

Class 1C antiarrhythmic agents are effective for treating atrial tachyarrhythmias, but their use is restricted in patients with coronary artery disease (CAD). Data on the safety of the use of 1C agents in patients with CAD in the absence of recent acute coronary syndromes are lacking.

OBJECTIVE

This study sought to evaluate the safety and feasibility of treatment with 1C agents in patients with varying degrees of CAD in a large serial, real-world cohort.

METHODS

We retrospectively identified all patients at our institution from January 2005 to February 2021 on a 1C agent (n = 3,445) and those on sotalol or dofetilide (n = 2,216) as controls, excluding those with a prior history of ventricular tachycardia, implantable cardioverter-defibrillator placement, or nonrevascularized myocardial infarction. Baseline clinical characteristics included degree of CAD (categorized as none, nonobstructive, or obstructive), other comorbid illness, and medication use. Clinical outcomes, including survival, were ascertained. We performed Cox regression analysis to evaluate the effect of 1C use on event-free survival across varying degrees of CAD.

RESULTS

After adjustment for baseline characteristics, there was an independent association between 1C use and improved mortality. However, there was an interaction between 1C use and degree of CAD (compared to sotalol) demonstrating poorer event-free survival among those with obstructive coronary disease (HR: 3.80; 95% CI: 1.67-8.67; P = 0.002).

CONCLUSIONS

Among select patients with nonobstructive CAD and without a history of ventricular tachycardia, 1C agents are not associated with increased mortality. Therefore, these agents may be an option for some patients in whom they are frequently restricted. Further prospective studies are warranted.

Leadless versus transvenous single-chamber ventricular pacemakers: 3 year follow-up of the Micra CED study

INTRODUCTION

The Micra Coverage with Evidence Development (CED) Study is a novel comparative analysis of Micra (leadless VVI) and transvenous single-chamber ventricular pacemakers (transvenous VVI) using administrative claims data. To compare chronic complications, device reinterventions, heart failure hospitalizations, and all-cause mortality after 3 years of follow-up.

METHODS

US Medicare claims data linked to manufacturer device registration information were used to identify Medicare beneficiaries with a de novo implant of either a Micra VR leadless VVI or transvenous VVI pacemaker from March 9, 2017 to December 31, 2018. Unadjusted and propensity score overlap-weight adjusted Fine-Gray competing risk models were used to compare outcomes at 3 years.

RESULTS

Leadless VVI patients (N = 6219) had a 32% lower rate of chronic complications and a 41% lower rate of reintervention compared with transvenous VVI patients (N = 10 212) (chronic complication hazard ratio [HR] 0.68; 95% confidence interval [CI], 0.59-0.78; reintervention HR 0.59; 95% CI 0.44-0.78). Infections rates were significantly lower among patients with a leadless VVI (<0.2% vs. 0.7%, p < .0001). Patients with a leadless VVI also had slightly lower rates of heart failure hospitalization (HR 0.90; 95% CI 0.84-0.97). There was no difference in the adjusted 3-year all-cause mortality rate (HR 0.97; 95% CI, 0.92-1.03).

CONCLUSION

This nationwide comparative evaluation of leadless VVI versus transvenous VVI de novo pacemaker implants demonstrated that the leadless group had significantly fewer complications, reinterventions, heart failure hospitalizations, and infections than the transvenous group at 3 years, confirming that the previously reported shorter-term advantages associated with leadless pacing persist and continue to accrue in the medium-to-long-term.

Two-year outcomes of leadless vs. transvenous single-chamber ventricular pacemaker in high-risk subgroups

AIMS

This study compares clinical outcomes between leadless pacemakers (leadless-VVI) and transvenous ventricular pacemakers (transvenous ventricular permanent-VVI) in subgroups of patients at higher risk of pacemaker complications.

METHODS AND RESULTS

This study is based on the Micra Coverage with Evidence Development (CED) study. Patients from the Micra CED study were considered in a high-risk subgroup if they had a diagnosis of chronic kidney disease Stages 4-5 (CKD45), end-stage renal disease, malignancy, diabetes, tricuspid valve disease (TVD), or chronic obstructive pulmonary disease (COPD) 12 months prior to pacemaker implant. A pre-specified set of complications and reinterventions were identified using diagnosis and procedure codes. Competing risks models were used to compare reinterventions and complications between leadless-VVI and transvenous-VVI patients within each subgroup; results were adjusted for multiple comparisons. A post hoc comparison of a composite outcome of reinterventions and device complications was conducted. Out of 27 991 patients, 9858 leadless-VVI and 12 157 transvenous-VVI patients have at least one high-risk comorbidity. Compared to transvenous-VVI patients, leadless-VVI patients in four subgroups [malignancy, HR 0.68 (0.48-0.95); diabetes, HR 0.69 (0.53-0.89); TVD, HR 0.60 (0.44-0.82); COPD, HR 0.73 (0.55-0.98)] had fewer complications, in three subgroups [diabetes, HR 0.58 (0.37-0.89); TVD, HR 0.46 (0.28-0.76); COPD, HR 0.51 (0.29-0.90)) had fewer reinterventions, and in four subgroups (malignancy, HR 0.52 (0.32-0.83); diabetes, HR 0.52 (0.35-0.77); TVD, HR 0.44 (0.28-0.70); COPD, HR 0.55 (0.34-0.89)] had lower rates of the combined outcome.

CONCLUSION

In a real-world study, leadless pacemaker patients had lower 2-year complications and reinterventions rates compared with transvenous-VVI pacing in several high-risk subgroups.

TRIAL REGISTRATION

ClinicalTrials.gov ID NCT03039712.

Correlation between AV synchrony and device collected AM-VP sequence counter in atrioventricular synchronous leadless pacemakers: A real-world assessment

INTRODUCTION

Micra atrioventricular (AV) provides leadless atrioventricular synchronous pacing by sensing atrial contraction (A4 signal). Real-world operation and reliability of AV synchrony (AVS) assessment using device data have not been described. The purposes of this study were to (1) assess the correlation between AVS and atrial mechanical sensed-ventricular pacing (AM-VP) percentages in patients with permanent high-degree AV block and (2) report on the real-world effectiveness of Micra AV.

METHODS

The correlation between ECG-determined AVS in-clinic and device-collected %AM-VP was assessed using data from 40 patients with high-degree AV block enrolled in the Micra Atrial tRacking using a Ventricular AccELerometer (MARVEL) 2 study. A retrospective analysis to assess continuously-sampled %AM-VP since last session, device programming, and electrical parameters was performed using Micra AV transmissions from the Medtronic CareLink database. Patients with transmissions ≥180 days postimplant were included.

RESULTS

Among the 40 MARVEL 2 AV block patients with a median %VP of 99.7%, AVS was highly correlated with AM-VP (median AVS 87.1%, median AM-VP 79.1%; R²  = 0.764, p < .001). The CareLink cohort included 4384 patients programmed to VDD mode. The mean A4 amplitude was 2.3 ± 1.8 m/s² at implant and 2.3 ± 1.6 m/s² at 28 weeks. In patients with %VP >90% (n = 1662), the median %AM-VP was 74.7%. For the full cohort, median %VP was 65.6% and median projected battery longevity was 10.5 years.

CONCLUSION

In patients with a high pacing burden, %AM-VP provides a reasonable estimation of AVS. The first large real-world analysis of Micra AV patients with >90% VP showed stable atrial sensing over time with a median %AM-VP, a correlate of AVS, of 74.7%.

Leadless Pacemakers: State of the Art and Selection of the Ideal Candidate

The field of cardiac pacing has been defined by constant development to provide efficacious, safe, and reliable therapy. Traditional pacing utilizes transvenous leads, which dwell in the venous system and place patients at risk for complications, including pneumothorax, bleeding, infection, vascular obstruction, and valvular compromise. Leadless pacemakers have been developed to overcome many of the challenges of transvenous pacing while providing safe and effective pacing therapy for an increasing population of patients. The Medtronic Micra transcatheter pacing system was approved by the FDA in April of 2016 and the Abbott Aveir pacemaker was approved in April of 2022. Several additional leadless pacemakers are in various stages of development and testing. There exists limited guidance on the selection of the ideal candidate for leadless pacemakers. Advantages of leadless pacemakers include decreased infection risk, overcoming limited vascular access, and avoidance of interaction with the tricuspid valve apparatus. Disadvantages of leadless pacemakers include right ventricular-only pacing, unclear lifecycle management, cost, perforation risk, and lack of integration with defibrillator systems. This review aims to provide an overview of the current state of the art of leadless pacemakers, currently approved systems, clinical trials and real-world evidence, considerations for patient selection, and future directions of this promising technology.

Ambulatory atrioventricular synchronous pacing over time using a leadless ventricular pacemaker: Primary results from the AccelAV study

BACKGROUND

Previous studies demonstrated that accelerometer-based, mechanically timed atrioventricular synchrony (AVS) is feasible using a leadless ventricular pacemaker.

OBJECTIVE

The purpose of this study was to determine the performance of a leadless ventricular pacemaker with accelerometer-based algorithms that provide AVS pacing.

METHODS

AccelAV was a prospective, single-arm study to characterize AVS in patients implanted with a Micra AV, which uses the device accelerometer to mechanically detect atrial contractions and promote VDD pacing. The primary objective was to characterize resting AVS at 1 month in patients with complete atrioventricular block (AVB) and normal sinus function.

RESULTS

A total of 152 patients (age 77 ± 11 years; 48% female) from 20 centers were enrolled and implanted with a leadless pacemaker. Among patients with normal sinus function and complete AVB (n = 54), mean resting AVS was 85.4% at 1 month, and ambulatory AVS was 74.8%. In the subset of patients (n = 20) with programming optimization, mean ambulatory AVS was 82.6%, representing a 10.5% improvement (P <.001). Quality of life as measured by the EQ-5D-3L (EuroQol Five-Dimensions Three-Level questionnaire) improved significantly from preimplant to 3 months (P = .031). In 37 patients with AVB at both 1 and 3 months, mean AVS during rest did not differ (86.1% vs 84.1%; P = .43). There were no upgrades to dual-chamber devices or cardiac resynchronization therapy through 3 months.

CONCLUSION

Accelerometer-based mechanical atrial sensing provided by a leadless pacemaker implanted in the right ventricle significantly improves quality of life in a select cohort of patients with AV block and normal sinus function. AVS remained stable through 3 months, and there were no system upgrades to dual-chamber pacemakers.

Infection in patients with subcutaneous implantable cardioverter-defibrillator: Results of the S-ICD Post Approval Study

BACKGROUND

Early subcutaneous implantable cardioverter-defibrillator (S-ICD) studies included atypical cohorts of patients who were younger with fewer comorbidities. Recent S-ICD studies included patient populations with more comorbidities.

OBJECTIVES

The goals of this study were to determine the incidence and predictors of S-ICD-related infection over a 3-year follow-up period and to use these results to develop an infection risk score.

METHODS

The S-ICD Post Approval Study is a US prospective registry of 1637 patients. Baseline demographic characteristics and outcomes with 3-year postimplantation follow-up were compared between patients with and without device-related infection. A risk score was derived from multivariable proportional hazards analysis of 22 variables.

RESULTS

Infection was observed in 55 patients (3.3%), with 69% of infections occurring within 90 days and a vast majority (92.7%) within 1 year of implantation. Late infections more likely involved device erosion; no infections occurred after year 2. The annual mortality rate postinfection was 0.6%/y. No lead extraction complications or bacteremia related to infection were observed. An infection risk score was created with diabetes, age, prior transvenous ICD implant, and ejection fraction as predictors. Patients with a risk score of ≥3 had an 8.8 hazard ratio (95% confidence interval 2.8-16.3) of infection compared with a 0 risk score.

CONCLUSION

Infection rates in the S-ICD Post Approval Study were similar to other S-ICD populations and not associated with systemic blood-borne infections. Late infection (>1 year) is uncommon and associated with system erosion. A high-risk infection cohort can be identified that may facilitate preventive measures.

Device-related complications in subcutaneous versus transvenous ICD: a secondary analysis of the PRAETORIAN trial

BACKGROUND

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial.

METHODS AND RESULTS

The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047).

CONCLUSION

This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice.

Leadless Pacing: Where We Currently Stand and What the Future Holds

PURPOSE OF REVIEW

Leadless pacemakers (LPs) are emerging as alternative cardiac implantable devices for the treatment of bradyarrhythmia. This article aims to review the data behind the safety and efficacy of these devices while highlighting their pros and cons.

RECENT FINDINGS

Prospective non-randomized studies and registries have found that LPs are associated with lower rate of device-related complications mainly driven by lower need for lead-related interventions as compared to traditional pacemakers. On the other hand, cardiac perforation appears to occur more frequently with LPs. LPs are associated with lower rate of device-related complications as compared to the traditional pacemakers. However, the rate of pericardial effusion is higher and is more severe. As we transition to multi-chamber LPs, it is important to ensure the safety and efficacy of these devices.

Process Mapping Strategies to Prevent Subcutaneous Implantable Cardioverter-Defibrillator Infections

BACKGROUND

Infection remains a major complication of cardiac implantable electronic devices (CIEDs) and can lead to significant morbidity and mortality. Implantable devices that avoid transvenous leads, such as the subcutaneous implantable cardioverter-defibrillator (S-ICD), can reduce the risk of serious infection-related complications, such as bloodstream infection and infective endocarditis. While the 2017 AHA/ACC/HRS guidelines include recommendations for S-ICD use for patients at high risk of infection, currently, there are no clinical trial data that address best practices for the prevention of S-ICD infections. Therefore, an expert panel was convened to develop consensus on these topics.

METHODS

An expert process mapping methodology was used to achieve consensus on the appropriate steps to minimize or prevent S-ICD infections. Two face-to-face meetings of high-volume S-ICD implanters and an infectious diseases specialist, with expertise on cardiovascular implantable electronic device infections, were conducted to develop consensus on useful strategies pre-, peri-, and post-implant to reduce S-ICD infection risk.

RESULTS

Expert panel consensus of recommended steps for patient preparation, S-ICD implantation, and post-operative management were developed to provide guidance in individual patient management.

CONCLUSION

Achieving expert panel consensus by process mapping methodology for S-ICD infection prevention was attainable, and the results should be helpful to clinicians in adopting interventions to minimize risks of S-ICD infection. This article is protected by copyright. All rights reserved.

Early experience with the second generation of leadless pacemakers and correlation with ecg parameters

Funding Acknowledgements

Type of funding sources: None.

Background

Leadless pacing has evolved as a safe and effective treatment option in selected patients. With the updated generation that allows sensing of atrial contraction, atrioventricular synchronized pacing is now possible in a VDD mode. Previous retrospective analyses have demonstrated that echocardiographic parameters may be helpful in selecting patients with a higher chance of good atrioventricular synchronous pacing behaviour.

Purpose

Analysis of the early experience with the second generation of leadless pacemaker and the role of ECG parameters to predict a good atrial contraction signal (so-called A4 amplitude) in patients who underwent leadless pacemaker implantation in four tertiary centres.

Methods and Results

In this retrospective analysis, a total of 136 patients were included. Mean age was 78.0 (64.7 - 84.2 years) years with 48.9 % being male. Coronary artery disease was the leading underlying heart disease with 27.1 % affected patients. 61.7 % of the population suffered from sinus rhythm with complete or intermittent atrioventricular block. The majority of devices were implanted at the mid-septal (61.2 %) or high-septal (25.6 %) right ventricle, respectively. Electrical parameters were optimal at implant (Table 1) and remained stable over time (Table 1). In addition, A4 signal amplitude remained stable too during follow-up compared to the value early after implantation (Table 1). From this entire cohort, patients with an ECG available at implant and those in which the device was working predominantly in the VDD mode were selected for further analyses (62 patients). PR interval measured from the ECG prior to implantation did not correlate with the A4 signal amplitude (Figure 1A; P = NS). Next, P wave amplitudes were measured in all 12 ECG leads. There was a correlation between P wave amplitude from lead V2 with the A4 amplitude (Figure 1B; P = 0.034, R2 = 0.09), whereas the other right-sided ECG leads (V1/aVR), either alone or in combination, did not correlate with the A4 signal amplitude (P = NS).

Conclusions

In our cohort of patients with the second generation of leadless pacemakers, offering VDD pacing, good electrical parameters can be achieved as it has been observed with the first generation. Also the A4 signal amplitude as a marker for atrial contraction remains stable over time. In regard to ECG parameters measured prior to device implantation, only the P wave amplitude in lead V2 correlated with a amplitude of the A4 signal.

Mechanism, follow-up and recurrence of inappropriate therapy in the PRAETORIAN trial: action reduces recurrence

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Boston Scientific Corporation

Background

The PRAETORIAN trial demonstrated that the subcutaneous ICD (S-ICD) is non-inferior to the transvenous ICD (TV-ICD) with regard to inappropriate shocks (IAS) and complications. Inappropriate therapy is an undesirable side effect of ICD therapy.

Purpose

This pre-specified secondary analysis evaluates all inappropriate therapy in the PRAETORIAN trial and subsequent action to reduce recurrence of IAS.

Methods

The PRAETORIAN trial is an international, multicentre, randomised trial, which included patients with an indication for ICD therapy. In total, 849 patients were randomised to receive an S-ICD (N=426) or TV-ICD (N=423). ICD programming was mandated by protocol. Inappropriate therapy was defined as any ICD therapy on a different rhythm than ventricular tachycardia or ventricular fibrillation. A day with inappropriate therapy was defined as all device episodes on the same day. Mechanism, actions and recurrence rate were determined using days with inappropriate therapy.

Results

In the S-ICD group, 42/426 (10%) patients received inappropriate therapy, compared to 42/423 (10%) patients in the TV-ICD group (P=0.97). In total, 41 patients in the S-ICD and 29 patients in the TV-ICD group received at least one IAS (P=0.14). The total number of IAS in the S-ICD and TV-ICD group is comparable (124 vs. 130, P=0.88). The most common underlying mechanism of inappropriate therapy was T-wave oversensing in the S-ICD group (45%) and a supraventricular tachycardia (SVT) in a therapy zone in the TV-ICD group (93%). When no action was undertaken after the first IAS, the recurrence rate of an IAS of the same etiology was 56% (5/9) in the S-ICD group and 50% (4/8) in the TV-ICD group. An action, such as a change in medication, a change in programming, an invasive action or lifestyle advise resulted in a recurrence rate of 23% (7/30) in the S-ICD group and 30% (6/20) in the TV-ICD group. The recurrence rate was significantly higher when no action was undertaken versus any action (P=0.04) (Figure 1.). A change in programming resulted in a lower recurrence rate than a change in medication (S-ICD, 40% vs. 27% and TV-ICD, 44% vs. 17%). After an invasive action no recurrence of IAS occurred in both groups. Invasive actions were more common in the S-ICD group (7/41, vs. 1/29). In the S-ICD group the most common action was a change in programming (17/41), mainly when the underlying mechanism of IAS was cardiac oversensing. In the TV-ICD group the most common action was a change in medication (12/29), mainly and only when the underlying mechanism of IAS was an SVT (Figure 2.).

Conclusion

The total number of IAS and total patients receiving IAS are not statistically different between the S-ICD group and the TV-ICD group. However, the underlying mechanism and action after IAS differ and are associated with the different sensing of the ICDs. The recurrence rate after a first IAS was significantly higher when no action was undertaken.

The impact of SMARTpass algorithm status on inappropriate shock rates in the UNTOUCHED Study

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Boston Scientific Corporation

Background

The current Subcutaneous ICD (S-ICD) model incorporates SMART Pass (SP) to improve sensing and discrimination capabilities to reduce inappropriate shocks (IAS). SP status is programmable but may also be disabled automatically in the setting of low amplitude signals or low heart rate in order to avoid under-sensing of VT/VF.

Objective

To evaluate SP impact on IAS, appropriate shocks (AS), complications and mortality in the UNTOUCHED S-ICD trial.

Methods

Primary prevention patients (pts, n=1111) with ejection fraction ≤35% and no pacing requirement were followed for up to 18 months. SP status during a study visit was programmed ON or OFF and status between visits was either consistently OFF, ON, or automatically disabled (DIS). The impact of SP status on pt outcomes was evaluated using Kaplan-Meier (K-M) analysis. Multivariable proportional hazard analysis identified predictors of IAS and SP disable events.

Results

Percent of pts with SP always ON, always OFF, ON with DIS, and OFF then ON with no DIS were 56, 16, 15, and 13%, respectively. At least one SP DIS occurred in 177 pts, but only 13% had 2 or more, mostly due to PVCs and low EGM amplitudes. Significant multivariable predictors of SP disable events are history of atrial fibrillation (hazard ratio (HR) 2.49, odds ratio (OR) (1.49-4.16); p=.0005), only one passing vector at S-ICD screening, (HR 1.85, OR (1.10-3.10; p=.0202) and lower left ventricular ejection fraction (HR 1.05, OR (1.01-1.08); p=.0074). K-M IAS rates were highest for pts experiencing DIS (fig 1) and lowest for SP ON. While neither AS (p=0.58) nor complication (p=0.58) rates varied significantly according to SP status, mortality was lower for pts with SP ON during any duration of time (p=0.044) by univariate analysis. Further analysis is planned to better understand the relationship between SP status and mortality.

Conclusion

Patients in the UNTOUCHED trial with SMART Pass (SP) consistently ON had significantly fewer inappropriate shocks, with no impact on appropriate therapy for VT/VF. Patients with history of atrial fibrillation, lower left ventricular ejection fraction, and only one passing vector at S-ICD screening are at higher risk of SP disable events; therefore, care should be taken for these patients to assess SP status and their higher risk for inappropriate shocks.

Leadless vs. transvenous single-chamber ventricular pacing in the Micra CED study: 2-year follow-up

AIMS

Clinical trials have demonstrated the safety and efficacy of the Micra leadless VVI pacemaker; however, longer-term outcomes in a large, real-world population with a contemporaneous comparison to transvenous VVI pacemakers have not been examined. We compared reinterventions, chronic complications, and all-cause mortality at 2 years between leadless VVI and transvenous VVI implanted patients.

METHODS AND RESULTS

The Micra Coverage with Evidence Development study is a continuously enrolling, observational, cohort study of leadless VVI pacemakers in the US Medicare fee-for-service population. Patients implanted with a leadless VVI pacemaker between March 9, 2017, and December 31, 2018, were identified using Medicare claims data linked to manufacturer device registration data (n = 6219). All transvenous VVI patients from facilities with leadless VVI implants during the study period were obtained directly from Medicare claims (n = 10 212). Cox models were used to compare 2-year outcomes between groups. Compared to transvenous VVI, patients with leadless VVI had more end-stage renal disease (12.0% vs. 2.3%) and a higher Charlson comorbidity index (5.1 vs. 4.6). Leadless VVI patients had significantly fewer reinterventions [adjusted hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.45-0.85, P = 0.003] and chronic complications (adjusted HR 0.69, 95% CI 0.60-0.81, P < 0.0001) compared with transvenous VVI patients. Adjusted all-cause mortality at 2 years was not different between the two groups (adjusted HR 0.97, 95% CI 0.91-1.04, P = 0.37).

CONCLUSION

In a real-world study of US Medicare patients, the Micra leadless VVI pacemaker was associated with a 38% lower adjusted rate of reinterventions and a 31% lower adjusted rate of chronic complications compared with transvenous VVI pacing. There was no difference in adjusted all-cause mortality at 2 years.

Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial

BACKGROUND

The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) showed noninferiority of subcutaneous implantable cardioverter defibrillator (S-ICD) compared with transvenous implantable cardioverter defibrillator (TV-ICD) with regard to inappropriate shocks and complications. In contrast to TV-ICD, S-ICD cannot provide antitachycardia pacing for monomorphic ventricular tachycardia. This prespecified secondary analysis evaluates appropriate therapy and whether antitachycardia pacing reduces the number of appropriate shocks.

METHODS

The PRAETORIAN trial was an international, investigator-initiated randomized trial that included patients with an indication for implantable cardioverter defibrillator (ICD) therapy. Patients with previous ventricular tachycardia <170 bpm or refractory recurrent monomorphic ventricular tachycardia were excluded. In 39 centers, 849 patients were randomized to receive an S-ICD (n=426) or TV-ICD (n=423) and were followed for a median of 49.1 months. ICD programming was mandated by protocol. Appropriate ICD therapy was defined as therapy for ventricular arrhythmias. Arrhythmias were classified as discrete episodes and storm episodes (≥3 episodes within 24 hours). Analyses were performed in the modified intention-to-treat population.

RESULTS

In the S-ICD group, 86 of 426 patients received appropriate therapy, versus 78 of 423 patients in the TV-ICD group, during a median follow-up of 52 months (48-month Kaplan-Meier estimates 19.4% and 17.5%; P=0.45). In the S-ICD group, 83 patients received at least 1 shock, versus 57 patients in the TV-ICD group (48-month Kaplan-Meier estimates 19.2% and 11.5%; P=0.02). Patients in the S-ICD group had a total of 254 shocks, compared with 228 shocks in the TV-ICD group (P=0.68). First shock efficacy was 93.8% in the S-ICD group and 91.6% in the TV-ICD group (P=0.40). The first antitachycardia pacing attempt successfully terminated 46% of all monomorphic ventricular tachycardias, but accelerated the arrhythmia in 9.4%. Ten patients with S-ICD experienced 13 electrical storms, versus 18 patients with TV-ICD with 19 electrical storms. Patients with appropriate therapy had an almost 2-fold increased relative risk of electrical storms in the TV-ICD group compared with the S-ICD group (P=0.05).

CONCLUSIONS

In this trial, no difference was observed in shock efficacy of S-ICD compared with TV-ICD. Although patients in the S-ICD group were more likely to receive an ICD shock, the total number of appropriate shocks was not different between the 2 groups. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Development and validation of a risk score for predicting pericardial effusion in patients undergoing leadless pacemaker implantation: experience with the Micra transcatheter pacemaker

AIMS

There is limited information on what clinical factors are associated with the development of pericardial effusion after leadless pacemaker implantation. We sought to determine predictors of and to develop a risk score for pericardial effusion in patients undergoing Micra leadless pacemaker implantation attempt.

METHODS AND RESULTS

Patients (n = 2817) undergoing implant attempt from the Micra global trials were analysed. Characteristics were compared between patients with and without pericardial effusion (including cardiac perforation and tamponade). A risk score for pericardial effusion was developed from 18 pre-procedural clinical variables using lasso logistic regression. Internal validation and future prediction performance were estimated using bootstrap resampling. The scoring system was also externally validated using data from the Micra Acute Performance European and Middle East (MAP EMEA) registry. There were 32 patients with a pericardial effusion [1.1%, 95% confidence interval (CI): 0.8-1.6%]. Following lasso logistic regression, 11 of 18 variables remained in the model from which point values were assigned. The C-index was 0.79 (95% CI: 0.71-0.88). Patient risk score profile ranged from -4 (lowest risk) to 5 (highest risk) with 71.8% patients considered low risk (risk score ≤0), 16.6% considered medium risk (risk score = 1), and 11.7% considered high risk (risk score ≥2) for effusion. The median C-index following bootstrap validation was 0.73 (interquartile range: 0.70-0.75). The C-index based on 9 pericardial effusions from the 928 patients in the MAP EMEA registry was 0.68 (95% CI: 0.52-0.83). The pericardial effusion rate increased significantly with additional Micra deployments in medium-risk (P = 0.034) and high-risk (P < 0.001) patients.

CONCLUSION

The overall rate of pericardial effusion following Micra implantation attempt is 1.1% and has decreased over time. The risk of pericardial effusion after Micra implant attempt can be predicted using pre-procedural clinical characteristics with reasonable discrimination.

CLINICAL TRIAL REGISTRATION

The Micra Post-Approval Registry (ClinicalTrials.gov identifier: NCT02536118), Micra Continued Access Study (ClinicalTrials.gov identifier: NCT02488681), and Micra Transcatheter Pacing Study (ClinicalTrials.gov identifier: NCT02004873).

Outcomes Of Manifest Right Free Wall Accessory Pathway Ablation: Data From A Single Center

Background

Right free wall (RFW) accessory pathways (AP) typically present anatomical challenges to ablation leading to high rates of procedural failure and recovery of AP conduction.

Methods

Patients with a diagnosis of Wolff-Parkinson-White Syndrome (WPW) and a manifest RFW AP undergoing an electrophysiology study (EPS) or an ablation at our center between 01/01/2008 and 08/01/2019 were identified from our databases using diagnosis codes and manual chart review.

Results

Twenty-one patients with manifest RFW AP underwent EPS, all of which were targeted for ablation. Single procedure success rate was 19 / 21 (90.5%). Of the 19 successful cases, 4 (17.4%) patients were found to have recurrent right free wall pathway conduction at follow-up and each underwent a successful 2nd procedure (9.5%). Fluoroscopic and 3D electroanatomic mapping software was used in all cases to guide ablation. A 4 mm or 8 mm non-irrigated radiofrequency (RF) ablation catheter was used in 76% of cases while an 8 mm cryo-catheter was used in one case. More than one type of ablation catheter was used in four cases (16%). A steerable sheath was used in 68% of cases.

Conclusions

In a tertiary center, RFW AP ablation has high acute success (>90%) but approximately 21% of patients with initially successful ablation required a 2nd procedure for recurrence of pathway conduction. A combination of a large tip ablation catheter and a steerable sheath were used in most cases.

Incidence of Cancer Treatment Induced Arrhythmia Associated with Immune Checkpoint Inhibitors

Background

Cancer treatmentinduced arrhythmia (CTIA) is a well-recognized form of cardiotoxicity associated with chemotherapy. Immune checkpoint inhibitors (ICI) have been associated with important forms of cardiotoxicity, including myocarditis. However, the incidence of CTIA associated with ICI has not been well characterized.

Methods

We reviewed all patients treated with ICIs at our institution from Jan. 2010 to Oct. 2015. CTIA was defined as a new diagnosis of clinically relevant arrhythmia within 6 months after ICI initiation.

Results

During the study period, 268 patients were treated with immune checkpoint inhibitors, of whom 190 received monotherapy with ipilimumab (n=114), nivolumab (n=52) or pembrolizumab (n=24) and 78 received combination therapy: ipilimumab & nivolumab (n=37), ipilimumab & pembrolizumab (n=39) and nivolumab & pembrolizumab (n=2). Four patients (1.5%) developed CTIA. Of these, 3 patients developed a new diagnosis of atrial fibrillation (AF), one of whom required cardioversion. In 2 cases of new-onset AF, significant provoking factors were present in addition to ICI therapy including thyrotoxicosis in one and metabolic disarray in another. Six patients (2.2%) with a pre-existing diagnosis of paroxysmal AF experienced episodes within 6 months of initiating ICI therapy. None of the arrhythmic events were associated with known or suspected myocarditis.

Conclusions

The incidence of arrhythmic complications associated with immune checkpoint inhibitors appears to be very low (~1.5%). Patients with a pre-existing diagnosis of AF may be at-risk of recurrence during ICI treatment and should be monitored accordingly. These suggest that from an arrhythmia perspective, ICIs appear to be very safe and well-tolerated.

Same-Day Versus Next-Day Discharge Strategies for Left Atrial Ablation Procedures: A Parallel, Intra-Institutional Comparison of Safety and Feasibility

Background

Head-to-head comparative data for the postoperative care of patients undergoing left atrial ablation procedures are lacking.

Objective

We sought to investigate complication and readmission rates between patients undergoing same-day (SD) or next-day (ND) discharges for ablative procedures in the left atrium, primarily atrial fibrillation (AF).

Methods

Two electrophysiology centers simultaneously perform left atrial ablations with differing discharge strategies. We identified all patients who underwent left atrial ablation from August 2017 to August 2019 (n = 409) undergoing either SD (n = 210) or ND (n = 199) discharge protocols. We analyzed any clinical events that resulted in procedural abortion, extended hospitalization, or readmission within 72 hours.

Results

The primary endpoint of complication and readmission rate was similar between SD and ND discharge (14.3% vs 12.6%, p = 0.665). Rates of complications categorized as major (2.4% vs 3.0%, p = 0. 776) and minor (11.9% vs 9.5%, p = 0.524) were also similar.Multivariable regression modeling revealed no significant correlation between discharge strategy and complication/readmission occurrence (OR 1.565 [0.754 - 3.248], p = 0.23), but a positive association of hypertension and procedure duration (OR 3.428 [1.436 - 8.184], p = 0.006) and (OR 1.01 [1 - 1.019], p = 0.046) respectively.

Conclusions

Left atrial ablation complication and readmission rates were similar between SD and ND discharge practices. Hypertension and procedural duration were associated with increased complication rates irrespective of discharge strategy. These data, which represent the first side-by-side comparison of discharge strategy, suggests same-day discharge is safe and feasible for left atrial ablation procedures.