Search Results for: Il pacemaker si ricarica con il battito del cuore

Circulation, Volume 150, Issue Suppl_1, Page A4138981-A4138981, November 12, 2024. Background:Conduction system disease, atrial and ventricular arrhythmias may require pacemaker or ICD implantation in transthyretin amyloid cardiomyopathy (ATTR-CM). The optimal pacing mode in ATTR-CM patients remains unknown.Objective:To assess how availability of cardiac resynchronization and conduction system pacing influenced pacemaker indications and to compare early electrical performance of conventional, resynchronisation and conduction system pacing in ATTR-CM.Methods and Results:67 of 250 (26.8%) patients presenting with ATTR-CM between June 2019 and February 2023 received a pacemaker [HA1] and were included in this retrospective analysis. Pacemaker implantation occurred in 25 patients (37.3%) prior to, and in 42 (62.7%) after ATTR-CM diagnosis. Implantation of conventional single- (VVI) or dual-chamber (DDD) pacemakers was more common (n=17/25, 68%) in undiagnosed ATTR-CM, while physiological pacing systems (CRT/ CSP) were preferably implanted in patients (n=24/42; 57.1%) after diagnosis. Sick sinus syndrome (11/35; 31.4% vs. 6/32; 18.8%) and higher degree AV-block (20/35; 57.1% vs. 9/32; 28.1%) were more common indications for VVI/DDD compared to CRT/CSP pacemakers, with pursuit of a pace/ablate strategy (12/32; 37.5%) and heart failure (5/32; 15.6%) contributing significantly to implantation of CRT/CSP. QRS width was significantly lower with CSP [122ms (IQR: 120-139)], compared to CRT [155ms (IQR: 141-160); p=0.005] or VVI/DDD [160ms (IQR: 144-180)], with the latter resulting in a significant increase in QRS width compared to intrinsic QRS [from 138 (IQR: 123-150) (p0.05).Conclusions:Pacing indications are changing with earlier diagnosis of ATTR-CM. CSP may offer improved electrical performance and resynchronization, the effect of conduction system pacing on clinical outcomes should be further explored.

Circulation, Volume 150, Issue Suppl_1, Page A4147722-A4147722, November 12, 2024. Introduction:Tricuspid regurgitation (TR) is a common complication of right ventricle lead extraction (RVLE) in 5 to 10% of cases. This study aims to identify clinical outcomes such as predictors of heart failure hospitalization, need for tricuspid valve intervention, and death among patients with new severe TR after device lead removal (DLR).Methods:Patients who underwent DLR (pacemaker/ICD) between 3/1997 and 3/2024 were identified. Those who had an echocardiogram before and after RVLE with evidence of new severe TR were included. Cox univariable regression controlling for current age was used to assess association with death. Prentice Williams Peterson total time (PWPTT) Cox univariable regression was used to determine the rate of heart failure hospitalization up to three events per subject. Bivariable cox regression was used to control for ejection fraction for ICD and coil removal. Analysis was conducted using Stata IC16.Results:We identified 2,122 people who underwent RVLE, of whom 90 (4.24%) developed new severe TR and were included in the analysis. There were 68 hospitalizations among 38 people at a median of 2 years following lead extraction (IQR 0.57 to 4.5 years). The rate of hospitalization was 11.60 [9.14 to 14.71] per 100 person-years. Removal of an ICD was associated with increased hospitalization (HR 5.48 p

Circulation, Volume 150, Issue Suppl_1, Page A4144490-A4144490, November 12, 2024. Background:Conduction disturbances (CD) following transcatheter aortic valve implantation (TAVI) are well known as one of the important predictors of poor post-TAVI prognosis. Although persistent CD are evidently associated with poor prognosis, data on transient CD are limited. The aim of this study was to investigate the prognostic impact of transient CD on long-term clinical outcomes after TAVI.Methods:Patients with severe aortic stenosis (AS) undergoing TAVI between February 2017 and October 2022 were retrospectively enrolled. CD were defined as any of the following: 2nd- or 3rd-degree atrioventricular block, right or left bundle branch block, and intraventricular CD with QRS duration ≥120 ms. Transient CD were defined as CD that appeared after TAVI but improved either before discharge or within 7 days. Persistent CD were defined as CD that appeared after TAVI and presented at hospital discharge or >7 days after TAVI. The primary endpoint was cardiovascular adverse events (CAE) after discharge, defined as a composite of cardiovascular death, heart failure hospitalization, and new pacemaker implantation.Results:Of 412 enrolled patients, transient CD occurred in 81 patients (19.7%), persistent CD in 72 patients (17.5%), and no CD in 259 patients (62.9%). In comparison between the transient and no CD groups, membranous septum length was significantly shorter in the transient CD group (5.0 mm vs. 6.1 mm, p=0.005). For a maximum of 2,000 days follow-up (the median follow-up period was 569 days), the transient CD group showed a significantly higher incidence of CAE compared with the no CD group (18.5% vs. 9.3%, p=0.012) (Figure). Although there was no significant difference in cardiovascular mortality (11.1% vs. 8.5%, p=0.48), the incidence of heart failure hospitalization tended to be higher in the transient CD group (6.2% vs. 2.3%, p=0.091), and new pacemaker implantation was more frequent in the transient CD group (4.9% vs. 0.0%, p

Circulation, Volume 150, Issue Suppl_1, Page A4145234-A4145234, November 12, 2024. Background:Leadless pacemakers (LPM) utilization has grown significantly, yet data on LPM removal and/or revision (LPM-RR) remains limited. This study aims to evaluate trends in 30-day readmission rate (30-dRr), mortality, and resource utilization associated with LPM-RRMethod:We analyzed data from the Nationwide Readmission Database from 2016 to 2021. Patients ≥ 18 years who underwent LPM-RR were identified using ICD-10 codes. The primary outcome was the trend on 30-dRr following LPM-RR. Secondary outcomes included mortality, resource utilization (Length of stay {LOS}&inflation-adjusted mean hospital cost),&most common readmission diagnosis. Predictive marginal effects over the years&regression analyses were conducted.Results:LPMs placement increased from 350 in 2016 to 16,225 in 2021 (p-trend < 0.001), while the rate of revisions and removals declined from 6.2% to 1.2% (p-trend < 0.001). The mean age at index admission was 70.9 years with 51.6% females, compared to 71.6 years and 60.8% males among readmitted patients. The 30-dRr increased slightly from 13.8% in 2016 to 16% in 2021 (p trend = 0.1). Index admission mortality trends were non-significant, decreasing from 7.4% in 2017 to 4.2% in 2021 (p-trend = 0.4). Readmission mortality trends also remained non-significant, from 8.3% in 2016 to 8.4% in 2021 (p-trend = 0.3). The index admission mean LOS was 12.1 days in 2016 to 10.2 days in 2021 (p trend = 0.09), while readmission mean LOS was 4.1 days to 3.8 days (p trend = 0.9). The inflation-adjusted mean hospital cost for index admissions decreased from $76,432.5 in 2016 to $61,501 in 2021 (p trend = 0.08), whereas readmission costs increased from $6,773 to $9,358 (p-trend = 0.7). The most common reason for readmission was hypertensive heart disease with heart failure.Conclusion:From 2016 to 2021, LPM implantation grew rapidly with a significant decline in revision and removal rates. During this period, 30-dRr&resource utilization have remained relatively stable, with a trend toward decreasing mortality within 30 days after LPM implantation, likely owing to technology/technique advancements, increased experience, as well as patient selection. Further research is needed to assess outcomes for the rapidly evolving use of LPM in an increasingly broader range of patient populations.

Circulation, Volume 150, Issue Suppl_1, Page A4138912-A4138912, November 12, 2024. Background:Cardiac resynchronization therapy (CRT) is a well-established therapy for patients with heart failure with reduced ejection fraction (HFrEF) and wide QRS. Whether CRT-defibrillators (CRT-D) reduce mortality more than CRT-pacemakers (CRT-P) remains controversial.Aims:To compare the clinical outcomes of CRT-D vs CRT-P using data from 5 landmark CRT trials, both overall and stratified by etiology of cardiomyopathy (ischemic vs non-ischemic), sex (male vs female), age (≥ 70 y/o vs < 70 y/o), and QRS morphology (IVCD, LBBB, RBBB).Methods:We performed a meta-analysis of patient level data from 5 prospective CRT trials (MIRACLE, REVERSE, RAFT, COMPANION and MADIT-CRT). Inclusion criteria were CRT-P vs CRT-D status (randomized comparison only in COMPANION), age ≥ 18 y/o and LVEF ≤ 35%. Exclusion criteria included secondary prevention ICD, QRS < 120ms, pacemaker upgrade, ventricular pacing indication, or missing data. Primary outcome was composite of time to heart failure hospitalization (HFH) or all-cause death. Secondary outcomes were time to HFH and death. Outcomes were analyzed using a frequentist Cox Proportional Hazards mixed effects model adjusted for 17 variables.Results:A total of 3407 patients met inclusion criteria. Relative to patients with CRT-P (n=843), those with CRT-D (n=2564) were of similar age (66 y/o, p=0.5), less often female (24% vs 34%, p

Circulation, Volume 150, Issue Suppl_1, Page A4126987-A4126987, November 12, 2024. Background:COVID-19 infection has been associated with a broad range of clinical manifestations. There are very few reported cases of COVID-19 patients presenting with syncope as an initial symptom. We present an extraordinary case of recurrent neurocardiogenic syncope in a COVID-19 patient.Case:A 66-year-old male presented after experiencing two episodes of syncope. He denied any prodromal or anginal symptoms. His medications included propranolol 10 mg twice daily for essential tremors. He had no family history of unexplained syncope or sudden cardiac death. He was hemodynamically stable and had one episode of fever at 102°F. Telemetry recording showed vagal-mediated sinus arrest and pauses without escape. Blood work showed normal cell counts, electrolytes, thyroid-stimulating hormone, and erythrocyte sedimentation rate, with a slightly elevated C-reactive protein of 22.2 mg/L. He tested positive for COVID-19 and had negative Lyme and Ehrlichia serologies.Decision Making:Due to symptomatic long sinus pauses, propranolol was discontinued, and he received a temporary pacemaker set at 50 beats per minute (bpm). He had another syncopal episode while being paced at 50 bpm, suggesting a neurocardiogenic mechanism, so the pacing rate was increased to 70 bpm. An echocardiogram showed a normal ejection fraction without any significant valvular disease. The syncope was determined to be vasovagal due to autonomic dysfunction in the setting of COVID-19. After 72 hours without further syncope, the temporary pacemaker was removed, and he was discharged home with an implantable loop recorder (ILR). A one-month follow-up showed no syncope, and ILR interrogation showed no bradycardia or pauses.Conclusion:Neurocardiogenic syncope with prolonged asystole and sinus pauses is an uncommon presentation of COVID-19 infection. The clinical course of autonomic dysfunction following COVID-19 is not very clear, and monitoring with an ILR is reasonable before considering permanent pacemaker implantation.

Circulation, Volume 150, Issue Suppl_1, Page A4136812-A4136812, November 12, 2024. Background:Cognitive decline and dementia are significant global health concerns, with hypertension being a major risk factor. Increasingly, the elderly population is receiving pacemakers, and the pacing rates are set as low as 50bpm. Moreover, the relationship between blood pressure (BP) components, particularly diastolic BP (DBP) and pulse pressure (PP), and the risk of cognitive decline or dementia remains complex. The highest risk is observed in patients with low DBP and concurrently increased PP, likely indicating vascular stiffness. To our knowledge, no studies have assessed the programming of pacemakers to increase heart rates to target DBP and PP improving cerebral perfusion.Objectives:In patients with permanent pacemakers, resting heart rate (HR) can be artificially increased, and its consequence on hemodynamics, including PP, can be easily measured. This study aims to investigate the impact of increasing resting HR on PP in patients with poor vascular compliance. Secondary outcomes include evaluating changes in DBP, SBP, and cardiac output, as well as assessing patient tolerance to higher-paced heart rates through recording subjective symptoms.Methods:The study will employ a prospective cross-sectional interventional design. Digital plethysmography will be utilized to measure hemodynamic parameters, including systolic blood pressure (SBP), DBP, PP, and cardiac output, at baseline resting-paced heart rates. Subsequently, the pacemaker resting heart rate will be incrementally increased to a final rate of 100 beats per minute (bpm), with measurements taken 2-5 minutes after each change.Results:Ten out of twenty patients were recruited, with a mean age of 75.3 years old. The median change in PP from baseline HR of 70 to 100 was -8.7% (IQR -18.8 – +2.8, p= 0.114), SBP 4.2% (IQR 0 – 11.9, p=0.059), and DBP 20.1% (IQR 12.9 -23, p=0.005). There were no adverse outcomes and no patient-reported symptoms during higher pacing rates.Conclusion:This study provides the basis for proof of concept. Since an increased HR decreases PP, this will be subsequently tested against improvement in cerebral perfusion by cerebral Doppler studies, and its impact on cognitive function will be tested. This has the potential to change the standard of practice for patients with pacemakers and allow for collaboration across multiple specialties such as neurology, geriatric medicine and cardiology.

Circulation, Volume 150, Issue Suppl_1, Page A4147872-A4147872, November 12, 2024. Introduction:Both self-expanding (SEV) and balloon-expandable (BEV) valves are used in transcatheter aortic valve implantation (TAVI) for patients with severe aortic stenosis (AS) and small aortic annulus (SAA). This updated meta-analysis compares the efficacy and safety of SEV versus BEV in TAVI for these patients.Hypothesis:This study investigates whether SEV valves are hemodynamically and clinically superior to BEV valves in patients with small aortic annulus.Methods:PubMed, SCOPUS, and Cochrane Central databases were systematically searched for randomized and observational studies comparing SEV and BEV in TAVI for SAA patients. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model for clinical outcomes (all-cause mortality, stroke, permanent pacemaker implantation [PPI]) and hemodynamic parameters (mean gradient [MG], indexed effective orifice area [iEOA], moderate to severe prosthesis-patient mismatch [PPM], and paravalvular leak [PVL]).Results:A total of 21 studies involving 6,515 patients (58.4% treated with SEV) were included. SEV valves were associated with lower all-cause mortality (OR 0.75; 95% CI 0.60-0.95; p=0.014), lower MG (OR -4.44; 95% CI -5.48-3.39; p

Circulation, Volume 150, Issue Suppl_1, Page A4139209-A4139209, November 12, 2024. Background:There has been growing awareness and recognition of discrepant health outcomes based on ethnic and racial background in patients undergoing cardiovascular procedures. Transcatheter aortic valve procedures has become the primary treatment for aortic stenosis and is currently the standard of care. Despite widespread adoption of TAVR, African Americans (AA) have continued to remain underrepresented and typically suffer poorer outcomes. Thus, we conducted a systematic review and meta-analysis to compare TAVR outcomes between AA and non-AA populations.Methodology:We systematically searched all electronic databases (PubMed, EMBASE, Scopus, Web of science) from inception until May 25th, 2024. A pooled analysis of data from observational studies and randomized controlled trials reporting post-TAVR outcomes based on racial background were included. The key endpoints evaluated were in-hospital mortality, post-procedure myocardial infarction (MI), pacemaker placement, in-hospital stroke, vascular complications, major bleeding, acute kidney injury (AKI). We used the I2 statistic to assess heterogeneity among studies using the Random-Effects model, with significance set at I2 > 50%. All analysis was carried out using R version 4.3.2.Results:The meta-analysis of eleven observational studies, involving 953,892 TAVR patients [912,301 (95.64%) Caucasians and 41,591 (4.36%) AAs], showed a statistically significant higher risk of post-procedure pacemaker placement (OR 1.08, 95% CI: 0.77-1.51, p=

Circulation, Volume 150, Issue Suppl_1, Page A4147674-A4147674, November 12, 2024. Background:Leadless pacemaker (LP) is a novel pacemaker offering an innovative approach to bradyarrhythmia treatment. Aveir LP and Micra LP are the two leadless pacing systems available in the United States. Aveir LP was approved by the Food and Drug Administration (FDA) in April 2022. Data regarding the adverse events (AE) following implantation of Aveir LP is scarce, largely limited to single centers, and no real-world comparative analyses were done previously.Methods:We queried the FDA Manufacturer and User Facility Device Experience (MAUDE) database between April 2022 and December 2023 to assess the safety and AE following implantation of Aveir LP. “AVIER” and “MICRA” were the key terms used to search the MAUDE database. The event types “death” and “injury” were included in our search to capture major clinical events related to the patient. Disproportionality analysis was performed using the reporting odds ratio (ROR) to compare the adverse events of Aveir LP with Micra LP. A signal to noise ratio was considered to be significant if the confidence interval (CI) did not cross the number “one”.Results:Our search resulted in 207 event reports for Aveir LP and 1969 event reports for Micra LP. Major device related adverse events with Aveir LP were capturing problem (33.8%) followed by dislodgement (16.9%), and sensing problem (7.2%). Most encountered device related AE with Micra LP were capturing problem (37.8%), pacing problem (11.5%), and sensing problem (9.3%). Frequencies of all the analyzed AE are shown in Figure 1. The reporting of pericardial effusion (ROR 2.84, 95% CI 2.18-3.71), and dislodgment (ROR 1.85, 95% CI 1.26-2.73) were significantly higher with Aveir, whereas cardiac arrest (ROR 0.18, 95% CI 0.04-0.74) was disproportionately lower. Overall, patient related AE were significantly higher (ROR 1.53, 95% CI 1.20-1.95) and device related events were significantly lower (ROR 0.65, 95% CI 0.51-0.83) with Aveir LP compared to Micra LP (Figure 2).Conclusion:This is the first real-world comparative analysis of two leadless pacing systems available in the United States. Our analysis showed that, when compared to Micra LP, the newer Aveir LP had lower device related events but higher patient related events, largely driven by pericardial effusion. These events could be attributed to the operator learning curve and long-term data are needed to further verify these findings.

Circulation, Volume 150, Issue Suppl_1, Page A4143294-A4143294, November 12, 2024. Introduction:Cardiac pacing devices, including Permanent Pacemakers (PPM) and Implanted Cardioverter Defibrillators (ICD), are essential in managing various cardiac conditions. Exercise capacity in patients hinges on both cardiac function enhancement and an appropriate chronotropic response. This case report underscores the strategic use of Cardiopulmonary Exercise Testing (CPET) to determine the activation of the Rate Response to Exercise (RRE) function in a patient with Heart Failure with reduced ejection fraction (HFrEF).Case Report:Our patient is a 64-year-old male with HFrEF due to hypertensive heart disease and ICD placement. He was undergoing therapy optimization at our advanced heart diseases clinic. Initially presenting with poor functional capacity, his condition improved significantly with ongoing therapy adjustments, as reflected by his KCCQ scores. This improvement enabled a comprehensive assessment using CPET. The initial CPET trial revealed moderately reduced exercise capacity and an absent chronotropic response, with a heart rate at 65 bpm and a peak VO2 of 67% predicted, categorizing him as Weber Class B. Based on these findings, we activated the RRE function and conducted a follow-up CPET. The re-evaluation demonstrated notable improvements: extended exercise duration post-anaerobic threshold, a peak VO2 of 72% predicted, and an upgraded Weber Class A status.Summary:This case exemplifies how tailored programming of pacing devices can significantly enhance exercise capacity in HF patients. Activating the RRE function in the patient’s PPM led to marked improvements in exercise capacity and prognostic indicators derived from CPET parameters, corroborating the limited existing data on this approach. Although specific guidelines are lacking, our findings highlight the utility of CPET in customizing PPM settings, particularly for HFrEF patients. This report underscores the importance of individualized treatment and invites further research into optimizing device settings to maximize patient outcomes. Leveraging CPET in routine clinical practice could revolutionize heart failure management, offering a precise and patient-centric approach.

Circulation, Volume 150, Issue Suppl_1, Page A4138782-A4138782, November 12, 2024. Background:One of the benefits of transcatheter aortic valve replacement (TAVR) over surgical aortic valve replacement (SAVR) is the possibility of same-day discharge, allowing for early mobilization and reduced total hospital stay. However, there is limited evidence comparing same-day discharge to later-day post-TAVR discharge. This meta-analysis aimed to compare the outcomes of same-day and later-day discharge post-TAVR in patients with aortic stenosis.Methods:A systematic bibliographic search was conducted using electronic databases, including PubMed, Embase, and the Cochrane Library, from inception to May 23, 2024. We pooled the risk ratios (RR) with 95% confidence intervals (CI) using the inverse-variance random-effects model. Statistical significance was set at p

Circulation, Volume 150, Issue Suppl_1, Page A4141415-A4141415, November 12, 2024. Lead related venous obstruction (LRVO) is an often underrecognized complication of pacemaker implantation. Symptoms of LRVO may include mild asymmetric upper extremity swelling to highly morbid superior vena cava (SVC) syndrome. We present an unusual case of a 54-year-old man with a history of retained pacemaker leads placed 26 years ago who presents with abdominal distention, lower extremity edema, and shortness of breath. He was found to have new onset ascites and significant pleural effusions. A liver biopsy showed hepatic fibrosis and pleural studies were consistent with chylothorax. After significant workup and diagnostic testing, it was believed that he had late complications often seen in Fontan physiology, notably hepatic fibrosis, lymphatic leakage, and protein losing enteropathy. A venogram and pressure measurements were performed which confirmed obstruction at the junction of the SVC and right atrium with elevated central filling pressures and significant flow through a markedly dilated azygous vein. A lymphangiogram suggested lymphatic leakage through the thoracic duct. An SVC stent was placed in an attempt to relieve the obstruction but the patient had progressive hemodynamic compromise leading to placement of mechanical circulatory support. Ultimately, the patient underwent surgical extraction of the retained pacemaker leads and reconstruction of the superior vena cava and right atrial junction, leading to near-resolution of his symptoms. This unusual presentation of SVC syndrome as a late complication of retained pacemaker leads highlights the potential severity of cardiac implanted electronic device lead-related complications.

Circulation, Volume 150, Issue Suppl_1, Page A4132498-A4132498, November 12, 2024. Background:Transcatheter aortic valve implantation (TAVI) is thought to be more effective than surgery for patients with small aortic annulus (SAA), however, the comparative efficacy of different transcatheter heart valves (THVs) remains uncertain. The objective of this meta-analysis was to compare the effects of balloon-expandable valves (BEVs) and self-expanding valves (SEVs) on hemodynamic parameters and clinical outcomes in patients with SAA who underwent TAVI.Methods:A thorough literature search was performed across PubMed/MEDLINE, Embase, and the Cochrane Library from their inception until May 2024 to identify eligible randomized controlled trials (RCTs) and propensity-score matched (PSM) studies. Clinical outcomes were evaluated using a random-effects model to pool risk ratios (RRs) with 95% confidence intervals (CIs).Results:The analysis included 8 studies; 2 RCTs and 6 PSM studies, with a total of 2,180 patients with SAA. BEVs were associated with a smaller indexed effective orifice area (MD: -0.18, 95% CI: -0.31 to -0.05) and a higher transvalvular mean pressure gradient (MD: 5.23, 95% CI 3.44 to 7.02) than SEVs. The risk for prosthesis-patient mismatch (PPM) (RR= 1.82, 95% CI: 1.27 to 2.60) and severe PPM (RR= 2.77, 95% CI: 1.93 to 3.98) was significantly higher for patients receiving BEVs than those receiving SEVs. However, no significant difference was observed between BEVs and SEVs regarding the risk of paravalvular leak (RR= 0.98, 95% CI: 0.57 to 1.69) and the permanent pacemaker implantation (RR= 0.78, 95% CI: 0.50 to 1.23). Although patients receiving BEVs showed a slightly lower risk of major bleeding events (RR= 0.69, 95% CI: 0.49 to 0.99), BEVs were associated with a significantly increased risk of 1-year cardiovascular mortality (RR= 1.61, 95% CI: 1.05 to 2.47) compared to those receiving SEVs. However, no significant differences were observed between BEVs and SEVs regarding 30-day all-cause mortality (RR= 1.19, 95% CI: 0.57 to 2.49), 1-year all-cause mortality (RR= 1.17, 95% CI: 0.89 to 1.53), stroke rates (RR= 0.83, 95% CI: 0.52 to 1.31) and any vascular complication (RR= 1.13, 95% CI: 0.72 to 1.75).Conclusion:In patients with SAA, SEVs showed reduced risks of PPM and severe PPM compared to BEVs, along with a larger indexed effective orifice area. Moreover, SEVs were associated with a lower risk of 1-year cardiovascular mortality.

Circulation, Volume 150, Issue Suppl_1, Page A4136330-A4136330, November 12, 2024. Introduction:Accurate assessment of pacing thresholds during permanent pacemaker implantation is critical to ensure device function and longevity. A few reports have described rate-related threshold variability during MicraTMleadless pacemaker (Medtronic Inc, Minneapolis, MN) procedures. Postulated mechanisms for this phenomenon include variable myocardial contact or micro-dislodgment, and inflammation-induced phase IV block. In this case series, we demonstrate the use of adenosine to induce transient heart block for accurate threshold assessment in patients with tachycardia during leadless pacemaker placement.Cases:A 69-year-old male with a history of atrial flutter presented with complete atrioventricular (AV) block requiring emergent transvenous pacing. A Micra placement was performed. During the procedure, the patient was tachycardic in rapid atrial flutter despite multiple doses of metoprolol. It was noted that with rapid pacing from the pacemaker at 120 pulses per minute (ppm) the threshold was ≤1V at 0.24 ms. An adequate “tug-test” was performed and at least 2 of 4 tines were noted to be fixated based on fluoroscopic motion. To confirm the capture threshold before final deployment, 12 mg of adenosine was given to induce heart block. However, at a rate of 60 ppm, there was no ventricular capture at 3V at 0.24ms. The device was repositioned and repeat threshold testing with adenosine at 60 ppm was 0.38V at 0.24ms. Pacing parameters were assessed the next day and remained stable.Similarly, a 75-year-old female with ischemic cardiomyopathy was admitted with new atrial fibrillation (AF). She then developed pauses prompting Micra placement. During initial threshold testing, she was in rapid AF despite receiving multiple doses of metoprolol. Heart block was induced with 12mg adenosine to assess the threshold at a lower pacing rate of 60 ppm. The capture threshold achieved was 0.5V at 0.24ms.Discussion:Nusbickel et al., Yoshiyama et al., and Sano et al. have reported rate dependent discrepancies in capture thresholds after Micra implantation. Our cases highlight the importance of capture threshold assessment at lower pacing rates during implantation. In patients who are tachycardic at the time of the procedure, adenosine may be useful to more reliably assess device capture threshold and determine the need for repositioning.

Circulation, Volume 150, Issue Suppl_1, Page A4136884-A4136884, November 12, 2024. Introduction:Breast cancer (BC) is the most common non-cutaneous cancer in women. Several BC treatments increase the risk of conduction abnormalities and heart failure, potentially requiring cardiac implantable electrical devices (CIEDs). Due to vascular access devices, surgical management, and chest wall radiation, these patients are subject to upper extremity vascular alterations. There is limited data regarding CIED use in this population.Research question:Do patients with BC and CIEDs have different procedural approaches or complications compared to the general population?Aims:This study aimed to evaluate CIED placement and periprocedural complications in patients with a history of BC.Methods:This was a retrospective study of CIEDs placed at our institution between 2005 and 2023. Patients with a diagnosis of BC prior to time of placement were included. Complications included those within 30 days of the procedure.Results:We analyzed 109 female patients (median age of 73 years, IQR 66-80) who received pacemaker (PPM, 58.7%), cardiac resynchronization therapy defibrillator (CRT-D, 22%), implantable cardioverter defibrillator (ICD, 16.5%), or cardiac resynchronization therapy pacemaker (CRT-P, 2.8%). The median time from cancer diagnosis to device placement was 13 years (IQR 7-21). Oncologic therapies are included in Figure 1. In patients with unilateral cancer, most devices (78.4%) were placed contralaterally, with 32% of all devices being right sided. Anatomy related to chemotherapy port altered intraoperative approach in 2 cases and bilateral lymph node dissection necessitated subcutaneous ICD in 1 case. Complications were noted in 12 patients (11%) and included hematoma, lead revision, upper extremity DVT, pericardial effusion, stress cardiomyopathy, perforation, site infection, and worsening of chronic lymphedema.Conclusions:BC survivors undergoing CIED placement appear to be at higher risk of periprocedural complications when compared to the general population. They are more likely to undergo right sided device placement to avoid vascular access ipsilateral to prior surgery or radiation. Further studies are required to understand the long-term outcomes of CIED placement in this cohort of patients.