Enhancing transvenous lead extraction risk prediction: Integrating imaging biomarkers into machine learning models.

BACKGROUND: Machine learning (ML) models have been proposed to predict risk related to transvenous lead extraction (TLE). OBJECTIVE: The purpose of this study was to test whether integrating imaging data into an existing ML model increases its ability to predict major adverse events (MAEs; procedure-related major complications and procedure-related deaths) and lengthy procedures (≥100 minutes). METHODS: We hypothesized certain features-(1) lead angulation, (2) coil percentage inside the superior vena cava (SVC), and (3) number of overlapping leads in the SVC-detected from a pre-TLE plain anteroposterior chest radiograph (CXR) would improve prediction of MAE and long procedural times. A deep-learning convolutional neural network was developed to automatically detect these CXR features. RESULTS: A total of 1050 cases were included, with 24 MAEs (2.3%) . The neural network was able to detect (1) heart border with 100% accuracy; (2) coils with 98% accuracy; and (3) acute angle in the right ventricle and SVC with 91% and 70% accuracy, respectively. The following features significantly improved MAE prediction: (1) ≥50% coil within the SVC; (2) ≥2 overlapping leads in the SVC; and (3) acute lead angulation. Balanced accuracy (0.74-0.87), sensitivity (68%-83%), specificity (72%-91%), and area under the curve (AUC) (0.767-0.962) all improved with imaging biomarkers. Prediction of lengthy procedures also improved: balanced accuracy (0.76-0.86), sensitivity (75%-85%), specificity (63%-87%), and AUC (0.684-0.913). CONCLUSION: Risk prediction tools integrating imaging biomarkers significantly increases the ability of ML models to predict risk of MAE and long procedural time related to TLE.

Persistent and Recurrent Device-Related Thrombus After Left Atrial Appendage Closure: Incidence, Predictors, and Outcomes.

BACKGROUND: Scarce data exist on the evolution of device-related thrombus (DRT) after left atrial appendage closure (LAAC). OBJECTIVES: This study sought to assess the incidence, predictors, and clinical impact of persistent and recurrent DRT in LAAC recipients. METHODS: Data were obtained from an international multicenter registry including 237 patients diagnosed with DRT after LAAC. Of these, 214 patients with a subsequent imaging examination after the initial diagnosis of DRT were included. Unfavorable evolution of DRT was defined as either persisting or recurrent DRT. RESULTS: DRT resolved in 153 (71.5%) cases and persisted in 61 (28.5%) cases. Larger DRT size (OR per 1-mm increase: 1.08; 95% CI: 1.02-1.15; P = 0.009) and female (OR: 2.44; 95% CI: 1.12-5.26; P = 0.02) were independently associated with persistent DRT. After DRT resolution, 82 (53.6%) of 153 patients had repeated device imaging, with 14 (17.1%) cases diagnosed with recurrent DRT. Overall, 75 (35.0%) patients had unfavorable evolution of DRT, and the sole predictor was average thrombus size at initial diagnosis (OR per 1-mm increase: 1.09; 95% CI: 1.03-1.16; P = 0.003), with an optimal cutoff size of 7 mm (OR: 2.51; 95% CI: 1.39-4.52; P = 0.002). Unfavorable evolution of DRT was associated with a higher rate of thromboembolic events compared with resolved DRT (26.7% vs 15.1%; HR: 2.13; 95% CI: 1.15-3.94; P = 0.02). CONCLUSIONS: About one-third of DRT events had an unfavorable evolution (either persisting or recurring), with a larger initial thrombus size (particularly >7 mm) portending an increased risk. Unfavorable evolution of DRT was associated with a 2-fold higher risk of thromboembolic events compared with resolved DRT.

Atrioventricular nodal ablation is an effective management strategy for atrial fibrillation in patients with hypertrophic cardiomyopathy.

BACKGROUND: Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HCM) and can be challenging to manage. Atrioventricular nodal (AVN) ablation may be an effective management strategy for AF in these patients. OBJECTIVE: The purpose of this study was to assess the efficacy of AVN ablation in HCM patients who have failed medical therapy and/or catheter ablation for AF. METHODS: A multicenter study with retrospective analysis of a prospectively collated HCM registry was performed. AVN ablation patients were identified. Baseline characteristics and device and procedural indications were collected. Symptoms defined by New York Heart Association and European Heart Rhythm Association classification and echocardiographic findings during follow-up were assessed. RESULTS: Fifty-nine patients were included in the study. Indications for AVN ablation were 6 (10.2%) inappropriate implantable cardioverter-defibrillator shock, 35 (59.3%) ineffective rate control, and 18 (30.5%) to regularize rhythm for symptom improvement. During post-AVN ablation follow-up of 79.4 ± 61.1 months, left ventricular ejection fraction (LVEF) remained stable (pre-LVEF 48.9% ± 12.6% vs post-LVEF 50.1% ± 10.1%; P = .29), even in those without a cardiac resynchronization therapy (CRT) device (pre-LVEF 54.3% ± 8.0% vs post-LVEF 53.8% ± 8.0%; P = .65). Forty-nine patients (83.1%) reported an improvement in symptoms regardless of AF type (17/21 [81.0%] paroxysmal vs 32/38 [84.2%] persistent; P = 1.00), presence of baseline left ventricular impairment (22/26 [84.6%] LVEF ≤50% vs 27/33 [81.8%] LVEF ≥50%; P = 1.00) or CRT device (27/32 [84.4%] CRT vs 22/27 [81.5%] no CRT; P = 1.00). Symptoms improved in 16 patients (89.0%) who underwent AVN ablation to regularize rhythm. CONCLUSION: AVN ablation improved symptoms without impacting left ventricular function in the majority of patients. The data suggest that AVN ablation is an effective and safe management approach for AF in HCM and should be further evaluated in larger prospective studies.

Anatomic, histologic, and mechanical features of the right atrium: implications for leadless atrial pacemaker implantation.

BACKGROUND: Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known. OBJECTIVES: We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human. METHODS AND RESULTS: Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery. CONCLUSIONS: Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations.

Left Atrial Function Predicts Atrial Arrhythmia Recurrence Following Ablation of Long-Standing Persistent Atrial Fibrillation.

BACKGROUND: Left atrial (LA) function following catheter or surgical ablation of de-novo long-standing persistent atrial fibrillation (AF) and its impact on AF recurrence was studied in patients participating in the CASA-AF trial (Catheter Ablation vs. Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation). METHODS: All patients underwent echocardiography preablation, 3 and 12 months post-ablation. LA structure and function were assessed by 2-dimensional volume and speckle tracking strain measurements of LA reservoir, conduit, and contractile strain. Left ventricular diastolic function was measured using transmitral Doppler filling velocities and myocardial tissue Doppler velocities to derive the e', E/e', and E/A ratios. Continuous rhythm monitoring was achieved using an implantable loop recorder. RESULTS: Eighty-three patients had echocardiographic data suitable for analysis. Their mean age was 63.6±9.7 years, 73.5% were male, had AF for 22.8±11.6 months, and had a mean LA maximum volume of 48.8±13.8 mL/m2. Thirty patients maintained sinus rhythm, and 53 developed AF recurrence. Ablation led to similar reductions in LA volumes at follow-up in both rhythm groups. However, higher LA emptying fraction (36.3±10.6% versus 27.9±9.9%; P<0.001), reservoir strain (22.6±8.5% versus 16.7±5.7%; P=0.001), and contractile strain (9.2±3.4% versus 5.6±2.5%; P<0.001) were noted in the sinus rhythm compared with AF recurrence group following ablation at 3 months. Diastolic function was better in the sinus rhythm compared with the AF recurrence group with an E/A ratio of 1.5±0.5 versus 2.2±1.2 (P<0.001) and left ventricular E/e' ratio of 8.0±2.1 versus 10.3±4.1 (P<0.001), respectively. LA contractile strain at 3 months was the only independent predictor of AF recurrence. CONCLUSIONS: Following ablation for long-standing persistent AF, improvement in LA function was greater in those who maintained sinus rhythm. LA contractile strain at 3 months was the most important determinant of AF recurrence following ablation. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02755688.

Rapid diagnostic testing for syphilis in Arctic communities (the STAR study): a multisite prospective field diagnostic accuracy study in an intended-use setting.

OBJECTIVES: We evaluated the field diagnostic accuracy of a syphilis rapid test (RDT), using serum and whole blood by non-laboratorians in two Canadian Arctic communities. METHODS: We implemented a multisite prospective field evaluation wherein patients were screened by an RDT containing treponemal and non-treponemal components (Chembio DPP® Syphilis Screen & Confirm) between January 2020 and December 2021. Venous whole blood and serum were collected for rapid testing and compared with laboratory-based serology reference testing using a reverse sequence algorithm of treponemal and rapid plasma reagin (RPR) testing. RESULTS: Overall, 135 whole blood and 139 serum specimens were collected from 161 participants during clinical encounters. Treponemal-RDT sensitivity against a treponemal-reference standard (38/161 confirmed cases) was similar for serum (78% [95% CI: 61-90%]) and whole blood (81% [95% CI: 63-93%]). In those with RPR titres ≥1:8 (i.e. suggestive of recent/active infection), sensitivity increased to 93% (95% CI: 77-99%) for serum and 92% (95% CI: 73-99%) for whole blood. Treponemal-RDT specificity was excellent (99% [95% CI: 95-100%]) for both specimen types. Non-treponemal-RDT sensitivity against RPR was 94% (95% CI: 80-99%) for serum and 79% (95% CI: 60-92%) for whole blood. Sensitivity increased to 100% (95% CI: 88-100%) for serum and 92% (95% CI: 73-99%) for whole blood when RPR titres ≥1:8. RDT performance with whole blood was similar to that with serum. DISCUSSION: Non-laboratorians using the RDT accurately identified individuals with infectious syphilis under real-world conditions in an intended-use setting at the point of care. Implementing the RDT can eliminate treatment delays and may enhance disease control.

Treatment of pathophysiologic propagation outside of the pulmonary veins in retreatment of atrial fibrillation patients: RECOVER AF study.

AIMS: RECOVER AF evaluated the performance of whole-chamber non-contact charge-density mapping to guide the ablation of non-pulmonary vein (PV) targets in persistent atrial fibrillation (AF) patients following either a first or second failed procedure. METHODS AND RESULTS: RECOVER AF was a prospective, non-randomized trial that enrolled patients scheduled for a first or second ablation retreatment for recurrent AF. The PVs were assessed and re-isolated if necessary. The AF maps were used to guide the ablation of non-PV targets through elimination of pathologic conduction patterns (PCPs). Primary endpoint was freedom from AF on or off antiarrhythmic drugs (AADs) at 12 months. Patients undergoing retreatment with the AcQMap System (n = 103) were 76% AF-free at 12 months [67% after single procedure (SP)] on or off AADs (80% free from AF on AADs). Patients who had only received a pulmonary vein isolation (PVI) prior to study treatment of non-PV targets with the AcQMap System were 91% AF-free at 12 months (83% SP). No major adverse events were reported. CONCLUSION: Non-contact mapping can be used to target and guide the ablation of PCPs beyond the PVs in persistent AF patients returning for a first or second retreatment with 76% freedom from AF at 12 months. The AF freedom was particularly high, 91% (43/47), for patients enrolled having only a prior de novo PVI, and freedom from all atrial arrhythmias for this cohort was 74% (35/47). These early results are encouraging and suggest that guiding individualized targeted ablation of PCPs may therefore be advantageous to target at the earliest opportunity in patients with persistent AF.

Variation in optimal hemodynamic atrio-ventricular delay of biventricular pacing with different endocardial left ventricular lead locations using precision hemodynamics.

INTRODUCTION: It is not known whether the optimal atrioventricular (AVopt ) delay varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration. METHODS: We assessed the hemodynamic AVopt in patients with chronic heart failure undergoing endocardial LV lead implantation. AVopt was assessed during atrio-BiVP with a "roving LV lead." Up to four locations were studied: mid-lateral wall, mid-septum (or a close alternative), site of greatest hemodynamic improvement, and LV lead implant site. The AVopt was compared to a fixed AV delay of 180 ms. RESULTS: Seventeen patients were included (12 male, aged 66.5 ± 12.8 years, ejection fraction 26 ± 7%, 16 left bundle branch block or high percentage of right ventricular pacing [RVP], QRS duration 167 ± 27 ms). In most locations (62/63), AVopt increased systolic blood pressure during BiVP compared with RVP (relative improvement 6 mmHg, interquartile range [IQR] 4-9 mmHg). Compared to a fixed AV delay, the hemodynamic improvement at AVopt was higher (1 mmHg, IQR 0.2-2.6 mmHg, p < .001). Within most patients (16/17), we observed a difference in AVopt between pacing sites (median paced AVopt 209 ms, IQR 117-250). Within this range, the hemodynamic impact of these differences was small (median loss 0.6 mmHg, IQR 0.1-2.6 mmHg). CONCLUSION: Within a patient, different endocardial LV lead locations have slightly different hemodynamic AVopt which are superior to a fixed AV delay. The hemodynamic consequence of applying an optimum from a different lead location is small.

Conduction System Pacing Versus Conventional Cardiac Resynchronization Therapy in Congenital Heart Disease.

BACKGROUND: Dyssynchrony-associated left ventricular systolic dysfunction is a major contributor to heart failure in congenital heart disease (CHD). Although conventional cardiac resynchronization therapy (CRT) has shown benefit, the comparative efficacy of cardiac conduction system pacing (CSP) is unknown. OBJECTIVES: The purpose of this study was compare the clinical outcomes of CSP vs conventional CRT in CHD with biventricular, systemic left ventricular anatomy. METHODS: Retrospective CSP data from 7 centers were compared with propensity score-matched conventional CRT control subjects. Outcomes were lead performance, change in left ventricular ejection fraction (LVEF), and QRS duration at 12 months. RESULTS: A total of 65 CSP cases were identified (mean age 37 ± 21 years, 46% men). The most common CHDs were tetralogy of Fallot (n = 12 [19%]) and ventricular septal defect (n = 12 [19%]). CSP was achieved after a mean of 2.5 ± 1.6 attempts per procedure (38 patients with left bundle branch pacing, 17 with HBP, 10 with left ventricular septal myocardial). Left bundle branch area pacing [LBBAP] vs HBP was associated with a smaller increase in pacing threshold (Δ pacing threshold 0.2 V vs 0.8 V; P = 0.05) and similar sensing parameters at follow-up. For 25 CSP cases and control subjects with baseline left ventricular systolic dysfunction, improvement in LVEF was non-inferior (Δ LVEF 9.0% vs 6.0%; P = 0.30; 95% confidence limits: -2.9% to 10.0%) and narrowing of QRS duration was more pronounced for CSP (Δ QRS duration 35 ms vs 14 ms; P = 0.04). Complications were similar (3 [12%] CSP, 4 [16%] conventional CRT; P = 1.00). CONCLUSIONS: CSP can be reliably achieved in biventricular, systemic left ventricular CHD patients with similar improvement in LVEF and greater QRS narrowing for CSP vs conventional CRT at 1 year. Among CSP patients, pacing electrical parameters were superior for LBBAP vs HBP.

Synchronous atrioventricular sequential pacing utilizing conventional and leadless pacemakers in an elderly patient: a case report.

Background: Leadless pacemakers present a viable alternative to conventional transvenous devices to mitigate the risk of lead- and/or pocket-related complications. In elderly patients who have encountered ventricular lead failures with transvenous pacemakers, this option may enable the delivery of atrioventricular synchronous pacing therapy, while obviating the requirement for lead extraction and lead-based pacemaker re-implantation. Case summary: This case report describes the successful implantation of a leadless pacemaker in a 90-year-old who had undergone two dual-chamber permanent pacemaker implantation procedures with a failure of three of four previously implanted leads. Atrioventricular synchronous pacing was achieved, as the leadless device was able to track the atrial-paced rhythm from the pre-existing right-sided device. Discussion: In elderly patients who have encountered issues with transvenous pacemakers, alternative approaches should be considered to mitigate the risk of future complications. Leadless pacemakers may offer a low-risk solution, enabling the delivery of atrioventricular synchronous pacing therapy in such patient groups. Future studies should be designed to delineate whether these devices could be utilized as a first-line approach in certain situations.

Conduction system pacing learning curve: Left bundle pacing compared to His bundle pacing.

Introduction: Conduction system pacing (CSP), consisting of His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) is a rapidly developing field. These pacing techniques result in single lead left ventricular resynchronisation. Understanding of the associated learning curve of the two techniques is an important consideration for new implanters/implanting centres. Methods: We conducted a review of the first 30 cases of both HBP and LBBAP at The Royal Brompton Hospital. The procedural duration and fluoroscopy time were used as surrogates for the learning curve of each technique. Results: Patient characteristics were similar in HBP and LBBAP groups; LV ejection fraction (46% vs 54%, p = 0.08), pre-procedural QRS duration (119 ms vs 128 ms, p = 0.32).Mean procedural duration was shorter for LBBAP than for HBP (87 vs 107mins, p = 0.04) and the drop in procedural duration was more marked in LBBAP, plateauing and remaining low at 80mins after the initial 10 cases. Fluoroscopic screening time mirrored procedural duration (8 min vs 16 min, p < 0.01). Discussion/Conclusion: Our data suggest that the CSP learning curve was shorter for LBBAP than for HBP and appears to plateaux after the first 10 cases, however the HBP learning curve is longer with continued improvement over the first 30 cases. The shorter learning curve of LBBAP in conjunction with the superior electrical parameters and simplified programming mean the establishment of a CSP program is potentially easier with LBBAP compared to with HBP.

Leadless Cardiac Pacing: New Horizons.

Since the introduction of transvenous cardiac pacing leads, pacemaker system design has remained similar for several decades. Progressive miniaturisation of electronic circuitry and batteries has enabled a smaller, single pacing unit comprising the intracardiac electrodes, generator and computer. This review explores the development of leadless pacing, the clinical trials comparing leadless to transvenous pacing in addition to the future developments of multi-chamber leadless pacing.

Long-term outcomes following catheter ablation versus medical therapy in patients with persistent atrial fibrillation and heart failure with reduced ejection fraction.

AIMS: The ARC-HF and CAMTAF trials randomized patients with persistent atrial fibrillation (AF) and heart failure (HF) to early routine catheter ablation (ER-CA) versus pharmacological rate control (RC). After trial completion, delayed selective catheter ablation (DS-CA) was performed where clinically indicated in the RC group. We hypothesized that ER-CA would result in a lower risk of cardiovascular hospitalization and death versus DS-CA in this population. METHODS AND RESULTS: Overall, 102 patients were randomized (age 60 ± 11 years, left ventricular ejection fraction [LVEF] 31 ± 11%): 52 to ER-CA and 50 to RC. After 12 months, patients undergoing ER-CA had improved self-reported symptom scores, lower New York Heart Association class (i.e. better functional capacity), and higher LVEF compared to patients receiving RC alone. During a median follow-up of 7.8 (interquartile range 3.9-9.9) years, 27 (54%) patients in the RC group underwent DS-CA and 34 (33.3%) patients died, including 17 (32.7%) randomized to ER-CA and 17 (34.0%) randomized to RC. Compared with DS-CA, a strategy of ER-CA exhibited similar risk of all-cause mortality (adjusted hazard ratio [aHR] 0.89, 95% confidence interval [CI] 0.44-1.77, p = 0.731) and combined all-cause mortality or cardiovascular hospitalization (aHR 0.80, 95% CI 0.43-1.47, p = 0.467). However, analyses according to treatment received suggested an association between CA and improved outcomes versus RC (all-cause mortality: aHR 0.43, 95% CI 0.20-0.91, p = 0.028; all-cause mortality/cardiovascular hospitalization: aHR 0.48, 95% CI 0.24-0.94, p = 0.031). CONCLUSIONS: In patients with persistent AF and HF, ER-CA produces similar long-term outcomes to a DS-CA strategy. The association between CA as a treatment received and improved outcomes means there is still a lack of clarity regarding the role of early CA in selected patients. Randomized trials are needed to clarify this question.

Biventricular endocardial pacing and left bundle branch area pacing for cardiac resynchronization: Mechanistic insights from electrocardiographic imaging, acute hemodynamic response, and magnetic resonance imaging.

BACKGROUND: Biventricular endocardial pacing (BiV-endo) has demonstrated superior cardiac resynchronization compared to conventional biventricular epicardial pacing (BiV-epi). Left bundle branch area pacing (LBBAP) may also achieve effective cardiac resynchronization therapy (CRT). OBJECTIVE: The purpose of this study was to compare the acute electrical and hemodynamic effects of BiV-epi, BiV-endo, and LBBAP delivered from the LV endocardium and to assess how myocardial scar affects response. METHODS: Eleven patients with heart failure and indications for CRT underwent a temporary pacing study with electrocardiographic imaging (ECGi) and hemodynamic assessment. BiV-endo was delivered by stimulation of the left ventricular (LV) lateral wall, and LBBAP was delivered by stimulation of the LV septum, at the site of a Purkinje potential. LV activation time (LVAT-95), LV dyssynchrony index (LVDI), biventricular activation time (BIVAT-90), and biventricular dyssynchrony index (BIVDI) were calculated. Myocardial scar was assessed using magnetic resonance imaging (MRI). RESULTS: The protocol was completed in 10 patients. Compared to BiV-epi (LVAT-95: 79.2 ± 13.1 ms; LVDI: 26.6 ± 3.4 ms) LV resynchronization was superior during BiV-endo (LVAT-95: 48.5 ± 14.9 ms; P = .001; LVDI: 16.6 ± 6.4 ms; P = .002) and LBBAP (LVAT-95: 48.9 ± 12.5 ms; P = .001; LVDI: 15.3 ± 3.4 ms; P = .001). Biventricular resynchronization was similarly superior during BiV-endo and LBBAP vs BiV-epi (BIVAT-90 and BIVDI; P <.05). The rate of acute hemodynamic responders was higher during BiV-endo (90%) and LBBAP (70%) vs BiV-epi (50%). The benefits of LBBAP (but not BiV-endo) on LV resynchronization were attenuated when septal scar was present in a subset of 8 patients who underwent MRI. CONCLUSION: Our findings suggest superior electrical resynchronization and a higher proportion of acute hemodynamic responders during BiV-endo and LBBAP compared to BiV-epi. Electrical resynchronization was similar between BiV-endo and LBBAP; however, septal scar seemed to attenuate response to LBBAP.

Left bundle branch area pacing in congenital heart disease.

AIMS: Left bundle branch area pacing (LBBAP) has been shown to be effective and safe. Limited data are available on LBBAP in the congenital heart disease (CHD) population. This study aims to describe the feasibility and safety of LBBAP in CHD patients compared with non-CHD patients. METHODS AND RESULTS: This is a single-centre, non-randomized observational study recruiting consecutive patients with bradycardia indication. Demographic data, ECGs, imaging, and procedural data including lead parameters were recorded. A total of 39 patients were included: CHD group (n = 13) and non-CHD group (n = 26). Congenital heart disease patients were younger (55 ± 14.5 years vs. 73.2 ± 13.1, P < 0.001). Acute success was achieved in all CHD patients and 96% (25/26) of non-CHD patients. No complications were encountered in either group. The procedural time for CHD patients was comparable (96.4 ± 54 vs. 82.1 ± 37.9 min, P = 0.356). Sheath reshaping was required in 7 of 13 CHD patients but only in 1 of 26 non-CHD patients, reflecting the complex and distorted anatomy of the patients in this group. Lead parameters were similar in both groups; R wave (11 ± 7 mV vs. 11.5 ± 7.5, P = 0.881) and pacing threshold (0.6 ± 0.3 V vs. 0.7 ± 0.3, P = 0.392). Baseline QRS duration was longer in the CHD group (150 ± 28.2 vs. 118.6 ± 26.6 ms, P = 0.002). Despite a numerically greater reduction in QRS and a similar left ventricular activation time (65.9 ± 6.2 vs. 67 ± 16.8 ms, P = 0.840), the QRS remained longer in the CHD group (135.5 ± 22.4 vs. 106.9 ± 24.7 ms, P = 0.005). CONCLUSION: Left bundle branch area pacing is feasible and safe in CHD patients as compared to that in non-CHD patients. Procedural and fluoroscopy times did not differ between both groups. Lead parameters were satisfactory and stable over a short-term follow-up.

Left Bundle Area Pacing for Tachycardia-Bradycardia Syndrome in a Patient With Dextrocardia.

We present the case of an 81-year-old woman with a background of situs inversus with dextrocardia who was successfully treated for tachycardia-bradycardia syndrome with left bundle area pacing. This report describes how this approach can circumvent the limitations of other pacing approaches to optimize patient outcomes. (Level of Difficulty: Intermediate.).

Stopping syphilis transmission in Arctic communities through rapid diagnostic testing: The STAR study protocol.

BACKGROUND: Intense transmission of syphilis has emerged in some Canadian Arctic communities despite screening and prevention efforts. The remoteness of most communities and limited diagnostic infrastructure yield long delays (≥14 days) between screening and treatment of cases. These hamper syphilis control efforts and may contribute to sustained transmission. Syphilis rapid diagnostic tests (RDTs) have been developed to make screening more accessible and to inform clinical decision-making within the same clinical encounter. These RDTs have been successfully deployed in several countries, but not yet in Canada. METHODS AND DESIGN: We describe the methodology of the "Stopping Syphilis Transmission in Arctic Communities Through Rapid Diagnostic Testing" (STAR) study, wherein the clinical and epidemiological impact of deploying a dual syphilis RDT in the context of ongoing transmission in Nunavut and Nunavik will be evaluated. In this prospective multisite field evaluation, sexually active individuals aged ≥14 years at risk for syphilis will be offered screening by an RDT at the point-of-care by non-laboratory trained registered nurses. Whole blood and serum specimens will be concurrently collected, when feasible, for rapid testing with an RDT containing both treponemal and non-treponemal components (Chembio DPP® Syphilis Screen & Confirm) and compared to laboratory-based reference testing according to a reverse sequence algorithm. The diagnostic accuracy of the RDT, using both whole blood and centrifuged serum specimens, will be validated under real-world conditions in remote Northern settings, outside of specialized laboratories. Additionally, screening-to-treatment time, case detection rates, and the number of infectious contacts averted by using the RDT relative to reference testing will be estimated. The impact of both diagnostic approaches on syphilis transmission dynamics will also be modeled. DISCUSSION: This study will provide much needed evidence for strengthening rapid responses to emerging syphilis outbreaks in remote Arctic regions, by supplementing traditional diagnostic strategies with an RDT to rapidly triage patients likely in need of treatment. These results will also inform the development and tailoring of future diagnostic strategies and public health responses to emerging outbreaks in the North.

The impact of ultra-high-density mapping on long-term outcome after catheter ablation of ventricular tachycardia.

Ultra-high-density (UHD) mapping can improve scar area detection and fast activation mapping in patients undergoing catheter ablation of ventricular tachycardia (VT). The aim of the present study was to compare the outcome after VT ablation guided by UHD and conventional point-by-point 3D-mapping. The acute and long-term ablation outcome of 61 consecutive patients with UHD mapping (64-electrode mini-basket catheter) was compared to 61 consecutive patients with conventional point-by-point 3D-mapping using a 3.5 mm tip catheter. Patients, whose ablation was guided by UHD mapping had an improved 24-months outcome in comparison to patients with conventional mapping (cumulative incidence estimate of the combination of recurrence or disease-related death of 52.4% (95% confidence interval (CI) [36.9-65.7]; recurrence: n = 25; disease-related death: n = 4) versus 69.6% (95% CI [55.9-79.8]); recurrence: n = 31; disease-related death n = 11). In a cause-specific Cox proportional hazards model, UHD mapping (hazard ratio (HR) 0.623; 95% CI [0.390-0.995]; P = 0.048) and left ventricular ejection fraction > 30% (HR 0.485; 95% CI [0.290-0.813]; P = 0.006) were independently associated with lower rates of recurrence or disease-related death. Other procedural parameters were similar in both groups. In conclusion, UHD mapping during VT ablation was associated with fewer VT recurrences or disease-related deaths during long-term follow-up in comparison to conventional point-by-point mapping. Complication rates and other procedural parameters were similar in both groups.

A new score for life-threatening ventricular arrhythmias and sudden cardiac death in adults with transposition of the great arteries and a systemic right ventricle.

AIMS: To investigate the incidence of major adverse ventricular arrhythmias and related events (MAREs) and to develop a stratification tool predicting MAREs in adults with a systemic right ventricle (sRV). METHODS AND RESULTS: In a multicentre approach, all adults (≥16 years old) with a sRV undergoing follow-up between 2000 and 2018 were identified. The incidence of MAREs, defined as sudden cardiac death, sustained ventricular tachycardia, and appropriate implantable cardioverter-defibrillator (ICD) therapy, was analysed. The association of MAREs with clinical, electrical, and echocardiographic parameters was evaluated. A total of 1184 patients (median age 27.1 years; interquartile range 19.9-34.9 years; 59% male; 70% with atrial switch repair for D-transposition of the great arteries) were included. The incidence of MAREs was 6.3 per 1000 patient-years. On multivariate analysis, age, history of heart failure, syncope, QRS duration, severe sRV dysfunction and at least moderate left ventricular outflow tract obstruction were retained in the final model with a C-index of 0.78 [95% confidence interval (CI) 0.72-0.83] and a calibration slope of 0.93 (95% CI 0.64-1.21). For every five ICDs implanted in patients with a 5-year MARE risk >10%, one patient may potentially be spared from a MARE. CONCLUSION: Sudden cardiac death remains a devastating cause of death in a contemporary adult cohort with a sRV. A prediction model based on clinical, electrocardiographic, and echocardiographic parameters was devised to estimate MARE risk and to identify high-risk patients who may benefit from primary prevention ICD implantation.