AIMS:Atrial fibrillation (AF) commonly coexists with hypertrophic obstructive cardiomyopathy (HOCM) and is associated with increased risks of stroke and mortality. While catheter ablation (CA) is effective in AF, outcomes in patients with HOCM remain underreported. We sought to evaluate the association between CA and long-term outcomes in patients with paroxysmal AF (PAF) and HOCM. METHODS AND RESULTS:Using the TriNetX Research Network, we identified adults (≥18 years) diagnosed with HOCM and PAF between 2015 and 2021. Patients were stratified into CA vs. non-CA groups. Propensity score matching (1:1) was used to adjust for differences in demographics, comorbidities, and medications. The primary outcome was all-cause mortality and ischemic stroke at 3 years; secondary outcomes included cardioversion and new-onset heart failure. Kaplan-Meier analysis and Cox proportional hazards regression were used to estimate adjusted hazard ratios (HRs). Among 8593 patients with HOCM and PAF, 1018 (11.8%) underwent CA. Post-PSM, 966 patients were matched per group. All-cause mortality was markedly reduced in the CA group (4.9% vs. 13.7%, HR: 0.35, 95% CI: 0.25-0.49, P < 0.0001). Ischemic stroke rates were significantly lower in the CA group (6.4% vs. 9.7%, HR: 0.63, 95% CI: 0.46-0.87, P < 0.01), including among patients without prior stroke (de novo stroke: 3.7% vs. 5.7%, HR: 0.63, 95% CI: 0.40-0.98, P < 0.05). Cardioversion was significantly higher following CA (30.1% vs. 10.1%, HR: 3.2, 95% CI: 2.5-4.0, P < 0.0001). There was no significant difference in new-onset heart failure between the CA and non-CA groups (69.1% vs. 72.0%; HR: 1.08, 95% CI: 0.84-1.40, P = 0.53). CONCLUSION:In patients with HOCM and PAF, CA was associated with significantly lower risks of ischemic stroke and all-cause mortality.

BACKGROUND:Conventional follow-up after atrial fibrillation (AF) catheter ablation relies on physician-led interval monitoring and often fails to characterize paroxysmal symptoms. An increasing number of patients use smartwatch-based ECG devices for rhythm monitoring, but their structured integration into clinical workflows and the handling of the resultant data are not well described. OBJECTIVES:To describe the design, operationalization, data pipeline, and user engagement of a patient-led smartwatch ECG follow-up strategy after AF ablation within a randomized clinical trial. METHODS:A prospective, randomized controlled trial of adults undergoing first-time AF ablation was conducted. Participants were randomized to an Apple Watch-based protocol (daily and symptom-triggered ECGs) or standard follow-up. A prespecified audit of the smartwatch-derived rhythm classification was conducted. User engagement, symptom annotation, and downstream resource use were quantified. Primary clinical outcomes are reported in a companion Brief Report. RESULTS:Of the 168 enrolled participants (mean age 60.5 ± 9.9 years, 52 (31.0%) female, 84 (50.0%) persistent AF), Active-arm participants recorded a median of 170 (IQR 93-380) ECGs over 12 months and transmitted a median of 1.9% (0.0-8.3) for review. Symptom-annotated ECGs were more likely to show AF compared with unannotated ECGs (OR 16.1, 95% CI 13.0-19.9, P < 0.001) Watch-derived AF and sinus rhythm labels had positive predictive values of 0.96 and 0.95 respectively, although one-third of ECGs were unclassified. CONCLUSIONS:A structured, patient-led smartwatch ECG workflow can be embedded into routine post-ablation care with high engagement, modest staff workload, and accurate device-level rhythm classification. This implementation framework provides a practical template for integrating patient-generated wearable data into AF follow-up pathways and future digitally enabled trials.

BACKGROUND:Atrial fibrillation (AF) significantly affects patients' health-related quality of life (HRQoL), influencing physical, psychological, and social wellbeing. Despite existing tools, there is a notable lack of AF-specific instruments that comprehensively assess HRQoL and are developed in collaboration with patients from the outset. OBJECTIVE:This study aimed to develop and validate the AF specific Patient Reported Outcome Measures questionnaire (AF-PROMs), a novel, patient-centered tool designed to measure HRQoL in patients with AF. METHODS:A prospective, observational study was conducted across 2 centers in the United Kingdom, enrolling 856 participants (265 in the pilot phase, 550 in the field-validation phase). Item generation and domain selection were guided by extensive patient and public involvement (PPI), through focus groups and qualitative interviews with patients, ensuring content validity. Psychometric evaluations included exploratory (EFA) and confirmatory factor analyses (CFA), along with assessments of reliability, responsiveness, and known-group validity. RESULTS:The AF-PROMs tool demonstrated excellent internal consistency across all domains (Cronbach's alpha ≥0.89) and strong test-retest reliability (intraclass correlation coefficient [ICC] >0.97), highlighting its stability. The tool showed robust responsiveness to clinical changes, particularly post-catheter ablation, with moderate to large effect sizes (Cohen's d ≥1.0 for overall score), underscoring its sensitivity to meaningful treatment effects. The 3-factor model achieved a satisfactory fit. Known-group validity was confirmed by significant score differences (P < .01) between healthy volunteers and patients with AF across all domains. CONCLUSION:AF-PROMs is a validated, patient-centered instrument, developed with the largest participant group to date, offering a comprehensive assessment of HRQoL in patients with AF. Its unique strengths include extensive patient involvement, high reliability, and sensitivity to clinical interventions, making it a valuable tool for both clinical practice and research in enhancing the measurement of HRQoL in AF.

BACKGROUND:The sympathetic autonomic nervous system plays a major role in arrhythmia development and maintenance. Historical preclinical studies describe preferential increases in cardiac sympathetic tone upon selective stimulation of the subclavian ansae (SA), a nerve cord encircling the subclavian artery. OBJECTIVES:This study sought to define, for the first time, the functional anatomy and physiology of the SA in humans using a percutaneous approach. METHODS:The authors prospectively recruited patients undergoing catheter ablation for paroxysmal atrial fibrillation (AF) under general anesthesia. SA stimulation (SAS) was performed on the left and/or the right (L/SAS and/or R/SAS, respectively) within the subclavian artery using an ablation catheter introduced via a femoral arterial sheath. Stimulation involved up to 70 V, 10 Hz, and a 2- to 4-millisecond pulse width for 15 to 30 seconds. Invasive blood pressure (BP), heart rate, and electrophysiological parameters were recorded. A positive response was a ≥10% increase in BP or heart rate from baseline. RESULTS:Seventeen patients (median age 60 years [Q1-Q3: 58-67 years];11 male subjects; paroxysmal AF duration 24 months [Q1-Q3: 10-60 months) underwent the stimulation protocol before their clinical AF ablation procedure. A positive hemodynamic response was observed in 11 patients; of these, arrhythmia was inducible in 5 patients. The median sinus cycle length decreased after stimulation, and there was a larger decrease with R/SAS (L/SAS 1,008 milliseconds to 926 milliseconds [P = 0.037] vs R/SAS 1,029.5 milliseconds to 917 milliseconds [P = 0.005]). Both L/SAS and R/SAS led to a notable increase in median systolic BP (L/SAS 81 to 128 mm Hg [P = 0.005] vs R/SAS 85 to 104 mm Hg [P = 0.007]) and a similar trend in diastolic BP. In addition, there was a demonstrable decrease in interatrial conduction time and increase in P-wave dispersion. CONCLUSIONS:This study represents the first successful application of selective SAS in humans. The SA is a potentially important site for targeted autonomic neuromodulation therapy.

A standardized step-by-step approach to vascular access during electrophysiological procedures: Begin by identifying patients at higher risk for vas-cular complications and consider alternative access routes in cases of inferior vena cava interruption. Allow the patient to drink clear fluids and adopt an uninterrupted anticoagulation strategy when feasible. Choose the access site based on procedural needs and patient anatomy, giving preference to ultrasound-guided puncture to improve accuracy and reduce complications. At the end of the procedure, select the most appropriate closure technique - manual compression, figure-of-eight suture, or a vascular closure device - based on access site, sheath size, and patient-specific factors.

Atrial fibrillation (AF) has a significant impact on patients' quality of life (QoL), affecting physical, psychological, and social well-being. Existing tools lack a comprehensive, AF-specific approach to health-related QoL (HRQoL) that involves patients in the development process from the outset. This study sought to develop and validate the AF-specific Patient Reported Outcome Measures questionnaire (AF-PROMs), a new, patient-centred tool for assessing HRQoL in individuals with AF. A prospective, observational study was conducted at two centres in the United Kingdom, with 895 participants enrolled. Extensive patient and public involvement (PPI) through focus groups and qualitative interviews guided item generation and domain selection to ensure content validity. Psychometric evaluations encompassed exploratory (EFA) and confirmatory factor analyses (CFA), as well as assessments of reliability, responsiveness, and known-group validity (Figure 1). Ethical approval was obtained from the Nottingham 1 Research Ethics Review Sub-Committee (reference 12/EM/0164), and the study was conducted in compliance with Good Clinical Practice and the Declaration of Helsinki. Tool development involved 41 participants in focus groups for item generation, followed by expert review and qualitative interviews for content and face validity, resulting in a draft questionnaire with 28 items (down from 31). Statistical item reduction was applied during the pilot phase (n=265) and field validation (n=550), with 39 participants excluded due to withdrawal or incomplete responses. EFA identified five optimal factors explaining 65.15% of the variance, with excellent sampling adequacy (KMO = 0.923) and significant Bartlett’s Test of Sphericity (χ² = 5057, p < .001), confirming data suitability. Clinical review refined this into a three-factor model: Physical Symptoms [F1], Social Wellbeing and Activities of Daily Living [F2], and Psychological/Treatment Concerns[F3]. CFA demonstrated excellent internal consistency (Cronbach’s alpha F1= 0.89, F2=0.92, F3=0.9) and strong test-retest reliability (Inter class correlation > 0.97). The tool was highly responsive to clinical changes, especially post-catheter ablation, with moderate to large effect sizes (Cohen’s d ≥ 1.0 for overall score). Known-group validity was supported by significant score differences (p < 0.01) between healthy volunteers and AF patients across all domains. AF-PROMs is a thoroughly validated, patient-centred tool developed with the largest cohort to date, delivering an in-depth assessment of HRQoL for AF patients. Its distinct advantages, grounded in significant patient involvement, high reliability, and sensitivity to treatment effects, make it an invaluable resource for clinical practice and research focused on improving quality of life in AF.

BACKGROUND The increasing demand for atrial fibrillation (AF) ablation, coupled with reduced inpatient hospital beds, presents challenges for health care providers, with limited data on the safety and efficacy of performing AF ablation in an ambulatory day surgery center (ADSC) outside the hospital walls. OBJECTIVE This study aimed to assess the safety and feasibility of catheter ablation for AF in an ADSC in a non-hospital setting. METHODS A retrospective review was conducted over 4 years of all consecutive patients who underwent catheter ablation at a newly established ADSC. Eligibility criteria included body mass index <45 and undergoing either first-time pulmonary vein isolation (PVI) or redo PVI/atrial tachycardia ablation. Procedures were performed under general anesthesia with transesophageal echocardiography-guided transseptal puncture. RESULTS A total of 450 patients underwent AF ablation, with a median age of 61 years (54-69), and 95% were undergoing their first AF ablation. Cryoballoon ablation was performed in 350 patients (78%), and 80% had paroxysmal AF. The median procedure duration was 58 (50-70) minutes, with successful PVI achieved in all cases. Two patients required same-day hospital transfer but were managed conservatively. The overall acute procedural adverse events rate was 1.2%, with no cases of tamponade or major complications requiring intervention. Three patients (0.6%) required medical attention within 30 days postprocedure. CONCLUSION Our large single-center experience represents the first report in Europe, demonstrating that AF catheter ablation in an ADSC is both safe and feasible. These results suggest that, with standardized protocols and the development of "one size fits all" technologies, this approach could see broader adoption.

Technological advances in atrial fibrillation (AF) ablation have improved procedural safety and patient outcomes over the past two decades. Whist novel technologies may offer the promise of improved outcomes with reduced complications, it is important to evaluate them against established therapies. Pulsed-field ablation (PFA) with a pentaspline catheter is the first single-shot PFA catheter approved for use in the European market. The most established single-shot technology for ablation of AF is the cryoballoon. To compare cost outcomes of the established cryoballoon system versus the PFA pentaspline in patients undergoing AF ablation from the English National Health Service (NHS) perspective. A cost-comparison was undertaken with a one-year time horizon for a population who underwent cryoballoon ablation for AF from April 2023 to March 2024 using Hospital Episode Statistics NHS Digital data. Patients could have an ablation with either the cryoballoon or PFA. Adverse events (AE), freedom from arrhythmia and repeat ablations were sourced from recently published comparative studies and the National Institute for Health and Care Excellence (NICE) AF guidelines (NG196). Unit costs were based on the NG196 and NHS reference costs (Table 1). The cost of the ablation procedure was calculated using the unit price for a day case from the 2024/25 NHS prices workbook, both with and without the cost of the catheters. Model input uncertainty was explored using deterministic sensitivity analysis. Over one year, treating patients with the cryoballoon catheter saved £144 per patient compared to the PFA pentaspline catheter, excluding catheter costs. Including catheter costs, savings increased to £1,885 per patient (Table 2). The primary driver in the base case was freedom from AF and fewer repeat ablations, as the group with higher AF freedom rate had lower costs related to repeat ablation. This was followed by AEs as the second key driver. When catheter costs were included, this became the main driver of savings. In all scenarios, cryoballoon ablation remained cost-saving (Table 2). The outcomes of the cost-comparison without the price of the catheters demonstrates that the established cryoballoon system remains a viable clinical and economic option, highlighting that its lower price is not the sole reason for considering cryoablation as a treatment compared to the PFA pentaspline. These financial benefits increased when catheter costs were included in the evaluation. Further evidence and economic analysis are needed to assess costs over a longer period and cost differences among the various PFA catheters available.Table 1.Clinical and Cost Inputs Table 2.Results

The sympathetic autonomic nervous system plays a major role in arrhythmia development and maintenance. Historical preclinical studies describe preferential increases in cardiac sympathetic tone upon selective stimulation of the subclavian ansae (SA), a nerve cord encircling the subclavian artery. This study sought to define, for the first time, the functional anatomy and physiology of the SA in humans using a percutaneous approach. The authors prospectively recruited patients undergoing catheter ablation for paroxysmal atrial fibrillation (AF) under general anesthesia. SA stimulation (SAS) was performed on the left and/or the right (L/SAS and/or R/SAS, respectively) within the subclavian artery using an ablation catheter introduced via a femoral arterial sheath. Stimulation involved up to 70 V, 10 Hz, and a 2- to 4-millisecond pulse width for 15 to 30 seconds. Invasive blood pressure (BP), heart rate, and electrophysiological parameters were recorded. A positive response was a ≥10% increase in BP or heart rate from baseline. Seventeen patients (median age 60 years [quartile 1-quartile 3: 58-67 years];11 male subjects; paroxysmal AF duration 24 months [quartile 1-quartile 3: 10-60 months) underwent the stimulation protocol before their clinical AF ablation procedure. A positive hemodynamic response was observed in 11 patients; of these, arrhythmia was inducible in 5 patients. The median sinus cycle length decreased after stimulation, and there was a larger decrease with R/SAS (L/SAS 1,008 milliseconds to 926 milliseconds [P = 0.037] vs R/SAS 1,029.5 milliseconds to 917 milliseconds [P = 0.005]). Both L/SAS and R/SAS led to a notable increase in median systolic BP (L/SAS 81 mm Hg to 128 mm Hg [P = 0.005] vs R/SAS 85 mm Hg to 104 mm Hg [P = 0.007]) and a similar trend in diastolic BP. In addition, there was a demonstrable decrease in interatrial conduction time and increase in P-wave dispersion. This study represents the first successful application of selective SAS in humans. The SA is a potentially important site for targeted autonomic neuromodulation therapy.

BACKGROUND There is a paucity of data comparing vitamin K antagonists (VKAs) to direct oral anticoagulants (DOACs) at the time of cardiac implantable electronic device (CIED) surgery. Furthermore, the best management of DOACs (interruption vs continuation) is yet to be determined. OBJECTIVES This study aimed to compare the incidence of device -related bleeds and thrombotic events based on anticoagulant type (DOAC vs VKA) and regimen (interrupted vs uninterrupted). METHODS This was an observational multicenter study. We included patients on chronic oral anticoagulation undergoing CIED surgery. Patients were matched using propensity scoring. RESULTS We included 1,975 patients (age 73.8 +/- 12.4 years). Among 1,326 patients on DOAC, this was interrupted presurgery in 78.2% (n =1,039) and continued in 21.8% (n = 287). There were 649 patients on continued VKA. The matched population included 861 patients. The rate of any major bleeding was higher with continued DOAC (5.2%) compared to interrupted DOAC (1.7%) and continued VKA (2.1%) (P = 0.03). The rate of perioperative thromboembolism was 1.4% with interrupted DOAC, whereas no thromboembolic events occurred with DOAC or VKA continuation (P = 0.04). The use of dual antiplatelet therapy, DOAC continuation, and male sex were independent predictors of major bleeding on a multivariable analysis. CONCLUSIONS In this large real -world cohort, a continued DOAC strategy was associated with a higher bleeding risk compared to DOAC interruption or VKA continuation in patients undergoing CIED surgery. However, DOAC interruption was associated with increased thromboembolic risk. Concomitant dual antiplatelet therapy should be avoided whenever clinically possible. A bespoke approach is necessary, with a strategy of minimal DOAC interruption likely to represent the best compromise. (J Am Coll Cardiol EP 2024;10:121-132) (c) 2024 by the American College of Cardiology Foundation.

Abstract Background Patients with persistent atrial fibrillation (pers.AF) commonly undergo catheter ablation (CA) for symptom relief and improved quality of life(QoL). However,the benefits of CA compared to DC cardioversion (DCCV) or medical therapy lack substantial evidence from blinded randomized trials. Purpose Conducting such a large-scale trial presents substantial challenges in terms of recruitment, maintaining blinding, and implementation.To address this, we conducted a pilot study prior to a definitive larger study. Methods This feasibility trial is a single-centre, prospective, randomised, double-blinded placebo control study. Patients with early pers AF (<2 years) eligible for pulmonary vein isolation (PVI) or DCCV were enrolled. Twenty patients were recruited, accounting for 10% of the proposed larger trial based on power calculation. The intervention arm (PVI + DCCV) and placebo arm (Placebo + DCCV) were randomised in a 1:1 manner after ultrasound-guided vascular access with local anaesthetic and deep sedation (Midazolam + opioid). All procedures were performed as day cases on uninterrupted oral anticoagulation. Phrenic nerve pacing was performed in the Placebo group, mimicking lab interactions and fluoroscopy system movements. Implantable loop monitors were inserted immediately after heparin reversal and groin sheath removal. A 6-week(wk) blanking period was observed post-procedure. Blinding was assessed using Bang's blinding index (BI) for both patients and medical staff and a successful blinding is considered BI between -0.2 to 0.2. Health-related quality of life (HRQoL) was evaluated using SF12, EQ5D-5L, and AF PROMS. The study obtained ethical approval (REC ref 19/LO/0775),adhered to the principles of the Declaration of Helsinki,and obtained written informed consent from all participants. Results A remarkable 92% of patients approached, expressed a willingness to participate in the study. Procedure time and time to discharge were similar between groups. The study successfully achieved blinding among the patients at day0 (BI = PVI-0.2 vs placebo- 0) and was maintained throughout the 6-wk and 3M follow-up, among the patients as well as clinical staff. HRQoL improved in the active group in terms of AF PROMS [Improved difference from baseline PVI 23 (±22); vs Placebo 2 (±10), p=<0.001 and SF-12 mental component (MCS) at 12M (PVI 11.8 (±11) vs placebo 8.54(±11.5), p= 0.017). Over a follow up period of 12M, there was a trend towards greater recurrence (60% vs 30%; p=0.07) and repeat procedures (70% vs 40%; p=0.4) in the placebo group. Conclusion: Performing a blinded placebo-controlled interventional study to assess the efficacy of PVI is feasible and high recruitment rates are achievable. CA appears to result in better arrhythmic and QoL outcomes;a full-scale follow-on study will assess the true efficacy of CA in patients with early pers.AF and allow consideration of whether there is a role for DCCV in many patients.

Abstract Introduction Radiation hazards are a major concern for both patients and staff. We have previously described a near-zero fluoroscopy technique for cardiac electronic device implantation. In this study, we aimed to investigate the long-term safety of this technique and compare outcomes and procedural metrics with a conventional approach in a larger population. Methods Low-dose fluoroscopy technique. Radiation exposure during fluoroscopy is directly proportional to the time the unit is activated. Typically, the pedal switch is depressed for at least a few seconds per imaging sequence in order to visualize "live" movements of either the leads during their positioning or the needle during a fluoroscopy-guided puncture of the subclavian vein. Our technique consists of setting a low frame rate per second (0.5-3.75fps) and momentarily triggering the foot pedal switch only to obtain screenshots of the position of the leads/needle. Use of live electrograms to assist spatial awareness of lead position (e.g. Atrial, Coronary Sinus, Ventricular signals) acts as an adjunct to guidance. Study design We included consecutive patients undergoing permanent pacemaker (PPM) or cardiac defibrillator (ICD) implant at our center from July 2018 to December 2022 using the near-zero fluoroscopy technique. Procedures were performed by three operators (AC, MD, MF). Cumulative radiation dose was measured using dose-area product (DAP). We assessed procedure success and complication rate during long-term follow-up. We compared the procedural metrics and outcomes with a cohort of patients with PPM or ICD implanted in our centre by senior operators, using a traditional fluoroscopic approach. Propensity score was adopted to match baseline characteristics between the study and control group. Results The total population consisted of 412 patients (74.2±13.9 years, 60.9% male). We included 206 who underwent PPM or ICD implantation using the low-dose fluoroscopy technique, and 206 matched-control. A PPM or ICD was successfully implanted in all patients. Fluoroscopy time and DAP were significantly lower in the low-dose fluoroscopy group, mean 2.3±2.0 seconds versus 258.4±252.1 seconds (P<0.001) and 3.4±3.5 µGym2 versus 29.8±55.4 µGym2 (P<0.001), respectively. Mean procedure time was 49.0±20.8 minutes in the low fluoroscopy group and 65.7±26.8 minutes in the control group (P<0.001). Median frame per second setting was 0.5 in the low-dose cohort. After a mean follow-up of 441±470 days, the rate of complications was identical across groups (2.4%, p = 1.0). Conclusion This near-zero dose fluoroscopy technique is effective and safe, enabling a 10x reduction in radiation exposure during device implant. Modification of traditional implant and imaging techniques can provide material reductions in fluoroscopy dose to even below that for a standard PA chest radiograph.

The transition of implantable loop recorder (ILR) explant procedures from physician to non-physician (NP) and from catheter labs (CL) to outpatient (OP) settings has not been as thoroughly investigated. We implemented a NP, OP ILR explant service in 2021, and hypothesized that it would have comparable safety outcomes, save time, and reduce costs.

Abstract Background Sympathetic nervous system activation plays a significant role in arrhythmia development and maintenance.Neuromodulation techniques such as stellate ganglion block and sympathectomy, are limited by off-target side effects and complex targeting.The Subclavian Ansae (SA,a nerve cord encircling the subclavian artery) may be an intravascular site allowing specific targeting of the cardiac afferent sympathetic system.Preclinical studies have revealed increased sympathetic tone upon selective SA stimulation. Objective We sought to define for the first time in Humans the functional anatomy and physiology of Subclavian Ansae via a percutaneous approach. Methods A prior cadaveric study defined the anatomical course of the subclavian ansae, encircling the subclavian arteries and connecting the middle cervical ganglia to inferior cervical ganglia/stellate.Patients undergoing catheter ablation for paroxysmal atrial fibrillation(pAF) under general anesthesia were prospectively recruited for the study. Subclavian Ansae stimulation (SAS) was performed on the left and/or the right (L/SAS ± R/SAS) within the subclavian artery using the TactiCath Ablation Catheter introduced via a femoral arterial sheath. Stimulation parameters included up to 70 V output, 10 Hz frequency, and pulse width of 2-4ms for 20-30s. Test pulses ensured no cardiac capture during stimulation. Participants discontinued antiarrhythmic agents at least 4-5 half-lives prior to the procedure. Invasive arterial blood pressure(BP), heart rate (HR), and electrophysiological parameters were recorded in response to selective stimulation. An increase of ten percent or more in either arterial blood pressure(BP) or heart rate(HR) from the initial baseline measurements was deemed a positive response. Results 15 patients (62±11 years, 9 males, pAF duration 51±24 months) underwent the simulation protocol prior to their clinical AF ablation procedure. A positive hemodynamic response was observed in nine patients, and among them, arrhythmia was inducible in 3 patients (atrial fibrillation in 2 patients and repeated runs of atrial ectopy in 1 patient) in response to SAS. Mean sinus cycle length(CL) decreased(chronotropic) after stimulation,particularly with a significant change observed in response to R/SAS. Additionally,L/SAS led to a notable increase in mean systolic (SBP) and diastolic(DBP) blood pressure (inotropic). While the mean right atrial effective refractory period (ERP) did not significantly decrease after stimulation, there was a demonstrable difference in interatrial conduction time(dromotropy). Six patients, including the initial 3 subjected to low-energy stimulation (up to 12V), did not exhibit an adrenergic response. Conclusion This study represents the first successful application of selective SAS in humans. A heterogeneity in electrophysiological modulation by SAS exists, including laterality.The SA is a potential important target for targeted autonomic neuromodulation therapy