Protocol for Home-Based Solution for Remote Atrial Fibrillation Screening to Prevent Recurrence Stroke (HUA-TUO AF Trial): a randomised controlled trial.

INTRODUCTION: Current international guidelines recommend ECG monitoring after an ischaemic stroke to detect atrial fibrillation (AF) in order to prevent stroke recurrence. However, optimal strategies to detect AF and the downstream management to prevent stroke recurrence remain to be established. The objective of the study was to explore the use of long-term home-based ECG monitoring for AF detection and stroke prevention in patients with a history of stroke. METHODS AND ANALYSIS: This prospective, randomised, open-label trial with blinded endpoint adjudication aimed to evaluate the efficacy of long-term home-based ECG monitoring for AF detection and stroke prevention in a 24-month period. Patients aged >18 years with a history of ischaemic stroke will be stratified according to the time from the index ischaemic stroke: <1, 1-3 and >3 years and then randomised in 1:1 to (1) home-based AF screening and (2) control. The home-based AF screening system comprises (1) a handheld single-lead ECG recorder (Comfit Healthcare Devices, Hong Kong SAR, China) and (2) a patient-facing smartphone application specially designed for the study. Patients randomised to the home-based AF group will record a 30 s single-lead ECG using a specially designed handheld ECG device every morning or when symptomatic. All remotely obtained data will be automatically transmitted in real-time through the study smartphone application to a secured cloud hosting and analysed using an artificial intelligence-based diagnostic system. When a diagnosis of AF is made with the system, the patients will be called back for a formal cardiology consultation within 1 week. The primary endpoint is the time to first detection of AF at 24 months of follow-up. Secondary endpoints include recurrent stroke or transient ischaemic attack, initiation of long-term anticoagulation therapy, hospitalisation for heart failure, cardiovascular death and all-cause death. ETHICS AND DISSEMINATION: The study protocol has been approved by the institutional review board of The University of Hong Kong, and Hong Kong West Cluster, Hospital Authority, Hong Kong SAR, China. Results will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04523649.

Obstructive sleep apnea and its management in patients with atrial fibrillation: An International Collaboration of Sleep Apnea Cardiovascular Trialists (INCOSACT) global survey of practicing cardiologists.

Background: Among international cardiologists it is unclear whether equipoise exists regarding the benefit of diagnosing and managing obstructive sleep apnea (OSA) to improve atrial fibrillation (AF) outcomes and whether clinical practice and equipoise are linked. Methods: Between January 2019 and June 2020 we distributed a web-based 12-question survey regarding OSA and AF management to practicing cardiologists in 16 countries. Results: The United States, Japan, Sweden, and Turkey accounted for two-thirds of responses. 863 cardiologists responded; half were general cardiologists, a quarter electrophysiologists. Responses regarding treating OSA with CPAP to improve AF endpoints were mixed. 33% of respondents referred AF patients for OSA screening. OSA was diagnosed in 48% of referred patients and continuous positive airway pressure (CPAP) was prescribed for 59% of them. Nearly 70% of respondents believed randomized controlled trials (RCTs) of OSA treatment in AF patients were necessary and indicated willingness to contribute to such trials. Conclusions: There was no clinical equipoise among surveyed cardiologists; a majority expressed certainty that combined OSA and AF treatment is superior to AF treatment alone for improving AF outcomes. However, a minority of surveyed cardiologists referred AF patients for OSA testing, and while half of screened AF patients had OSA, CPAP was prescribed in little more than half of them, reflecting the view that better clinical trial evidence is needed to support this practice. Our results underscore the need for larger, multi-national prospective studies of OSA treatment and AF outcomes to inform more uniform society guideline recommendations.

Mendelian randomization analysis of vitamin D in the secondary prevention of hypertensive-diabetic subjects: role of facilitating blood pressure control.

BACKGROUND: Vitamin D (Vit-D) promotes vascular repair and its deficiency is closely linked to the development of type 2 diabetes mellitus (T2DM) and hypertension. Whether genetially predicted vitamin D status (serological 25-hydroxyvitamin D [25(OH)D]) confers secondary protection against cardiovascular diseases (CVD) among high-risk hypertensive-diabetic subjects was unknown. METHODS: This is a prospective, individual-data, two-sample Mendelian randomization study. We interrogated 12 prior GWAS-detected SNPs of comprehensive Vit-D mechanistic pathways using high-throughput exome chip analyses in a derivation subcohort (n = 1460) and constructed a genetic risk score (GRS) (rs2060793, rs4588, rs7041; F-statistic = 32, P < 0.001) for causal inference of comprehensive CVD hard clinical endpoints in an independent sample of hypertensive subjects (n = 3746) with prevailing co-morbid T2DM (79%) and serological 25(OH)D deficiency [< 20 ng/mL] 45%. RESULTS: After 55.6 ± 28.9 months, 561 (15%) combined CVD events including myocardial infarction, unstable angina, ischemic stroke, congestive heart failure, peripheral vascular disease, and cardiovascular death had occurred. Kaplan-Meier analysis showed that genetically predicted reduced vitamin D status was associated with reduced event-free survival from combined CVD events (log-rank = 13.5, P = 0.001). Multivariate-adjusted per-allele increase in GRS predicted reduced combined CVD events (HR = 0.90 [0.84 to 0.96], P = 0.002). Mendelian randomization indicates that increased Vit-D exposure, leveraged through each 1 ng/mL genetically instrumented rise of serum Vit-D, protects against combined CVD events (Wald's estimate: OR = 0.86 [95%CI 0.75 to 0.95]), and myocardial infarction (OR = 0.76 [95%CI 0.60 to 0.90]). Furthermore, genetically predicted increase in Vit-D status ameliorates risk of deviation from achieving guideline-directed hypertension control (JNC-8: systolic target < 150 mmHg) (OR = 0.89 [95%CI 0.80 to 0.96]). CONCLUSIONS: Genetically predicted increase in Vit-D status [25(OH)D] may confer secondary protection against incident combined CVD events and myocardial infarction in a hypertensive-diabetic population where serological 25(OH)D deficiency is common, through facilitating blood pressure control.

Mendelian Randomization Focused Analysis of Vitamin D on the Secondary Prevention of Ischemic Stroke.

BACKGROUND AND PURPOSE: Experimental studies showed vitamin D (Vit-D) could promote vascular regeneration and repair. Prior randomized studies had focused mainly on primary prevention. Whether Vit-D protects against ischemic stroke and myocardial infarction recurrence among subjects with prior ischemic insults was unknown. Here, we dissected through Mendelian randomization any effect of Vit-D on the secondary prevention of recurrent ischemic stroke and myocardial infarction. METHODS: Based on a genetic risk score for Vit-D constructed from a derivation cohort sample (n=5331, 45% Vit-D deficient, 89% genotyped) via high-throughput exome-chip screening of 12 prior genome-wide association study-identified genetic variants of Vit-D mechanistic pathways (rs2060793, rs4588, and rs7041; F statistic, 73; P<0.001), we performed a focused analysis on prospective recurrence of myocardial infarction (MI) and ischemic stroke in an independent subsample with established ischemic disease (n=441, all with prior first ischemic event; follow-up duration, 41.6±14.3 years) under a 2-sample, individual-data, prospective Mendelian randomization approach. RESULTS: In the ischemic disease subsample, 11.1% (n=49/441) had developed recurrent ischemic stroke or MI and 13.3% (n=58/441) had developed recurrent or de novo ischemic stroke/MI. Kaplan-Meier analyses showed that genetic risk score predicted improved event-free survival from recurrent ischemic stroke or MI (log-rank, 13.0; P=0.001). Cox regression revealed that genetic risk score independently predicted reduced risk of recurrent ischemic stroke or MI combined (hazards ratio, 0.62 [95% CI, 0.48-0.81]; P<0.001), after adjusted for potential confounders. Mendelian randomization supported that Vit-D is causally protective against the primary end points of recurrent ischemic stroke or MI (Wald estimate: odds ratio, 0.55 [95% CI, 0.35-0.81]) and any recurrent or de novo ischemic stroke/MI (odds ratio, 0.64 [95% CI, 0.42-0.91]) and recurrent MI alone (odds ratio, 0.52 [95% CI, 0.30-0.81]). CONCLUSIONS: Genetically predicted lowering in Vit-D level is causal for the recurrence of ischemic vascular events in persons with prior ischemic stroke or MI.

Single-chamber leadless pacemaker for atrial synchronous or ventricular pacing.

Leadless pacing is a major breakthrough in the management of bradyarrhythmia. Results of initial clinical trials that have demonstrated a significant reduction in acute and long-term pacing-related complications have been confirmed by real-world experience in a broader spectrum of patients. Nonetheless current use of a leadless pacemaker is hampered by its limited atrial sensing and pacing capability, as well as battery life-span and retrievability. We review the current clinical outcome data, indications and contraindications, implantation and retrieval techniques, synchronous ventricular pacing, and other clinical considerations. We also provide an overview of the latest advancements in leadless pacing technology including device-to-device communication and energy harvesting technology.

Protocol, rationale and design of DAbigatran for Stroke PreVention In Atrial Fibrillation in MoDerate or Severe Mitral Stenosis (DAVID-MS): a randomised, open-label study.

INTRODUCTION: Current international guidelines recommend non-vitamin K oral anticoagulants (NOACs) for stroke prevention among patients with non-valvular atrial fibrillation (AF) at significant ischaemic stroke risk given the superior safety and comparable efficacy of NOACs over warfarin. Nonetheless, the safety and effectiveness of NOACs have not been evaluated in patients with AF with underlying moderate or severe mitral stenosis (MS), hence the recommended stroke prevention strategy remains warfarin therapy. METHOD AND ANALYSIS: MS remains disproportionately prevalent in Asian countries compared with the developed countries. This prospective, randomised, open-label trial with blinded endpoint adjudication aims to evaluate the safety and efficacy of dabigatran for stroke prevention in AF patients with moderate or severe MS. Patients with AF aged ≥18 years with moderate or severe MS not planned for valvular intervention in the coming 12 months will be randomised in a 1:1 ratio to receive dabigatran 110 mg or 150 mg two times per day or warfarin with international normalised ratio 2-3 in an open-label design. Patients with estimated creatinine clearance <30 mL/min, or with a concomitant indication for antiplatelet therapy will be excluded. The primary outcome is a composite of stroke and systemic embolism. Secondary outcomes are ischaemic stroke, systemic embolism, haemorrhagic stroke, intracranial haemorrhage, major bleeding and death. The estimated required sample size is approximately 686 participants. ETHICS AND DISSEMINATION: The study protocol has been approved by the Institutional Review Board of the University of Hong Kong and Hong Kong West Cluster, Hospital Authority, Hong Kong for Fung Yiu King Hospital, Grantham Hospital, Queen Mary Hospital and Tung Wah Hospital in Hong Kong. Results will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT04045093); pre-results.

Expression of Lmna-R225X nonsense mutation results in dilated cardiomyopathy and conduction disorders (DCM-CD) in mice: Impact of exercise training.

AIMS: To recapitulate progressive human dilated cardiomyopathy (DCM) and heart block in the Lmna R225X mutant mice model and investigate the molecular basis of LMNA mutation induced cardiac conduction disorders (CD); To investigate the potential interventional impact of exercise endurance. METHODS AND RESULTS: A Lmna R225X knock-in mice model in either heterozygous or homozygous genotype was generated. Electrical remodeling was observed with higher occurrence of AV block from neonatal and aged mutant mice as measured by surface electrocardiogram and atrio-ventricular Wenckebach point detection. Histological and molecular profiles revealed an increase in apoptotic cells and activation of caspase-3 activities in heart tissue. Upon aging, extracellular cellular matrix (ECM) remodeling appeared with accumulation of collagen in Lmna R225X mutant hearts as visualized by Masson's trichrome stain. This could be explained by the upregulated ECM gene expression, such as Fibronectin: Fn1, collagen: Col12a1, intergrin: Itgb2 and 3, as detected by microarray gene chip. Also, endurance exercise for 3 month improved the ventricular ejection fraction, attenuated fibrosis and cardiomyocytes apoptosis in the aged mutant mice. CONCLUSIONS: The mechanism of LMNA nonsense mutation induced cardiac conduction defects through AV node fibrosis is due to upregulated ECM gene expression upon activation of cardiac apoptosis. Lmna R225X mutant mice hold the potential for serving as in vivo models to explore the mechanism and therapeutic methods for AV block or myopathy associated with the aging process.

Missing pouches in high-density mapping of atrial tachyarrhythmia in congenital heart diseases.

BACKGROUND: The use of high-density electroanatomical mapping in the Chinese population for congenital heart disease (CHD) is not well reported. METHODS: Retrospective review of consecutive transcatheter ablation of atrial tachyarrhythmia using high-density mapping for CHD patients (at least moderate complexity) in the only tertiary congenital heart center in the territory from January 2017 to January 2019 was conducted. Orion mapping catheter in Rhythmia system (Boston Scientific) was used to create activation and voltage maps. Parameters including mechanism of arrhythmia, acute success, and follow-up data were recorded. RESULTS: Eight patients were identified (median age 35.5 years) who underwent transcatheter ablation of atrial arrhythmia. More than one reentry circuits of IART were identified in five patients. It took a median of 32.4 minutes with 15,952 (IQR 13,395-18,530) mapping points per map. Cavo-annulus isthmus-dependent mechanism was the predominant reentry mechanism. Acute success with the elimination of all inducible tachycardia was achieved in six patients (75%), and partial success in two patients. There was recurrence of atrial arrhythmia in four patients (50%), in which three patients could be maintained in sinus rhythm with low-dose antiarrhythmic medication. Targeted substrate ablation was performed in six patients with multiple IART circuits. Critical anatomical pouches were identified in three patients, which were missed in the initial mapping using Orion basket mapping catheter. CONCLUSIONS: High acute success rate of atrial arrhythmia ablation can be achieved using high-density anatomical mapping in CHD. Substrate ablation was required with multiple IART circuits identified. Vigilance should be sought to identify anatomical pouches.

Guideline-Based Critical Care Pathway Improves Long-Term Clinical Outcomes in Patients with Acute Coronary Syndrome.

Implementation of a critical care pathway (CCP) for acute coronary syndrome (ACS) has been shown to improve early compliance to guideline-directed therapies and reduce early mortality. Nevertheless its long-term impact on the compliance with medications or clinical outcomes remains unknown. Between 2004 and 2015, 2023 consecutive patients were admitted to our coronary care unit with ACS. We retrospectively compared the outcomes of 628 versus 1059 patients (mean age 66.1 ± 13.3 years, 74% male) managed before and after full implementation of a CCP. Compared with standard care, implementation of the CCP significantly increased coronary revascularization and long-term compliance with guideline-directed medical therapy (both P < 0.01). After a mean follow-up of 66.5 ± 44.0 months, 46.7% and 22.2% patients admitted before and after implementation of the CCP, respectively, died. Kaplan-Meier analyses showed that patients managed by CCP had better overall survival (P = 0.03) than those managed with standard care. After adjustment for clinical covariates and coronary anatomy, CCP remained independently predictive of better survival from all-cause mortality [hazard ratio (HR): 0.75, 95%confidence intervals (CI): 0.62-0.92, P < 0.01]. Stepwise multivariate cox regression model showed that both revascularization (HR: 0.55, 95%CI: 0.45-0.68, P < 0.01) and compliance to statin (HR: 0.70, 95%CI: 0.58-0.85, P < 0.01) were accountable for the improved outcome.

Risk of venous thromboembolism in Chinese pregnant women: Hong Kong venous thromboembolism study.

BACKGROUND: Previous Caucasian studies have described venous thromboembolism in pregnancy; however, little is known about its incidence during pregnancy and early postpartum period in the Chinese population. We investigated the risk of venous thromboembolism in a "real-world" cohort of pregnant Chinese women with no prior history of venous thromboembolism. METHODS: In this observational study, 15,325 pregnancies were identified in 14,162 Chinese women at Queen Mary Hospital, Hong Kong between January 2004 and September 2016. Demographic data, obstetric information, and laboratory and imaging data were retrieved and reviewed. RESULTS: The mean age at pregnancy was 32.4±5.3 years, and the median age was 33 years (interquartile range, 29-36 yr). Pre-existing or newly diagnosed diabetes mellitus was present in 627 women (4.1%); 359 (0.7%) women had pre-existing or newly detected hypertension. There was a small number of women with pre-existing heart disease and/or rheumatic conditions. Most deliveries (86.0%) were normal vaginal; the remaining were Cesarean section 2,146 (14.0%). The incidence of venous thromboembolism was 0.4 per 1,000 pregnancies, of which 83.3% were deep vein thrombosis and 16.7% were pulmonary embolism. In contrast to previous studies, 66.7% of venous thrombosis occurred in the first trimester. CONCLUSION: Chinese women had a substantially lower risk of venous thromboembolism during pregnancy and the postpartum period compared to that of Caucasians. The occurrence of pregnancy-related venous thromboembolism was largely confined to the early pregnancy period, probably related to the adoption of thromboprophylaxis, a lower rate of Cesarean section, and early mobilization.

Screening Of Pulmonary Hypertension in Methamphetamine Abusers (SOPHMA): rationale and design of a multicentre, cross-sectional study.

INTRODUCTION: Methamphetamine misuse is classified as a 'likely' risk factor for pulmonary arterial hypertension (PAH). Nevertheless, the actual prevalence of and a screening strategy for PAH in methamphetamine users have not been established. We plan to study the prevalence of PAH and identify its independent risk factors among methamphetamine users. METHODS AND ANALYSIS: The Screening Of Pulmonary Hypertension in Methamphetamine Abusers (SOPHMA) study will be a multicentre, cross-sectional screening study that will involve substance abuse clinics, hospitals and rehabilitation facilities in Hong Kong that cater to more than 20 methamphetamine users. A total of 400 patients who (1) are ≥18 years at enrolment; (2) report methamphetamine use in the last 2 years; (3) are diagnosed with methamphetamine use disorder; and (4) voluntarily agree to participate by providing written informed consent will be included. Patients will undergo standard echocardiography-based PAH screening procedures recommended for those with systemic sclerosis. Right heart catheterisation will be offered to participants with intermediate or high echocardiographic probability of PAH. For participants with a low echocardiographic probability of PAH, rescreening will be performed within 1 year. The primary measure will be the prevalence of PAH in methamphetamine users. The secondary measures will be the risk factors and a prediction model for PAH in methamphetamine users. ETHICS AND DISSEMINATION: The SOPHMA study has been approved by the institutional review board. The findings of this study will provide the necessary evidence to establish universal guidelines for screening of PAH in methamphetamine users. Our results will be disseminated through immediate feedback to study participants, press release to the general public, as well as presentation in medical conferences and publications in peer-reviewed journals to healthcare providers and academia worldwide.

Prognostic implications of statin intolerance in stable coronary artery disease patients with different levels of high-sensitive troponin.

BACKGROUND: The prognostic implication of statin in tolerance (SI) in those with stable CAD remains unclear. We hypothesized that SI is of higher prognostic significance in stable CAD patients with elevated high-sensitive cardiac troponin I (hs-cTnI). METHODS: A total of 952 stable CAD patients from the prospective Hong Kong CAD study who had complete clinical data, biomarker measurements and who were prescribed statin therapy were studied. RESULTS: We identified 13 (1.4%) and 125 (13.1%) patients with complete and partial SI, respectively. At baseline, patients with SI were more likely to have diabetes mellitus and a higher hs-cTnI level, but no difference in LDL-C level compared with those without SI. After 51 months of follow-up, patients with SI had a higher mean LDL-C level than those without SI. A total of 148 (15.5%) patients developed major adverse cardiovascular events (MACEs). Both SI (HR 1.52, 95% CI 1.06-2.19, P = 0.02) and elevated hs-cTnI (HR 3.18, 95% CI 2.07-4.89, P < 0.01) were independent predictors of a MACE in patients with stable CAD. When stratified by hs-cTnI level, SI independently predicted MACE-free survival only in those with elevated hs-cTnI (HR 1.51, 95% CI 1.01-2.24, P = 0.04). CONCLUSIONS: SI independently predicted MACE in patients with stable CAD and high hs-cTnI, but not in those with low hs-cTnI. Hs-cTnI may be used to stratify stable CAD patients who have SI for intensive lipid-lowering therapy using non-statin agents.

Thrombolysis in Myocardial Infarction Risk Score for Secondary Prevention of Recurrent Cardiovascular Events in a Real-World Cohort of Post-Acute Myocardial Infarction Patients.

BACKGROUND: Patients who survive myocardial infarction (MI) are at risk of recurrent cardiovascular (CV) events. This study stratified post-MI patients for risk of recurrent CV events using the Thrombolysis in Myocardial Infarction (TIMI) Risk Score for Secondary Prevention (TRS 2°P). Methods and Results: This was an observational study that applied TRS 2°P to a consecutive cohort of post-MI patients. The primary outcome was a composite endpoint of CV death, non-fatal MI, and non-fatal ischemic stroke. A total of 1,688 post-MI patients (70.3±13.6 years; male, 63.1%) were enrolled. After a mean follow-up of 41.5±34.4 months, 405 patients (24.0%) had developed a primary outcome (9.3%/year) consisting of 278 CV deaths, 134 non-fatal MI, and 33 non-fatal strokes. TRS 2°P was strongly associated with the primary outcome. The annual incidence of primary composite endpoint for patients with TRS 2°P 0 was 1.0%, and increased progressively to 39.9% for those with TRS 2°P ≥6 (HR, 27.6; 95% CI: 9.87-77.39, P<0.001). The diagnostic sensitivity of TRS 2°P for the primary composite endpoint was 76.3% (95% CI: 72.1-80.5%). Similar associations were also observed between TRS 2°P and CV death and non-fatal MI, but not non-fatal ischemic stroke. CONCLUSIONS: TRS 2°P reliably stratified post-MI patients for risk of future CV events.

Characteristics, Mechanism and Long-Term Ablation Outcome of Atrial Tachycardias After Mitral Valvular Surgery and Concomitant Cox-MAZE IV Procedure.

The incidence of atrial tachycardia (AT) after rheumatic mitral valvular (RMV) surgery has been well described. However, there have been few reports on the characteristics, mechanism, and long-term ablation outcome of ATs after RMV surgery and concomitant Cox-MAZE IV procedure.The present study reviewed consecutive patients who underwent AT ablation between May 2008 and July 2013. All patients were refractory to antiarrhythmic drugs (AADs) and had a history of RMV surgery and Cox-MAZE IV procedure. A total of 34 patients underwent AT ablation after RMV surgery and concomitant Cox-MAZE IV procedure, and presented 57 mappable and 2 unmappable ATs. The 57 mappable ATs included 14 focal-ATs and 43 reentry-ATs. Ten of the 14 focal-like ATs were located at the pulmonary vein (PV) antrum and border of a box lesion. Of the 43 reentry-ATs, 16 were marco-reentrant around the mitral annulus (MA) and 16 around the tricuspid annulus. There were 41 atypical ATs (non-cavotricuspid isthmus related) including 16 ATs related to the box lesion and 21 ATs related to other Cox-MAZE IV lesions. The AT were successfully terminated in 33 (97.1%) patients. After mean follow-up of 46.9 ± 15.7 months, 25 (73.5%) patients maintained sinus rhythm without AADs after a single procedure and 28 (82.4%) patients after repeated procedures.The recurrent ATs after RMV surgery and concomitant Cox-MAZE IV were mainly reentry mechanism, and largely related to LA. An incomplete lesion or re-conductive gaps in a prior lesion might be the predominant mechanisms for these ATs. Catheter-based mapping and ablation of these ATs seems to be effective and safe during a long-term follow-up.

Safety and feasibility of a midseptal implantation technique of a leadless pacemaker.

BACKGROUND: The major risk of implanting a leadless pacemaker at the right ventricular (RV) apex is cardiac perforation. OBJECTIVE: The purpose of this study was to describe and prospectively evaluate the safety and feasibility of a technique for midseptal implantation of the Micra leadless pacemaker. METHODS: We positioned the device at the center of the cardiac silhouette in the right anterior oblique (RAO) view, toward the left in the left anterior oblique (LAO) view, and away from the sternum in the left lateral view. RESULTS: Among the 51 patients (mean age 81.3 ± 9.3 years; 47% men) included in the study, 29 (57%) were >80 years old, 7 (14%) had body mass index <20 kg/m2, 48 (94%) had renal dysfunction, and 33 (65%) had valvular heart disease. The implantation sites were mid and apical septum in 46 (90%) and 5 (10%) patients, respectively. Although RAO and LAO views suggested a septal location, 9 (17.6%) devices were found to be directing at the free wall in the left lateral view and required repositioning. One patient (2%) developed cardiac perforation due to contrast injection against the RV anterior wall before verification of sheath location by lateral view. Mean R-wave sensing and pacing threshold at implantation were 9.7 ± 4.0 mV and 0.61 ± 0.31 V/0.24 ms, respectively. After median follow-up of 218.7 days, the pacing threshold remained stable. CONCLUSION: In this high-risk patient cohort, midseptal implantation of a leadless pacemaker as guided by RAO, LAO, and left lateral views was achieved in 90% of patients, with a low risk of complications.