Sinus Node Dysfunction Triggered by Tonsillar Abscess: Effects of Vagal Nerve Compression.

BACKGROUND Compression of the vagus nerve by a pharyngeal mass is a well-documented condition that can result in sinus node dysfunction (SND). However, there is scarce literature on extrinsic vagal nerve compression from a tonsillar abscess. CASE REPORT A 59-year-old woman with a history of asthma and chronic throat discomfort presented to the Emergency Department with bradycardia, palpitations, and voice changes. Following a shellfish allergy hospitalization, an otolaryngology evaluation revealed an enlarged right tonsil, recommending tonsillectomy, but scheduling challenges persisted. The patient reported mild throat pain, dysphagia, hoarseness, rhinorrhea, and exertional dyspnea and was admitted for the evaluation of peritonsillar mass. She was found to be bradycardic with a heart rate of 47, with an electrocardiogram revealing SND. Albuterol and ipratropium nebulizers, as well as dexamethasone and pantoprazole, were initiated. With this treatment, the patient symptomatically improved with a new heart rate of 68. She was discharged with outpatient appointments, but was unfortunately lost to follow-up. CONCLUSIONS This case reveals sinus node dysfunction resulting from extrinsic vagal nerve compression by a tonsillar abscess. Pressure on the vagus nerve can trigger bradycardia and low blood pressure, possibly due to compensatory overfiring of afferent vagal nerve signals from local mass effect. Early recognition and antibiotic treatment are essential to prevent cardiac complications. Clinicians must remain vigilant for such extrinsic causes, particularly in patients with chronic sore throat and cardiac symptoms. Further research and case reports are needed to deepen our understanding of this rare yet significant association.

Lead Extraction and Baffle Stenting in a Patient with Transposition of the Great Arteries.

This case report discusses a 42-year-old male with dextro-transposition of the great arteries (D-TGA) status post Mustard repair and sick sinus syndrome status post dual-chamber pacemaker implant, who developed symptomatic superior vena cava (SVC) baffle stenosis. He was treated with a combined pacemaker extraction and subsequent SVC baffle stenting. The case highlights the complexities of treating SVC baffle stenosis in the presence of cardiac implantable devices and demonstrates the efficacy of this combined approach. Furthermore, the authors delve into the intricacies of D-TGA, its surgical history, and the long-term complications associated with atrial switch procedures.

Atrial fibrillation ablation compared to pacemaker therapy in patients with tachycardia-bradycardia syndrome: A systematic review and updated meta-analysis.

BACKGROUND: Tachycardia-bradycardia syndrome (TBS) is a subtype of sick sinus syndrome characterized by prolonged sinus pause (≥3 s) following termination of tachyarrhythmias, primarily atrial fibrillation (AF). There is controversy regarding whether the long-term prognosis of AF ablation is superior to pacemaker implantation. This study aimed to compare the effects of AF ablation and pacemaker therapy in patients with TBS. METHODS: We conducted a comprehensive search of electronic databases, including PubMed, Cochrane, EmBase, Web of Science, and Chinese BioMedical, up until December 1, 2023. We included studies that reported the effects of AF ablation vs pacemaker therapy in patients with TBS. From this search, we identified 5 studies comprising 843 participants with TBS who underwent catheter AF ablation or pacemaker therapy. RESULTS: Our meta-analysis revealed that AF ablation and pacemaker therapy had similar effects on cardiovascular death (odds ratio [OR] = 0.62 and 95% confidence interval [CI]: 0.14-2.65), procedural complications (OR = 1.53 and 95% CI: 0.67-3.48), and cardiovascular rehospitalization (OR = 0.57 and 95% CI: 0.26-1.22). However, AF ablation provided greater benefits than pacemaker therapy in terms of all-cause mortality (OR = 0.37 and 95% CI: 0.17-0.82), thromboembolism (OR = 0.25 and 95% CI: 0.12-0.49), stroke (OR = 0.28 and 95% CI: 0.13-0.57), heart failure (OR = 0.27 and 95% CI: 0.13-0.56), freedom from AF (OR = 23.32 and 95% CI: 7.46-72.92), and prevention of progression to persistent AF (OR = 0.12 and 95% CI: 0.06-0.24). Furthermore, AF ablation resulted in a reduced need for antiarrhythmic agents (OR = 0.21 and 95% CI: 0.08-0.59). CONCLUSION: AF ablation can effectively reduce the risk of all-cause mortality, thromboembolism, stroke, heart failure, and progression to persistent AF in patients with TBS. Additionally, it may eliminate the need for further pacemaker therapy in most cases after ablation. Therefore, AF ablation is considered superior to pacemaker therapy in the management of patients with TBS.

First in man right atrial appendage implantation of a Micra leadless pacemaker.

INTRODUCTION: Pacemaker implantation can be challenging in patients with congenital heart disease. METHODS AND RESULTS: In a patient with Ebstein disease and symptomatic sinus node dysfunction, despite multiple attempts, the Micra® pacemaker could not be implanted in the severely dilated right ventricle. In that context, and after iodine injection to confirm the appropriate location, the Micra® pacemaker was successfully implanted in the right appendage at the first attempt. CONCLUSION: Despite the recent development of dedicated dual-chamber leadless pacemaker, to the best of our knowledge, this case is the first off-label Micra® implantation in a right appendage.

Transvenous lead advancement in pediatric pacing to overcome growth-induced lead straightening and stretching.

BACKGROUND: The stretching of the lead caused by somatic growth may lead to complications (dislodgement, fracture, failure) of transvenous leads implanted in pediatric patients. Atrial loop and absorbable ligatures may prevent it. Periodical lead advancement with lead pushing from the pocket may be an option to growth-induced stretching. Our aim was to analyze retrospectively the outcome of periodical transvenous lead advancement in children with pacemaker (PM). METHODS: A procedure of lead advancement was performed in patients with a single-chamber PM implanted for isolated congenital complete atrioventricular block or sinus node dysfunction with growth-induced lead straightening/stretching. The PM pocket was opened, the lead was released from subcutaneous adherences and was gently advanced to shape again a loop/semi-loop in the atrium without dislodging the tip. Lead data (threshold, sensing, impedance) were compared before and after the procedure. Data are described as median (25th-75th centiles). RESULTS: 14 patients with 13 VVIR and 1 AAIR PM implanted at 6.8 (5.9-8.0) years of age, 23 (19-26) kg, 118 (108-124) cm, underwent 30 advancement procedures, 1.5 (1.0-2.3) per patient, during follow-up [45 (35-63) months]. Delta between procedures was: 18 (14-25) months, 11 (7-13) cm, 6 (4-9) kg; 90% of leads were successfully advanced without complications. Three unsuccessful procedures occurred with longer times [30 (14-37) months]. Electrical lead parameters did not show significant differences pre-/post-procedures. CONCLUSION: the advancement of transvenous leads in children seems safe and effective. This procedure may be another possible choice to preserve transvenous lead position and function until growth has completed.

Transvenous Pacemaker Placement: A Review for Emergency Clinicians.

BACKGROUND: Transvenous pacemaker placement is an integral component of therapy for severe dysrhythmias and a core skill in emergency medicine. OBJECTIVE: This narrative review provides a focused evaluation of transvenous pacemaker placement in the emergency department setting. DISCUSSION: Temporary cardiac pacing can be a life-saving procedure. Indications for pacemaker placement include hemodynamic instability with symptomatic bradycardia secondary to atrioventricular block and sinus node dysfunction; overdrive pacing in unstable tachydysrhythmias, such as torsades de pointes; and failure of transcutaneous pacing. Optimal placement sites include the right internal jugular vein and left subclavian vein. Insertion first includes placement of a central venous catheter. The pacing wire with balloon is then advanced until electromechanical capture is obtained with the pacer in the right ventricle. Ultrasound can be used to guide and confirm lead placement using the subxiphoid or modified subxiphoid approach. The QRS segment will demonstrate ST segment elevation once the pacing wire tip contacts the endocardial wall. If mechanical capture is not achieved with initial placement of the transvenous pacer, the clinician must consider several potential issues and use an approach to evaluating the equipment and correcting any malfunction. Although life-saving in the appropriate patient, complications may occur from central venous access, right heart catheterization, and the pacing wire. CONCLUSIONS: An understanding of transvenous pacemaker placement is essential for emergency clinicians.

Atrial Pacing Negatively Affects Left Atrial Morphological and Functional Parameters Similarly to Atrioventricular Dyssynchrony.

Background and Objectives: Atrioventricular (AV) dyssynchrony as well as atrial and ventricular pacing affect left atrial (LA) function. We conducted a study evaluating the effect of atrial and ventricular pacing on LA morphological and functional changes after dual-chamber pacemaker implantation. Materials and Methods: The study prospectively enrolled 121 subjects who had a dual-chamber pacemaker implanted due to sinus node disease (SND) or atrioventricular block (AVB). Subjects were divided into three groups based on indication and pacemaker programming: (1) SND DDDR 60; (2) AVB DDD 60 and (3) AVB DDD 40. Subjects were invited to one- and three-month follow-up visits. Three subsets based on pacing burden were analyzed: (1) high atrial (A) low ventricular (V); (2) high A, high V and (3) low A, high V. LA function was assessed from volumetric parameters and measured strains from echocardiography. Results: The high A, low V group consisted of 38 subjects; while high A, high V had 26 and low A, high V had 23. A significant decrease in reservoir and contractile LA strain parameters were only observed in the high A, low V pacing group after three months (reservoir 25.9 ± 10.3% vs. 21.1 ± 9.9%, p = 0.003, contractile -14.0 ± 9.0% vs. -11.1 ± 7.8, p = 0.018). While the re-established atrioventricular synchrony in the low A, high V group maintained reservoir LA strain at the baseline level after three months (21.4 ± 10.4% vs. 22.5 ± 10.4%, p = 0.975); in the high A, high V group, a further trend to decrease was noted (20.3 ± 8.9% vs. 18.7 ± 8.3%, p = 0.231). Conclusions: High atrial pacing burden independently of atrioventricular dyssynchrony and ventricular pacing impairs LA functional and morphological parameters. Changes appear soon after pacemaker implantation and are maintained.

The effectiveness and safety of temporary transvenous cardiac pacing leads placement into coronary sinus vein in patients with sick sinus syndrome.

BACKGROUND: The temporary pacing lead routinely is placed into right ventricular (RV), which pose a risk of dislocation and cardiac perforation. OBJECTIVE: We aim to evaluate the effectiveness and safety of temporary transvenous cardiac pacing (TTCP) leads placement into the coronary sinus vein (CSV) in patients with sick sinus syndrome (SSS). METHODS: We investigated patients with SSS who underwent TTCP lead placement into the CSV under the guidance of X-ray between January 2013 and May 2023. Patients were randomly divided into two groups: RV group (n = 33) and CSV group (n = 22). The ordinary passive bipolar electrodes were applied in both groups. In RV groups, electrodes were placed into RV. In CSV group, electrodes were placed into CSV. We evaluated the operation duration, fluoroscopic exposure, first-attempt success rate of leads placement, pacing threshold, success rate of leads placement, rate of leads displacement, and complications. RESULTS: Compared with that in RV group, the procedure time, fluoroscopic exposure was significantly prolonged, while the first-attempt success rate of lead placement was obviously increased in CSV group (both p < .05). Compared with that in RV group, the rate of leads displacement is lower in CSV group (both p < .05). There were three patients occurred cardiac perforation in RV group, but no cardiac perforation was reported in CSV group (p > .05). CONCLUSION: TTCP leads placement into the CSV is an effective and safe strategy in patients with SSS. It indicates a high rate of pacing effectiveness with low device replacement and complication rates.

Tachy-brady syndrome: Electrophysiology and evolving principles of management.

Sudden alterations in the heart rate may be associated with diverse symptoms. Sinus node dysfunction (SND), also known as sick sinus syndrome, is a sinoatrial (SA) node disorder. SND is primarily caused by the dysfunction of the pacemaker, as well as impaired impulse transmission resulting in a multitude of abnormalities in the heart rhythms, such as bradycardia-tachycardia, atrial bradyarrhythmias, and atrial tachyarrhythmias. The transition from bradycardia to tachycardia is generally referred to as "tachy-brady syndrome" (TBS). Although TBS is etiologically variable, the manifestations remain consistent throughout. Abnormal heart rhythms have the propensity to limit tissue perfusion resulting in palpitations, fatigue, lightheadedness, presyncope, and syncope. In this review, we examine the physiology of tachy-brady syndrome, the practical approach to its diagnosis and management, and the role of adenosine in treating SND.

Corrected sinus node recovery time as a screening test in patients with typical atrial flutter post-ablation to predict pacemaker implantation.

OBJECTIVE: The objective of the study was to establish the prognostic value of CSNRT regarding the necessity for pacemaker implantation in patients with atrial flutter (AFL) post-ablation. METHODS: This prospective cohort study, conducted at the National Institute of Cardiology "Ignacio Chavez" in Mexico City, assessed patients who had undergone ablation procedures to correct AFL, posterior to which an autonomic blockade was performed, and CSNRT was measured. RESULTS: The sample for this investigation was 40 patients. These were subdivided into two study groups depending on their requirement of pacemaker implant post-ablation (Pacemaker P, No Pacemaker NP). Sinus node (SN) dysfunction was diagnosed in 13 (32.5%) of the 40 participants, 10 (71.43%) of which required a pacemaker implant, while only 4 participants (28.57%) with normal SN function required pacemakers. Ten out of the 14 patients (71.43%) who required a pacemaker had an elevated CSNRT > 500 ms (p ≤ 0.01). Post-ablation CSNRT mean was 383.54 ms ± 67.96 ms in the NP group versus 1972.57 ms ± 3423.56 ms in the P group. Furthermore, SN pause in the P group had a mean of 1.86 s ± 0.96 s versus the NP group with 1.196 s ± 0.52 s. CONCLUSION: CSNRT has the potential to be a quantitative prognostic tool for the assessment of future pacemaker implants in patients with AFL post-ablation. This could aid in the timely diagnosis of sinus node dysfunction, which could, in the long run, result in the reduction of cardiac functional capacity loss due to cardiac remodeling.

OBJETIVO: Establecer el valor pronóstico del TRNSC basado en la necesidad de marcapasos en pacientes diagnosticados con aleteo atrial, pos-ablación. MÉTODOS: Este cohorte prospectivo, realizado en el Instituto Nacional de Cardiología "Ignacio Chávez" en la Ciudad de México, evaluó pacientes sometidos a ablación para corregir el aleteo atrial; se midió el TRNSC post bloqueo autonómico. RESULTADOS: La muestra de 40 pacientes se subdividió en 2 grupos según su requerimiento de marcapasos posterior a la ablación (P y NP). Se diagnosticó disfunción del nodo sinusal en 13 participantes (32.5%), de los cuales 10 (71.43%) requirieron marcapasos en comparación a 4 (28.57%) con función normal. En el grupo P la pausa del nodo sinusal post-ablación tuvo una media de 1.86 ± 0.96 s versus el grupo NP con 1.196 ± 0.52 s. En relación con el TRNSC, el grupo NP tuvo una media de 383.54 ± 67.96 ms vs. 1972.57 ± 3423.56 ms en el grupo P. 10 pacientes (25%) obtuvieron un TRNSC > 500 ms, de los cuales 100% requirieron marcapasos; de los 14 pacientes que requirieron marcapasos 10 (71.43%) tenían un TRNSC elevado (p ≤ 0.01). CONCLUSIONES: El TRNSC tiene el potencial de ser una herramienta de pronóstico cuantitativo para la necesidad de futuros implantes de marcapasos en pacientes con disfunción del nodo sinusal, resultado de aleteo atrial pos-ablación. Esto podría ayudar a diagnosticar más temprano una disfunción del nodo sinusal, resultando en la reducción de la pérdida a largo plazo de la función cardíaca como efecto de la remodelación.

Sinus node dysfunction and stroke risk: a systematic review and meta-analysis.

OBJECTIVES: The role of cardiac arrhythmia in ischaemic stroke is widely studied, but the size of the stroke risk in patients with sinus node dysfunction (SND) with and without atrial fibrillation (AF) is unclear. This systematic review and meta-analysis aimed to compare the risk of stroke and its associated factors in patients with SND with and without AF. DESIGN: A systematic review and meta-analysis was conducted based on the Grading of Recommendations, Assessment, Development and Evaluation approach. DATA SOURCES: PubMed, EMBASE and Cochrane Database were searched until December 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies that investigate stroke in patients with SND diagnosed with or without AF/atrial flutter. DATA EXTRACTION AND SYNTHESIS: Two independent authors screened studies for inclusion and extracted data. Literature quality assessment was performed using the Newcastle-Ottawa Scale and the Cochrane Collaboration Tool. The overall risk of stroke was estimated using the random-effects model. The generic inverse variance method was used to calculate the pooled estimates of stroke-associated factors. We performed a sensitivity analysis using a fixed-effects model. RESULTS: Of the 929 records retrieved, 6 papers (106 163 patients) met the inclusion criteria. The average yearly stroke incidence in patients with SND was 1.542% (95% CI: 1.334% to 1.749%). The stroke incidence was similar between the isolated SND (1.587%; 95% CI: 1.510% to 1.664%) and non-isolated (SND+AF) (1.660%; 95% CI: 0.705% to 2.615%) groups. AF (HR, 95% CI: 1.53 (1.01 to 2.33)), stroke/transient ischaemia attack/other thrombotic events (HR, 95% CI: 2.54 (1.14 to 5.69)), hypertension (HR, 95% CI: 1.51 (1.11 to 2.07)) and heart failure (HR, 95% CI: 1.41 (1.01 to 1.97)) were associated with stroke in the SND population. CONCLUSION: Our findings suggest that patients with SND carry a similar risk of stroke to those with combined SND and AF. Future studies are needed to investigate whether interventions targeting stroke prevention, such as anticoagulation therapy, can help to prevent stroke in patients with SND. PROSPERO REGISTRATION NUMBER: CRD42023408436.

Hospitalization for permanent pacemaker implantation in the context of isolated sinus node dysfunction is associated with increased mortality compared with an outpatient strategy.

BACKGROUND: Permanent pacemaker (PPM) implantation is a well-established treatment for symptomatic sinus node dysfunction (SND). The optimal timing of this intervention is unclear, with atrioventricular blocks often prioritized in resource stressed waiting lists due to mortality concerns. METHODS: Mortality data was compared between patients receiving elective outpatient (OP) PPM implantation, and those presenting to hospital for urgent inpatient (IP) management for symptomatic SND. Survival analysis was conducted using Kaplan-Meier plots and compared using the log-rank test. Univariable and multivariable Cox regression, as well as propensity score matching analyses were performed to assess the prognostic effect on 30-day and 1-year all-cause mortality of inpatient implant. RESULTS: Of the 1269 patients identified with isolated SND, 740 (58%) had PPMs implanted on an OP and 529 (42%) on an IP basis. Mortality was significantly worse in patients where management was driven by hospital admission on an urgent basis (Log-Rank χ2 = 21.6, p < 0.001) and remained an independent predictor of 1-year all-cause mortality (HR 3.40, 95% CI 1.97-5.86, p < 0.001) on multivariable analysis. CONCLUSIONS: SND is predominantly a disease associated with ageing and comorbid populations, where avoidance of deconditioning, hospitalization acquired infections, and polypharmacy is advantageous. Admission avoidance is therefore the preferable strategy.

Sick sinus syndrome diagnosed after a sinus arrest during treatment for zygomatic fracture: a case report.

BACKGROUND: Intraoperative sinus arrest is rarely seen during zygomatic fracture treatment. The patient was diagnosed with sick sinus syndrome based on repeated postoperative sinus arrest, which could have resulted in death if diagnosed late, making this case very significant to report. CASE PRESENTATION: Sick sinus syndrome is an arrhythmia associated with reduced automaticity of the sinoatrial node or impaired sinoatrial node conduction. We report the case of a 67-year-old man diagnosed with the syndrome after a sinus arrest that occurred during a zygomatic fracture treatment. The patient had cheek pain and mouth opening disorder, dizziness after fainting and sustaining a facial injury. Preoperative examination determined that the syncope was due to drug-induced arrhythmia, and surgery was authorized after drug withdrawal. During the operation, sinus arrest was observed due to trigeminal vagal reflex, and heart rate was restarted by stopping the operation and chest compressions. After the surgery, the patient showed symptoms of dizziness and palpitations, and sinus arrest following atrial fibrillation and supraventricular tachycardia, which was diagnosed as sick sinus syndrome, and a pacemaker was implanted. Currently, 8 years have passed since the surgery, and there are no symptoms of mouth opening disorder, dizziness, or palpitations. CONCLUSIONS: In the case of maxillofacial injuries due to syncope, cardiogenic syncope is a possibility, and repeated syncope is a risk for death due to delayed diagnosis. There are no reports of maxillofacial trauma leading to a diagnosis of sick sinus syndrome. The purpose of this case report is to disseminate the importance of diagnosing the cause of syncope as well as injury treatment.

Epicardial Versus Endocardial Pacing in Paediatric Patients with Atrioventricular Block or Sinus Node Dysfunction: A Systematic Review and Meta-analysis.

Pacing indications in children are clearly defined, but whether an epicardial (EPI) or an endocardial (ENDO) pacemaker performs better remains to be elucidated. This systematic review and meta-analysis aimed to directly compare the incidence of pacemaker (PM) lead-related complications, mortality, hemothorax and venous occlusion between EPI and ENDO in children with atrioventricular block (AVB) or sinus node dysfunction (SND). Literature search was conducted in MEDLINE (via PubMed), Scopus by ELSEVIER, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and OpenGrey databases until June 25, 2022. Random-effects meta-analyses were performed to assess the pacing method's effect on lead failure, threshold rise, post-implantation infection and battery depletion and secondarily on all-cause mortality, hemothorax and venous occlusion. Several sensitivity analyses were also performed. Of 22 studies initially retrieved, 18 were deemed eligible for systematic review and 15 for meta-analysis. Of 1348 pediatric patients that underwent EPI or ENDO implantation, 542 (40.2%) had a diagnosis of congenital heart disease (CHD). EPI was significantly associated with higher possibility of PM-lead failure [pooled odds ratio (pOR) 3.00, 95% confidence interval (CI) 2.05-4.39; I2 = 0%]; while possibility for threshold rise, post-implantation infection and battery depletion did not differ between the PM types. Regarding the secondary outcome, the mortality rates between EPI and ENDO did not differ. In sensitivity analyses the results were consistent results between the two PM types. The findings suggest that EPI may be associated with increased PM-lead failure compared to ENDO while threshold rise, infection, battery depletion and mortality rates did not differ.

Incidence and predictors of pacemaker implantation at follow-up after reversible high-degree sinus node dysfunction or atrioventricular block.

BACKGROUND: A pacemaker implantation is not indicated in cases of reversible high-degree symptomatic sinus node dysfunction (SND) and atrioventricular block (AVB). However, it remains uncertain whether these reversible automaticity/conduction disorders may recur in some patients at follow-up, in the absence of reversible cause. This retrospective study aimed to determine the incidence and predictive factors of permanent pacemaker (PPM) implantation at follow-up and after reversible high-degree SND/AVB. METHODS: Based on medical electronic files codes, we identified patients who were hospitalized in our cardiac intensive care unit between January 2003 and December 2020 due to reversible high-degree SND/AVB and who were discharged from the hospital alive and without PPM implantation. Acute myocardial infarction and post-cardiac surgery patients were excluded. We categorized the patients according to the need for PPM at follow-up due to non-reversible high-degree SND/AVB. RESULTS: Of the 93 patients included, 26 patients (28%) were readmitted for PPM implantation at follow-up after hospital discharge. Among baseline characteristics, compared with patients who did not have high-degree SND/AVB recurrence, those who had subsequent PPM implantation had less frequent previous hypertension (70% vs. 46%, p = .031). Regarding the initial causes of reversible SND/AVB, isolated hyperkalemia was found more often in the patients readmitted for PPM (19% vs. 3% vs. p = .017). Moreover, recurrence of high-degree SND/AVB was significantly associated with the presence of intraventricular conduction disorders (either bundle branch block or left bundle branch hemiblock) on ECG at discharge (36% in patients without PPM vs. 68% in PPM patients, p = .012). CONCLUSION: Almost one third of the patients discharged alive from the hospital after a reversible high-degree SND/AVB needed a pacemaker implantation at follow-up. Complete bundle branch block or left bundle branch hemiblock on discharge ECG after recovery of atrioventricular conduction and/or sinus automaticity was associated with a greater risk of recurrence leading to pacemaker implantation.

Sinus Node Dysfunction.

Sinus node dysfunction (SND) is a multifaceted disorder most prevalent in older individuals, but may also occur at an earlier age. In most cases, the SND diagnosis is ultimately established by documenting its ECG manifestations. EPS has limited utility. The treatment strategy is largely dictated by symptoms and ECG manifestations. Not infrequently, both bradycardia and tachycardia coexist in the same patients, along with other diseases common in the elderly (e.g., hypertension, coronary artery disease), thereby complicating treatment strategy. Prevention of the adverse consequences of both bradyarrhythmia and tachyarrhythmia is important to reduce susceptibility to syncope, falls, and thromboembolic complications.

Permanent single-chamber atrial pacing: an obsolete or viable alternative to dual-chamber pacing in selected patients with sinus node disease?

INTRODUCTION: Single atrial stimulation (AAI) has been commonly used for permanent pacing in sick sinus syndrome and significant bradycardia. OBJECTIVE: The study aimed to evaluate long­term AAI pacing and to identify timing and reasons for pacing mode change. PATIENTS AND METHODS: Retrospectively, we included 207 patients (60% women) with initial AAI pacing, who were followed­up for an average of 12 years. RESULTS: At the time of death or loss to follow­up, 71 patients (34.3%) had unchanged AAI pacing mode. The reason for an upgrade of the pacing system was development of atrial fibrillation (AF) in 43 patients (20.78%) and atrioventricular block (AVB) in 34 patients (16.4%). The cumulative ratio for a pacemaker upgrade reoperation reached 2.77 per 100 patient­years of the follow­up. Cumulative ventricular pacing below 10% after an upgrade to dual­chamber pacemaker was observed in 28.6% of the patients. Younger age at implant was the leading independent predictor of the change to dual­chamber simulation (hazard ratio, 1.98; 95% CI, 1.976-1.988; P = 0.001). There were 11 (5%) lead malfunctions that required reoperation. Subclavian vein occlusion was noted in 9 upgrade procedures (11%). One cardiac device-related infection was observed. CONCLUSIONS: The reliability of AAI pacing decreases with each year of observation due to development of AF and AVB. However, in the current era of effective AF treatment, the advantages of AAI pacemakers, such as lower incidence of lead malfunction, venous occlusion, and infection, as compared with dual-chamber pacemakers, may make AAI pacemakers a viable option.

Outcomes in orthotopic heart transplantation following pacemaker implantation.

BACKGROUND: Bradyarrhythmias including sinus node dysfunction (SND) and atrioventricular block (AVB) can necessitate pacemaker (PPM) implantation in orthotopic heart transplant (OHT) recipients. Prior studies have shown conflicting findings regarding the effect of PPM implantation on survival. We evaluated the effect of PPM indication on long-term re-transplant-free survival in OHT patients. METHODS: We conducted a retrospective cohort study of OHT patients at UCLA Medical Center from 1985 to 2018. Indication for PPM (SND, AVB) was identified. Cox proportional hazards model with pacemaker implantation as a time-varying covariate was used to evaluate its effect on the primary endpoint of retransplant or death. We included 1609 OHTs in 1511 adult patients with median follow-up of 12 years. RESULTS: At transplant, patients were aged 53 ± 13 years and 1125 (74.5%) were male. Pacemakers were implanted in 109 (7.2%) patients; 65 for SND (4.3%) and 43 for AVB (2.8%). Repeat OHT was performed in 103 (6.4%) cases and 798 (52.8%) patients died during the follow-up period. The risk of the primary endpoint was significantly higher in patients requiring PPM for AVB (HR 3.0, 95% CI 2.1-4.2, p < .01) after controlling for age at OHT, gender, hypertension, diabetes, renal disease, history of repeat OHT, acute rejection, transplant coronary vasculopathy, and atrial fibrillation, but not PPM for SND (HR 1.0, 95% CI 0.70-1.4, p = 1.0). CONCLUSIONS: Patients who required PPM for AVB, but not SND, were at significantly higher risk of death or retransplant compared to patients who did not require PPM.

Association between sick sinus syndrome and atrial fibrillation: A systematic review and meta-analysis.

AIMS: Sick sinus syndrome (SSS) and atrial fibrillation (AF) frequently coexist and show a bidirectional relationship. This systematic review and meta-analysis aimed to decipher the precise relationship between SSS and AF, further exploring and comparing different therapy strategies on the occurrence or progression of AF in patients with SSS. METHODS AND RESULTS: A systematic literature search was conducted until November 2022. A total of 35 articles with 37,550 patients were included. Patients with SSS were associated with new-onset AF compared to those without SSS. Catheter ablation was associated with a lower risk of AF recurrence, AF progression, all-cause mortality, stroke and hospitalization of heart failure compared to pacemaker therapy. Regarding the different pacing strategies for SSS, VVI/VVIR has higher risk of new-onset AF than DDD/DDDR. No significant difference was found between AAI/AAIR and DDD/DDDR, as well as between DDD/DDDR and minimal ventricular pacing (MVP) for AF recurrence. AAI/AAIR was associated with higher risk of all-cause mortality when compared to DDD/DDDR, but lower risk of cardiac death when compared to DDD/DDDR. Right atrial septum pacing was associated with a similar risk of new-onset AF or AF recurrence compared to right atrial appendage pacing. CONCLUSION: SSS is associated with a higher risk of AF. For patients with both SSS and AF, catheter ablation should be considered. This meta-analysis re-emphasizes that high percentage of ventricular pacing should be avoided in patients with SSS in order to decrease AF burden and mortality.