Factors of mortality in patients with cardiac implantable electronic device: 5-year experience.

OBJECTIVE: The use of cardiac implantable electronic devices has increased in recent years. It has also brought some issues. Among these, the complications of cardiac implantable electronic devices infection and pocket hematoma are difficult to manage. It can be fatal with the contribution of patient-related risk factors. In this study, we aimed to find mortality rates in patients who developed cardiac implantable electronic devices infection and pocket hematoma over 5 years. We also investigated the risk factors affecting mortality in patients with cardiac implantable electronic devices. METHODS: A total of 288 cardiac implantable electronic devices patients were evaluated. Demographic details, history, and clinical data of all patients were recorded. Cardiac implantable electronic devices infection was defined according to the modified Duke criteria. The national registry was used to ascertain the mortality status of the patients. The patients were divided into two groups (exitus and survival groups). In addition, the pocket hematoma was defined as significant bleeding at the pocket site after cardiac implantable electronic devices placement. RESULTS: The cardiac implantable electronic devices infection was similar in both groups (p=0.919), and the pocket hematoma was higher in the exitus group (p=0.019). The exitus group had higher usage of P2Y12 inhibitors (p≤0.001) and novel oral anticoagulants (p=0.031). The Cox regression analysis, including mortality-related factors, revealed that renal failure is the most significant risk factor for mortality. Renal failure was linked to a 2.78-fold higher risk of death. CONCLUSION: No correlation was observed between cardiac implantable electronic devices infection and mortality, whereas pocket hematoma was associated with mortality. Furthermore, renal failure was the cause of the highest mortality rate in patients with cardiac implantable electronic devices.

Forensic perspectives on postmortem CIED interrogation: A systematic review and meta-analysis.

BACKGROUND: Cardiac implantable electronic devices (CIED) are a heterogeneous group of medical devices with increasingly sophisticated diagnostic capabilities, which could be exploited in forensic investigations. However, current guidelines are lacking clear recommendations on the topic. The first aim of this systematic review is to provide an updated assessment of the role of postmortem CIED interrogation, and to give practical recommendations, which can be used in daily practice. Secondly, the authors aim to determine the rates of postmortem CIED interrogation and autopsy investigations, the type of final rhythm detected close to death (with a focus on the significance of documented arrhythmias), as well as the role of postmortem CIED interrogation in the determination of final cause/time of death, and any potentially fatal device malfunctions. METHODS: A systematic search in MEDLINE and Scopus aiming to identify reports concerning postmortem human CIED interrogation was performed, including a systematic screening of reference lists. Case reports, letters to the editors, commentaries, review articles or guidelines were excluded, along with studies related to cardiac devices other than CIED. All data were pooled and analyzed using fixed-effects meta-analysis models, and the I2 statistic was used to assess heterogeneity. RESULTS: A total of 25 articles were included in the systematic review, enrolling 3194 decedent CIED carriers. Ten studies (40%) had a 100% autopsy rate, whereas in further 6 studies autopsy findings were variably reported; CIED interrogation was available from 22 studies (88%), and it was never performed prior to autopsy. The overall rate of successful postmortem CIED interrogation was 89%, with high heterogeneity among studies, mainly due to device deactivation/battery discharge. Twenty-four percent of CIED carriers experienced sudden cardiac death (SCD), whereas non-sudden cardiac and non-cardiac death (NSCD, NCD) were reported in 37% and 30% of decedents, respectively. Ventricular tachyarrhythmias were recorded in 34% of overall successfully interrogated CIED, and in 62% of decedents who experienced a SCD; of all ventricular tachyarrhythmias recorded, 40% was found in NSCD or NCD. A clear interpretation of the etiological role of recorded arrhythmias in the causation of death required integration with autopsy findings. Overall, potentially fatal device malfunctions were detected in 12% of cases. CONCLUSIONS: Postmortem CIED interrogation is a valuable tool for the determination of the cause of death, and may complement autopsy. Forensic pathologists need to know the potential utility, pitfalls, and limitations of this diagnostic examination to make this tool as much reliable as possible.

Long-term stimulation by implanted pacemaker enables non-atrophic treatment of bilateral vocal fold paresis in a human-like animal model.

A wide variety of treatments have been developed to improve respiratory function and quality of life in patients with bilateral vocal fold paresis (BVFP). One experimental method is the electrical activation of the posterior cricoarytenoid (PCA) muscle with a laryngeal pacemaker (LP) to open the vocal folds. We used an ovine (sheep) model of unilateral VFP to study the long-term effects of functional electrical stimulation on the PCA muscles. The left recurrent laryngeal nerve was cryo-damaged in all animals and an LP was implanted except for the controls. After a reinnervation phase of six months, animals were pooled into groups that received either no treatment, implantation of an LP only, or implantation of an LP and six months of stimulation with different duty cycles. Automated image analysis of fluorescently stained PCA cross-sections was performed to assess relevant muscle characteristics. We observed a fast-to-slow fibre type shift in response to nerve damage and stimulation, but no complete conversion to a slow-twitch-muscle. Fibre size, proportion of hybrid fibres, and intramuscular collagen content were not substantially altered by the stimulation. These results demonstrate that 30 Hz burst stimulation with duty cycles of 40% and 70% did not induce PCA atrophy or fibrosis. Thus, long-term stimulation with an LP is a promising approach for treating BVFP in humans without compromising muscle conditions.

Third-Degree Atrioventricular Block And Asystole After Lung Resection: A Rare Complication.

Surgical resection remains the optimal therapeutic option for early-stage operable NSCLC. Despite significant advances in recent years related to anesthetic and surgical techniques, cardiopulmonary complications remain major causes for postoperative morbimortality. In this paper we present a case of a patient who developed complete AV block followed by asystole after lung resection surgery. The patient underwent surgery via right VATS and the procedure was uneventful.  On the first post-operative day patient developed a third-degree atrioventricular block followed by 6 seconds asystole. Pharmacological treatment was instituted and implementation of a permanent pacemaker occurred on the third post-operative day, without complications. The remaining postoperative course was uneventful and the patient was discharged home on the sixth post-operative day. It is the objective of the authors to report and highlight this rare and potencial fatal complication of lung resection.

Factors Associated with the Treatment Costs within the First Year after Pacemaker Implantation or Pulse Generator Replacement. / Fatores Associados aos Custos do Tratamento no Primeiro Ano após Implantes Iniciais ou Trocas de Geradores de Pulsos de Marca-passos Cardíacos.

BACKGROUND: The use of artificial cardiac pacemakers has grown steadily in line with the aging population. OBJECTIVES: To determine the rates of hospital readmissions and complications after pacemaker implantation or pulse generator replacement and to assess the impact of these events on annual treatment costs from the perspective of the Unified Health System (SUS). METHODS: A prospective registry, with data derived from clinical practice, collected during index hospitalization and during the first 12 months after the surgical procedure. The cost of index hospitalization, the procedure, and clinical follow-up were estimated according to the values reimbursed by SUS and analyzed at the patient level. Generalized linear models were used to study factors associated with the total annual treatment cost, adopting a significance level of 5%. RESULTS: A total of 1,223 consecutive patients underwent initial implantation (n=634) or pulse generator replacement (n=589). Seventy episodes of complication were observed in 63 patients (5.1%). The incidence of hospital readmissions within one year was 16.4% (95% CI 13.7% - 19.6%) after initial implants and 10.6% (95% CI 8.3% - 13.4%) after generator replacements. Chronic kidney disease, history of stroke, length of hospital stays, need for postoperative intensive care, complications, and hospital readmissions showed a significant impact on the total annual treatment cost. CONCLUSIONS: The results confirm the influence of age, comorbidities, postoperative complications, and hospital readmissions as factors associated with increased total annual treatment cost for patients with pacemakers.

FUNDAMENTO: O uso de marca-passos cardíacos artificiais tem crescido constantemente, acompanhando o envelhecimento populacional. OBJETIVOS: Determinar as taxas de readmissões hospitalares e complicações após implante de marca-passo ou troca de gerador de pulsos e avaliar o impacto desses eventos nos custos anuais do tratamento sob a perspectiva do Sistema Único de Saúde (SUS). MÉTODOS: Registro prospectivo, com dados derivados da prática clínica assistencial, coletados na hospitalização índice e durante os primeiros 12 meses após o procedimento cirúrgico. O custo da hospitalização índice, do procedimento e do seguimento clínico foram estimados de acordo com os valores reembolsados pelo SUS e analisados ao nível do paciente. Modelos lineares generalizados foram utilizados para estudar fatores associados ao custo total anual do tratamento, adotando-se um nível de significância de 5%. RESULTADOS: No total, 1.223 pacientes consecutivos foram submetidos a implante inicial (n= 634) ou troca do gerador de pulsos (n= 589). Foram observados 70 episódios de complicação em 63 pacientes (5,1%). A incidência de readmissões hospitalares em um ano foi de 16,4% (IC 95% 13,7% - 19,6%) após implantes iniciais e 10,6% (IC 95% 8,3% - 13,4%) após trocas de geradores. Doença renal crônica, histórico de acidente vascular encefálico, tempo de permanência hospitalar, necessidade de cuidados intensivos pós-operatórios, complicações e readmissões hospitalares mostraram um impacto significativo sobre o custo anual total do tratamento. CONCLUSÕES: Os resultados confirmam a influência da idade, comorbidades, complicações pós-operatórias e readmissões hospitalares como fatores associados ao incremento do custo total anual do tratamento de pacientes com marca-passo.

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.

Stepwise transvenous lead extraction due to pacemaker pocket infection following lactational mastitis complicated with breast abscess.

BACKGROUND: Lactational mastitis is a common painful and debilitating inflammation of breast tissue, generally treated conservatively or with pus puncture in case of breast abscess. However, treating mastitis in patients with implantable surgical material located in the affected breast region can be extremely challenging. We present an unusual case of lactational mastitis complicated by pacemaker pocket infection in a breastfeeding mother. CASE PRESENTATION: A 35-year-old pacemaker-dependent female developed lactational mastitis seven weeks postpartum. Initially, the condition was treated conservatively with analgesics and antibiotics. After abscess formation, pus was aspirated using fine-needle aspiration technique. Four weeks after mastitis resolution, pacemaker pocket infection developed. According to current cardiovascular implantable electronic device infection treatment guidelines a complete surgical extraction of the entire electronic system, followed by targeted antibiotic treatment and reimplantation of a new device after infection resolution, was recommended. However, after thorough discussion with the young woman and her family and after detailed review of surgery-related risks, she declined a potentially high-risk surgical procedure. Thus, only the pulse generator was explanted; pacing leads positioned in the sub-pectoral pocket; new pacemaker implanted on the contralateral side and broad-spectrum antibiotic therapy continued for six weeks. After breastfeeding cessation, and with chronic fistula development at the primary pacemaker implantation site, the possibility of delayed surgical intervention including complete extraction of retained pacemaker leads was again thoroughly discussed with her. After thoughtful consideration the woman consented to the proposed treatment strategy. A surgical procedure including transvenous lead extraction through the primary implantation venous entry site, using hand-powered bidirectional rotational sheaths, was successfully performed, removing all retained leads through the left subclavian venous entry site, and leaving the fully functional and clinically uninfected pacemaker on the contralateral site intact. CONCLUSION: Although patients' decisions for delayed extraction in a case of cardiovascular implantable electronic device infection should be discouraged by attending physicians and members of interdisciplinary teams, our case shows that a stepwise treatment strategy may be successful as a bailout clinical scenario in patients with specific requests, demands and / or clinical needs.

Permanent Pacemaker Implantation and Long-Term Outcomes of Patients Undergoing Concomitant Mitral and Tricuspid Valve Surgery.

BACKGROUND: Tricuspid valve annuloplasty (TA) during mitral valve repair (MVr) is associated with increased risk of permanent pacemaker (PPM) implantation, but the magnitude of risk and long-term clinical consequences have not been firmly established. OBJECTIVES: This study assesses the incidence rates of PPM implantation after isolated MVr and following MVr with TA as well as the associated long-term clinical consequences of PPM implantation. METHODS: State-mandated hospital discharge databases of New York and California were queried for patients undergoing MVr (isolated or with concomitant TA) between 2004 and 2019. Patients were stratified by whether or not they received a PPM within 90 days of index surgery. After weighting by propensity score, survival, heart failure hospitalizations (HFHs), endocarditis, stroke, and reoperation were compared between patients with or without PPM. RESULTS: A total of 32,736 patients underwent isolated MVr (n = 28,003) or MVr + TA (n = 4,733). Annual MVr + TA volumes increased throughout the study period (P < 0.001, trend), and PPM rates decreased (P < 0.001, trend). The incidence of PPM implantation <90 days after surgery was 7.7% for MVr and 14.0% for MVr + TA. In 90-day conditional landmark-weighted analyses, PPMs were associated with reduced long-term survival among MVr (HR: 1.96; 95% CI: 1.75-2.19; P < 0.001) and MVr + TA recipients (HR: 1.65; 95% CI: 1.28-2.14; P < 0.001). In both surgical groups, PPMs were also associated with an increased risk of HFH (HR: 1.56; 95% CI: 1.27-1.90; P < 0.001) and endocarditis (HR: 1.95; 95% CI: 1.52-2.51; P < 0.001), but not with stroke or reoperation. CONCLUSIONS: Compared to isolated MVr, adding TA to MVr was associated with a higher risk of 90-day PPM implantation. In both surgical groups, PPM implantation was associated with an increase in mortality, HFH, and endocarditis.

Infective Endocarditis Involving Implanted Cardiac Electronic Devices: JACC Focus Seminar 1/4.

Cardiac implantable electronic device-related infective endocarditis (CIED-IE) encompasses a range of clinical syndromes, including valvular, device lead, and bloodstream infections. However, accurately diagnosing CIED-IE remains challenging owing in part to diverse clinical presentations, lack of standardized definition, and variations in guideline recommendations. Furthermore, current diagnostic modalities, such as transesophageal echocardiography and [18F]-fluorodeoxyglucose positron emission tomography-computed tomography have limited sensitivity and specificity, further contributing to diagnostic uncertainty. This can potentially result in complications and unnecessary costs associated with inappropriate device extraction. Six hypothetical clinical cases that exemplify the diverse manifestations of CIED-IE are addressed herein. Through these cases, we highlight the importance of optimizing diagnostic accuracy and stewardship, understanding different pathogen-specific risks for bloodstream infections, guiding appropriate device extraction, and preventing CIED-IE, all while addressing key knowledge gaps. This review both informs clinicians and underscores crucial areas for future investigation, thereby shedding light on this complex and challenging syndrome.

Acute Mitral Valve Regurgitation Caused by Left Ventricular Pacing Wire During Transcatheter Aortic Valve Replacement.

Transcatheter aortic valve replacement is quickly becoming the standard of care for patients with severe aortic stenosis thanks to its minimally invasive nature and favorable outcomes. Recently, left ventricular pacing has been proposed as a safer alternative to traditional right heart pacing, which could simplify the transcatheter aortic valve replacement procedure overall, although procedural complications may still occur. This report describes a rare case of left ventricular pacing wire-induced acute severe mitral valve regurgitation during transcatheter aortic valve replacement.

Transient 2:1 Atrioventricular Block with Peri-Conduction System Pacing After Leadless Pacemaker Implantation.

This report discusses a case of transient 2:1 atrioventricular block with conduction system pacing 4 hours after leadless right ventricular pacemaker implantation in a 19-year-old patient with a history of cardioinhibitory syncope and asystole cardiac arrest but without preexisting atrioventricular block. The atrioventricular block was resolved spontaneously. Pacing morphology was suggestive of right bundle branch pacing. Neither 2:1 atrioventricular block nor conduction system pacing has previously been a reported outcome of right ventricular leadless pacemaker implantation. The report demonstrates that conduction system pacing with leadless devices is achievable. Further study of techniques, limitations, and complications related to intentional right ventricular leadless conduction system pacing is warranted.

Cardiac implantable electronic device-induced tricuspid regurgitation: Implications and management.

Tricuspid regurgitation (TR) secondary to cardiac implantable electronic devices (CIEDs) has been well documented and is associated with worse cardiovascular outcomes. A variety of mechanisms have been proposed including lead-induced mechanical disruption of the tricuspid valvular or subvalvular apparatus and pacing-induced electrical dyssynchrony. Patient characteristics such as age, sex, baseline atrial fibrillation, and pre-existing TR have not been consistent predictors of CIED-induced TR. While two-dimensional echocardiography is helpful in assessing the severity of TR, three-dimensional echocardiography has significantly improved accuracy in identifying the etiology of TR and whether lead position contributes to TR. Three-dimensional echocardiography may therefore play a future role in optimizing lead positioning during implant to reduce the risk of CIED-induced TR. Optimal lead management strategies in addition to percutaneous interventions and surgery in alleviating TR are very important.

Prediction of pacemaker-induced cardiomyopathy using a convolutional neural network based on clinical findings prior to pacemaker implantation.

Risk factors for pacemaker-induced cardiomyopathy (PICM) have been previously reported, including a high burden of right ventricular pacing, lower left ventricular ejection fraction, a wide QRS duration, and left bundle branch block before pacemaker implantation (PMI). However, predicting the development of PICM remains challenging. This study aimed to use a convolutional neural network (CNN) model, based on clinical findings before PMI, to predict the development of PICM. Out of a total of 561 patients with dual-chamber PMI, 165 (mean age 71.6 years, 89 men [53.9%]) who underwent echocardiography both before and after dual-chamber PMI were enrolled. During a mean follow-up period of 1.7 years, 47 patients developed PICM. A CNN algorithm for prediction of the development of PICM was constructed based on a dataset prior to PMI that included 31 variables such as age, sex, body mass index, left ventricular ejection fraction, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left atrial diameter, severity of mitral regurgitation, severity of tricuspid regurgitation, ischemic heart disease, diabetes mellitus, hypertension, heart failure, New York Heart Association class, atrial fibrillation, the etiology of bradycardia (sick sinus syndrome or atrioventricular block) , right ventricular (RV) lead tip position (apex, septum, left bundle, His bundle, RV outflow tract), left bundle branch block, QRS duration, white blood cell count, haemoglobin, platelet count, serum total protein, albumin, aspartate transaminase, alanine transaminase, estimated glomerular filtration rate, sodium, potassium, C-reactive protein, and brain natriuretic peptide. The accuracy, sensitivity, specificity, and area under the curve of the CNN model were 75.8%, 55.6%, 83.3% and 0.78 respectively. The CNN model could accurately predict the development of PICM using clinical findings before PMI. This model could be useful for screening patients at risk of developing PICM, ensuring timely upgrades to physiological pacing to avoid missing the optimal intervention window.

Postoperative Atrioventricular Block in Pediatric Patients: Impact of Congenital Cardiac Malformations and Medications.

Postoperative atrioventricular block may occur after pediatric cardiac surgery. A small proportion of those who develop atrioventricular block will require pacemaker placement. The primary aim of this study was to determine factors associated with postoperative atrioventricular block. Secondary aims included determining factors associated with pacemaker placement in those with atrioventricular block. Data from the PHIS data were utilized to identify patients under 18 years of age who underwent cardiac surgery. Those who did and did not develop atrioventricular block. Univariable analyses and regression analyses were conducted to determine factors associated with postoperative atrioventricular block. Similar analyses were conducted to determine factors associated with pacemaker placement in those with atrioventricular block. A total of 43,716 admissions were identified. Of these, 2093 (5%) developed atrioventricular block and 480 (1% of total admissions) underwent pacemaker placement. Approximately 70% of those with atrioventricular block received steroids but this was not associated with a decrease in pacemaker placement. Risk factors (congenital malformations of the heart, comorbidities, medications) associated with increased risk of atrioventricular block and pacemaker placement were identified. Postoperative atrioventricular block occurred in 5% of pediatric admissions for cardiac surgery. Of these admissions with postoperative atrioventricular block, 23% required pacemaker placement. Isoproterenol and steroids were not associated with a reduction in the likelihood of pacemaker placement.

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.

Flecainide causing elevated capture thresholds on pacemaker implantation.

Flecainide is a Vaughan Williams class 1c antiarrhythmic used to treat supraventricular and ventricular arrhythmias. It has been described as a rare cause for increased pacemaker capture thresholds. We describe a report of a patient, in her early 80s, presenting with tachy-brady syndrome on a background of permanent atrial fibrillation. She was treated with metoprolol and flecainide by her private cardiologist. Permanent right ventricular chamber pacing was recommended for her slow heart rate. At insertion of her single chamber pacemaker, she was noted to have elevated capture thresholds despite appropriate lead positioning. A flecainide level was elevated at 1.1 µg/mL, and it was subsequently ceased. This was associated with a rapid improvement in her capture threshold. Flecainide should be considered as a cause for elevated pacing thresholds at the time of implant. Particular care should be taken for at-risk groups such as the elderly and patients with renal impairment.

Leadless pacemakers at 5-year follow-up: the Micra transcatheter pacing system post-approval registry.

BACKGROUND AND AIMS: Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed. METHODS: All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models. RESULTS: 1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001). CONCLUSIONS: Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection.

Cardiovascular images: pacemaker-lead fracture and excessive coiling in a dog.

A seven-year-old male castrated Labrador Retriever presented emergently due to concern for pacemaker malfunction five years after successful transvenous pacemaker implantation to treat partial atrial standstill. On presentation, the dog's pulse rate was 30-50 beats per minute. An electrocardiogram showed no spontaneous atrial activity or paced ventricular activity. Pacemaker interrogation revealed an increased impedance of 7557 ohms, indicating a lead malfunction. Thoracic radiographs confirmed the lead was fractured and had excessive coiling. The transvenous pacing system was turned off, left in place, and an epicardial pacing system was implanted the following day. The dog was discharged with no perioperative complications. The dog eventually required escalated medical therapy for progressive cardiac disease and was euthanized two years after implantation of the replacement pacemaker. This manuscript illustrates a complete lead fracture and excessive lead coiling, which has not previously been detailed in veterinary medicine.