Ion channel dysfunction and fibrosis in atrial fibrillation: Two sides of the same coin.

BACKGROUND: Atrial fibrillation (AF) is a common heart rhythm disorder that is associated with an increased risk of stroke and heart failure (HF). Initially, an association between AF and ion channel dysfunction was identified, classifying the pathology as a predominantly electrical disease. More recently it has been recognized that fibrosis and structural atrial remodeling play a driving role in the development of this arrhythmia also in these cases. PURPOSE: Understanding the role of fibrosis in genetic determined AF could be important to better comprise the pathophysiology of this arrhythmia and to refine its management also in nongenetic forms. In this review we analyze genetic and epigenetic mechanisms responsible for AF and their link with atrial fibrosis, then we will consider analogies with the pathophysiological mechanism in nongenetic AF, and discuss consequent therapeutic options.

Cardiac resynchronization therapy: present and future.

Cardiac resynchronization therapy (CRT) via biventricular pacing (BVP) is a well-established therapy for patients with heart failure with reduced ejection fraction and left bundle branch block, who remain symptomatic despite optimal medical therapy. Despite the long-standing clinical evidence, as well as the familiarity of cardiac electrophysiologists with the implantation technique, CRT via BVP cannot be achieved or may result ineffective in up to one-third of the patients. Therefore, new alternative techniques, such as conduction system pacing and left ventricular pacing, are emerging as potential alternatives to this technique, not only in case of BVP failure, but also as a stand-alone first choice due to several potential advantages over traditional CRT. Specifically, due to its procedural characteristics, left bundle branch area pacing appears to be the most convincing technique, showing comparable efficacy outcomes when compared with traditional CRT, not increasing short-term device-related complications, as well as improving procedural times. However, transvenous leads remain a major limitation of all these pacing modalities. To overcome this limit, a leadless left ventricular endocardial pacing has been developed as an additional tool to achieve a left endocardial activation, although being still associated with non-negligible pitfalls, limiting its current use in clinical practice. This article focuses on the current state and latest progresses in cardiac resynchronization therapy.

Lead-related infective endocarditis with vegetations: Prevalence and impact of pulmonary embolism in patients undergoing transvenous lead extraction.

INTRODUCTION: The prevalence and impact of pulmonary embolism (PE) in patients with lead-related infective endocarditis undergoing transvenous lead extraction (TLE) are unknown. METHODS: Twenty-five consecutive patients with vegetations ≥10 mm at transoesophageal echocardiography were prospectively studied. Contrast-enhanced chest computed tomography (CT) was performed before (pre-TLE) and after (post-TLE) the lead extraction procedure. RESULTS: Pre-TLE CT identified 18 patients (72%) with subclinical PE. The size of vegetations in patients with PE did not differ significantly from those without (median 20.0 mm [interquartile range: 13.0-30.0] vs. 14.0 mm [6.0-18.0], p = 0.116). Complete TLE success was achieved in all patients with 3 (2-3) leads extracted per procedure. There were no postprocedure complications related to the presence of PE and no differences in terms of fluoroscopy time and need for advanced tools. In the group of positive pre-TLE CT, post-TLE scan confirmed the presence of silent PE in 14 patients (78%). There were no patients with new PE formation. Large vegetations (≥20 mm) tended to increase the risk of post-TLE subclinical PE (odds ratio 5.99 [95% confidence interval (CI): 0.93-38.6], p = 0.059). During a median 19.4 months follow-up, no re-infection of the implanted system was reported. Survival rates in patients with and without post-TLE PE were similar (hazard ratio: 1.11 [95% CI: 0.18-6.67], p = 0.909). CONCLUSION: Subclinical PE detected by CT was common in patients undergoing TLE with lead-related infective endocarditis and vegetations but was not associated with the complexity of the procedure or adverse outcomes. TLE procedure seems safe and feasible even in patients with large vegetations.

Hybrid transvenous and surgical approach for the extraction of coronary sinus leads: A case series.

BACKGROUND: Transvenous lead extraction is the standard therapy for cardiac device-related infection. In some patients, however, a hybrid surgical and transvenous approach may be necessary. METHODS AND RESULTS: We present three cases who underwent transvenous lead extraction for an infected CRT-D system. In all cases the CS lead could not be retrieved transvenously due to extensive fibrosis. The lead was successfully extracted through left minithoracotomy in two patients and midline sternotomy in one patient. CONCLUSION: In cases where the coronary sinus lead shows severe fibrosis, a transvenous approach can be used to free the proximal part of the lead, while the distal adhesions can be removed surgically through a limited thoracic incision.

Leadless pacemakers as a new alternative for pacemaker lead-related superior vena cava syndrome: A case report.

Superior vena cava (SVC) syndrome is a rare disease induced by thrombosis and consequent occlusion of SVC, negatively affecting morbidity and mortality. The incidence of SVC syndrome from central venous catheters and pacemaker or defibrillator leads is increasing. Optimal treatment of pacemaker or defibrillator-related SVC syndrome is not well defined. Lead extraction causes mechanical trauma to the vessel wall. In addition, subsequent device implantation on the contralateral side can be an added factor for venous occlusion. The use of leadless pacemakers could be an interesting option to reduce the risk of SVC restenosis after lead extraction. We report a clinical case of PM leads-related SVC syndrome referred to our centers and treated with transvenous lead extraction, leadless pacemaker implantation and subsequent percutaneous angioplasty and stenting of the SVC and left innominate vein.

Leadless Pacemaker Implantation in the Emergency Bradyarrhythmia Setting: Results from a Multicenter European Registry.

Background. Data on leadless pacemaker (LPM) implantation in an emergency setting are currently lacking. Objective. We aimed to investigate the feasibility of LPM implantation for emergency bradyarrhythmia, in patients referred for urgent PM implantation, in a large, multicenter, real-world cohort of LPM recipients. Methods. Two cohorts of LPM patients, stratified according to the LPM implantation scenario (patients admitted from the emergency department (ED+) vs. elective patients (ED−)) were retrieved from the iLEAPER registry. The primary outcome of the study was a comparison of the peri-procedural complications between the groups. The rates of peri-procedural characteristics (overall procedural and fluoroscopic duration) were deemed secondary outcomes. Results. A total of 1154 patients were enrolled in this project, with patients implanted due to an urgent bradyarrhythmia (ED+) representing 6.2% of the entire cohort. Slow atrial fibrillation and complete + advanced atrioventricular blocks were more frequent in the ED+ cohort (76.3% for ED+ vs. 49.7% for ED−, p = 0.025; 37.5% vs. 27.3%, p = 0.027, respectively). The overall procedural times were longer in the ED+ cohort (60 (45−80) mins vs. 50 (40−65) mins, p < 0.001), showing higher rates of temporary pacing (94.4% for ED+ vs. 28.9% for ED−, p < 0.001). Emergency LPM implantation was not correlated with an increase in the rate of major complications compared to the control group (6.9% ED+ vs. 4.2% ED−, p = 0.244). Conclusion. LPM implantation is a feasible procedure for the treatment of severe bradyarrhythmia in an urgent setting. Urgent LPM implantation was not correlated with an increase in the rate of major complications compared to the control group, but it was associated with longer procedural times.

Intraprocedural PRAETORIAN score for early assessment of S-ICD implantation: A proof-of-concept study.

INTRODUCTION: The PRAETORIAN score (PS) was developed to assess the implant position and predict defibrillation success of the subcutaneous implantable cardioverter defibrillators (S-ICD). The main critique moved to the routine use of PS has been its postprocedural timing, that limits its usefulness on procedure guidance. The aim of this proof-of-concept study was to assess the feasibility of an intraprocedural use of PS. METHODS: Forty consecutive patients undergoing S-ICD implantation were enrolled. Intraprocedural PS (IP-PS) obtained with fluoroscopy before closure of the pocket and postprocedural PS (PP-PS) obtained with two-views chest X-ray were compared. Intraprocedural data and PS were compared with the historic cohorts of the involved institutions. RESULTS: When assessing IP-PS and PP-PS, a complete overall agreement was observed (100%, 1.00-κ; p < .001). When assessing a per-step agreement, a very high-degree of concordance in evaluating Step 1 of the PS was observed (95%, 0.81-κ; p < .001). A complete agreement in Step 2-3 (100%, 1.00-κ; p < .001) of the PS was reported. In comparison with our historical cohort, procedural time in the IP-PS cohort did not increase (45 [41-52] vs. 45 [39-49] min; p = .351) while the expected increase in fluoroscopy time resulted scarce (15 [10-15] s). CONCLUSION: An IP-PS can be reliably obtained using fluoroscopy guidance during S-ICD implantation, without a significant increase in procedural duration and may serve as guidance for implanting physicians, to avoid postprocedural S-ICD repositioning, leading to patient discomfort and significantly enhancing infective risks. IP-PS showed a very high agreement with the PP-PS obtained from two-views chest X-ray.

Clinical impact of defibrillation testing in a real-world S-ICD population: Data from the ELISIR registry.

BACKGROUND: Current guidelines recommend defibrillation testing (DT) performance in patients with a subcutaneous implantable cardioverter defibrillator (S-ICD), theoretically to reduce the amount of ineffective shocks. DT, however, has been proven unnecessary in transvenous ICD and real-world data show a growing trend in avoidance of DT after S-ICD implantation. METHODS: All patients undergoing S-ICD implant at nine associated Italian centers joining in the ELISIR registry (ClinicalTrials.gov Identifier: NCT04373876) were enrolled and classified upon DT performance. Long-term follow-up events were recorded and compared to report the long-term efficacy and safety of S-ICD implantations without DT in a real-world setting. RESULTS: A total of 420 patients (54.0 ± 15.5 years, 80.0% male) were enrolled in the study. A DT was performed in 254 (60.5%) patients (DT+ group), while in 166 (39.5%) was avoided (DT- group). Over a median follow-up of 19 (11-31) months, a very low rate (0.7%) of ineffective shocks was observed, and no significant differences in the primary combined arrhythmic outcome were observed between the two groups (p = .656). At regression analysis, the only clinical predictor associated with the primary combined outcome was S-ICD placement for primary prevention (odds ratio: 0.42; p = .013); DT performance instead was not associated with a reduction in primary outcome (p = .375). CONCLUSION: Implanting an S-ICD without DT does not appear to impact the safety of defibrillation therapy and overall patients' survival.

Atrioventricular synchronous leadless pacemaker: state of art and broadened indications.

Leadless pacemakers (LLPMs) have become a major breakthrough in the management of bradyarrhythmia as an attractive alternative to the standard transvenous pacemakers (TV-PMs). Recently, the introduction of a second-generation LLPMs (Micra AV-MC1AVR1) has expanded pacing modes to obtain atrioventricular (AV) synchronous pacing, providing an interesting alternative in the actual scenario of leadless pacing. Nevertheless, actual reports have highlighted some concerns regarding those devices. In this review, we sought to provide an overview of this technology based on its approval studies and major reports.

Second-generation laser balloon ablation for the treatment of atrial fibrillation assessed by continuous rhythm monitoring: the LIGHT-AF study.

AIMS: Balloon-based technologies have been developed to simplify catheter ablation of atrial fibrillation (AF), to improve the clinical outcome of the procedure and to achieve durable pulmonary vein isolation (PVI). The objective of this study is to evaluate the safety and efficacy of second-generation laser balloon (LB2) ablation in the treatment of AF using a continuous cardiac rhythm monitoring strategy. Atrial tachyarrhythmias (ATas) recurrences were assessed with implantable cardiac monitors (ICMs) or devices. METHODS AND RESULTS: All patients underwent LB2 ablation procedure. The primary endpoint was the first recurrence of any, >5.5 and >24 h duration ATas after the blanking period (90 days). In-hospital visits were performed at 3, 6, and 12 months. Seventy-three patients (68% male, mean age 59.8 ± 11.3) were included in the study. The average procedure, fluoroscopy, and laser ablation times were 81.5 ± 30.1, 21.5 ± 12.4, and 33.8 ± 9.7, respectively. All PVs were isolated using the LB2 with no need of touch-up using focal catheters. No major complications occurred during or after the procedures. The one-year freedom from recurrences was 66.9% (95% CI: 57.0-76.7%), 81.0% (69.5-88.5%), and 86.8% (76.1-92.9%) considering any, 5.5-h and 24-h cut-off duration, respectively. At 3, 6, and 12 months, any ATas was recorded in 22%, 32%, and 25% of patients, with a ≥5% arrhythmic burden documented in 4%, 5%, and 3%, respectively. Few patients reported AF-related symptoms (7%, 8%, and 5%). CONCLUSION: LB2 ablation is a safe and effective procedure, showing a high freedom from recurrences and low arrhythmic burden as documented by a continuous rhythm monitoring strategy.

Micra-AV leadless pacemaker and atrioventricular (dys)synchrony: A stepwise process.

Leadless pacemakers have become a major breakthrough in the management of bradyarrhythmia as an attractive alternative to the standard transvenous pacemakers, but safety and long-term outcomes of the new Micra-AV, which is capable guarantee atrioventricular (AV) synchrony, have been poorly described. Hence, we describe how we managed a 57-year-old patient who developed pacemaker syndrome due to significant Micra-AV dyssynchrony. This case emphasizes how leadless pacemaker AV synchrony could be overestimated, thereby requiring a stepwise process leading to adequate device reprogramming. Holter-ECG monitoring and exercise test resulted to be valuable tools for an early detection of inadequate AV synchrony, integrating and completing device reports.

Neglected lead tip erosion: An unusual case of S-ICD inappropriate shock.

A 52-year-old man experienced a subcutaneous implantable cardioverter-defibrillator (S-ICD) inappropriate shock due to electrode tip decubitus. The device, implanted two years before with a three-incision technique, was extracted, and a new electrode was implanted along the contralateral parasternal line with a two-incision technique, in a one-stage procedure. One-year follow-up was eventless. Early S-ICD electrode extraction and reimplantation during the same procedure is effective and should be considered as soon as initial signs of decubitus appear to avoid inappropriate shocks. A two-incision technique should be preferred to reduce the risk of electrode tip decubitus.

Arrhythmic safety of hydroxychloroquine in COVID-19 patients from different clinical settings.

AIMS: The aim of the study was to describe ECG modifications and arrhythmic events in COVID-19 patients undergoing hydroxychloroquine (HCQ) therapy in different clinical settings. METHODS AND RESULTS: COVID-19 patients at seven institutions receiving HCQ therapy from whom a baseline and at least one ECG at 48+ h were available were enrolled in the study. QT/QTc prolongation, QT-associated and QT-independent arrhythmic events, arrhythmic mortality, and overall mortality during HCQ therapy were assessed. A total of 649 COVID-19 patients (61.9 ± 18.7 years, 46.1% males) were enrolled. HCQ therapy was administrated as a home therapy regimen in 126 (19.4%) patients, and as an in-hospital-treatment to 495 (76.3%) hospitalized and 28 (4.3%) intensive care unit (ICU) patients. At 36-72 and at 96+ h after the first HCQ dose, 358 and 404 ECGs were obtained, respectively. A significant QT/QTc interval prolongation was observed (P < 0.001), but the magnitude of the increase was modest [+13 (9-16) ms]. Baseline QT/QTc length and presence of fever (P = 0.001) at admission represented the most important determinants of QT/QTc prolongation. No arrhythmic-related deaths were reported. The overall major ventricular arrhythmia rate was low (1.1%), with all events found not to be related to QT or HCQ therapy at a centralized event evaluation. No differences in QT/QTc prolongation and QT-related arrhythmias were observed across different clinical settings, with non-QT-related arrhythmias being more common in the intensive care setting. CONCLUSION: HCQ administration is safe for a short-term treatment for patients with COVID-19 infection regardless of the clinical setting of delivery, causing only modest QTc prolongation and no directly attributable arrhythmic deaths.

First-in-human retrieval of chronically implanted Micra transcatheter pacing system.

We report the first-in-human retrieval of a chronically implanted Micra transcatheter pacing system (TPS; Medtronic, Minneapolis, MN, USA). A 41-year-old woman suffering from third-degree atrioventricular block was successfully implanted with a TPS in the low septum of the right ventricle. After 29 months, due to an increased electrical threshold and 100% pacing percentage, the device showed low battery voltage. Despite the long implant duration, the attempt of device retrieval using a snare loop inserted in the delivery system of a TPS was successful. In the same procedure, a new leadless pacemaker was implanted in the high right ventricular septum with optimal pacing threshold.

Management of a leadless pacemaker recall via extraction in a patient with a history of multiple previous device implants.

We describe a management strategy of a leadless pacemaker recall (LP) via extraction in a pacemaker-dependent patient with a history of multiple previous device implants. We performed a two-step procedure. First, we implanted a second LP in the right ventricle. Then, 3 days later for concerns about the stability of the newly-implanted device, we retrieved the first LP, 3 years after its original implant. The patient was hemodynamically stable throughout the two procedures and no adverse event occurred in the 3 days of coexistence of the two LPs. Although the limitation of a single case experience, this approach may be taken into consideration when facing similar high-risk cases.

Beneficial effects of acute inhibition of the oxidative pentose phosphate pathway in the failing heart.

In vitro studies suggested that glucose metabolism through the oxidative pentose phosphate pathway (oxPPP) can paradoxically feed superoxide-generating enzymes in failing hearts. We therefore tested the hypothesis that acute inhibition of the oxPPP reduces oxidative stress and enhances function and metabolism of the failing heart, in vivo. In 10 chronically instrumented dogs, congestive heart failure (HF) was induced by high-frequency cardiac pacing. Myocardial glucose consumption was enhanced by raising arterial glycemia to levels mimicking postprandial peaks, before and after intravenous administration of the oxPPP inhibitor 6-aminonicotinamide (80 mg/kg). Myocardial energy substrate metabolism was measured with radiolabeled glucose and oleic acid, and cardiac 8-isoprostane output was used as an index of oxidative stress. A group of five chronically instrumented, normal dogs served as control. In HF, raising glycemic levels from ∼ 80 to ∼ 170 mg/dL increased cardiac isoprostane output by approximately twofold, whereas oxPPP inhibition normalized oxidative stress and enhanced cardiac oxygen consumption, glucose oxidation, and stroke work. In normal hearts glucose infusion did not induce significant changes in cardiac oxidative stress. Myocardial tissue concentration of 6P-gluconate, an intermediate metabolite of the oxPPP, was significantly reduced by ∼ 50% in treated versus nontreated failing hearts, supporting the inhibitory effect of 6-aminonicotinamide. Our study indicates an important contribution of the oxPPP activity to cardiac oxidative stress in HF, which is particularly pronounced during common physiological changes such as postprandial glycemic peaks.

Implantable loop recorder in Brugada syndrome: Insights from a single-center experience.

Background: This study aimed to investigate the characteristics and outcomes of patients diagnosed with Brugada syndrome (BrS) who underwent implantable loop recorder (ILR) insertion during routine clinical activity. Methods: We conducted a comprehensive screening of all consecutive patients diagnosed with BrS at our institution. We analyzed baseline clinical characteristics, arrhythmic findings, and outcomes. Results: Out of 147 BrS patients, 42 (29 %) received an ILR, 13 (9 %) underwent implantable cardioverter-defibrillator (ICD) placement, and 92 patients (63 %) continued regular cardiological follow-up. Patients who received an ILR had a higher prevalence of suspected arrhythmic syncope (43 % vs. 22 %, p = 0.012) and tended to be younger (median age 38 years, interquartile range 30-52, vs. 43 years, 35-55, p = 0.044) with a higher presence of SCN5A gene mutations (17 % vs. 6 %, p = 0.066) compared to those who continued regular follow-up. Additionally, compared to patients with an ICD, those with an ILR had a significantly lower frequency of positive programmed ventricular stimulation (0 % vs. 91 %, p < 0.001). During a median follow-up period of 14.7 months (4.7-44.8), no deaths occurred among the patients with ILR. Eight individuals (19 %) were diagnosed with arrhythmic findings through continuous ILR monitoring, primarily atrial fibrillation, and asystolic pauses. The median time from insertion to the occurrence of these events was 8.7 months (3.6-46.4). No adverse events related to ILR were reported. Conclusion: Continuous monitoring with ILR may facilitate the timely detection of non-malignant rhythm disorders in BrS patients with risk factors but without an indication for primary prevention ICD implantation.

Left ventricular assist device in the presence of subcutaneous implantable cardioverter defibrillator: Data from a multicenter experience.

BACKGROUND: Left ventricular assist devices (LVADs) are an increasingly used strategy for the management of patients with advanced heart failure (HF). Subcutaneous implantable cardioverter defibrillator (S-ICD) might be a viable alternative to conventional ICDs with a lower risk of short- and long-term of device-related complications and infections.The aim of this multicenter study was to evaluate the outcomes and management of S-ICD recipients who underwent LVAD implantation. METHODS: The study population included patients with a preexisting S-ICD who underwent LVAD implantation for advanced HF despite optimal medical therapy. RESULTS: The study population included 30 patients (25 male; median age 45 [38-52] years).The HeartMate III was the most common LVAD type. Median follow-up in the setting of concomitant use of S-ICDs and LVADs was 7 months (1-20).There were no reports of inability to interrogate S-ICD systems in this population. Electromagnetic interference (EMI) occurred in 21 (70%) patients. The primary sensing vector was the one most significantly involved in determining EMI. Twenty-seven patients (90%) remained eligible for S-ICD implantation with at least one optimal sensing vector. The remaining 3 patients (10%) were ineligible for S-ICD after attempts of reprogramming of sensing vectors. Six patients (20%) experienced inappropriate shocks (IS) due to EMI. Six patients (20%) experienced appropriate shocks. No S-ICD extraction because of need for antitachycardia pacing, ineffective therapy or infection was reported. CONCLUSIONS: Concomitant use of LVAD and S-ICD is feasible in most patients. However, the potential risk of EMI oversensing, IS and undersensing in the post-operative period following LVAD implantation should be considered. Careful screening for EMI should be performed in all sensing vectors after LVAD implantation.

Leadless pacemakers in patients with different stages of chronic kidney disease: real-world data from the updated i-LEAPER registry.

BACKGROUND: Limited data are available on leadless pacemaker (LPM) outcomes according to different stages of chronic kidney disease (CKD). OBJECTIVE: To investigate differences regarding safety and efficacy in LPMs patients stratified per different stages of renal function. METHODS: Consecutive patients enrolled in the multicenter, international i-LEAPER registry were analyzed. Patients were divided into three groups according to CKD stage. The primary endpoint was the comparison of LPM-related major complication rate at implant and during follow-up. Differences in electrical performance were deemed secondary outcomes. RESULTS: Among 1748 patients enrolled, 33% were CKD stage G3a/G3b and 9.4% were CKD stage G4/G5. CKD patients presented cardiovascular comorbidities more frequently. During a median follow-up of 39 [interquartile range (IQR) 18-59] months, major complications rate did not differ between groups (normal kidney function, NKF=1.8% vs CKD stage-G3a/G3b 2.9% vs CKD stage-G4/G5 2.4%, p=0.418). All-cause mortality resulted higher in CKD stage-G4/G5 when compared with NKF group (19.5% vs 9.8%, aHR:1.9, 95%CI 1.25-2.89, p=0.003). LPM electrical performance was comparable between groups, except for CKD patients who showed a slightly higher pacing threshold during the 1-month follow-up (NKF group 0.50 [IQR 0.35-0.70]V vs G3a/G3b group 0.56 [IQR 0.38-0.81]V vs G4/G5 group, 0.51 [0.38-0.84]V @0.24 msec, p<.001). CONCLUSION: In a real-world setting, advanced CKD patients who underwent LPM implantation were underrepresented. Although all-cause mortality was higher in end-stage CKD, periprocedural complications and LPM performance were overall comparable between NKF and different stages of CKD, except for higher values of pacing threshold in CKD patients up to first-month follow-up.