Successful ventricular arrhythmia (VA) ablation requires identification of functionally critical sites during contact mapping. Estimation of the peak frequency (PF) component of the EGM may improve correct near field (NF) annotation to identify circuit segments on the mapped surface. In turn, assessment of near- and far field (FF) EGMs may delineate the 3-dimensional path of a VT circuit. A proprietary NF detection algorithm was applied retrospectively to scar-related re-entry VT maps and compared to manually reviewed maps employing first deflection (FDcorr) for VT activation maps and last deflection (LD) for substrate maps. VT isthmus location and characteristics mapped with FDcorr vs. NF were compared. Omnipolar low voltage areas, late activating areas and deceleration zones in LD vs NF substrate maps were compared. On substrate maps, PF estimation was compared between isthmus and bystander-sites. Activation mapping with entrainment and/or VT termination with RF ablation confirmed critical sites. 18 patients with high-density VT activation and substrate maps (55.6% ischemic) were included. NF detection correctly located critical parts of the circuit in 77.7% of the cases compared to manually reviewed VT maps as reference. In substrate maps NF detection identified deceleration zones in 88.8% of cases which overlapped with FDcorr VT isthmus in 72.2% compared to 83.3% overlap of DZ assessed by LD. Applied to substrate maps, PF as a stand-alone feature did not differentiate VT isthmus-sites from low voltage bystander-sites. Omnipolar voltage was significantly higher at isthmus-sites with longer EGM durations compared to low voltage bystander-sites. The NF algorithm may enable rapid high-density activation mapping of VT circuits in the near field of the mapped surface. Integrated assessment and combined analysis of near and far field EGMs could support characterisation of 3-dimensional VT circuits with intramural segments. For scar-related substrate mapping, PF as a stand-alone EGM feature did not enable the differentiation of functionally critical sites of the dominant VT from low voltage bystander sites in this cohort.

Debulking of infective mass to reduce the burden if infective material is a fundamental principle in the surgical management of infection. The aim of this study was to investigate the validity of this principle in patients undergoing transvenous lead extraction in the context of bloodstream infection (BSI). We performed an observational single-centre study on patients that underwent transvenous lead extraction due to a BSI, with or without lead-associated vegetations, in combination with a percutaneous aspiration system during the study period 2015-22. One hundred thirty-seven patients were included in the final analysis. In patients with an active BSI at the time of intervention, the use of a percutaneous aspiration system had a significant impact on survival (log-rank: P = 0.0082), while for patients with a suppressed BSI at the time of intervention, the use of a percutaneous aspiration system had no significant impact on survival (log-rank: P = 0.25). A reduction of the infective burden by percutaneous debulking of lead vegetations might improve survival in patients with an active BSI.

KCNQ1 mutations cause QTc prolongation increasing life-threatening arrhythmias risks. Heterozygous mutations [type 1 long QT syndrome (LQT1)] are common. Homozygous KCNQ1 mutations cause type 1 Jervell and Lange-Nielsen syndrome (JLNS) with deafness and higher sudden cardiac death risk. KCNQ1 variants causing JLNS or LQT1 might have distinct phenotypic expressions in heterozygous patients. The aim of this study is to evaluate QTc duration and incidence of long QT syndrome-related cardiac events according to genetic presentation. We enrolled LQT1 or JLNS patients with class IV/V KCNQ1 variants from our inherited arrhythmia clinic (September 1993 to January 2023). Medical history, ECG, and follow-up were collected. Additionally, we conducted a thorough literature review for JLNS variants. Survival curves were compared between groups, and multivariate Cox regression models identified genetic and clinical risk factors. Among the 789 KCNQ1 variant carriers, 3 groups were identified: 30 JLNS, 161 heterozygous carriers of JLNS variants (HTZ-JLNS), and 550 LQT1 heterozygous carriers of non-JLNS variants (HTZ-Non-JLNS). At diagnosis, mean age was 3.4 ± 4.7 years for JLNS, 26.7 ± 21 years for HTZ-JLNS, and 26 ± 21 years for HTZ-non-JLNS; 55.3% were female; and the mean QTc was 551 ± 54 ms for JLNS, 441 ± 32 ms for HTZ-JLNS, and 467 ± 36 ms for HTZ-Non-JLNS. Patients with heterozygous JLNS mutations (HTZ-JLNS) represented 22% of heterozygous KCNQ1 variant carriers and had a lower risk of cardiac events than heterozygous non-JLNS variant carriers (HTZ-Non-JLNS) [hazard ratio (HR) = 0.34 (0.22-0.54); P < 0.01]. After multivariate analysis, four genetic parameters were independently associated with events: haploinsufficiency [HR = 0.60 (0.37-0.97); P = 0.04], pore localization [HR = 1.61 (1.14-1.2.26); P < 0.01], C-terminal localization [HR = 0.67 (0.46-0.98); P = 0.04], and group [HR = 0.43 (0.27-0.69); P < 0.01]. Heterozygous carriers of JLNS variants have a lower risk of cardiac arrhythmic events than other LQT1 patients.

Elective cardioversion (ECV) is routinely used in atrial fibrillation (AF) to restore sinus rhythm. However, it includes a risk of thromboembolism even during adequate oral anticoagulation treatment. The aim of this study was to evaluate the risk of thromboembolic and bleeding complications after ECV in a real-life setting utilizing data from a large AF population. This nationwide register-based study included all (n = 9625) Finnish AF patients undergoing their first-ever ECV between 2012 and 2018. The thromboembolic and bleeding complications within 30 days after ECV were analysed. The mean age of the patients was 67.7 ± 9.9 years, 61.2% were men, and the mean CHA2DS2-VASc score was 2.6 ± 1.6. Warfarin was used in 6245 (64.9%) and non-vitamin K oral anticoagulants (NOACs) in 3380 (35.1%) cardioversions. Fifty-two (0.5%) thromboembolic complications occurred, of which 62% were ischaemic strokes, 25% transient ischaemic attacks, and 13% other systemic embolisms. Thromboembolic events occurred in 14 (0.4%) NOAC-treated patients and in 38 (0.6%) warfarin-treated patients (odds ratio 0.77; confidence interval: 0.42-1.39). The median time from ECV to the thromboembolic event was 2 days, and 78% of the events occurred within 10 days. Age and alcohol abuse were significant predictors of thromboembolic events. Among warfarin users, thromboembolic complications were more common with international normalized ratio (INR) <2.5 than INR ≥2.5 (0.9% vs. 0.4%, P = 0.026). Overall, 27 (0.3%) bleeding events occurred. The rate of thromboembolic and bleeding complications related to ECV was low without significant difference between NOAC- and warfarin-treated patients. With warfarin, INR ≥2.5 at the time of cardioversion reduced the risk of thromboembolic complications.

We examine the effects of symptoms and cardiovascular disease (CVD) events on health-related quality of life (HRQOL) and healthcare costs in a European population with atrial fibrillation (AF). In the EURObservational Research Programme on AF long-term general registry, AF patients from 250 centres in 27 European countries were enrolled and followed for 2 years. We used fixed effects models to estimate the association of symptoms and CVD events on HRQOL and annual healthcare costs. We found significant decrements in HRQOL in AF patients in whom ST-segment elevation myocardial infarction (STEMI) [-0.075 (95% confidence interval -0.144, -0.006)], angina or non-ST-elevation myocardial infarction (NSTEMI) [-0.037 (-0.071, -0.003)], new-onset/worsening heart failure [-0.064 (-0.088, -0.039)], bleeding events [-0.031 (-0.059, -0.003)], thromboembolic events [-0.071 (-0.115, -0.027)], mild symptoms [0.037 (-0.048, -0.026)], or severe/disabling symptoms [-0.090 (-0.108, -0.072)] occurred during the follow-up. During follow-up, annual healthcare costs were associated with an increase of €11 718 (€8497, €14 939) in patients with STEMI, €5823 (€4757, €6889) in patients with angina/NSTEMI, €3689 (€3219, €4158) in patients with new-onset or worsening heart failure, €3792 (€3315, €4270) in patients with bleeding events, and €3182 (€2483, €3881) in patients with thromboembolic events, compared with AF patients without these events. Healthcare costs were primarily driven by inpatient costs. There were no significant differences in HRQOL or healthcare resource use between EU regions or by sex. Symptoms and CVD events are associated with a high burden on AF patients and healthcare systems throughout Europe.

Human induced pluripotent stem cell-derived atrial cardiomyocytes (hiPSC-aCM) could be a helpful tool to study the physiology and diseases of the human atrium. To fulfil this expectation, the electrophysiology of hiPSC-aCM should closely resemble the situation in the human atrium. Data on the contribution of the slowly activating delayed rectifier currents (IKs) to repolarization are lacking for both human atrium and hiPSC-aCM. Human atrial tissues were obtained from patients with sinus rhythm (SR) or atrial fibrillation (AF). Currents were measured in human atrial cardiomyocytes (aCM) and compared with hiPSC-aCM and used to model IKs contribution to action potential (AP) shape. Action potential was recorded by sharp microelectrodes. HMR-1556 (1 µM) was used to identify IKs and to estimate IKs contribution to repolarization. Less than 50% of hiPSC-aCM and aCM possessed IKs. Frequency of occurrence, current densities, activation/deactivation kinetics, and voltage dependency of IKs did not differ significantly between hiPSC-aCM and aCM, neither in SR nor AF. β-Adrenoceptor stimulation with isoprenaline did not increase IKs neither in aCM nor in hiPSC-aCM. In tissue from SR, block of IKs with HMR-1556 did not lengthen the action potential duration, even when repolarization reserve was reduced by block of the ultra-rapid repolarizing current with 4-aminopyridine or the rapidly activating delayed rectifier potassium outward current with E-4031. I Ks exists in hiPSC-aCM with biophysics not different from aCM. As in adult human atrium (SR and AF), IKs does not appear to relevantly contribute to repolarization in hiPSC-aCM.

Pulmonary vein isolation (PVI) is the corner stone of modern rhythm control strategies in patients with atrial fibrillation (AF). Sleep-disordered breathing (SDB) is prevalent in more than 50% of patients undergoing AF ablation, and studies have indicated a greater recurrence rate after PVI in patients with SDB. Herein, we study the effect of catheter-based PVI on AF in a pig model for SDB. In 11 sedated spontaneously breathing pigs, obstructive apnoeas were simulated by 75 s of intermittent negative upper airway pressure (INAP) applied by a negative pressure device connected to the endotracheal tube. Intermittent negative upper airway pressures were performed before and after PVI. AF-inducibility and atrial effective refractory periods (aERPs) were determined before and during INAP by programmed atrial stimulation. Pulmonary vein isolation prolonged the aERP by 48 ± 27 ms in the right atrium (RA) (P < 0.0001) and by 40 ± 34 ms in the left atrium (LA) (P = 0.0004). Following PVI, AF-inducibility dropped from 28 ± 26% to 0% (P = 0.0009). Intermittent negative upper airway pressure was associated with a transient aERP-shortening (ΔaERP) in both atria, which was not prevented by PVI (INAP indued ΔaERP after PVI in the RA: -57 ± 34 ms, P = 0.0002; in the LA: -42 ± 24 ms, P < 0.0001). Intermittent negative upper airway pressure was associated with a transient increase in AF-inducibility (from 28 ± 26% to 69 ± 21%; P = 0.0008), which was not attenuated by PVI [INAP-associated AF-inducibility after PVI: 58 ± 33% (P = 0.5)]. Transient atrial arrhythmogenic changes related to acute obstructive respiratory events are not prevented by electrical isolation of the pulmonary veins, which partially explains the increased AF recurrence in patients with SDB after PVI procedures.