Treatment Option For Atrial Fibrillation Research Articles

Understanding the role of the left atrial appendage on the flow in the atrium.

The exclusion/occlusion of the left atrial appendage (LAA) is a treatment option for atrial fibrillation (AF) patients who are at high risk of stroke and high risk of bleeding. As the role of the LAA is not well understood or explored, this study aims to assess its role on flow dynamics in the left atrium. Computational fluid dynamics (CFD) simulations were carried out for nine AF patients before and after LAA exclusion. The flow parameters investigated included the LA velocities, Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), Relative Residence Time (RRT), and Pressure in the LA. This study shows that, on average, a decrease in TAWSS (1.82 ± 1.85 Pa to 1.27 ± 0.96 Pa, p < 0.05) and a slight increase in OSI (0.16 ± 0.10 to 0.17 ± 0.10, p < 0.05), RRT (1.87 ± 1.84 Pa-1 to 2.11 ± 1.78 Pa-1, p < 0.05), and pressure (-19.2 ± 6.8 mmHg to -15.3 ± 8.3 mmHg, p < 0.05) were observed in the LA after the exclusion of the LAA, with a decrease in low-magnitude velocities. The exclusion of the LAA seems to be associated with changes in LA flow dynamics. Further studies are needed to elucidate the clinical implications of these changes.

Prediction of the success of electrical cardioversion in patients with atrial fibrillation using parameters obtained by spectral and vectorcardiographic analysis of the ECG

Abstract Introduction Electrical cardioversion (ECV) still presents a treatment option for atrial fibrillation (AF). Despite the great success rate in the acute setting, its long-term success rate is low. The aim of the study was to find predictors of SR maintenance after ECV using spectral and vectorcardiographic (VCG) analysis of the ECG curve. Methods Consecutive patients with AF referred for elective ECV were prospectively enrolled. The digital ECG recording obtained before the ECV was analyzed using spectral and VCG analysis. All patients had Holter monitoring and clinical follow-up three months after cardioversion to assess SR maintenance. Atrial fibrillation activity was analyzed by spectral analysis, determining the dominant frequency (DF), RI (regularity index) and OI (organization index). QRS complexes were analyzed by vectorcardiography and dXmean, dYmean and dZmean (derivation of VCG signals) parameters were determined. Using logistic regression (LR) with backward parameter reduction, separate and combined predictive models of SR maintenance were calculated based on both the analysis from the VCG data and the spectral analysis data. Additional models with a forward selection of clinical variables were also calculated. The efficiency of the models was evaluated on a separate test subset of the data (N=32). Results A total of 80 patients were enrolled (age 70+10 years, 48 (64%) men, CHADSVASc 3.17+1.5, BMI 29.75kg/m2). At the 3-month follow-up, AF recurrence was present in 36 patients (45%). Using only vectorcardiographic parameters, dXmean (OR 3.07, 95 %CI 1.14- 8.63), p=0.001) and dYmean (OR 0.26, 95% CI 0.09-0.72), p &amp;lt;0.001) best predicted the SR maintenance (AUC of 0.72). Using only spectral analysis parameters, the best predictor was DF (OR 3.07, 95%CI 1.14-8.63), p=0.012) with AUC of 0.66. By combining the results of spectral analysis and vectorcardiography, an AUC of 0.78 was achieved. Among the clinical parameters, the most significant predictors were insufficiently controlled arterial hypertension and previous history of stroke. Conclusion Digital analysis of ECG curves using deeper mathematical models provides a better predictive model than classical clinical and echocardiographic models. The combination of spectral analysis of fibrillation atrial activity and vectorocardiographic analysis of QRS complexes revealed more accurate predictive information compared to both analyses alone.

Persistent iatrogenic atrial septal defect after cryoballoon ablation for atrial fibrillation

Aims: Pulmonary vein isolation (PVI) by cryoballoon ablation (CB) technology is effective and safe treatment option for atrial fibrillation (AF). CB is performed by large diameter, 15Fr (4.95mm) transseptal sheath that may lead to creation of iatrogenic atrial septal defect (iASD). The objective of this study was to assess the incidence of iASD in patients who had undergone CB. Methods: Patients with AF having undergone Arctic Front® CB ablation and a subsequent transesophageal echocardiography (TEE) examination during post-ablation follow up period were consecutively enrolled. During all CB procedures, 15Fr transseptal sheath (Flex Cath, Medtronic, Minneapolis, MN) was utilized via single transseptal puncture (TsP). Results: Twenty-eight patients (15 females, mean age 55.8+15.5) with paroxysmal (n=24) or persistent (n=4) AF formed study group. iASD was present 11 (39.3%) of them after mean follow-up time of 17.3+6.2 months. The procedural time is significantly longer in patient with iASD (119.0+8.8 minutes, p=0.01). No patients died or suffered from any clinically significant cerebral ischemic event. There was no sign of increase in systolic pulmonary arterial pressure (sPAP). Conclusion: iASD after CB was found to be present in 39.3% of patient during a mean follow-up time of 17.3+6.2 months. The prolonged CB procedural time was the only factor that predicted iASD in our study. No adverse clinic events that might be related to iASD was observed during follow-up period.

Unveiling the Role of Endothelial Dysfunction: A Possible Key to Enhancing Catheter Ablation Success in Atrial Fibrillation.

Atrial fibrillation, a prevalent type of arrhythmia, is increasingly contributing to the economic burden on healthcare systems. The development of innovative treatments, notably catheter ablation, has demonstrated both impressive and promising outcomes. However, these treatments have not yet fully replaced pharmaceutical approaches, primarily due to the relatively high incidence of atrial fibrillation recurrence post-procedure. Recent insights into endothelial dysfunction have shed light on its role in both the onset and progression of atrial fibrillation. This emerging understanding suggests that endothelial function might significantly influence the effectiveness of catheter ablation. Consequently, a deeper exploration into endothelial dynamics could potentially elevate the status of catheter ablation, positioning it as a primary treatment option for atrial fibrillation.

Incidence and predictors of asymptomatic cerebral infarction following radiofrequency catheter ablation for atrial fibrillation

Abstract Backgrounds Left atrial catheter ablation has been established as an important treatment option for atrial fibrillation (AF), but it carries the risk of periprocedural thromboembolism. Periprocedural major stroke is rare, but silent stroke does not appear to be rare. Accurate risk stratification for stroke and appropriate anticoagulation management are essential. Purpose We aimed to investigate the incidence and predictors of silent cerebral infarction (CI) associated with AF catheter ablation, detected by diffusion-weighted magnetic resonance imaging (DW-MRI). Methods and Results We performed a retrospective analysis of 618 consecutive patients (age 72±10 years, persistent atrial fibrillation (PEF) 45%, CHA2DS2-VASc score 2.6±1.4) with persistent or paroxysmal AF that underwent pulmonary vein (PV) or additional ablation and post-procedural cerebral MRI 1 day after ablation. During the ablation procedure, activated clotting time (ACT) was checked every 20 minutes, and additional heparin boluses were administered as needed to maintain ACT &amp;gt;320 seconds. Patients were analyzed for possible demographical, medical, echocardiographic, and procedural predictors of infarction events. Post-procedure DW-MRI detected new infarction lesions in 83 patients (13.4%:CI-group). There were no differences between the CI and non-CI groups with respect to age, type of anticoagulant and complex fractionated atrial electrogram ablation. Body weight, brain natriuretic peptide and left atrial diameter were significantly higher in the CI group. Left ventricular ejection fraction (LVEF) was significantly lower in the CI than non-CI group (58.6±12.6 vs. 64.2±11.8, P&amp;lt;0.001). PEF was more frequent in patients with CI than non-CI group (63.9 vs. 42.1%, P&amp;lt;0.001). In a multivariate regression model revealed only EF was a significant predictor for the occurrence of new asymptomatic lesions on post-procedural DW-MRI (OR 0.949, 95% CI 0.92-0.98, P=0.001). Conclusions This study shows a high incidence of silent micro-embolic events after AF ablation. Lower LVEF were potential predictors of this complication.

Abstract 15076: Long-Term Recurrence Free Survival in Second Generation Cryoballoon Ablation for Persistent Atrial Fibrillation: It’s All About the Autonomic Nervous System

Introduction: Cryoballon (CB)-guided pulmonary vein isolation (PVI) is an accepted treatment option for atrial fibrillation (AF). The cardiac autonomic nervous system (ANS) plays a crucial role in the regulation of AF. Hypothesis: ANS modulation has an impact on patients’ AF free survival following CB-ablation. The aim of this observational clinical trial was to analyze the impact of vagal reactions (VRs), as a surrogate parameter for ANS modulation, on the long-term outcome of CB-ablation in patients with persistent AF (PERS AF). Methods: Data from consecutive PERS AF patients treated with a CB-guided PVI for symptomatic drug refractory AF between 2013-2023 were analyzed. VRs were defined as bradycardia &lt; 40 beats/min, asystole or higher-degree atrioventricular block. All patients were continuously followed up in our outpatient clinic. AF-recurrence was defined as AF lasting &gt; 30 seconds beyond a 3-month blanking period. Results: A total of 250 consecutive patients (mean age 63.9 ± 10.0 years, 70% male) were included. VRs were recorded in 61 patients (24%). The mean follow-up duration amounted to 84±14 months. Within this observation period 101 patients (40%) developed AF recurrence a mean of 1.75 ± 0.80 times. Re-ablation procedures were performed in 61 patients (60%) a mean of 1.28 ± 0.55 times. Reconnected PVs were documented in 41 cases (67%). An additional substrate modification was performed in 34 procedures (42%). Patients with procedure associated VRs presented with a significantly higher estimated AF-free survival rate compared to those without (log-rank p-value=0.016) (Figure1). Multivariate analyses revealed the days to first AF recurrence following primary CB-ablation as an independent predictor for AF-free survival (CI 0.841-0.928, HR, 0.883, p&lt;0.01). Conclusions: CB-ablation procedure associated VRs seem to be associated with a favorable long-term outcome in PERS AF. Thus, our findings may influence future CB-ablation strategies.

Abstract 17865: Machine Learning With Multimodal Pre Ablation Imaging for Predicting Recurrence in Atrial Fibrillation Patients

Purpose: Catheter ablation is a popular treatment option for atrial fibrillation (AF), but AF recurrence is common. Currently, no marker exists to reliably predict the risk or location of recurrence (AF+). In this work, a multimodal imaging approach was employed to identify surface of interest (SOI) associated with recurrence using pre-ablation MRI and CT scans. Hypothesis: Shape of the left atrium (LA) plays a critical role in AF recurrence. The difference between AF+ and AF- may be identified on pre-ablation scan and may find potential sites for additional pre-emptive ablation. Method: Two representative template scans were selected from each group and all patients were registered to these respective templates to develop an atlas for each group. The two atlases were then co-registered, and the difference areas were obtained using a t-test with 500 permutations. The SOI was identified as the area that showed statistically significant (p &lt;0.05) differences between the AF+ and AF-. The process was repeated 5 times to obtain most frequent SOI. Since no ground truth for SOI exists, we used a multimodal imaging approach to construct atlases on CT and MRI; the corresponding SOIs were compared. Results: 102 CT (51 AF+) and 160 MRI (79 AF+) scans collected from Cleveland Clinic and Vanderbilt University were randomly sampled 5 times. At each iteration 20 patients from AF+ and AF- patients were randomly chosen and employed to create atlases for generating SOIs. The dice sore of MRI and CT derived SOI were 0.75± 0.08 and 0.82±0.05, respectively. The SOI region was below the LA appendage and left inferior pulmonary vein on both CT and MRI. The ratio of significant region to LA volume were [9%-18%] and [8%-19%] for CT and MRI, respectively indicating a good agreement between two SOIs. Conclusion: We identified SOI associated with AF+ from CT and MRI and found correlation between them at sites expected to be near the vein of Marshall, an area increasingly targeted for recurrent AF after prior ablation.

Long-term success after catheter ablation of atrial fibrillation

Ablation is an established treatment option for atrial fibrillation (AF) and is associated with convincing success rates and areasonable safety profile. Ablation strategies going beyond pulmonary vein isolation in patients with chronic forms of AF are less well established and reproducible. Especially in patients with progressed AF forms multiple ablation procedures might be mandatory to achieve reasonable clinical success. An early ablation strategy might stop or prolong the progress from paroxysmal to persistent AF. In addition, ablation is more effective than drug-based treatment and comparably safe. Long-term success rates after asingle and after multiple ablation procedures in paroxysmal AF are reported with 60-70% and up to 80%, while success rates in persistent or long-standing persistent AF are less favorable (single procedure 40-50%, multiple procedures 70%). However, currently non-recurrence of AF is the most established but potentially not the best endpoint. The burden of AF after ablation as assessed by novel monitoring modalities might gain further clinical importance.

An Effective Novel Index for Predicting the Recurrence of Atrial Fibrillation Ablation: P Wave Duration-to-Amplitude Ratio.

Atrial fibrillation is the most common arrhythmia observed in the clinical practice. Pulmonary vein isolation is a well established treatment option for atrial fibrillation but is limited by recurrence. Previous studies have demonstrated that abnormal P wave indices were associated with adverse atrial remodeling and its role in predicting atrial fibrillation recurrence. In the present study, we aimed to evaluate the place of a novel index as we named P wave duration-to-amplitude ratio in predicting the recurrence of atrial fibrillation. Patients who underwent pulmonary vein isolation for symptomatic drug-resistant atrial fibrillation between January 2016 and March 2018 were retrospectively screened. A total of 111 patients were enrolled in the current study. P wave indices of the patients were calculated by precisely measuring the electrocardiogram traces recorded with an electrophysiology recording system. While P wave duration (129 ± 18.4 vs. 109 ± 15.7 ms, P &lt;.001), P wave duration-toamplitude ratio (1072.7 ± 528.3 vs. 626.9 ± 368 ms/mV, P &lt;.001), P wave peak time (65 ± 12 vs. 54 ± 10 ms, P &lt;.001), and P wave dispersion (49 ± 14.1 vs. 27.9 ± 17 ms, P =.001) values were significantly higher in the atrial fibrillation recurrence (+) group, the P wave amplitude (0.12 ± 0.05 vs. 0.18 ± 0.02 mV, P &lt;.001) value was found to be lower. A P wave duration-t o-amplitude ratiovalue of &gt;830 ms/mV has 61.8% sensitivity and 88.4% specificity for the prediction of the atrial fibrillation recurrence (area of under the curve [AUC], 0.727). P wave duration-to-amplitude ratio, which may be considered as an indicator of the temporal and electrical propagation of the P wave in the atria, can predict atrial fibrillation ablation recurrence.

Refining the Eikonal Model to Reproduce the Influence of Atrial Tissue Geometry on Conduction Velocity

Abstract Atrial fibrillation is responsible for a significant and steadily rising burden. Simultaneously, the treatment options for atrial fibrillation are far from optimal. Personalized simulations of cardiac electrophysiology could assist clinicians in the risk stratification and therapy planning for atrial fibrillation. However, the use of personalized simulations in clinics is currently not possible due to either too high computational costs or non-sufficient accuracy. Eikonal simulations come with low computational costs but cannot replicate the influence of cardiac tissue geometry on the conduction velocity of the wave propagation. Consequently, they currently lack the required accuracy to be applied in clinics. Biophysically detailed simulations on the other hand are accurate but associated with too high computational costs. To tackle this issue, a regression model is created based on biophysically detailed bidomain simulation data. This regression formula calculates the conduction velocity dependent on the thickness and curvature of the heart wall. Afterwards the formula was implemented into the eikonal model with the goal to increase the accuracy of the eikonal model without losing its advantage of computational efficiency. The results of the modified eikonal simulations demonstrate that (i) the local activation times become significantly closer to those of the biophysically detailed bidomain simulations, (ii) the advantage of the eikonal model of a low sensitivity to the resolution of the mesh was reduced further, and (iii) the unrealistic occurrence of endo-epicardial dissociation in simulations was remedied. The results suggest that the accuracy of the eikonal model was significantly increased. At the same time, the additional computational costs caused by the implementation of the regression formula are neglectable. In conclusion, a successful step towards a more accurate and fast computational model of cardiac electrophysiology was achieved.

An iPS-derived in vitro model of human atrial conduction.

Atrial fibrillation (AF) is the most common arrhythmia in the United States, affecting approximately 1 in 10 adults, and its prevalence is expected to rise as the population ages. Treatment options for AF are limited; moreover, the development of new treatments is hindered by limited (1) knowledge regarding human atrial electrophysiological endpoints (e.g., conduction velocity [CV]) and (2) accurate experimental models. Here, we measured the CV and refractory period, and subsequently calculated the conduction wavelength, in vivo (four subjects with AF and four controls), and ex vivo (atrial slices from human hearts). Then, we created an in vitro model of human atrial conduction using induced pluripotent stem (iPS) cells. This model consisted of iPS‐derived human atrial cardiomyocytes plated onto a micropatterned linear 1D spiral design of Matrigel. The CV (34–41 cm/s) of the in vitro model was nearly five times faster than 2D controls (7–9 cm/s) and similar to in vivo (40–64 cm/s) and ex vivo (28–51 cm/s) measurements. Our iPS‐derived in vitro model recapitulates key features of in vivo atrial conduction and may be a useful methodology to enhance our understanding of AF and model patient‐specific disease.

Catheter ablation for patients with atrial fibrillation and heart failure: insights from the Swedish Heart Failure Registry.

To investigate the association between catheter ablation for atrial fibrillation (AF) and mortality as well as hospitalization for heart failure (HF) in patients with HF across the ejection fraction (EF) spectrum. Patients with first-time catheter ablation for AF (ablation group) compared to only medical treated AF patients (no ablation group) were identified from the Swedish Heart Failure Registry between 2005 and 2019. The primary outcome (all-cause mortality/first HF hospitalization) was assessed by Cox regression models in a 1:2 propensity score (PS) matched cohort and pre-specified EF subgroups (preserved EF [≥50%], mildly reduced EF [40-49%], reduced EF [&lt;40%]) of this cohort. A total of 452 patients in the ablation group and 43 766 patients in the no ablation group were identified. After PS matching, 434 patients in the ablation group were compared to 868 patients in the no ablation group. Over a median follow-up of 2.6 years (0.0-14.1 years), catheter ablation was associated with a lower risk of the primary outcome (all-cause mortality/first HF hospitalization) (hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.65-0.94). Results were consistent across all EF subgroups. In HF with preserved EF (HFpEF), catheter ablation was also associated with a lower risk of recurrent HF hospitalization (incidence rate ratio 0.17, 95% CI 0.07-0.42). In HF patients across the EF spectrum, catheter ablation for AF was associated with lower risk of the primary outcome (all-cause mortality/first HF hospitalization). This study supports catheter ablation as a treatment option for AF in HF patients, including those with HFpEF.

Fifty-fifty - a comparison of two 50 watts high power short duration protocols using temperature- versus power- controlled radiofrequency ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Radiofrequency-guided catheter ablation (RFCA) is an established treatment option for atrial fibrillation (AF). New approaches applying higher than usual energy levels for shorter periods (high power short duration, HPSD) to improve lesion quality have been reported. The novel DiamondTemp (DT) catheter allows for temperature-guided high power RFCA. Data on a direct comparison of the two emerging RFCA approaches are lacking. Purpose This observational single center study aimed to compare the efficacy, safety and characteristics of the novel DT catheter to an ablation index (AI) guided 50 W high power short duration (HPSD) ablation protocol using a conventional force-sensing equipped ablation catheter with surround-flow. Methods A total number of 101 patients undergoing RFA for AF were included. 33 patients treated with the DT catheter (50 W, 9 sec), were compared to 69 consecutive patients undergoing AI-guided AF ablation (AI anterior 550; AI posterior 400) with an open-irrigated catheter adherent to a 50 W HPSD protocol. Procedural data and recurrence rates were documented. Follow-up examinations were scheduled after 3, 6 and 12 months. Results Acute procedural success was achieved in all patients (n=101, 100%). DT-guided AF ablation was associated with a significantly longer mean procedure duration (98.8±30.1min vs. 78.2±25.6, p=0.002*). PVI using the DT ablation catheter required significantly more RF applications (75.4±30.8min vs. 61.3±14.1, p=0.019*). Total RF duration was significantly lower in the DT group (792.1±311.2sec vs. 1035.5±287.2sec, p&amp;lt;0.001*) as well as fluoroscopy time (4.6±2.1min vs.5.5±2.5min, p&amp;lt;0.006*) and dose (183.8±178.1yGym2 vs. 295.8±247.5yGym2, p&amp;lt;0.013*). Procedure related mayor complications occurred in 1 patient from the DT group (acute stroke; 3%) and in no patients from the HPSD cohort. Early recurrence was reported from 4 patients treated with the DT catheter (12%) compared to 8 patients undergoing HPSD RFA (12 %) (p=1.000). Conclusion Temperature- and power- controlled AF ablation using 50 W was safe and effective. AI-guided HPSD ablation resulted in significantly shorter procedure times with significantly fewer RF applications for PVI, whereas total RF duration and fluoroscopy times were significantly higher in this cohort. Further studies are needed to confirm this initial observation.

Transvenous electrical cardioversion of atrial fibrillation in horses: Horse and procedural factors correlated with success and recurrence.

BackgroundTransvenous electrical cardioversion (TVEC) is 1 of the main treatment options for atrial fibrillation (AF) in horses. Large‐scale studies on factors affecting success and prognosis have primarily been performed in Standardbred populations.Hypothesis/ObjectivesTo determine factors affecting cardioversion success, cardioversion difficulty and recurrence in a predominant Warmblood study sample.AnimalsTVEC records of 199 horses.MethodsRetrospective study of TVEC procedures of horses admitted for AF without severe echocardiographic abnormalities. Horse and procedural factors for success and cumulative amount of energy (≤ 600 J vs > 600 J) were determined using multivariable logistic regression. A survival analysis was performed to determine risk factors for recurrence.ResultsTwo hundred and thirty‐one TVEC procedures were included, with a 94.4% success rate and 31.9% recurrence rate (51/160). Mitral regurgitation (OR 0.151, 95% CI 0.032‐0.715, P = .02) and AF cycle length (OR 1.05, 95% CI 1.01‐1.09, P = .02) were independent determinants for success. Catheter type (OR 0.154, 95% CI 0.074‐0.322, P < .001), previous AF episode (OR 3.10, 95% CI 1.20‐8.01, P = .02), tricuspid regurgitation (OR 2.54, 95% CI 1.25‐5.13, P = .01), and body weight (OR 1.009, 95% CI 1.003‐1.015, P = .004) were significantly correlated with cumulative amount of energy delivered. Significant risk factors for recurrence after a first AF episode were sex (stallion; HR 3.05, 95% CI 1.34‐6.95, P = .008), mitral regurgitation (HR 1.91, 95% CI 1.08‐3.38, P = .03), and AF duration (HR 1.001, 95% CI 1.0001‐1.0026, P = .04).Conclusions and Clinical ImportanceBoth horse and procedural factors should be considered when assessing treatment options and prognosis in horses with AF.

Atrial fibrillation ablation in heart failure: Findings from the ESC-EHRA EORP Atrial Fibrillation Ablation long-term (AFA LT) registry

BackgroundThe current practice of atrial fibrillation ablation (AFA) as a treatment option for atrial fibrillation (AF) in patients with heart failure (HF) across Europe, their clinical profiles and outcomes is still undefined. MethodsThe European Society of Cardiology (ESC) led a prospective observational registry of consecutive patients undergoing AFA, in 27 member countries. The subgroup of patients with HF, followed-up for 1 year, was analyzed and the results are reported. ResultsOf the 3582 AF patients in the Registry, 537 (14.9%) had HF. Diabetes, hypertension, hypercholesterolemia, CHA2DS2-VASc score ≥ 2, structural heart disease and persistent AF were more common in HF than non-HF patients (all p < 0.001). However the in-hospital complications were less frequent in HF patients (5.0% vs. 8.2% p = 0.01). Both in-hospital and 1-year outcomes, including 1-year AF recurrence (15.4%) and repeat ablations (9.5%), were similar in both groups. We subdivided HF patients according to their left ventricular ejection fraction (EF) at baseline into reduced (HFrEF, <40%), mid-range (HFmEF, 40–49%), or preserved EF (HFpEF, ≥ 50%). Most patients were HFpEF (n 375, 77%), 72 (15%) were HFmEF and 8% HFrEF. The most frequent underlying conditions in HFpEF were hypertension and ischemic heart disease, while those most common in HFmEF and HFrEF were valvular and dilated cardiomyopathy. ConclusionIn routine care in Europe, HF patients represent a minority of patients undergoing AFA, and most belong to the HFpEF phenotype. The limited clinical research on AFA HFpEF patients is reflected by the uncertainty expressed in the current AF Guidelines and Expert statements.

Transvenous electrical cardioversion of atrial fibrillation in horses: patient and procedural factors correlated with success and recurrence

Background: Transvenous electrical cardioversion (TVEC) is one of the main treatment options for atrial fibrillation (AF) in horses. Large-scale studies on factors affecting success and prognosis have primarily been performed in Standardbred populations. Objectives: To determine the factors affecting success, difficulty of TVEC and recurrence in a mainly Warmblood population. Study Design: Retrospective study. Methods: TVEC records of patients admitted for AF without severe echocardiographic abnormalities were studied. Patient and procedural factors for success rate and cumulative amount of energy (≤600J versus >600J) were determined using multiple logistic regression. A survival analysis was performed to determine risk factors for recurrence within one year after a first AF episode. Results: 231 TVEC procedures were included, with a 94.4% success rate and 34.3% recurrence rate. The depth of pulmonary artery catheter insertion was the only independent predictor for success (OR 1.143, 95%CI [1.005-1.300], P=0.041). Catheter type (OR 0.257, 95%CI [0.109-0.606], P=0.002), height at the withers (OR 1.087, 95%CI [1.021-1.157], P=0.009) and previous AF episode (OR 2.909, 95%CI [1.043-8.112], P=0.041) were significantly correlated with cumulative amount of energy. Significant risk factors for recurrence were male sex (HR 6.648, 95%CI [2.591-17.060], P<0.001), immediate AF recurrence during TVEC (HR 6.232, 95%CI [1.627-23.877], P=0.007), AF duration (HR 1.002, 95%CI [1.0003-1.003], P=0.017) and need for ventricular pacing (HR 3.455, 95%CI [1.005-11.879], P=0.049). Main Limitations: The retrospective nature of the study resulted in missing values. Conclusion: TVEC success and difficulty depend both on patient factors and procedural factors such as catheter insertion depth and catheter type.

B-PO05-073 THE FASTR-AF TRIAL: ASSESSING THE DIAMOND TIP TEMPERATURE-CONTROLLED RADIOFREQUENCY ABLATION CATHETER TO TREAT PATIENTS WITH ATRIAL FIBRILLATION

Catheter ablation (CA) technology evolves as practitioners look to improve treatment options for atrial fibrillation (AF). A novel diamond tip, irrigated, radiofrequency (RF) ablation system accurately measures tip-tissue temperature in real-time and modulates power to maintain a target therapeutic tissue temperature. Recently, the DiamondTemp Ablation (DTA) system demonstrated strong outcomes against a contact force-sensing RF ablation system in a paroxysmal AF (PAF) population. However, no data pertaining to persistent AF (PsAF) has been reported in literature. This study sought to characterize the performance of the DTA system for the treatment of patients with drug-refractory PAF and PsAF with the second-generation RF DTA generator. DIAMOND FASTR-AF (NCT03626649) was a prospective, single-arm, multicenter European trial. Primary effectiveness endpoint was freedom from atrial arrhythmia recurrence following a 90-day blanking period through 12 months. Primary safety endpoint was a composite of serious adverse events. In total, 60 subjects (34 PAF and 26 PsAF) underwent CA with the DTA system at three centers. Patient demographics were consistent with contemporary AF studies (male 71.7%, age 63.9 ± 10.2 yrs, AF history 3.1 ± 3.9 yrs, LA size 4.4 ± 0.8 cm). The PAF cohort showed marked procedural efficiencies, as compared to PsAF, in total procedure time (76.9 ± 21.7 min vs 108.9 ± 33.6 min, p<0.001, respectively), total RF time (10.4 ± 3.5 min vs 20.4 ± 8.0 min, p<0.001), and number of RF applications (62.1 ± 25.3 vs 109.5 ± 45.5, p<0.001). Pulmonary vein isolation only was performed in 82% of PAF and 23% of PsAF subjects. Additional left-sided lesions were performed in 69% of PsAF subjects (vs 6% of PAF subjects). Safety event rate in the PAF and PsAF groups were 5.9% (2/34) and 11.5% (3/26), respectively. Freedom from recurrence was observed in 67.6% (23/34) of PAF and 61.5% (16/26) of PsAF subjects. The DiamondTemp Ablation system demonstrated long-term safety and effectiveness through 12 months post-ablation for patients with PAF or PsAF. Procedures were demonstrated to be highly efficient, with shorter time and fewer applications seen in PAF procedures.

Atrial fibrillation during pregnancy: a9-month period with limited options.

Pregnancy is aphysiological condition with reversible hemodynamic, neurohormonal and coagulation changes to the maternal body during this 9‑month period. The occurrence of atrial fibrillation (AF) is altogether rare among pregnant women, but necessitates immediate treatment und further work-up. Despite numerous pharmacological and invasive therapeutic modalities for AF in non-pregnant patients, very few options are considered safe enough for the fetus and the mother during pregnancy. Commonly used medications such as beta blockers, calcium channel antagonists, antiarrhythmic drugs and anticoagulation therapy must be carefully individualized according to the week of gestation and possible underlying comorbidities of the mother, thus highlighting the importance of an interdisciplinary evaluation by acardiologist and agynecologist. The current review summarizes the existing knowledge and treatment options for AF in pregnancy and suggests asimplified algorithm for this clinical constellation.

Current Drug Treatment Strategies for Atrial Fibrillation and TASK-1 Inhibition as an Emerging Novel Therapy Option.

Atrial fibrillation (AF) is the most common sustained arrhythmia with a prevalence of up to 4% and an upwards trend due to demographic changes. It is associated with an increase in mortality and stroke incidences. While stroke risk can be significantly reduced through anticoagulant therapy, adequate treatment of other AF related symptoms remains an unmet medical need in many cases. Two main treatment strategies are available: rate control that modulates ventricular heart rate and prevents tachymyopathy as well as rhythm control that aims to restore and sustain sinus rhythm. Rate control can be achieved through drugs or ablation of the atrioventricular node, rendering the patient pacemaker-dependent. For rhythm control electrical cardioversion and pharmacological cardioversion can be used. While electrical cardioversion requires fasting and sedation of the patient, antiarrhythmic drugs have other limitations. Most antiarrhythmic drugs carry a risk for pro-arrhythmic effects and are contraindicated in patients with structural heart diseases. Furthermore, catheter ablation of pulmonary veins can be performed with its risk of intraprocedural complications and varying success. In recent years TASK-1 has been introduced as a new target for AF therapy. Upregulation of TASK-1 in AF patients contributes to prolongation of the action potential duration. In a porcine model of AF, TASK-1 inhibition by gene therapy or pharmacological compounds induced cardioversion to sinus rhythm. The DOxapram Conversion TO Sinus rhythm (DOCTOS)-Trial will reveal whether doxapram, a potent TASK-1 inhibitor, can be used for acute cardioversion of persistent and paroxysmal AF in patients, potentially leading to a new treatment option for AF.

Epigenetic regulation of cardiac electrophysiology in atrial fibrillation: HDAC2 determines action potential duration and suppresses NRSF in cardiomyocytes.

Atrial fibrillation (AF) is associated with electrical remodeling, leading to cellular electrophysiological dysfunction and arrhythmia perpetuation. Emerging evidence suggests a key role for epigenetic mechanisms in the regulation of ion channel expression. Histone deacetylases (HDACs) control gene expression through deacetylation of histone proteins. We hypothesized that class I HDACs in complex with neuron-restrictive silencer factor (NRSF) determine atrial K+ channel expression. AF was characterized by reduced atrial HDAC2 mRNA levels and upregulation of NRSF in humans and in a pig model, with regional differences between right and left atrium. In vitro studies revealed inverse regulation of Hdac2 and Nrsf in HL-1 atrial myocytes. A direct association of HDAC2 with active regulatory elements of cardiac K+ channels was revealed by chromatin immunoprecipitation. Specific knock-down of Hdac2 and Nrsf induced alterations of K+ channel expression. Hdac2 knock-down resulted in prolongation of action potential duration (APD) in neonatal rat cardiomyocytes, whereas inactivation of Nrsf induced APD shortening. Potential AF-related triggers were recapitulated by experimental tachypacing and mechanical stretch, respectively, and exerted differential effects on the expression of class I HDACs and K+ channels in cardiomyocytes. In conclusion, HDAC2 and NRSF contribute to AF-associated remodeling of APD and K+ channel expression in cardiomyocytes via direct interaction with regulatory chromatin regions. Specific modulation of these factors may provide a starting point for the development of more individualized treatment options for atrial fibrillation.