Conversion Of Atrial Fibrillation Research Articles

Defibrillation of Atrial Fibrillation is not Associated with Increased Risk of Ventricular Fibrillation – The VCD-Trial (Clinical Trial of Electrical Therapy for Atrial Fibrillation using R-wave Guided Cardioversion Versus Defibrillation)

Background: Because of a possible risk of induction of Ventricular Fibrillation (VF) by defibrillation of atrial fibrillation (AF) postulated by LOWN and coworkers, synchronized cardioversion is used worldwide. This prospective, randomized study assessed the efficacy and safety between R-wave controlled cardioversion and defibrillation of AF at 2 study centers in Cologne, Germany. Hypothesis: Defibrillation is not significantly different from cardioversion primarily in the occurrence of VF or sustained Ventricular Tachycardia (VT) and secondarily in restoring sinus rhythm, inducing non-sustained VT, asystole, or bradycardia. Methods: 146 patients at an outpatient practice and 122 at the university hospital were randomized to cardioversion (n = 140) or defibrillation (n = 124). Results: Cardioversion was successful in 92.1% of cases and defibrillation in 87.1%. The difference in efficacy was not statistically significant. In n = 1 patients receiving defibrillation, VF occurred after the first shock (200J) and immediate defibrillation (200J) restored sinus rhythm. In the n = 1 case, asystole occurred during cardioversion which terminated spontaneously. In n = 1 patients cardioverted and n = 2 who were defibrillated, sinus bradycardia occurred requiring Atropine in two cases. There were no thromboembolic events within 10 days. N = 9 patients reverted to AF within two hours. No patients died. Conclusion: Electrical conversion of AF can be performed with similar results and low risk with both R-wave-triggered cardioversion and defibrillation. In particular, defibrillation with higher energies (> 100J) can be performed as effectively and safely without a statistically significant increased risk of VF or VT. There was no difference in efficacy and risk between electrotherapy performed in the outpatient and inpatient settings.

Paradoxical SERCA dysregulation contributes to atrial fibrillation in a model of diet-induced obesity.

Obesity is a major risk factor for atrial fibrillation (AF) the most common serious cardiac arrhythmia, but the molecular mechanisms underlying diet-induced AF remain unclear. In this study, we subjected mice to a chronic high-fat diet and acute sympathetic activation ('two-hit' model) to study the mechanisms by which diet-induced obesity promotes AF. Surface electrocardiography revealed that diet-induced obesity and sympathetic activation synergize during intracardiac tachypacing to induce AF. At the cellular level, diet-induced obesity and acute adrenergic stimulation facilitate the formation of delayed afterdepolarizations in atrial myocytes, implicating altered Ca2+ dynamics as the underlying cause of AF. We found that diet-induced obesity does not alter the expression of major Ca2+-handling proteins in atria, including the sarcoplasmic reticulum Ca2+-ATPase (SERCA), a major component of beat-to-beat Ca2+ cycling in the heart. Paradoxically, obesity reduces phospholamban phosphorylation, suggesting decreased SERCA activity, yet atrial myocytes from obese mice showed a significantly increased Ca2+ transient amplitude and SERCA-mediated Ca2+ uptake. Adrenergic stimulation further increases the Ca2+ transient amplitude but does not affect Ca2+ reuptake in atrial myocytes from obese mice. Transcriptomics analysis showed that a high-fat diet prompts upregulation of neuronatin, a protein that has been implicated in obesity and is known to stimulate SERCA activity. We propose a mechanism in which obesity primes SERCA for paradoxical activation, and adrenergic stimulation facilitates AF conversion through a Ca2+-induced Ca2+ release gain in atrial myocytes. Overall, this study links obesity, altered Ca2+ signaling, and AF, and targeting this mechanism may prove effective for treating obesity-induced AF.

Direct epicardial validation of posterior wall isolation in persistent atrial fibrillation: pulsed field versus radiofrequency ablation

Abstract Background Lesion transmurality is an important determinant of durable effectiveness of catheter ablation (CA) for atrial fibrillation (AF). The impact of different energy sources on the achievement of transmural left atrial (LA) ablation has not been explored so far. Purpose We sought to compare the transmurality associated with pulsed field ablation (PFA) and radiofrequency (RF) ablation of LA posterior wall (PW) among patients with persistent AF. Methods Eight patients (mean age, 70±7 years; 88% male) undergoing CA for persistent AF with PW ablation and adjunctive high-density epicardial mapping were included in a multicenter international registry. In four patients, PW ablation was performed using PFA, while in the remaining four, RF energy was used with high/very-high-power short-duration settings. The primary study outcome was transmural PW isolation (PWI) with endocardial-only ablation. Results A trend towards shorter times required to complete endocardial PW ablation was observed with PFA compared to RF (9±1 vs 11±2min, p=0.065). At endocardial mapping, apparent PWI was observed in all cases. However, transmural PWI after endocardial-only ablation was demonstrated in each patient in the PFA group, but only in one RF case, in whom 50 Watt/≥10 sec settings were used (100% vs 25%, p=0.143). Interestingly, in three patients in the RF group, endocardial ablation resulted in conversion of AF into atypical flutter, which could be successfully terminated by epicardial ablation. Conclusions We observed a trend towards greater transmurality with PFA compared to high/very-high power RF ablation in the region of septopulmonary bundle. This observation may have potential implications on clinical outcomes after endocardial AF CA.

Incidence and impact on arrhythmia recurreces of atrial fibrillation termination during linear radiofrequency ablation in the left atrium

Abstract Atrial Fibrillation Termination During Linear Radiofrequency Ablation in the Left Atrium: Incidence and Impact on Arrhythmia Recurrences Background Termination of atrial fibrillation (AF) during persistent atrial fibrillation (peAF) ablation is infrequent and has shown no clear association with reduced recurrences during follow-up. Linear ablation, often considered to have minimal impact on efficacy, has been primarily explored through creating ablation lines from the mitral annulus to the inferior pulmonary vein or by isolating the posterior wall. Purpose This study aims to assess the incidence of AF termination using an alternative linear ablation approach and its correlation with arrhythmia recurrence during follow-up. Methods Patients enrolled in the PowerFast III trial (a multicenter randomized trial comparing high- power short-duration radiofrequency (RF) application to conventional RF application) with peAF and undergoing linear ablation were included in this sub-study. Conventional pulmonary vein isolation (PVI) was performed using two different RF settings along with a set of RF lines, including anteroseptal (AS), anterolateral (AL), posterior wall isolation between the pulmonary veins, and between the two anterior lines. Patients were categorized into two groups based on AF termination or flutter organization (Group 1) or no AF termination (Group 2) during RF application. All patients were monitored with EKG transmission for one year. Results Fifty-one consecutive patients (mean age 61 years, male 39) were included. AF terminated in 21 patients (41%) during RF application (9 converting to AF and 12 to atrial flutter). AF did not terminate during RF application for PVI, except for one patient during right PV ablation following left PVI. AF termination occurred by posterior wall lines in three patients, roof line in three, and anterior line in two. AF converted into atrial flutter during ablation by a roof line in 5 patients and by an anterior line in 7. No significant differences in atrial arrhythmia recurrence were observed between the two groups (three patients in Group 1 vs. eleven in Group 2, P = 0.11). However, Group 1 exhibited fewer AF recurrences (zero patients) than Group 2 (eight patients, P = 0.015). Conclusions Extensive linear RF ablation resulted in a substantial proportion of patients experiencing AF termination or conversion into atrial flutter. AF termination or conversion did not appear to be correlated with atrial arrhythmia freedom during follow-up but was associated with fewer AF recurrences.Any arrhythmia recurrenceAF recurrence

Orally Inhaled Flecainide for Conversion of Atrial Fibrillation to Sinus Rhythm: INSTANT Phase 2 Trial

BackgroundINSTANT (INhalation of flecainide to convert recent-onset SympTomatic Atrial fibrillatioN to sinus rhyThm) was a multicenter, open-label, single-arm study of flecainide acetate oral inhalation solution (FlecIH) for acute conversion of recent-onset (≤48 hours) symptomatic atrial fibrillation (AF) to sinus rhythm. ObjectivesThis study investigated the efficacy and safety in 98 patients receiving a single dose of FlecIH delivered via oral inhalation. MethodsPatients self-administered FlecIH over 8 minutes in a supervised medical setting using a breath-actuated nebulizer and were continuously monitored for 90 minutes using a 12-lead Holter. ResultsMean age was 60.5 years, mean body mass index was 27.0 kg/m2, and 34.7% of the patients were women. All patients had ≥1 AF-related symptoms at baseline, and 87.8% had AF symptoms for ≤24 hours. The conversion rate was 42.6% (95% CI: 33.0%-52.6%) with a median time to conversion of 14.6 minutes. The conversion rate was 46.9% (95% CI: 36.4%-57.7%) in a subpopulation that excluded predose flecainide exposure for the current AF episode. Median time to discharge among patients who converted was 2.5 hours, and only 2 patients had experienced AF recurrence by day 5. In the conversion-no group, 44 (81.5%) patients underwent electrical cardioversion by day 5. The most common adverse events were related to oral inhalation of flecainide (eg, cough, oropharyngeal irritation/pain), which were mostly of mild intensity and limited duration. ConclusionsThe risk-benefit of orally inhaled FlecIH for acute cardioversion of recent-onset AF appears favorable. FlecIH could provide a safe, effective, and convenient first-line therapeutic option. (INhalation of Flecainide to Convert Recent Onset SympTomatic Atrial Fibrillation to siNus rhyThm [INSTANT]; NCT03539302)

La identificación subjetiva y ablación de impulsores auriculares mejora el control del ritmo en la fibrilación auricular persistente. Estudio CHAOS-AF

Introduction and objectivesThe optimal approach for persistent atrial fibrillation (AF) ablation remains unknown. In patients with persistent AF, we compared an ablation strategy based on pulmonary vein isolation (PVI) plus ablation of drivers (PVI+D), with a conventional PVI-only approach performed in a 1:1 propensity score-matched cohort. MethodsDrivers were subjectively identified using conventional high-density mapping catheters (IntellaMap ORION, PentaRay NAV or Advisor HD Grid), without dedicated software, as fractionated continuous or quasicontinuous electrograms on 1 to 2 adjacent bipoles, which were ablated first; and as sites with spatiotemporal dispersion (the entire cycle length comprised within the mapping catheter) plus noncontinuous fractionation, which were only targeted in patients without fractionated continuous electrograms, or without AF conversion after ablation of fractionated continuous electrograms. Ablation included PVI plus focal or linear ablation targeting drivers. ResultsA total of 50 patients were included in each group (61±10 years, 25% women). Fractionated continuous electrograms were found and ablated in 21 patients from the PVI+D group (42%), leading to AF conversion in 7 patients. In the remaining 43 patients, 143 sites with spatiotemporal dispersion plus noncontinuous fractionation were targeted. Globally, AF conversion was achieved in 21 patients (42%). The PVI+D group showed lower atrial arrhythmia recurrences at 1 year of follow-up (30.6% vs 48%; P=.048) and at the last follow-up (46% vs 72%; P=.013), and less progression to permanent AF (10% vs 40%; P=.001). ConclusionsSubjective identification and ablation of drivers, added to PVI, increased 1-year freedom from atrial arrhythmia and decreased long-term recurrences and progression to permanent AF.

Analysis of the success rate of conversion using ibutilide administration in radiofrequency catheter ablation of persistent atrial fibrillation and its effects on postoperative recurrence

ObjectiveTo assess the efficacy of ibutilide administration during radiofrequency catheter ablation of persistent atrial fibrillation (AF), to explore the success rate of conversion and related influential factors, and to analyze the effects of ibutilide on postoperative recurrence.MethodsA total of 192 patients with persistent AF who underwent catheter ablation from January 1, 2019, to December 31, 2021. These patients failed in conversion of AF to normal sinus rhythm by intraoperative catheter ablation. Patients were categorized into effective group (115 cases) and ineffective group (77 cases) based on whether sinus rhythm was restored after application of ibutilide.ResultsThe overall success rate of conversion using ibutilide administration was 59.9%. The success rate was associated with weight ((68.12 ± 11.72 vs. 72.83 ± 12.08) kg, P = 0.008), the duration of AF ((34.67 ± 55.68 vs. 66.52 ± 95.21) months, p = 0.008), diameter of left atrium (LAD) ((44.39 ± 5.80 vs. 47.36 ± 6.10) mm,P = 0.002), and N-terminal pro-brain natriuretic peptide (NT-proBNP) level ((854.85 ± 770.84 vs. 662.88 ± 659.18) pg/ml,P = 0.030). The results showed the duration of AF was associated with early recurrence, while early recurrence was not a risk factor for late recurrence. And duration of AF was associated with postoperative maintenance time of normal sinus rhythm, whereas successful conversion into normal sinus rhythm using ibutilide administration had no influence on postoperative maintenance time of normal sinus rhythm.ConclusionIbutilide showed to be effective in catheter ablation of AF, the success rate of conversion was correlated with the duration of AF, LA diameter, and NT-proBNP level. Besides, the duration of AF was found as a risk factor for early postoperative recurrence, while ibutilide administration for successful conversion had no influence on predicting postoperative recurrence and had no influence on postoperative maintenance time of sinus rhythm.

Subjective identification and ablation of drivers improves rhythm control in patients with persistent atrial fibrillation. The CHAOS-AF study

Introduction and objectivesThe optimal approach for persistent atrial fibrillation (AF) ablation remains unknown. In patients with persistent AF, we compared an ablation strategy based on pulmonary vein isolation (PVI) plus ablation of drivers (PVI+D), with a conventional PVI-only approach performed in a 1:1 propensity score-matched cohort. MethodsDrivers were subjectively identified using conventional high-density mapping catheters (IntellaMap ORION, PentaRay NAV or Advisor HD Grid), without dedicated software, as fractionated continuous or quasicontinuous electrograms on 1 to 2 adjacent bipoles, which were ablated first; and as sites with spatiotemporal dispersion (the entire cycle length comprised within the mapping catheter) plus noncontinuous fractionation, which were only targeted in patients without fractionated continuous electrograms, or without AF conversion after ablation of fractionated continuous electrograms. Ablation included PVI plus focal or linear ablation targeting drivers. ResultsA total of 50 patients were included in each group (61±10 years, 25% women). Fractionated continuous electrograms were found and ablated in 21 patients from the PVI+D group (42%), leading to AF conversion in 7 patients. In the remaining 43 patients, 143 sites with spatiotemporal dispersion plus noncontinuous fractionation were targeted. Globally, AF conversion was achieved in 21 patients (42%). The PVI+D group showed lower atrial arrhythmia recurrences at 1 year of follow-up (30.6% vs 48%; P=.048) and at the last follow-up (46% vs 72%; P=.013), and less progression to permanent AF (10% vs 40%; P=.001). ConclusionsSubjective identification and ablation of drivers, added to PVI, increased 1-year freedom from atrial arrhythmia and decreased long-term recurrences and progression to permanent AF.

Efficacy and safety of antazoline vs propafenone for conversion of paroxysmal atrial fibrillation to sinus rhythm: a randomized, double-blind study (AnProAF).

Antazoline is a frequently used antiarrhythmic drug (AAD); however, to date, no randomized controlled trial has evaluated its efficacy and safety for cardioversion of recent‑onset atrial fibrillation (AF) in comparison with other approved AADs. This study aimed to compare clinical efficacy and safety of antazoline and propafenone for a rapid conversion of nonvalvular paroxysmal AF to sinus rhythm in patients without heart failure. This was a single‑center, randomized, double‑blind study. It included patients with AF (lasting <48 hours) who were in a stable cardiopulmonary condition and eligible for cardioversion. The individuals who fulfilled the inclusion criteria were randomly assigned to receive either antazoline (up to 300 mg) or propafenone (up to 140 mg) intravenously. The primary end point was conversion of AF to sinus rhythm confirmed on electrocardiography. Overall, 94 participants (46 [48.9%] in the antazoline group and 48 [51.1%] in the propafenone group) were included. The mean (SD) age was 67.5 (14) years, and 40 participants (42.5%) were men. Successful AF conversion was observed in 29 patients (63%) from the antazoline group and 25 individuals (52.1%) from the propafenone group (P = 0.39). The median time to conversion was 10 minutes in the antazoline group and 30 minutes in the propafenone group (P = 0.03). Severe adverse events were observed in 5 patients (10.8%) treated with antazoline and 5 individuals (10.4%) who received propafenone. Intravenous antazoline demonstrated efficacy and safety comparable to those of intravenous propafenone for acute conversion of nonvalvular paroxysmal AF to sinus rhythm in patients without heart failure.

Analysis of drug-induced and spontaneous cardioversions reveals similar patterns leading to termination of atrial fibrillation.

The mechanisms leading to the conversion of atrial fibrillation (AF) to sinus rhythm are poorly understood. This study describes the dynamic behavior of electrophysiological parameters and conduction patterns leading to spontaneous and pharmacological AF termination. Five independent groups of goats were investigated: (1) spontaneous termination of AF, and drug-induced terminations of AF by various potassium channel inhibitors: (2) AP14145, (3) PA-6, (4) XAF-1407, and (5) vernakalant. Bi-atrial contact mapping was performed during an open chest surgery and intervals with continuous and discrete atrial activity were determined. AF cycle length (AFCL), conduction velocity and path length were calculated for each interval, and the final conduction pattern preceding AF termination was evaluated. AF termination was preceded by a sudden episode of discrete activity both in the presence and absence of an antiarrhythmic drug. This episode was accompanied by substantial increases in AFCL and conduction velocity, resulting in prolongation of path length. In 77% ± 4% of all terminations the conduction pattern preceding AF termination involved medial to lateral conduction along Bachmann's bundle into both atria, followed by anterior to posterior conduction. This finding suggests conduction block in the interatrial septum and/or pulmonary vein area as final step of AF termination. AF termination is preceded by an increased organization of fibrillatory conduction. The termination itself is a sudden process with a critical role for the interplay between spatiotemporal organization and anatomical structure.

Impact of Prolonged Cycle Length Resulting From Conversion of Atrial Fibrillation to Atrial Tachycardia on Ablation Outcome in Persistent Atrial Fibrillation Ablation

Impact of Prolonged Cycle Length Resulting From Conversion of Atrial Fibrillation to Atrial Tachycardia on Ablation Outcome in Persistent Atrial Fibrillation Ablation

Effectiveness of Amiodarone, Propafenone And Synchronized Electrical Cardioversion for Conversion of Atrial Fibrillation Paroxysm to Sinus Rhythm in Rigas Stradins University Hospital Department of Emergency Medicine

Introduction: Atrial fibrillation remains one of the major causes of stroke, heart failure, sudden death, and cardiovascular morbidity in the world. Its incidence increases with age and the presence of structural heart disease. Materials and methods: The retrospective analysis was performed on 127 patients over a period of three years (73 men, median age 62, range 37-75, and 54 women, median age 60, range 42-78) duration of atrial fibrillation 48 hours or less. Results: Efficiency of amiodarone i/v converting atrial fibrillation to sinus rhythm detected in 56 of 69 patients (81.2%). Efficiency of propafenone i/v converting atrial fibrillation to sinus rhythm detected in 26 of 33 patients (78.8%). Efficiency of electrical cardioversion was pronounced in 24 of 25 patients (96.0%). (p&lt;0.001 compared to both amiodarone and propafenone). In case if atrial fibrillation duration is less than 8h propafenone is more effective and for atrial fibrillation with duration over 24h more effective is amiodarone. Efficacy of amiodarone and propafenone in converting atrial fibrillation paroxysm to sinus rhythm was almost the same. The effect of amiodarone was slightly superior that of propafenon. Conclusion: Amiodarone, propafenone, and electrical cardioversion all three options provide physicians with effective tools to restore sinus rhythm in patients with atrial fibrillation. Atrial fibrillation duration should be taken into account more often to choose an appropriate treatment in emergency department.

Changes in cardiac output, rhythm regularity, and symptom severity after electrical cardioversion of atrial fibrillation

Objectives Symptoms in atrial fibrillation (AF) range from none to disabling. The physiological correlates of AF symptoms are not well characterized. This study investigated the association between physiological parameters and symptom severity before and after electrical cardioversion (EC) of AF. Design We studied 44 patients with persistent AF (age 66.2 ± 7.9 years, 16% females) 4 ± 2 days before and 5 ± 2 days after EC. Physiological parameters included cardiac output (CO; non-invasive inert gas rebreathing), heart rate (HR), RR variability and resting and ambulatory blood pressure (BP). Symptoms and quality of life (QoL) were assessed by the modified European Heart Rhythm Association score (mEHRA), the Atrial Fibrillation Effect on Quality of Life (AFEQT) and the Symptom Checklist for frequency and severity of symptoms (SCL). Results 28 of 44 patients were still in sinus rhythm (SR) at post EC evaluation. Those in SR had a decreased HR (-15.4 ± 13.1 bpm, p < 0.001), and an increased CO (+0.8 ± 0.7 L/min, p < 0.001) as compared to those with recurrent AF. Changes in CO after EC correlated with symptom improvement as scored by AFEQT (r = 0.36; p < 0.05), AFEQT symptoms subscore (r = 0.46; p < 0.01), SCL for frequency (r = 0.62; p < 0.01) and severity (r = 0.33; p < 0.05) of symptoms, and the mEHRA score (r = 0.50; p < 0.01). A decrease in RR variability showed similar correlations with these measures of symptom improvement. Conclusions Improvements in symptoms and quality of life experienced by patients after electrical conversion of atrial fibrillation are correlated with an increase in CO and a decreased RR variability.

Two-incision totally thoracoscopic mitral valve repair combined with radiofrequency atrial fibrillation ablation in rheumatic mitral valve disease: Early results of a case series of 43 consecutive patients

BackgroundFew studies have reported the outcomes of two-incision total thoracoscopic mitral valve repair (MVr) and concomitant radiofrequency atrial fibrillation ablation (RAFA) in patients with rheumatic mitral valve disease and atrial fibrillation (AF). MethodsWe retrospectively analyzed 43 consecutive patients who underwent MVr and RAFA through two-incision total thoracoscopic technique from October 2018 to June 2022. We collected data on baseline characteristics, perioperative outcomes, and early-term results. ResultsThe mean age was 55.67 ± 7.64 years and 29 (67.4%) patients had New York Heart Association (NYHA) class III or IV. The mean cardiopulmonary bypass (CPB) time was 115.56 ± 8.53 min and aortic clamping time was 81.42 ± 7.54 min. There were no in-hospital deaths or strokes. The mean preoperative mitral valve orifice area (MVOA) was 0.95 (0.84–1.16) cm2 and increased to 2.56 (2.41–2.87) cm2 at discharge and 2.54 (2.44–2.76) cm2 at 3 months after surgery (P < .001). At discharge, 32 (74.4%) patients were in sinus rhythm, 7 (20.9%) were in junctional or atrial flutter rhythm, and 4 (9.3%) remained in AF. At 6 months, 35 (81.4%) patients were in sinus rhythm, 5 (11.63%) were in junctional or atrial flutter rhythm, and 3 (4.7%) were in AF. ConclusionsTwo-incision total thoracoscopic MVr and RAFA is a safe and effective procedure that can improve the MVOA and promote conversion of AF to sinus rhythm in patients with rheumatic mitral valve disease and AF. Further studies with larger sample size and longer follow-up are needed to confirm the long-term benefits of this approach.

Improvement in cerebral oxygen saturation with sinus conversion during off pump coronary artery bypass graft: A case report.

Near-infrared spectroscopy (NIRS) is a noninvasive bedside tool for monitoring regional cerebral oxygen saturation (rSO2). The sinus conversion of atrial fibrillation (AF) was shown to be responsible for increasing rSO2. However, the reason for this improvement has not yet been clearly explained. We report the case of a 73-year-old woman who underwent cardioversion during an off-pump coronary artery bypass under NIRS and live hemodynamic monitoring. Unlike previous studies that failed to control and compare all conditions during procedures, this case showed real-time fluctuating hemodynamic and hematological values, such as hemoglobin (Hgb), central venous pressure (CVP), mean arterial pressure (MAP), cardiac index (CI), left ventricular end-diastolic pressure (LVEDP), and SVO2. The rSO2 increased immediately after cardioversion and decreased during the obtuse marginal (OM) graft and after AF was obtained. However, no other hemodynamic data showed the same or opposite directional changes in the rSO2. Significant instantaneous changes were observed in rSO2 using NIRS after sinus conversion, without obvious hemodynamic alterations in the systemic circulation or other monitoring values.

Marked QTc Reduction Immediately Following Direct Current Cardioversion of Atrial Fibrillation: Clinical Implications and Mechanisms

BackgroundThe QTc in sinus rhythm (SR) following direct current cardioversion (DCCV) of atrial fibrillation (AF) is commonly used as a baseline QTc for patients who require initiation of antiarrhythmic drugs for rhythm control. Inaccurate baseline QTc may cause drug-induced torsades de pointes. ObjectivesThis study sought to assess time-dependent QTc changes following DCCV. MethodsWe prospectively assessed QTc changes with Bazett’s QTc and Fridericia’s QTc formulas in 65 patients following conversion of AF to SR. Among these 65 patients, 48 underwent DCCV and 17 spontaneously converted to SR. ResultsThere was a large and statistically significant decrease in QTc in SR immediately following DCCV in 40 patients, which occurred with an abrupt reduction in heart rate postcardioversion. This finding excluded 8 patients with ventricular-paced QRS. The mean decrease from QTc in AF was 70.7 ± 37.2 milliseconds in the QTc interval for heart rate using Bazett’s formula and 33.8 ± 17.9 milliseconds in the QTc interval for heart rate using Fridericia’s formula at 1-minute post-DCCV. In 17 patients with spontaneous conversion from AF to SR, the QTc reduction was comparable to those in patients with DCCV. The QTc increased with time and reached a steady state at 5 minutes following conversion. Initiation of Class III drugs based on the “shortened” baseline QTc following DCCV was associated with drug-induced torsades de pointes. ConclusionsIn patients with AF following conversion, regardless spontaneous or DCCV, the QTc shortened significantly with decreases in heart rate, likely via the mechanism of time-dependent rate adaption of ventricular repolarization. A steady-state QTc at 5-minutes following DCCV should be used as real baseline for guidance of pharmacotherapy in patients with AF.

Meta‑analysis of the efficacy and safety of nifekalant in the conversion of atrial fibrillation.

Atrial fibrillation (AF) is the most common type of supraventricular tachyarrhythmia. Nifekalant is a new class III antiarrhythmic drug approved for the treatment of ventricular tachyarrhythmias, but its effectiveness in converting AF to sinus rhythm remains unclear. The present analysis aimed to investigate the effect of nifekalant in the conversion of AF. PubMed, Cochrane Library and China National Knowledge Infrastructure databases were systematically used to search relevant studies published between 1999 (data at which the drug was first approved for marketing in Japan) and 2022. Randomized clinical trials, prospective studies and retrospective studies on the use of nifekalant for AF were screened. The study metrics included the success rate of the conversion of AF, the mean time to conversion, the success rate of 12 months after a single AF catheter ablation procedure and the incidence of adverse events. The eligible studies screened included six randomized clinical trials, three prospective studies and three retrospective studies, totalling 12 studies with 1,162 patients. The risk ratio (RR) for successful conversion in the nifekalant and control groups was 1.95 [95% confidence interval (CI), 1.23-3.08; P=0.005] and the mean difference for the mean time to conversion was -1.73 [95% CI, -2.69-(-0.77); P=0.0004]. Statistically significant differences were observed between nifekalant and control groups. Subgroup analysis revealed a statistically significant difference in the success rate of conversion following catheter ablation in the nifekalant group compared with the amiodarone group and the RR value was 1.95 (95% CI, 1.37-2.77; P=0.0002). Statistically significant difference was observed compared with the electrical cardioversion group and the RR value was 0.90 (95% CI, 0.84-0.98; P=0.01). However, the combined RR values for the two groups were 1.18 (95% CI, 0.85-1.65; P<0.0002). The RR value for adverse events was 0.85 (95% CI, 0.51-1.43; P=0.55), with no statistically significant differences between nifekalant and control groups. In conclusion, the results demonstrated that the success rate and time to conversion in the nifekalant group were improved compared with those in the control group, particularly after catheter ablation, and the conversion effect with nifekalant was significantly improved compared with that in the control group.

Abstract 15427: Reduction of Epicardial Fat, Clinical Risk Factors &amp; Symptomatology in Paroxysmal AF Patient With Severe Aortic Stenosis and Metabolic Syndrome via Mobile Cardiometabolic Health &amp; Weight Loss Program

Atrial fibrillation (AF) is dependent on epicardial fat (EpF) accumulation and infiltration. Complementary therapeutic strategies specifically targeting EpF present an opportunity for slowing progression and reversing the course of AF. A 73-year-old man with a history paroxysmal AF (managed by rate control/anticoagulation), severe aortic valve stenosis (AVS, area 1cm 2 , EF 55%), controlled hypertension, diabetes, and obesity (BMI 37.9) completed a 2-month cardiometabolic health program (CHP). The ‘tech plus touch’ CHP, delivered via a smartphone, utilized a comprehensive approach with physiological, nutritional, and behavioral components. Along with patented dietary regimens and nutritional supplementation implemented with personalized treatment algorithms, the CHP included direct daily engagement (messaging &amp; telehealth) with a staff clinician via the HIPAA compliant mobile app. Patient data visible to both the patient and staff clinician was synced automatically via Bluetooth-linked devices. EpF dropped by 25.5% over 9w (transthoracic echo, Fig1). BMI, visceral adiposity, and body fat were significant reduced, while lean body mass (LBM), muscle mass (MM) and intracellular fluid (ICF, a validated surrogate of chronic inflammation) improved (Fig1). Encouragingly, LBM, MM, and ICF improvements were unusual and particularly large in this older, physically inactive patient. Other clinical risk factors improved including diabetes, kidney function and inflammation. The patient reported resolution of chest pain and dyspnea, improved cardiorespiratory fitness, and began aerobic exercise. Our data demonstrate a nonpharmacologic complementary approach produces significant reductions of EpF and modifiable risk factors linked to hypertension, diabetes, and chronic inflammation in an AF patient with AVS and metabolic syndrome. Whether this will lead to a reduction in AF burden or conversion to persistent AF, remains to be determined.

Abstract 12420: Orally Inhaled Flecainide for the Conversion of Recent-Onset, Symptomatic Atrial Fibrillation to Sinus Rhythm: Final Results From the Phase 2 Instant Trial

Introduction: The INSTANT trial was a multicenter, open-label, single-arm study of flecainide acetate oral inhalation solution (FlecIH) for acute conversion of recent-onset, symptomatic atrial fibrillation (AF) to sinus rhythm (SR). The initial dose-ranging stage of the trial established safety and feasibility, while showing a dose- and concentration-dependent increase in efficacy (dose range: 30-120 mg); the highest dose was selected for this evaluation. Methods: Patients with symptomatic paroxysmal AF (≤ 48 hours) self-administered 120 mg FlecIH over 8 minutes in a monitored setting using a breath-actuated nebulizer and were continuously monitored for 90 minutes using a 12-lead Holter. Symptoms, vital signs and adverse events were recorded. Safety analyses included all patients who received 120 mg FlecIH (N=98). Efficacy analyses were performed on a modified intention to treat population (N=81) that excluded patients with systemic flecainide present prior to dosing with study drug. Results: The population had a mean age of 60.5 years, a mean BMI of 27.0 kg/m2 and 34.7% were female. All patients reported ≥1 AF-related symptoms at baseline and 87.8% presented with AF symptoms ≤ 24 hours in duration. The conversion rate was 46.9% (95% CI: 36.4%, 57.7%), with a median time of 13.7 minutes from the start of the inhalation. A greater proportion of patients were asymptomatic or had improved symptoms following conversion of AF to SR with inhaled flecainide compared to patients whose AF did not convert (92.1% and 45.4%, respectively, p &lt; 0.001). Two patients had CV events that were considered serious (bradycardia and atrial flutter with 1:1 AV conduction). Both CV events were transient (12 and 6 minutes, respectively), required no treatment and resolved without sequelae. Median time to discharge was 2.5 hours for patients whose AF converted to SR with inhaled flecainide and by Day 5 none had experienced AF recurrence. In contrast, 35 (81.4%) patients in the no conversion group had undergone ECV by Day 5. Conclusions: The risk-benefit of orally inhaled flecainide acetate inhalation solution for acute cardioversion of recent onset AF appears favorable and may provide a safe, effective, and convenient first-line therapeutic option for AF conversion.

Association of Intravenous Potassium and Magnesium Administration With Spontaneous Conversion of Atrial Fibrillation and Atrial Flutter in the Emergency Department

Whether the simultaneous intravenous administration of potassium and magnesium is associated with the probability of spontaneous conversion to sinus rhythm (SCV) in the acute treatment of atrial fibrillation (AF) and atrial flutter (AFL) is unknown. To assess potassium and magnesium administration and SCV probability in AF and AFL in the emergency department. A registry-based cohort study was conducted in the Department of Emergency Medicine of the Medical University of Vienna, Austria. All consecutive patients with AF or AFL were screened between February 6, 2009, and February 16, 2020. Intravenous administration of potassium, 24 mEq, and magnesium, 145.8 mg. The primary outcome was the probability of SCV during the patient's stay in the emergency department. Multivariable cluster-adjusted logistic regression was used to estimate the association between potassium and magnesium administration and the probability of SCV. A total of 2546 episodes of nonpermanent AF (median patient age, 68 [IQR, 58-75] years, 1411 [55.4%] men) and 573 episodes of nonpermanent AFL (median patient age, 68 [IQR, 58-75] years; 332 [57.9%] men) were observed. In AF episodes, intravenous potassium and magnesium administration vs no administration was associated with increased odds of SCV (19.2% vs 10.4%; odds ratio [OR], 1.98; 95% CI, 1.53-2.57). In AFL episodes, in contrast, no association was noted for the probability of SCV with potassium and magnesium vs no administration (13.0% vs 12.5%; OR, 1.05; 95% CI, 0.65-1.69). The findings of this registry-based cohort study on intravenous administration of potassium and magnesium suggest an increased probability of SCV in nonpermanent AF, but not AFL, during a patients' stay in the emergency department.