Project description:Atrial fibrillation (AF), the most common cardiac arrhythmia worldwide, is driven by complex mechanisms that differ between subgroups of patients. This complexity is apparent from the different forms in which AF presents itself (post-operative, paroxysmal and persistent), each with heterogeneous patterns and variable progression. Our current understanding of the mechanisms responsible for initiation, maintenance and progression of the different forms of AF has increased significantly in recent years. Nevertheless, antiarrhythmic drugs for the management of AF have not been developed based on the underlying arrhythmia mechanisms and none of the currently used drugs were specifically developed to target AF. With the increased knowledge on the mechanisms underlying different forms of AF, new opportunities for developing more effective and safer AF therapies are emerging. In this review, we provide an overview of potential novel antiarrhythmic approaches based on the underlying mechanisms of AF, focusing both on the development of novel antiarrhythmic agents and on the possibility of repurposing already marketed drugs. In addition, we discuss the opportunity of targeting some of the key players involved in the underlying AF mechanisms, such as ryanodine receptor type-2 (RyR2) channels and atrial-selective K+-currents (IK2P and ISK) for antiarrhythmic therapy. In addition, we highlight the opportunities for targeting components of inflammatory signaling (e.g., the NLRP3-inflammasome) and upstream mechanisms targeting fibroblast function to prevent structural remodeling and progression of AF. Finally, we critically appraise emerging antiarrhythmic drug principles and future directions for antiarrhythmic drug development, as well as their potential for improving AF management.
Project description:Background: The efficacy of antiarrhythmic drugs (AAD) can vary in patients with atrial fibrillation (AF), and the PITX2 gene affects the responsiveness of AADs. We explored the virtual AAD (V-AAD) responses between wild-type and PITX2 +/--deficient AF conditions by realistic in silico AF modeling. Methods: We tested the V-AADs in AF modeling integrated with patients' 3D-computed tomography and 3D-electroanatomical mapping, acquired in 25 patients (68% male, 59.8 ± 9.8 years old, 32.0% paroxysmal type). The ion currents for the PITX2 +/- deficiency and each AAD (amiodarone, sotalol, dronedarone, flecainide, and propafenone) were defined based on previous publications. Results: We compared the wild-type and PITX2 +/- deficiency in terms of the action potential duration (APD90), conduction velocity (CV), maximal slope of restitution (Smax), and wave-dynamic parameters, such as the dominant frequency (DF), phase singularities (PS), and AF termination rates according to the V-AADs. The PITX2 +/--deficient model exhibited a shorter APD90 (p < 0.001), a lower Smax (p < 0.001), mean DF (p = 0.012), PS number (p < 0.001), and a longer AF cycle length (AFCL, p = 0.011). Five V-AADs changed the electrophysiology in a dose-dependent manner. AAD-induced AFCL lengthening (p < 0.001) and reductions in the CV (p = 0.033), peak DF (p < 0.001), and PS number (p < 0.001) were more significant in PITX2 +/--deficient than wild-type AF. PITX2 +/--deficient AF was easier to terminate with class IC AADs than the wild-type AF (p = 0.018). Conclusions: The computational modeling-guided AAD test was feasible for evaluating the efficacy of multiple AADs in patients with AF. AF wave-dynamic and electrophysiological characteristics are different among the PITX2-deficient and the wild-type genotype models.
Project description:BackgroundAntiarrhythmic drugs (AADs) are used to reduce the frequency, severity, and duration of atrial fibrillation (AF) events, which should reduce hospitalizations; however, little is known about the associations between different AADs and hospitalization—particularly among younger AF patients without structural heart disease.Methods and resultsUsing MarketScan® claims data, we identified AF patients without coronary artery disease or heart failure who received their first AAD prescription (amiodarone, sotalol, dronedarone, or Class Ic) within 14 days post-first AF encounter. The primary outcome was time from first AAD prescription to AF hospitalization, and secondary outcomes included time to cardiovascular and all-cause hospitalizations. We used inverse probability-weighted estimators to adjust for differences in treatment allocation in the Cox proportional hazards model for each outcome. Among 8562 AF patients with a median age of 56 years (interquartile range 49, 61), risk of AF hospitalization was greater with dronedarone than Class Ic (hazard ratio [HR] 1.59; 95% confidence interval 1.13-2.24), amiodarone (HR 2.63; 1.77-3.89), and sotalol (HR 1.72; 1.17-2.54), but lower with amiodarone versus Class Ic (HR 0.68; 0.57-0.80) and sotalol (HR 0.63; 0.53-0.75). Risk of cardiovascular hospitalization was lower with amiodarone than Class Ic (HR 0.80; 0.70-0.92), but not non-AF cardiovascular hospitalization (HR 1.26; 1.01-1.57). There was no difference in all-cause hospitalization between amiodarone, Class Ic, and sotalol.ConclusionsDifferences in hospitalization rates were found between AADs in younger AF patients without structural heart disease. Amiodarone had the lowest risk of AF hospitalization and dronedarone had the greatest risk. Additional research is needed to better understand associations between AADs and hospitalization risk.
Project description:Pharmacologic management of atrial fibrillation (AF) is a pressing problem. This arrhythmia afflicts >5 million individuals in the United States and prevalence is estimated to rise to 12 million by 2050. Although the pill-in-the-pocket regimen for self-administered AF cardioversion introduced over a decade ago has proven useful, significant drawbacks exist. Among these are the relatively long latency of effects in the range of hours along with potential for hypotension and other adverse effects. This experience prompted development of a new strategy for increasing plasma concentrations of antiarrhythmic drugs rapidly and for a limited time, namely, pulmonary delivery. In preclinical studies in Yorkshire pigs, intratracheal administration of flecainide was shown to cause a rapid, reproducible increase in plasma drug levels. Moreover, pulmonary delivery of flecainide converted AF to normal sinus rhythm by prolonging atrial depolarization, which slows intra-atrial conduction and seems to be directly correlated with efficacy in converting AF. The rapid rise in plasma flecainide levels optimizes its anti-AF effects while minimizing adverse influences on ventricular depolarization and contractility. A more concentrated and soluble formulation of flecainide using a novel cyclodextrin complex excipient reduced net drug delivery for AF conversion when compared to the acetate formulation. Inhalation of the beta-adrenergic blocking agent metoprolol slows ventricular rate and can also terminate AF. In human subjects, oral inhalation of flecainide acetate with a hand-held, breath-actuated nebulizer results in signature prolongation of the QRS complex without serious adverse events. Thus, pulmonary delivery is a promising advance in pharmacologic approach to management of AF.
Project description:BackgroundAtrial fibrillation (AF) is associated with an increased risk of hospital admission, but few data on reasons for hospitalization and on the role of anti-arrhythmic drugs are available.ObjectivesThe purpose of this study was to investigate the incidence rate and factors associated with all-cause, cardiovascular, and AF-related hospitalizations.MethodsProspective ongoing ATHERO-AF (Atherosclerosis in Atrial Fibrillation) cohort study enrolling AF patients on oral anticoagulants. Primary end points were all-cause, cardiovascular, and AF-related hospitalization, the latter defined as AF recurrences for paroxysmal AF and high-rate symptomatic AF episodes for persistent/permanent AF patients.Results2,782 patients were included (43.5% female; mean age was 74.6 ± 9.1 years). During a mean follow-up of 31 ± 26.8 months, 1,205 (12.1%/year) all-cause, 533 cardiac (5.7%/year), and 180 (2.0%/year) AF-related hospitalizations occurred. Predictors of AF-related hospitalizations were the use of flecainide/propafenone in both paroxysmal and persistent/permanent AF patients (HR: 1.861; 95% CI: 1.116 to 3.101 and 1.947; 95% CI: 1.069 to 3.548, respectively). Amiodarone (HR: 3.012; 95% CI: 1.835-4.943), verapamil/diltiazem (HR: 2.067; 95% CI: 1.117-3.825), and cancer (HR: 1.802; 95% CI: 1.057-3.070) but not beta-blockers and digoxin were associated with an increased risk of AF-related hospitalizations in persistent/permanent AF patients.ConclusionsElderly AF patients frequently undergo hospitalizations for both cardiovascular and noncardiovascular causes. The use of anti-arrhythmic drugs was associated with an increased risk of AF-related hospitalization suggesting a scarce effect of these drugs in preventing AF episodes. Therefore, their use should be carefully considered and reserved for symptomatic patients with frequent AF recurrences.
Project description:ImportanceThe association between obesity, an established risk factor for atrial fibrillation (AF), and response to antiarrhythmic drugs (AADs) remains unclear.ObjectiveTo test the hypothesis that obesity differentially mediates response to AADs in patients with symptomatic AF and in mice with diet-induced obesity (DIO) and pacing induced AF.Design, setting, and participantsAn observational cohort study was conducted including 311 patients enrolled in a clinical-genetic registry. Mice fed a high-fat diet for 10 weeks were also evaluated. The study was conducted from January 1, 2018, to June 2, 2019.Main outcomes and measuresSymptomatic response was defined as continuation of the same AAD for at least 3 months. Nonresponse was defined as discontinuation of the AAD within 3 months of initiation because of poor symptomatic control of AF necessitating alternative rhythm control therapy. Outcome measures in DIO mice were pacing-induced AF and suppression of AF after 2 weeks of treatment with flecainide acetate or sotalol hydrochloride.ResultsA total of 311 patients (mean [SD] age, 65 [12] years; 120 women [38.6%]) met the entry criteria and were treated with a class I or III AAD for symptomatic AF. Nonresponse to class I AADs in patients with obesity was less than in those without obesity (30% [obese] vs 6% [nonobese]; difference, 0.24; 95% CI, 0.11-0.37; P = .001). Both groups had similar symptomatic response to a potassium channel blocker AAD. On multivariate analysis, obesity, AAD class (class I vs III AAD [obese] odds ratio [OR], 4.54; 95% Wald CI, 1.84-11.20; P = .001), female vs male sex (OR, 2.31; 95% Wald CI, 1.07-4.99; P = .03), and hyperthyroidism (OR, 4.95; 95% Wald CI, 1.23-20.00; P = .02) were significant indicators of the probability of failure to respond to AADs. Pacing induced AF in 100% of DIO mice vs 30% (P < .001) in controls. Furthermore, DIO mice showed a greater reduction in AF burden when treated with sotalol compared with flecainide (85% vs 25%; P < .01).Conclusions and relevanceResults suggest that obesity differentially mediates response to AADs in patients and in mice with AF, possibly reducing the therapeutic effectiveness of sodium channel blockers. These findings may have implications for the management of AF in patients with obesity.
Project description:AimsTreatment guidelines for patients with atrial fibrillation (AF) suggest that patients should be managed with an antiarrhythmic drug (AAD) before undergoing catheter ablation (CA). This study evaluated whether pulmonary vein isolation employing cryoballoon CA is superior to AAD therapy for the prevention of atrial arrhythmia (AA) recurrence in rhythm control naive patients with paroxysmal AF (PAF).Methods and resultsA total of 218 treatment naive patients with symptomatic PAF were randomized (1 : 1) to cryoballoon CA (Arctic Front Advance, Medtronic) or AAD (Class I or III) and followed for 12 months. The primary endpoint was ≥1 episode of recurrent AA (AF, atrial flutter, or atrial tachycardia) >30 s after a prespecified 90-day blanking period. Secondary endpoints included the rate of serious adverse events (SAEs) and recurrence of symptomatic palpitations (evaluated via patient diaries). Freedom from AA was achieved in 82.2% of subjects in the cryoballoon arm and 67.6% of subjects in the AAD arm (HR = 0.48, P = 0.01). There were no group differences in the time-to-first (HR = 0.76, P = 0.28) or overall incidence [incidence rate ratio (IRR)=0.79, P = 0.28] of SAEs. The incidence rate of symptomatic palpitations was lower in the cryoballoon (7.61 days/year) compared with the AAD arm (18.96 days/year; IRR = 0.40, P < 0.001).ConclusionsCryoballoon CA was superior to AAD therapy, significantly reducing AA recurrence in treatment naive patients with PAF. Additionally, cryoballoon CA was associated with lower symptom recurrence and a similar rate of SAEs compared with AAD therapy.
Project description:In patients with recurrent atrial fibrillation (AF), the hallmark of treatment has been the use of antiarrhythmic drugs (AADs). Goals of therapy include reduction in the frequency and duration of episodes of arrhythmia as well an emerging goal of reducing mortality and hospitalizations associated with AF. Safety and efficacy are important factors when choosing an antiarrhythmic drug for the treatment of AF, hence, if AAD are required for maintenance of sinus rhythm, their safety profi le, together with individual patient characteristics, should be of utmost concern. In the next paragraphs we would like to review some aspects (electrophysiologic effects, metabolism, side effects, current evidence and indication) of the most commonly used AAD for the management of patients with AF, following the Vaughan-Williams classification. However, this system is mainly based on ventricular activity, therefore, and due to its relatively atrial selective actions, some agents will not readily fit in the Vaughan Williams AAD classification. For that reason, in the final part of the manuscript, new promising agents will be reviewed separately.
Project description:BackgroundThe optimal first-line approach for patients with symptomatic atrial fibrillation (AF) remains unclear. We compared the efficacy and safety of cryoballoon ablation (CBA) and antiarrhythmic drugs (AADs) in the initial management of symptomatic AF.HypothesisCBA is superior to AAD as initial therapy for symptomatic AF.MethodsWe searched the EMBASE, PubMed, and Cochrane Library databases for randomized controlled trials (RCTs) that compared CBA with AAD as first-line treatment for AF from the date of database establishment until March 18, 2021. The risk ratio (RR) with a 95% confidence interval (CI) was used as a measure of treatment effect.ResultsThree RCTs that enrolled 724 patients in total were included in this meta-analysis. Majority of the patients were relatively young and had paroxysmal AF. CBA was associated with a significant reduction in the recurrence of atrial arrhythmia compared with AAD therapy, with low heterogeneity (RR, 0.59; 95% CI, 0.49-0.71; p < .00001; I2 = 0%). There was a significant difference in the rate of symptomatic atrial arrhythmia recurrence (RR, 0.44; 95% CI, 0.29-0.65; p < .0001; I2 = 0%); however, the rate of serious adverse events was similar between the two treatment groups (RR: 1.18; 95% CI: 0.71-1.97, p = .53; I2 = 0%). Transient phrenic nerve palsy occurred in four patients after the CBA procedure.ConclusionThe current meta-analysis suggests that CBA is more effective than AAD as initial therapy in patients with symptomatic paroxysmal AF. Serious iatrogenic adverse events are uncommon in CBAs.