Predictors of long-term maintenance of normal sinus rhythm after successful electrical cardioversion

Size matters in atrial fibrillation: the underestimated importance of reduction of contiguous electrical mass underlying the effectiveness of catheter ablation

Evidence has accumulated over the last century of the importance of a critical electrical mass in sustaining atrial fibrillation (AF). AF ablation certainly reduces electrically contiguous atrial mass, but this is not widely accepted to be an important part of its mechanism of action. In this article, we review data showing that atrial size is correlated in many settings with AF propensity. Larger mammals are more likely to exhibit AF. This is seen both in the natural world and in animal models, where it is much easier to create a goat model than a mouse model of AF, for example. This also extends to humans-athletes, taller people, and obese individuals all have large atria and are more likely to exhibit AF. Within an individual, risk factors such as hypertension, valvular disease and ischaemia can enlarge the atrium and increase the risk of AF. With respect to AF ablation, we explore how variations in ablation strategy and the relative effectiveness of these strategies may suggest that a reduction in electrical atrial mass is an important mechanism of action. We counter this with examples in which there is no doubt that mass reduction is less important than competing theories such as ganglionated plexus ablation. We conclude that, when considering future strategies for the ablative therapy of AF, it is important not to discount the possibility that contiguous electrical mass reduction is the most important mechanism despite the disappointing consequence being that enhancing success rates in AF ablation may involve greater tissue destruction.

Atrial Fibrillation Recurrence Prevention after Electrical Cardioversion in High-Risk Patients – Benefits of Non-Antiarrhythmic Drugs

Background:

Recurrence prevention after Atrial Fibrillation (AF) termination by Eelectrical Cardioversion (ECV) remains challenging. Increasing attention is paid to pathophysiological effects of non-Antiarrhythmic Drugs (non-AADs), nevertheless, with heterogeneous results.

Objective:

We evaluated the potential benefits of different non-AADs as adjunctive therapy to Antiarrhythmic Drugs (AADs) for AF recurrence prevention after sinus rhythm restoration by ECV in high-risk patients.

Methods:

The study was conducted among high-risk AF patients after successful ECV. Prescription of class IC or class III AAD was required. Data were acquired in a face-to-face baseline interview and 1-, 3-, 6-, 9-, 12-month follow-up interviews.

Results:

113 patients were included. Total AF recurrence rate reached 48.7%. Angiotensin-Converting Enzyme Inhibitor (ACEI) or angiotensin receptor blocker (ARB) intake, compared with non-use, demonstrated AF recurrence rate reduction by 8.5% (46.3 vs. 54.8%), with odds ratio (OR) reduced by 28.9% (OR 0.711, 95% confidence interval (CI) 0.310-1.631, p = 0.420). Among mineralocorticoid receptor antagonist (MRA) users, AF recurrence rate was reduced by 25.1% (29.6 vs. 54.7%) and OR by 65.1% (OR 0.349, 95%CI 0.138-0.884, p = 0.023). Present statin therapy reduced AF recurrence rate by 4.2% (46.8 vs. 51.0%) and OR by 15.5% (OR 0.845, 95%CI 0.402-1.774, p = 0.656). Diuretic use showed reduction of AF recurrence rate by 10.2% (41.7 vs. 51.9%) and OR by 33.9% (OR 0.661, 95%CI 0.297-1.469, p = 0.308).

Conclusion:

Non-AADs demonstrated practical benefits as adjunctive therapy to AADs for AF recurrence prevention after ECV in high-risk patients, with statistically significant results established for concomitant MRA intake.

Pharmacological Cardioversion after Pre-Treatment with Antiarrythmic Drugs Prior to Electrical Cardioversion in Persistent Atrial Fibrillation: Impact on Maintenance of Sinus Rhythm

BACKGROUND

Antiarrhythmic drugs (AADs) are frequently initiated in patients with persistent atrial fibrillation (AF) prior to electrical cardioversion (ECV), achieving pharmacological cardioversion (PCV) in some cases. Little is known about the mode of cardioversion and the effect of the type of AAD used in the maintenance of sinus rhythm (SR).

METHODS

From three national surveys of patients with persistent AF referred for ECV, we selected those who were pre-treated with AADs (amiodarone or group Ic AADs). We analyzed the effect of the type of cardioversion (pharmacological vs. electrical) and the AAD used in the maintenance of SR at three months.

RESULTS

Among the 665 patients selected, 151 had a successful PCV prior to the planned ECV. In the remaining 514 patients, 460 had a successful ECV. A successful PCV was related to a higher rate of SR maintenance than a successful ECV (77.9% vs. 57.5%; p < 0.0001). After a successful PCV, the maintenance of SR was identical in those patients treated with amiodarone and those treated with group Ic AADs (77.4% vs. 77.5%; p = 0.99), whereas after a successful ECV, amiodarone was clearly superior to group Ic AADs (61.3% vs. 43.0%; p = 0.001). Considering patients with successful PCV and ECV together, PCV was an independent factor related to the maintenance of SR.

CONCLUSIONS

In patients with persistent AF, successful PCV selects a subgroup with a high probability of maintenance of SR. With regard to drugs, amiodarone was superior to group Ic AADs in patients with ECV, whereas in PCV, no differences were observed.

Role for machine learning in sex-specific prediction of successful electrical cardioversion in atrial fibrillation?

Objective

Electrical cardioversion is frequently performed to restore sinus rhythm in patients with persistent atrial fibrillation (AF). However, AF recurs in many patients and identifying the patients who benefit from electrical cardioversion is difficult. The objective was to develop sex-specific prediction models for successful electrical cardioversion and assess the potential of machine learning methods in comparison with traditional logistic regression.

Methods

In a retrospective cohort study, we examined several candidate predictors, including comorbidities, biochemistry, echocardiographic data, and medication. The outcome was successful cardioversion, defined as normal sinus rhythm immediately after the electrical cardioversion and no documented recurrence of AF within 3 months after. We used random forest and logistic regression models for sex-specific prediction.

Results

The cohort comprised 332 female and 790 male patients with persistent AF who underwent electrical cardioversion. Cardioversion was successful in 44.9% of the women and 49.9% of the men. The prediction errors of the models were high for both women (41.0% for machine learning and 48.8% for logistic regression) and men (46.0% for machine learning and 44.8% for logistic regression). Discrimination was modest for both machine learning (0.59 for women and 0.56 for men) and logistic regression models (0.60 for women and 0.59 for men), although the models were well calibrated.

Conclusions

Sex-specific machine learning and logistic regression models showed modest predictive performance for successful electrical cardioversion. Identifying patients who will benefit from cardioversion remains challenging in clinical practice. The high recurrence rate calls for thoroughly informed shared decision-making for electrical cardioversion.

The Role of Anxiety in Patients With Persistent Atrial Fibrillation Undergoing Elective Cardioversion: An Observational Study

OBJECTIVE

Anxiety is often present among patients with atrial fibrillation (AF). This condition has been associated with greater symptom severity and worse quality of life in these patients. However, the influence of anxiety on the risk of AF recurrence is not well known. We aimed to define the level of anxiety in patients with persistent AF undergoing elective cardioversion (EC) and determine whether there is an association between anxiety and the risk of early AF recurrence after EC.

METHODS

Anxiety was measured before EC using the State-Trait Anxiety Inventory. Early AF recurrence was assessed with a control electrocardiogram at 30-day follow-up.

RESULTS

We included 107 patients undergoing effective EC. Early AF recurrence was diagnosed in 40 patients (37.4%). Compared with those who remained in sinus rhythm, individuals with early AF recurrence had significantly higher levels of trait anxiety (23.1 [10.4] versus 17.9 [9.5]; p = .013) and larger left atrial volume index (45.8 [12.3] versus 37.9 [13.3] ml/m; p = .004). Both variables remained independently associated with early AF recurrence after multivariate analysis. A predictive model including trait anxiety score >20 and left atrial volume index >41 ml/m showed acceptable accuracy for the diagnosis of early AF recurrence (area under the curve = 0.733; 95% confidence interval = 0.634-0.832; p < .001).

CONCLUSIONS

Our study shows that trait anxiety is an independent risk factor for early AF recurrence after EC. Further studies are warranted to assess the beneficial role of anxiety-reducing strategies on the outcomes of patients with AF.

Effectiveness of dual external direct current cardioversion for initial cardioversion in atrial fibrillation

INTRODUCTION

Dual external direct current cardioversion (dual-DCCV) is a rhythm control strategy for persistent atrial fibrillation (AF), involving simultaneous delivery of two shocks from two defibrillators. The long-term effectiveness of this approach has not been studied in the biphasic cardioversion era.

METHODS

Seventy-seven consecutive patients at a single center were identified to receive dual-DCCV at the time of their initial cardioversion for AF, when maximum output standard external direct current cardioversion failed in two vectors. Logistic regression was used to analyze risk factors for dual-DCCV in a historical control group of 77 patients undergoing standard cardioversion and Cox proportional hazard models were used to compare time to AF recurrence.

RESULTS

The dual-DCCV group had a significantly larger body mass index (BMI), but similar AF duration and left atrial size as controls. Multivariable logistic regression revealed that BMI and absence of prior paroxysmal AF were risk factors for dual-DCCV (P < 0.05). There was no difference observed between dual-DCCV and control groups (adjusted hazard ratio = 0.57; P = .12) after adjusting for number of shocks and age. Transient hypoxia was the only acute complication in either group (P > .999).

CONCLUSION

Dual-DCCV appears to be a safe and effective cardioversion strategy for patients with AF. The need for dual-DCCV in the treatment of AF appears to be influenced more by body habitus than atrial substrate.

A review of factors associated with maintenance of sinus rhythm after elective electrical cardioversion for atrial fibrillation

Atrial fibrillation is the most common heart-rhythm disorder, affecting about 1.5% to 2% of the population with an increased risk of mortality and morbidity due to stroke, thromboembolism, and heart failure. If the conversion back to sinus rhythm does not happen spontaneously, pharmacological or electrical cardioversion (ECV) is the next available treatment options for some patients. However, the long-term success following ECV is variable. This review describes the factors that are associated with maintenance of sinus rhythm following ECV and proposes a clinical strategy based on the available evidence.

Use of acoustic cardiography immediately following electrical cardioversion to predict relapse of atrial fibrillation

Predicting atrial fibrillation (AF) recurrence after successful electrical cardioversion (ECV) is difficult. The main aim of this study was to investigate whether acoustic cardiography (AUDICOR® 200) immediately post-ECV might provide indices for AF relapse following cardioversion. Acoustic cardiography parameters included Electromechanical Activation Time (EMAT), Left Ventricular Systolic Time (LVST), QRS duration, heart rate and third heart sound intensity (S3 Strength). We analysed data from 140 patients who underwent successful cardioversion and in whom AUDICOR results and echocardiographic measurements immediately after (baseline) ECV were available. Patients were prospectively followed-up at 4-6 weeks, 3 and 12 months post-ECV, and sinus rhythm maintenance was evaluated using acoustic cardiography and Holter electrocardiography. The effect of each baseline AUDICOR parameter on the hazard of AF relapse was investigated using Cox proportional hazards (PH) models. Fifty patients (35.7%) had AF relapse. Of all the AUDICOR parameters, only S3 Strength exhibited consistent predictive value. Increasing S3 Strength increased the hazard of relapse in a univariable Cox PH model (HR=2.52, p=0.003), and in two multivariable Cox PH model constructions (Model 1 excluded heart rate and Model II excluded EMAT/RR, LVST and LVST/RR) both of which included the parameters as continuous variables (Model I: HR=1.15, p=0.042; Model II: HR=1.14, p=0.045) or the parameters dichotomized according to suggested cut-points (Model I: HR=2.5, p=0.007; Model II: HR=2.09, p=0.031). In conclusion, this study suggests that acoustic cardiography may be a simple inexpensive and quantitative bedside method to assist in prediction of AF recurrence after ECV.

Atrial fibrillation: mechanisms, therapeutics, and future directions

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia, affecting 1% to 2% of the general population. It is characterized by rapid and disorganized atrial activation leading to impaired atrial function, which can be diagnosed on an EKG by lack of a P-wave and irregular QRS complexes. AF is associated with increased morbidity and mortality and is a risk factor for embolic stroke and worsening heart failure. Current research on AF support and explore the hypothesis that initiation and maintenance of AF require pathophysiological remodeling of the atria, either specifically as in lone AF or secondary to other heart disease as in heart failure-associated AF. Remodeling in AF can be grouped into three categories that include: (i) electrical remodeling, which includes modulation of L-type Ca(2+) current, various K(+) currents and gap junction function; (ii) structural remodeling, which includes changes in tissues properties, size, and ultrastructure; and (iii) autonomic remodeling, including altered sympathovagal activity and hyperinnervation. Electrical, structural, and autonomic remodeling all contribute to creating an AF-prone substrate which is able to produce AF-associated electrical phenomena including a rapidly firing focus, complex multiple reentrant circuit or rotors. Although various remodeling events occur in AF, current AF therapies focus on ventricular rate and rhythm control strategies using pharmacotherapy and surgical interventions. Recent progress in the field has started to focus on the underlying substrate that drives and maintains AF (termed upstream therapies); however, much work is needed in this area. Here, we review current knowledge of AF mechanisms, therapies, and new areas of investigation.

High-Sensitivity Troponin I and Rhythm Outcome after Electrical Cardioversion for Persistent Atrial Fibrillation

OBJECTIVES

We hypothesised that high-sensitivity troponin I (hs-TnI) might predict long-term rhythm outcome after cardioversion for persistent atrial fibrillation (AF), and that maintenance of sinus rhythm and/or treatment with the angiotensin II type 1 receptor blocker candesartan would reduce hs-TnI levels.

METHODS

In a double-blind, placebo-controlled study, 171 patients referred for electrical cardioversion for AF were randomised to receive candesartan or placebo for 3-6 weeks before cardioversion and for 6 months after electrical cardioversion. Blood samples for analysis of hs-TnI (Abbott Diagnostics) were available in 129 patients at baseline and in 60 successfully cardioverted patients at study end.

RESULTS

Hs-TnI was detectable in all subjects, with a median value of 5.3 ng/l (25th percentile 3.7, 75th percentile 7.2). hs-TnI at baseline was not predictive of rhythm outcome 6 months after electrical cardioversion for persistent AF. Treatment with candesartan did not influence the levels of hs-TnI. hs-TnI was unchanged from baseline to study end in patients who maintained sinus rhythm [4.9 (3.7, 7.0) and 5.0 (4.0, 6.4) ng/l, respectively; p = 0.699).

CONCLUSIONS

hs-TnI did not predict AF recurrence after cardioversion. hs-TnI levels were unchanged in patients maintaining sinus rhythm for 6 months after electrical cardioversion. hs-TnI levels were not influenced by treatment with candesartan.