Cardioversion of atrial fibrillation in the setting of mild to moderate heart failure

Predicting the Outcomes of External Direct Current Cardioversion for Atrial Fibrillation: A Narrative Review of Current Evidence

Atrial fibrillation (AF) is the most common sustained arrhythmia associated with significant morbidity and mortality. External direct current cardioversion (DCCV) is a cornerstone intervention for rhythm control in AF; however, its success is influenced by various patient-specific and procedural factors. This review examines the predictors of DCCV success and AF recurrence with specific focus upon demographics, biochemical, cardiovascular imaging, and P-wave parameters and their likely ability to predict procedural outcomes. Demographic factors such as age, sex, and comorbidities influence DCCV outcomes, with prolonged AF duration, obesity, and heart failure being associated with higher failure rates. Elevated biochemical markers of inflammation and fibrosis, including C-reactive protein, galectin-3, and Type III procollagen-N-peptide, were predictive of poor outcomes. Imaging parameters, particularly left atrial (LA) volume and strain, emerged as critical indicators of atrial remodelling and DCCV failure. Increased P-wave duration and dispersion on electrocardiography were associated with an increased risk of recurrence. Biphasic waveforms and antiarrhythmic drugs, such as amiodarone and flecainide, improved cardioversion success. The predictors of DCCV success and recurrence reflect the interplay of structural, biochemical, and electrical remodelling in AF. Integrating these parameters into clinical practice can guide individualised patient management and improve outcomes. Further research is needed to validate these predictors and enhance precision medicine approaches in DCCV.

The role of cardiopulmonary exercise testing in risk stratification and prognosis of atrial fibrillation: a scoping review of the literature

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a significant tool for evaluating exercise capacity in healthy individuals and in various pulmonary and cardiovascular conditions, quantifying symptoms and predicting outcomes. Atrial fibrillation (AF) poses a significant burden on patients and health systems; a research marathon is ongoing for discovering the pathophysiologic substrate, natural history, prognostic tools and optimal treatment strategies for AF. Among the plethora of variables measured during CPET, there is a series of parameters of interest concerning AF.

METHODS

We conducted a scoping review aiming to identify significant CPET-related parameters linked to AF, as well as indicate the impact of other cardiac disease-related variables. We searched PubMed from its inception to 12 January 2022 for reports underlining the contribution of CPET in the assessment of patients with AF. Only clinical trials, observational studies and systematic reviews were included, while narrative reviews, expert opinions and other forms of manuscripts were excluded.

RESULTS

In our scoping review, we report a group of heterogeneous, thus noteworthy parameters relevant to the potential contribution of CPET in AF. CPET helps phenotype AF populations, evaluates exercise capacity after cardioversion or catheter ablation, and assesses heart rate response to exercise; peak VO2 and VE/VCO2, commonly measured indices during CPET, also serve as prognostic tools in patients with AF and heart failure.

CONCLUSIONS

CPET seems to hold a clinically important predictive value for future cardiovascular events both in patients with pre-existing cardiac conditions and in healthy individuals. CPET variables may play a fundamental role in the prediction of future AF-related events.

Routine versus aggressive upstream rhythm control for prevention of early atrial fibrillation in heart failure: background, aims and design of the RACE 3 study

Background

Rhythm control for atrial fibrillation (AF) is cumbersome because of its progressive nature caused by structural remodelling. Upstream therapy refers to therapeutic interventions aiming to modify the atrial substrate, leading to prevention of AF.

Objective

The Routine versus Aggressive upstream rhythm Control for prevention of Early AF in heart failure (RACE 3) study hypothesises that aggressive upstream rhythm control increases persistence of sinus rhythm compared with conventional rhythm control in patients with early AF and mild-to-moderate early systolic or diastolic heart failure undergoing electrical cardioversion.

Design

RACE 3 is a prospective, randomised, open, multinational, multicenter trial. Upstream rhythm control consists of angiotensin converting enzyme inhibitors and/or angiotensin receptor blockers, mineralocorticoid receptor antagonists, statins, cardiac rehabilitation therapy, and intensive counselling on dietary restrictions, exercise maintenance, and drug adherence. Conventional rhythm control consists of routine rhythm control therapy without cardiac rehabilitation therapy and intensive counselling. In both arms, every effort is made to keep patients in the rhythm control strategy, and ion channel antiarrhythmic drugs or pulmonary vein ablation may be instituted if AF relapses. Total inclusion will be 250 patients. If upstream therapy proves to be effective in improving maintenance of sinus rhythm, it could become a new approach to rhythm control supporting conventional pharmacological and non-pharmacological rhythm control.

Atrial fibrillation is associated with increased neurohumoral activation and reduced exercise tolerance in patients with non-ischemic dilated cardiomyopathy

OBJECTIVES

To assess atrial fibrillation (AF) associated differences in proinflammatory cytokines, natriuretic peptide levels and exercise capacity in patients with heart failure (HF) secondary to non-ischemic dilated cardiomyopathy (NIDC).

METHODS

We studied 147 NIDC patients, mean age 58.3+/-12.5 years, left ventricular (LV) ejection fraction 27.8+/-10.9% and NYHA class II-III. Neurohumoral activation was assessed by measurement of interleukin IL-1, IL-6, tumor necrosis factor-a (TNF-a), its soluble receptors sTNFR I and II, N-terminal atrial (NT-ANP) and -brain (NT-BNP) natriuretic peptide levels, and functional class was assessed by cardiopulmonary exercise test.

RESULTS

Forty patients (27.5%) had chronic AF and they did not differ in age, LV ejection fraction or HF duration compared to patients in sinus rhythm (SR). AF was associated with increased levels of IL-6 (p=0.001), TNF-a (p=0.002), sTNFRI (p=0.023), NT-ANP (p<0.001) and NT-BNP (p=0.003), decreased exercise duration (p<0.001) and slightly reduced maximal oxygen consumption at peak exercise (p=0.07) compared to SR patients. No significant differences in cytokine and natriuretic peptide levels or exercise tolerance were noted when patients in AF were compared to the subgroup of SR with restrictive LV filling pattern. Multivariate analysis showed that NT-ANP (p=0.003) and IL-6 (p=0.006) plasma levels were independently associated with the presence of AF in our patient population.

CONCLUSION

AF is associated with increased inflammatory state, natriuretic peptide levels and reduced exercise capacity in patients with HF secondary to NIDC. These findings suggest that the presence of AF in HF represents a more advanced stage of the syndrome.

Presence and development of atrial fibrillation in chronic heart failure

BACKGROUND

Atrial fibrillation is common in heart failure, but data regarding beta-blockade in these patients and its ability to prevent new occurrence of atrial fibrillation are scarce.

METHODS

Baseline ECGs in MERIT-HF were coded regarding baseline rhythm, and outcome was analyzed in relation to rhythm. Occurrence of atrial fibrillation during follow-up was also analyzed.

RESULTS

At baseline atrial fibrillation was diagnosed in 556 patients (13.9%). Mean metoprolol CR/XL dose in patients in atrial fibrillation (154 mg) and sinus rhythm (158 mg) was similar, as well as decrease in heart rate (14.8 and 13.7 bpm, respectively). Only 61 (total of 362) deaths occurred in those in atrial fibrillation at baseline, 31 on placebo and 30 on metoprolol (RR 1.0; 95% CI 0.61-1.65). During follow-up, new atrial fibrillation was observed in 85 patients on placebo and 47 patients on metoprolol (RR 0.53; 95% CI 0.37-0.76; p=0.0005).

CONCLUSION

First, given the wide confidence interval, it was impossible to detect an interaction between metoprolol and mortality in patients with atrial fibrillation and heart failure. Second, in patients with sinus rhythm at baseline, metoprolol reduced the incidence of atrial fibrillation during follow-up. However, we must be extremely cautious in over-interpreting effects in these subgroups.

Atrial and ventricular volume and function evaluated by magnetic resonance imaging in patients with persistent atrial fibrillation before and after cardioversion

Atrial fibrillation (AF) is the most common cardiac arrhythmia and 25% of those >40 years old will experience AF. Left atrial size and left ventricular function are independently related to cardiovascular morbidity and mortality. Our aim was to evaluate cardiac volume and function using magnetic resonance imaging in patients with persistent AF and to describe the changes after cardioversion (CV). Sixty consecutive patients with persistent AF and 19 healthy volunteers had cardiac volumes evaluated by cinematographic breath-hold magnetic resonance imaging. Patients with AF were evaluated before CV and at 1, 30, and 180 days after CV, if still in sinus rhythm. All atrial and ventricular volumes and left ventricular mass decreased and ejection fractions increased significantly after CV (p <0.0001 for all variables). Atrial and ventricular diastolic volumes increased significantly the day after CV. The atrial diastolic volumes had decreased significantly at 30 days and ventricular volumes at 180 days. The atrial systolic volumes decreased significantly the day after CV, but the ventricular systolic volumes remained constant the day after CV and decreased thereafter. Only the right atrial volumes were normalized 180 days after CV. The same results were found in a subgroup of patients with lone AF. In conclusion, reversal of atrial dimensions and function happened earlier than ventricular reversal after CV in persistent AF. Atrial reversal began immediately and ventricular reversal was not seen before 30 days after CV. Our results suggest that the changes to the left atrium and both ventricles caused by AF could be permanent and that CV of AF may be preferable.

Natriuretic peptide response to dynamic exercise in patients with atrial fibrillation

BACKGROUND

In patients with atrial fibrillation (AF) information regarding exercise release of atrial natriuretic peptide (ANP) is sparse and data on plasma brain natriuretic peptide (BNP) response to exercise is lacking. The aim of this study was to investigate plasma ANP and BNP response to exercise in patients with permanent AF and to assess if the response was different from the response in healthy age- and sex-matched control subjects.

METHODS

Plasma venous concentrations of ANP and BNP were determined at rest, at peak exercise and 30 min from the end of exercise in 38 patients with permanent AF and in 43 age- and sex-matched healthy control subjects.

RESULTS

Plasma concentrations of ANP and BNP were significantly higher in AF patients compared with the healthy control group at rest, peak exercise and after 30 min of recovery (p<0.0001). ANP and BNP increased significantly during exercise in both patients with AF and in the healthy control subjects (p<0.05). The increase in plasma concentration of ANP and BNP during exercise was significantly higher in AF patients compared with healthy controls (p=0.0002 for ANP; p<0.0001 for BNP). In the recovery period plasma BNP decreased significantly (p<0.0001) where as the decrease in plasma ANP was insignificant (p=0.4).

CONCLUSIONS

Patients with permanent AF have elevated levels of ANP and BNP at rest and exhibit much higher exercise release compared to healthy control subjects. This enhanced secretion of potent vasodilating and natriuretic agents may represent an important compensatory mechanism to improve exercise capacity in patients with AF.

Role of carvedilol in atrial fibrillation: insights from clinical trials

Atrial fibrillation affects approximately 2 million people in the United States and is a common comorbidity among patients with heart failure. Clinical studies indicate that the benefits of the beta-blocker carvedilol in patients with heart failure extend to patients with heart failure complicated by atrial fibrillation. The results of the Carvedilol in Atrial Fibrillation Evaluation (CAFE) trial provide support that carvedilol has incremental benefit when added to digoxin for the management of atrial fibrillation in patients with heart failure. Additional recent studies suggest that carvedilol may be useful in managing postsurgical atrial fibrillation and also may prevent recurrence of atrial fibrillation among patients who undergo cardioversion.

Rate control in atrial fibrillation: choice of treatment and assessment of efficacy

The clinical relevance and high social costs of atrial fibrillation have boosted interest in rate control as a cost-effective alternative to long-term maintenance of sinus rhythm (i.e. rhythm control). Prospective studies show that rate control (coupled with thromboembolic prophylaxis) is a valuable treatment option for all forms of atrial fibrillation. The rationale for rate control is that high ventricular rates, frequently found in atrial fibrillation, lead to haemodynamic impairment, consisting of a variable combination of loss of atrial kick, irregularity in ventricular response and inappropriately rapid ventricular rate, depending on the type of underlying heart disease. Long-term persistence of tachycardia at a high ventricular rate can lead to various degrees of ventricular dysfunction and even to tachycardiomyopathy-related heart failure. Identification of this reversible and often concealed form of left ventricular dysfunction can permit effective management by rate (or rhythm) control. Although acute rate control (to reduce ventricular rate within hours) is still often based on digoxin administration, for patients without left ventricular dysfunction, calcium channel antagonists or beta-adrenoceptor antagonists (beta-blockers) are generally more appropriate and effective. In chronic atrial fibrillation, long-term rate control (to reduce morbidity/mortality and improve quality of life) must be adapted to patients' individual characteristics to grant control during daily activities, including exercise. According to current guidelines, the clinical target of rate control should be a ventricular rate below 80-90 bpm at rest. However, in many patients, assessment of the appropriateness of different drugs should include exercise testing and 24h-Holter monitoring, for which specific guidelines are needed. In practice, rate control is considered a valid alternative to rhythm control. Recent prospective trials (e.g. the Pharmacological Intervention in Atrial Fibrillation [PIAF] and the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] trials) have shown that in selected patients, rate control provides similar benefits, more economically, in terms of quality of life and long-term mortality. The choice of a rate control medication (digoxin, beta-blockers, calcium channel antagonists or possibly amiodarone) or a non-pharmacological approach (mainly atrioventricular node ablation coupled with pacing) must currently be based on clinical assessment, which includes assessing the presence of underlying heart disease and haemodynamic impairment. Definite guidelines are required for each different subset of patients. Rate control is particularly tricky in patients with heart failure, for whom non-pharmacological options can also be considered. The preferred pharmacological options are beta-blockers for stabilised heart failure and digoxin for unstabilised forms.

Anti-thrombotic strategies for patients with atrial fibrillation and heart failure

Atrial fibrillation occurs commonly in the setting of congestive heart failure and, in fact can cause left ventricular dysfunction due to a rapid ventricular response over time, termed tachycardia-mediated cardiomyopathy. The combination of atrial fibrillation and congestive heart failure leads to a high risk of stroke for the patient and appropriate antithrombotic therapy can minimize this incidence of stroke. Stroke risk can be markedly reduced by treatment with warfarin and complications of anticoagulation minimized by close attention to maintaining the INR between 2.0 and 3.0.

Prevention of and medical therapy for atrial arrhythmias in heart failure

A large proportion of heart failure patients suffer from atrial arrhythmias, prime amongst them being atrial fibrillation (AF). Ventricular dysfunction and the syndrome of heart failure can also be a concomitant pathology in up to 50% of patients with AF. However this association is more than just due to shared risk factors, research from animal and human studies suggest a causal relationship between AF and heart failure. There are numerous reports of tachycardia-induced heart failure where uncontrolled ventricular rate in AF results in heart failure, which is reversible with cardioversion to sinus rhythm or ventricular rate control. However the relationship extends beyond tachycardia-induced cardiomyopathy. Optimal treatment of AF may delay progressive ventricular dysfunction and the onset of heart failure whilst improved management of heart failure can prevent AF or improve ventricular rate control. Prevention and treatment of atrial arrhythmias, and in particular atrial fibrillation, is therefore an important aspect of the management of patients with heart failure. This review describes the incidence and possible predictors of AF and other atrial arrhythmias in patients with heart failure and discusses the feasibility of primary prevention. The evidence for the management of atrial fibrillation in heart failure is systematically reviewed and the strategies of rate versus rhythm control discussed in light of the prevailing evidence.