Renin–angiotensin blockade in atrial fibrillation: where are we now?

Effects of mineralocorticoid receptor antagonists on new-onset or recurrent atrial fibrillation: a Bayesian and frequentist network meta-analysis of randomized trials

Background Clinical and translational research suggests that mineralocorticoid receptor antagonists (MRAs) may prevent atrial fibrosis and electrical remodeling associated with atrial fibrillation (AF). This study aimed to consolidate existing evidence from randomized controlled trials (RCTs) evaluating the effect of MRAs on incident or recurrent AF. Methods Medline, Cochrane Library and Scopus were searched until February 12, 2024. Triple-independent study selection, data extraction and quality assessment were performed. Evidence was pooled using both pairwise and Bayesian and frequentist network meta-analyses. Results Twenty-three RCTs (13,358 participants) were identified. Based on the pairwise random effects meta-analysis, MRAs were associated with a significant reduction in AF events compared to placebo or usual care (risk ratio {RR}= 0.75; 95% confidence interval {CI}= [0.66, 0.87]; P< 0.001; I2= 3%). This protective effect was robust both for new-onset and recurrent AF episodes (subgroup p-value= 0.69), while the baseline HF status was not a significant effect modifier (subgroup p-value= 0.58). MRAs demonstrated a significantly higher reduction in AF events for patients with chronic renal disease compared to placebo (RR= 0.78; 95% CI= [0.62, 0.98]; P= 0.03; I2= 0%). The network meta-analyses revealed that only spironolactone was associated with a significant reduction in AF events (Bayesian RR= 0.76; 95% CI= [0.65, 0.89]; P< 0.001; level of evidence moderate; SUCRA 0.731), while eplerenone and finerenone showed a neutral effect. Conclusion MRAs confer a significant benefit in terms of reducing incident or recurrent AF episodes, irrespective of HF status. In this context, spironolactone may be preferable compared to eplerenone or finerenone.

Implications of Atrial Fibrillation for Guideline-Directed Therapy in Patients With Heart Failure: JACC State-of-the-Art Review

Atrial fibrillation (AF) and heart failure (HF) are common cardiovascular conditions that frequently coexist. Among patients with HF, more than one-half also have AF. Both are associated with significant morbidity and mortality. Moreover, the prevalence of each is increasing globally, and this trend is expected to continue owing to an aging population and increased life expectancy. Diagnosis of AF in a patient with HF is associated with greater symptom burden, more frequent hospitalizations, and a worse prognosis. Guideline-directed medical therapy (GDMT) for HF can affect the incidence of AF. Once present, AF can influence the efficacy of some components of GDMT for HF. In this review, we discuss the effect of GDMT for HF across the spectrum of ejection fraction on prevention of AF as well as the benefit of GDMT in patients with vs without AF.

Renin-angiotensin-aldosterone system inhibitors and mortality risk in elderly patients with atrial fibrillation. Insights from the nationwide START registry

BACKGROUND

Arterial hypertension is the most common cardiovascular comorbidity in atrial fibrillation (AF). Few studies investigated management strategies of hypertension in AF.

MATERIALS AND METHODS

We included 5769 AF patients on oral anticoagulants from the nationwide ongoing Italian START registry. We investigated the prescription of antihypertensive drugs and mortality risk. Subgroup analyses according to sex and major cardiovascular comorbidities were performed.

RESULTS

Mean age was 80.8 years, 46.1% were women; 80.3% of patients were hypertensive. Furosemide (30.1%) was the most frequent diuretic followed by hydrochlorothiazide (15.4%) and potassium canrenoate (7.9%). 61.1% received β-blockers: 34.2% bisoprolol, 6.2% atenolol. Additionally, 36.9% were on angiotensin converting enzyme inhibitors (ACE-I): ramipril (20.9%), enalapril (5.3%) and perindopril (2.8%); 31.7% were on angiotensin receptors blockers (ARBs): valsartan (7.6%) and irbesartan (6.4%). Amlodipine and lercanidipine were prescribed in 14.0% and 2.3%, respectively. ACE-I (p < 0.001), α-blockers (p = 0.020) and Dihydropyridines calcium channel blockers (p = 0.004) were more common in men, while ARBs (p = 0.008), thiazide diuretics (p < 0.001) and β-blockers (p < 0.001) in women. During 22.61 ± 17.1 months, 512 patients died. Multivariable Cox regression analysis showed that ACE-I (Hazard ratio [HR] 0.758, 95% Confidence Interval [95%CI] 0.612-0.940, p = 0.012) and ARBs (HR 0.623, 95%CI 0.487-0.796, p < 0.001) inversely associated with mortality. ACE-I/ARBs inversely associated with mortality in both sexes and in patients with diabetes. This associastion was evident for ACE-I in patients with previous cardiovascular disease, and for ARBs in HF.

CONCLUSION

A lower mortality risk was found in AF patients on ACE-I/ARBs. Different prescription patterns of antihypertensive drugs between men and women do exist.

Developing Pharmacological Therapies for Atrial Fibrillation Targeting Mitochondrial Dysfunction and Oxidative Stress: A Scoping Review

Atrial fibrillation (AF) is a cardiac arrhythmia caused by electrophysiological anomalies in the atrial tissue, tissue degradation, structural abnormalities, and comorbidities. A direct relationship exists between AF and altered mitochondrial activity resulting from membrane potential loss, contractile dysfunction, or decreased ATP levels. This review aimed to elucidate the role of mitochondrial oxidative mechanisms in AF pathophysiology, the impact of mitochondrial oxidative stress on AF initiation and perpetuation, and current therapies. This review followed the Preferred Reporting Items for Systematic Reviews and the Meta-Analysis Extension for Scoping Reviews. PubMed, Excerpta Medica Database, and Scopus were explored until June 2023 using "MESH terms". Bibliographic references to relevant papers were also included. Oxidative stress is an imbalance that causes cellular damage from excessive oxidation, resulting in conditions such as AF. An imbalance in reactive oxygen species production and elimination can cause mitochondrial damage, cellular apoptosis, and cardiovascular diseases. Oxidative stress and inflammation are intrinsically linked, and inflammatory pathways are highly correlated with the occurrence of AF. AF is an intricate cardiac condition that requires innovative therapeutic approaches. The involvement of mitochondrial oxidative stress in the pathophysiology of AF introduces novel strategies for clinical treatment.

Atrial fibrosis and substrate based characterization in atrial fibrillation: Time to move forwards

Atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia in clinical practice. However, current therapeutic interventions for atrial fibrillation have limited clinical efficacy as a consequence of major knowledge gaps in the mechanisms sustaining atrial fibrillation. From a mechanistic perspective, there is increasing evidence that atrial fibrosis plays a central role in the maintenance and perpetuation of atrial fibrillation. Electrophysiologically, atrial fibrosis results in alterations in conduction velocity, cellular refractoriness, and produces conduction block promoting meandering, unstable wavelets and micro-reentrant circuits. Clinically, atrial fibrosis has also linked to poor clinical outcomes including AF-related thromboembolic complications and arrhythmia recurrences post catheter ablation. In this article, we review the pathophysiology behind the formation of fibrosis as AF progresses, the role of fibrosis in arrhythmogenesis, surrogate markers for detection of fibrosis using cardiac magnetic resonance imaging, echocardiography and electroanatomic mapping, along with their respective limitations. We then proceed to review the current evidence behind therapeutic interventions targeting atrial fibrosis, including drugs and substrate-based catheter ablation therapies followed by the potential future use of electro phenotyping for AF characterization to overcome the limitations of contemporary substrate-based methodologies.

Genetics and Epigenetics of Atrial Fibrillation

Atrial fibrillation (AF) is known to be the most common supraventricular arrhythmia affecting up to 1% of the general population. Its prevalence exponentially increases with age and could reach up to 8% in the elderly population. The management of AF is a complex issue that is addressed by extensive ongoing basic and clinical research. AF centers around different types of disturbances, including ion channel dysfunction, Ca²⁺-handling abnormalities, and structural remodeling. Genome-wide association studies (GWAS) have uncovered over 100 genetic loci associated with AF. Most of these loci point to ion channels, distinct cardiac-enriched transcription factors, as well as to other regulatory genes. Recently, the discovery of post-transcriptional regulatory mechanisms, involving non-coding RNAs (especially microRNAs), DNA methylation, and histone modification, has allowed to decipher how a normal heart develops and which modifications are involved in reshaping the processes leading to arrhythmias. This review aims to provide a current state of the field regarding the identification and functional characterization of AF-related epigenetic regulatory networks