Effect of ethanol on the electrophysiological characteristics of pulmonary vein cardiomyocytes

The impact of lifestyle factors on atrial fibrillation

Atrial fibrillation (AF), with its significant associated morbidity and mortality contributes to significant healthcare utilisation and expenditure. Given its progressively rising incidence, strategies to limit AF development and progression are urgently needed. Lifestyle modification is a potentially potent but underutilised weapon against the AF epidemic. The purpose of this article is to review the role of lifestyle factors as risk factors for AF, outline potential mechanisms of pathogenesis and examine the available evidence for lifestyle intervention in primary and secondary AF prevention. It will also highlight the need for investment by physicians, researchers, health services and governments in order to facilitate delivery of the comprehensive, multidisciplinary AF care that is required to manage this complex and multifactorial disease.

Clinical and Structural Factors Affecting Ablation Outcomes in Atrial Fibrillation Patients - A Review

Catheter ablation is an effective and durable treatment option for patients with atrial fibrillation (AF). Ablation outcomes vary widely, with optimal results in patients with paroxysmal AF and diminishing results in patients with persistent or long-standing persistent AF. A number of clinical factors including obesity, hypertension, diabetes, obstructive sleep apnea, and alcohol use contribute to AF recurrence following ablation, likely through modulation of the atrial electroanatomic substrate. In this article, we review the clinical risk factors and the electro-anatomic features that contribute to AF recurrence in patients undergoing ablation for AF.

Alcohol consumption and atrial fibrillation risk: An updated dose-response meta-analysis of over 10 million participants

Background

The treatment of atrial fibrillation (AF) has made significant progress, but the prevention of AF has not received the attention it deserves. A few recent large-sized studies have conducted dose response analysis and reported different conclusions from previous studies on alcohol consumption and AF risk.

Objectives

The aim of this study is to examine the potential non-linear association between alcohol consumption and risk of AF and explore the potential differences of gender.

Methods

In this updated dose-response meta-analysis, PubMed, Embase and Cochrane databases were searched until June 2022. Risk estimates were reported as relative risk (RR) with 95% confidence intervals (CIs). The random-effects restricted cubic spline models are used to evaluate the potential non-linear association between alcohol consumption and AF risk.

Results

A total of 10,151,366 participants with 214,365 cases of AF enrolled in 13 prospective studies. The overall meta-analysis showed that a 1 drink/day increase in alcohol consumption increased the risk of AF by 6% (RR: 1.06; 95% CI: 1.03–1.08). In gender subgroup analysis, pooled results were different between men (RR: 1.08; 95% CI: 1.05–1.11) and women (RR: 1.05; 95% CI: 0.96–1.14). A linear relationship between alcohol consumption and risk of AF was found in men (p = 0.87) while a J-shaped curve was observed in women (p = 0.00). Regional subgroup analysis yielded broadly comparable results in Americas (RR: 1.07; 95% CI: 1.03–1.12), Europe (RR: 1.04; 95% CI: 0.99–1.1) and Asia (RR: 1.07; 95% CI: 0.99–1.14).

Conclusion

The relationship between AF risk and alcohol consumption is linear in men, while a potential non-linear J-shaped relationship is shown in women.

Condensed abstract

We conducted a dose-response meta-analysis on the relationship between alcohol consumption and risk of atrial fibrillation. We merged the data of over 10 million participants and found gender differences in the pattern of association with AF and alcohol consumption. The relationship between AF risk and alcohol consumption is linear in men, while a potential non-linear J-shaped relationship is shown in women. In summary, this research is vital in furthering our understanding of the role of alcohol consumption in new-onset AF, especially among different genders.

Harmful Impact of Tobacco Smoking and Alcohol Consumption on the Atrial Myocardium

Tobacco smoking and alcohol consumption are widespread exposures that are legal and socially accepted in many societies. Both have been widely recognized as important risk factors for diseases in all vital organ systems including cardiovascular diseases, and with clinical manifestations that are associated with atrial dysfunction, so-called atrial cardiomyopathy, especially atrial fibrillation and stroke. The pathogenesis of atrial cardiomyopathy, atrial fibrillation, and stroke in context with smoking and alcohol consumption is complex and multifactorial, involving pathophysiological mechanisms, environmental, and societal aspects. This narrative review summarizes the current literature regarding alterations in the atrial myocardium that is associated with smoking and alcohol.

The Impact of Alcohol Intake on Atrial Fibrillation

PURPOSE OF REVIEW

To evaluate (1) the impact of acute and habitual alcohol consumption on atrial fibrillation (AF) and atrial remodeling and (2) the role of alcohol reduction and/or abstinence in the primary and secondary prevention of AF.

RECENT FINDINGS

Acute alcohol consumption appears to be a common AF trigger, with animal and human studies demonstrating changes in electrophysiological parameters, autonomic tone, and cellular properties expected to promote AF. Habitual consumption is associated with adverse atrial remodeling, higher risk of incident AF, and AF recurrence. Randomized data suggest that reduction in excessive alcohol consumption may reduce the risk of recurrent AF episodes and AF burden. Alcohol is an increasingly recognized risk factor for both new onset AF and discrete AF episodes. Excessive consumption should be avoided for primary and secondary prevention of AF.

[Alcohol and arrhythmias]

The effects of alcohol on induction of arrhythmias is dose-dependent, independent of preexisting cardiovascular diseases or heart failure and can affect otherwise healthy subjects. While the probability of atrial fibrillation increases with the alcohol dosage, events of sudden cardiac death are less frequent with low and moderate consumption but occur more often in heavy drinkers with alcoholic cardiomyopathy. Men are first affected at higher dosages of alcohol but women can suffer from arrhythmias at lower dosages. Thromboembolisms and ischemic stroke can occur less often at lower dosages of alcohol; however, hemorrhagic stroke and subarachnoid hemorrhage are increased with higher alcohol dosages. Recognizable protective mechanisms of alcohol with respect to cardiovascular diseases only occur with lower amounts of alcohol of less than 10 g per day. Underlying mechanisms explain these controversial effects. Specific therapeutic options for alcohol-related arrhythmias apart from abstinence from alcohol consumption are not known.

Alcohol and Atrial Fibrillation: A Sobering Review

Alcohol is popular in Western culture, supported by a perception that modest intake is cardioprotective. However, excessive drinking has detrimental implications for cardiovascular disease. Atrial fibrillation (AF) following an alcohol binge or the "holiday heart syndrome" is well characterized. However, more modest levels of alcohol intake on a regular basis may also increase the risk of AF. The pathophysiological mechanisms responsible for the relationship between alcohol and AF may include direct toxicity and alcohol's contribution to obesity, sleep-disordered breathing, and hypertension. We aim to provide a comprehensive review of the epidemiology and pathophysiology by which alcohol may be responsible for AF and determine whether alcohol abstinence is required for patients with AF.

B-Type Natriuretic Peptide Modulates Pulmonary Vein Arrhythmogenesis: A Novel Potential Contributor to the Genesis of Atrial Tachyarrhythmia in Heart Failure

BACKGROUND

Heart failure (HF) plays a critical role in the genesis of atrial fibrillation (AF). A high B-type natriuretic peptide (BNP) level occurs in patients with HF and in patients with AF. However, the role of BNP in the pathophysiology of AF is not clear. The purposes of this study were to evaluate the effects of BNP on pulmonary vein (PV) arrhythmogenesis.

METHODS AND RESULTS

Whole-cell patch clamp and fluorescence were used to study the action potential, ionic currents, and calcium homeostasis in isolated single rabbit PV cardiomyocytes before and after a BNP infusion, with or without ODQ (10 μM), milrinone (50 μM), or ouabain (1 μM). BNP increased PV spontaneous activity by 28.2 ± 7.5% at 100 nM and by 23.8 ± 9.1% at 300 nM. Similar to those with BNP, milrinone 50 μM increased the PV beating rate from 3.0 ± 0.2 to 3.6 ± 0.3 Hz (P < 0.0005, n = 7). In the presence of ODQ application, BNP didn't change PV spontaneous activity. BNP (100 nM) increased calcium transients (F/F₀ from 1.6 ± 0.1 to 1.9 ± 0.2, n = 20, P < 0.05) and increased the pacemaker current (0.4 ± 0.1 to 1.0 ± 0.2 pA/pF, n = 17, P < 0.0005) in PV cardiomyocytes. Moreover, BNP (100 nM) increased the transient inward current, sodium currents, sodium-calcium exchanger currents, and L-type calcium current; but reduced late sodium currents and the Na-K pump in PV cardiomyocytes.

CONCLUSION

BNP increases PV arrhythmogenesis, which may contribute to the genesis of atrial tachyarrhythmogenesis in HF. Cyclic GMP activation, phosphodiesterase 3 inhibition and Na⁺ /K⁺ -ATPase inhibition might participate in the BNP modulation of PV electrophysiology.

The Estimated Risk of Atrial Fibrillation Related to Alcohol Consumption

The risk of acute heavy alcohol intake on the development of atrial fibrillation (AF), aka ?holiday heart syndrome?, has been well-described. However, whether chronic alcohol intake is also associated with increased risk of AF, or might even be protective as has been observed with other cardiac conditions, is more uncertain. A number of studies, from basic science to large cohort studies have been performed to analyze the association between alcohol and AF. Basic-level studies have found that alcohol causes changes in tissue electrophysiology, ion channels, and circulating hormones, which might promote development and maintenance of AF. Clinical studies have generally shown groups with the highest regular intake of alcohol to be at increased risk, with no association with more moderate use. However, these studies have not always accounted for other AF risk factors, been inconsistent in the assessment and validation of the quantity of alcohol consumed across populations, and been unable to completely separate drinking patterns from overall health of participants. As a result, solid conclusions about a threshold level for ?safe? chronic alcohol intake cannot be made with regard to AF risk, but it appears to be safe within currently recommended limits of 1 drink daily for women and 2 for men. In this review, we discuss these findings, limitations, and conclusions.

Mechanical characterization of rabbit pulmonary vein sleeves in in vitro intact ring preparation

BACKGROUND

Pulmonary vein (PV) sleeves, composed of cardiomyocytes, play certain roles in arrhythmogenesis. In the literature, it has been frequently reported that PV sleeves possess intrinsic spontaneous pacemaking activity and triggered activity in normal dogs and rabbits. In contrast, other research groups presented totally opposite findings which showed absence of such pacemakers in dogs, rabbits and rats. The present study was designed to clarify this puzzle and contradiction.

METHODS

A novel methodology using in vitro experimentation was used to examine the electromechanical activity of whole segments of PV sleeves. The ring preparation was composed of a small piece of left atrial (LA) free wall, PV ostium and sleeve from rabbits. A circumferential contraction of the PV sleeve was measured when the preparation was electrically driven from the LA free wall. Mechanical force of the ring preparation was measured using a force transducer. The action potentials were recorded using conventional intracellular recording technique in strip preparation.

RESULTS

In 15 rabbits, no spontaneous pacemaking activity or triggered activity was found in the in vitro ring preparation of PV sleeve. The circumferential contraction of PV sleeves was external calcium-dependent. Frequency-force relation displayed a negative staircase at 0.1-0.5 Hz and a positive staircase at 1-5 Hz. Post-rest potentiation was prominent between 15 s and 120 s. Intracellular action potential recording did not display any automaticity or triggered activity in PV sleeves.

CONCLUSION

In an intact ring preparation of rabbit PV sleeves, intrinsic spontaneous pacemaking activity or triggered activity was not found.

Effects of alcohol on atrial fibrillation: myths and truths

Alcohol is the most consumed drug worldwide. Both acute and chronic alcohol use have been associated with cardiac arrhythmias, in particular atrial fibrillation, or so-called 'holiday heart syndrome'. Epidemiological, clinical and experimental studies have attempted to elucidate the mechanisms involved in this association. However, because most of these studies have shown conflicting results, the connection between ethanol and atrial arrhythmias remains controversial. Historical, epidemiological and pharmacological aspects of alcohol, as well as recent concepts on atrial fibrillation are reviewed. We then examine the literature and provide a critical point of view on the still elusive association between alcohol and atrial fibrillation.

Characterization of the Acute Cardiac Electrophysiologic Effects of Ethanol in Dogs

BACKGROUND

Alcohol has been related to atrial fibrillation (holiday heart syndrome), but its electrophysiologic actions remain unclear.

METHODS

We evaluated the effects of alcohol in 23 anesthetized dogs at baseline and after 2 cumulative intravenous doses of ethanol: first dose 1.5 ml/kg (plasma level 200 mg/dl); second dose 1.0 ml/kg (279 mg/dl). In 13 closed-chest dogs (5 with intact autonomic nervous system, 5 under combined autonomic blockade and 3 sham controls), electrophysiologic evaluation and monophasic action potential (MAP) recordings were undertaken in the right atrium and ventricle. In 5 additional dogs, open-chest biatrial epicardial mapping with 8 bipoles on Bachmann's bundle was undertaken. In the remaining 5 dogs, 2D echocardiograms and ultrastructural analysis were performed.

RESULTS

In closed-chest dogs with intact autonomic nervous system, ethanol had no effects on surface electrocardiogram and intracardiac variables. At a cycle length of 300 milliseconds, no effects were noted on atrial and ventricular refractoriness and on the right atrial MAP. These results were not altered by autonomic blockade. No changes occurred in sham controls. In open-chest dogs, ethanol did not affect inter-atrial conduction time, conduction velocity, and wavelength. Atrial arrhythmias were not induced in any dog, either at baseline or after ethanol. Histological and ultrastructural findings were normal but left ventricular (LV) ejection fraction decreased in treated dogs (77 vs. 73 vs. 66%; p = 0.04).

CONCLUSION

Ethanol at medium and high doses depresses LV systolic function but has no effects on atrial electrophysiological parameters. These findings suggest that acute alcoholic intoxication does not directly promote atrial arrhythmias.