Idiopathic atrial fibrillation revisited in a large longitudinal clinical cohort

A case report of atrial fibrillation in early adulthood: dig deeper

Background

Atrial fibrillation (AF) is a common cardiac arrhythmia, which is often associated with underlying risk factors and undiagnosed conditions, including congenital heart disease. Atrial septal defects (ASDs) come to mind, albeit arrhythmias usually present later in life. We present herewith a young patient with cor triatriatum sinister (CTS), with some delay in establishing the diagnosis, following new onset AF in early adulthood.

Case summary

A 31-year-old man presented with pre-syncope and coryzal symptoms and was newly diagnosed with AF in the context of an intercurrent viral illness. After treatment with oral anticoagulation and successful outpatient cardioversion, he was discharged from cardiology review. Two years later he re-presented with exercise intolerance and a 12-lead electrocardiogram revealing recurrence of AF. Subsequent investigation with transthoracic echocardiography revealed the underlying congenital cardiac defect of CTS, together with an ASD and patent foramen ovale. After corrective surgery, which involved membrane resection, a Cox-maze procedure and ASD closure, sinus rhythm was restored and at follow-up the patient had returned to baseline function.

Discussion

Young patients presenting with new onset AF should undergo thorough cardiovascular assessment to identify treatable causes and reversible risk factors. Cor triatriatum sinister is a rare congenital anomaly that may present in adulthood and give rise to symptomatic AF. Surgical correction including a Cox-maze procedure in our patient resulted in restoration of sinus rhythm and a return of the patient’s baseline functional status and improved quality of life.

Epidemiology of atrial fibrillation in a representative sample of the European part of the Russian Federation. Analysis of EPOCH-CHF study

Aim    To study true prevalence of atrial fibrillation (AF) in a representative sample from the European part of the Russian Federation; to describe characteristics of patients with AF; and to provide the frequency of anticoagulant treatment.Material and methods    Cross-sectional data of the EPOCH epidemiological study (2017) were used. Data were collected in 8 constituent entities of the Russian Federation; the sample size was 11 453 people. The sample included all respondents who had given their consent for participation and were older than 10 years. Statistical tests were performed in the R system for statistical data analysis.Results    The prevalence of AF in the representative sample from the European part of the Russian Federation was 2.04 %. The AF prevalence increased with age and reached a maximum value of 9.6% in the age group of 80 to 89 years. The AF prevalence among females was 1.5 times higher than among men. With age standardization, the AF prevalence was 18.95 and 21.33 per 1,000 people for men and women, respectively. The AF prevalence increased in the presence of concurrent cardiovascular diseases (CVDs) or diabetes mellitus as well as with an increased number of comorbidities in the same person and reached 70.3 and 60.0 % in patients with 4 and 5 comorbidities, respectively. Patients with AF had a greater number of comorbidities and higher CHA2DS2VASc scores (5.0 vs. 2.0, p<0.001) compared to patients with CVDs without AF. Only 22.6 % of patients with CVD and AF took anticoagulants. Only 23.9% of patients with absolute indications for the anticoagulant treatment received anticoagulants.Conclusion    The AF prevalence in the European part of the Russian Federation was 2.04 %; it increased with age and in patients with concurrent CVDs or diabetes mellitus. Most of AF patients (93.2 %) required a mandatory treatment with oral anticoagulants.

Prognosis of Atrial Fibrillation with or without Comorbidities: Analysis of Younger Adults from a Nationwide Database

Objective: To assess the prognosis of AF patients with or without cardiac or extra-cardiac concomitant conditions. Participants and Methods: All consecutive patients diagnosed with AF admitted to French hospitals between 2011 and 2020 were identified. Patients were classified into four groups: (1) > 60 yo; (2) with known cardiac disease (KCD group); (3) with extra-cardiac comorbidities (ECC); and 4) AF without KCD or ECC (“Lone AF”). Results: Altogether 2,435,541 patients were identified, from which 2,203,702 patients aged >60 years and 231,839 patients aged <60 years (with KCD (55.2%), with ECC (14.7%) and with “Lone AF” (30.1%)). During follow-up, the incidences of all-cause and CV deaths were 13.7%, 5.7%, 6.2%, and 2.3%, and 4.2%, 1.7%, 0.8%, and 0.3% in the older than 60 yo group, KCD group, ECC group and “Lone AF” AF group, respectively. In the age and sex-adjusted analysis (patients < 60 yo), patients with AF and KCD had worse outcomes than patients with “Lone AF” for all major cardiac events. Conclusion: There are three distinct prognostic criteria based on the presence or lack of HD or extra-cardiac concomitant comorbidities. Patients in the so-called “Lone AF” group remain severe in terms of CV events but still with a lower incidence than the patients with associated KCD or ECC. The presence of KCD or ECC makes it possible to distinguish a profile in terms of events that are very different between the patients.

A Population-Based Study of Unexplained/Lone Atrial Fibrillation: Temporal Trends, Management, and Outcomes

Background

Previous studies on lone/unexplained atrial fibrillation and atrial flutter (AF) did not exclude patients with contemporary secondary AF triggers. We characterized unexplained AF using a strict definition, and compared it to secondary AF.

Methods

In this population-based study, unexplained AF was defined by the lack of any identifiable triggering medical/surgical diagnosis. Comparisons by AF type (unexplained vs secondary), age-of-onset (≤ / > 65 years), and sex were undertaken. Data were acquired by linking 6 population databases maintained by the Alberta Ministry of Health over a 9-year period (April 2006 to March 2015). The primary composite outcome of stroke, transient ischemic attack, thromboembolism, and/or death was assessed.

Results

There were 33,150 incident AF diagnoses identified, including 1145 patients (3.5%) with unexplained AF, 931 (81.2%) of whom were aged ≤ 65 years (2.8% of diagnoses, and 79% male). Patients with unexplained AF less often received rate/rhythm-control drugs (P < 0.0001), but they more often underwent electrical cardioversion (P < 0.0001) vs secondary AF patients. Men were younger at unexplained AF diagnosis (45 [interquartile range: 34-59] vs 58 [interquartile range: 40-69] years; P < 0.001). After adjusting for age at diagnosis, there were no sex-based differences in the primary outcome. Event-free survival in young unexplained AF (age ≤ 65 years) was 99.4% at 1 year and 98.3% at 3 years. At 3 years, hospitalization(s)/emergency visit(s) for noncardiovascular reasons and for AF occurred in 56.6% and 23.8% of these patients, respectively.

Conclusions

Using a strict contemporary definition of unexplained AF, this study shows that the condition is rare, predominantly male, and has excellent event-free survival. However, the high rate of acute hospital utilization after diagnosis is concerning.

Concealed Coronary Atherosclerosis In Idiopathic Paroxysmal Atrial Fibrillation is Associated with Imminent Cardiovascular Diseases

Background

Previous research showed a significant difference in the presence of subclinical coronary artery disease (CAD) on cardiac CT angiography (CTA) between patients with idiopathic paroxysmal atrial fibrillation (iAF) versus a matched sinus rhythm population (iSR). Here we present 5-year follow-up data and the consequences of subclinical CAD on baseline CTA on the development of cardiovascular disease in iAF.

Methods

In 99 iAF patients (who underwent CTA as part of work-up for pulmonary vein isolation) and 221 matched iSR controls (who underwent CTA for CAD assessment), the incidence of hypertension, diabetes and major cardiovascular events (MACCE) during follow-up was obtained. Multivariable Cox regression analysis was used to reveal predictors of incident cardiovascular disease in the iAF group.

Results

During a follow-up of 68±11 months, over one third of patients developed cardiovascular disease, with no difference between iAF and iSR (log-rank p=0.56), and comparable low rates of MACCE (4.0% vs 5.0%,p=0.71). Within the iAF group, age (HR1.12(1.03-1.20);p=0.006), left atrial diameter (HR1.16(1.03-1.31);p=0.01), Segment Involvement Score (total number of coronary segments with atherosclerotic plaque; HR1.43(1.09-1.89);p=0.01) and the number of calcified plaques on CTA (HR0.53(0.30-0.92);p=0.01) were independent predictors of incident cardiovascular disease.

Conclusions

Subclinical coronary disease on CTA may be useful to identify the subset of patients with iAF that harbour concealed cardiovascular risk factors and need intensive clinical follow-up to ensure timely initiation of appropriate therapy once CV disease develops, including anticoagulation and vascular prophylactic therapy.

Characteristics and outcomes of atrial fibrillation in patients without traditional risk factors: an RE-LY AF registry analysis

AIMS

Data on patient characteristics, prevalence, and outcomes of atrial fibrillation (AF) patients without traditional risk factors, often labelled 'lone AF', are sparse.

METHODS AND RESULTS

The RE-LY AF registry included 15 400 individuals who presented to emergency departments with AF in 47 countries. This analysis focused on patients without traditional risk factors, including age ≥60 years, hypertension, coronary artery disease, heart failure, left ventricular hypertrophy, congenital heart disease, pulmonary disease, valve heart disease, hyperthyroidism, and prior cardiac surgery. Patients without traditional risk factors were compared with age- and region-matched controls with traditional risk factors (1:3 fashion). In 796 (5%) patients, no traditional risk factors were present. However, 98% (779/796) had less-established or borderline risk factors, including borderline hypertension (130-140/80-90 mmHg; 47%), chronic kidney disease (eGFR < 60 mL/min; 57%), obesity (body mass index > 30; 19%), diabetes (5%), excessive alcohol intake (>14 units/week; 4%), and smoking (25%). Compared with patients with traditional risk factors (n = 2388), patients without traditional risk factors were more often men (74% vs. 59%, P < 0.001) had paroxysmal AF (55% vs. 37%, P < 0.001) and less AF persistence after 1 year (21% vs. 49%, P < 0.001). Furthermore, 1-year stroke occurrence rate (0.6% vs. 2.0%, P = 0.013) and heart failure hospitalizations (0.9% vs. 12.5%, P < 0.001) were lower. However, risk of AF-related re-hospitalization was similar (18% vs. 21%, P = 0.09).

CONCLUSION

Almost all patients without traditionally defined AF risk factors have less-established or borderline risk factors. These patients have a favourable 1-year prognosis, but risk of AF-related re-hospitalization remains high. Greater emphasis should be placed on recognition and management of less-established or borderline risk factors.

The Euro Heart Survey and EURObservational Research Programme (EORP) in atrial fibrillation registries: contribution to epidemiology, clinical management and therapy of atrial fibrillation patients over the last 20 years

Management of atrial fibrillation (AF) may be challenging in clinical practice. Given the complexity of AF patients and the continuous advances in AF clinical management, there is a need for standardized programmes aimed at collecting so-called 'real-world clinical practice data' regarding the epidemiology, diagnostic/therapeutic/management practices and assessing adherence to guidelines. Over the past 20 years, the number of registries and surveys based on real-world AF patients has been dramatically increased. In Europe, based on the Euro Heart Survey (EHS) and the EURObservational Research Programme (EORP), a large series of studies based on these prospective, observational, large-scale multicentre registries on AF have been published. This narrative review gives an overview of these two projects on AF led by the European Society of Cardiology, focusing mainly on the contribution that these studies have provided to AF management and patient outcomes. Both the EHS and the EORP registries have collected a large amount of data regarding contemporary clinical practice, and despite some limitations, mainly related to their observational nature, these registries have contributed to our knowledge and clinical management of AF patients.

Opportunistic screening for atrial fibrillation by clinical pharmacists in UK general practice during the influenza vaccination season: A cross-sectional feasibility study

BACKGROUND

Growing prevalence of atrial fibrillation (AF) in the ageing population and its associated life-changing health and resource implications have led to a need to improve its early detection. Primary care is an ideal place to screen for AF; however, this is limited by shortages in general practitioner (GP) resources. Recent increases in the number of clinical pharmacists within primary care makes them ideally placed to conduct AF screening. This study aimed to determine the feasibility of GP practice-based clinical pharmacists to screen the over-65s for AF, using digital technology and pulse palpation during the influenza vaccination season.

METHODS AND FINDINGS

Screening was conducted over two influenza vaccination seasons, 2017-2018 and 2018-2019, in four GP practices in Kent, United Kingdom. Pharmacists were trained by a cardiologist to pulse palpate, record, and interpret a single-lead ECG (SLECG). Eligible persons aged ≥65 years (y) attending an influenza vaccination clinic were offered a free heart rhythm check. Six hundred four participants were screened (median age 73 y, 42.7% male). Total prevalence of AF was 4.3%. All participants with AF qualified for anticoagulation and were more likely to be male (57.7%); be older; have an increased body mass index (BMI); and have a CHA2DS2-VASc (Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes, previous Stroke, Vascular disease, Age 65-74 years, Sex category) score ≥ 3. The sensitivity and specificity of clinical pharmacists diagnosing AF using pulse palpation was 76.9% (95% confidence interval [CI] 56.4-91.0) and 92.2% (95% CI 89.7-94.3), respectively. This rose to 88.5% (95% CI 69.9-97.6) and 97.2% (95% CI 95.5-98.4) with an SLECG. At follow-up, four participants (0.7%) were diagnosed with new AF and three (0.5%) were initiated on anticoagulation. Screening with SLECG also helped identify new non-AF cardiovascular diagnoses, such as left ventricular hypertrophy, in 28 participants (4.6%). The screening strategy was cost-effective in 71.8% and 64.3% of the estimates for SLECG or pulse palpation, respectively. Feedback from participants (422/604) was generally positive. Key limitations of the study were that the intervention did not reach individuals who did not attend the practice for an influenza vaccination and there was a limited representation of UK ethnic minority groups in the study cohort.

CONCLUSIONS

This study demonstrates that AF screening performed by GP practice-based pharmacists was feasible, economically viable, and positively endorsed by participants. Furthermore, diagnosis of AF by the clinical pharmacist using an SLECG was more sensitive and more specific than the use of pulse palpation alone. Future research should explore the key barriers preventing the adoption of national screening programmes.

Differential Association of Cx37 and Cx40 Genetic Variants in Atrial Fibrillation with and without Underlying Structural Heart Disease

Atrial fibrillation (AF) appears in the presence or absence of structural heart disease. The majority of foci causing AF are located near the ostia of pulmonary veins (PVs), where cardiomyocytes and vascular smooth muscle cells interdigitate. Connexins (Cx) form gap junction channels and participate in action potential propagation. Genetic variants in genes encoding Cx40 and Cx37 affect their expression or function and may contribute to PV arrhythmogenicity. DNA was obtained from 196 patients with drug-resistant, symptomatic AF with and without structural heart disease, who were referred for percutaneous catheter ablation. Eighty-nine controls were matched for age, gender, hypertension, and BMI. Genotyping of the Cx40 -44G > A, Cx40 +71A > G, Cx40 -26A > G, and Cx37 1019C > T polymorphisms was performed. The promoter A Cx40 polymorphisms (-44G > A and +71A > G) showed no association with non-structural or structural AF. Distribution of the Cx40 promoter B polymorphism (-26A > G) was different in structural AF when compared to controls (p = 0.03). There was no significant difference with non-structural AF (p = 0.50). The distribution of the Cx37 1019C > T polymorphism was different in non-structural AF (p = 0.03) but not in structural AF (p = 0.08) when compared to controls. Our study describes for the first time an association of drug-resistant non-structural heart disease AF with the Cx37 1019C > T gene polymorphism. We also confirmed the association of the Cx40 - 26G > A polymorphism in patients with AF and structural disease.

Catheter ablation in patients with persistent atrial fibrillation

Catheter ablation is increasingly offered to patients who suffer from symptoms due to atrial fibrillation (AF), based on a growing body of evidence illustrating its efficacy compared with antiarrhythmic drug therapy. Approximately one-third of AF ablation procedures are currently performed in patients with persistent or long-standing persistent AF. Here, we review the available information to guide catheter ablation in these more chronic forms of AF. We identify the following principles: Our clinical ability to discriminate paroxysmal and persistent AF is limited. Pulmonary vein isolation is a reasonable and effective first approach for catheter ablation of persistent AF. Other ablation strategies are being developed and need to be properly evaluated in controlled, multicentre trials. Treatment of concomitant conditions promoting recurrent AF by life style interventions and medical therapy should be a routine adjunct to catheter ablation of persistent AF. Early rhythm control therapy has a biological rationale and trials evaluating its value are underway. There is a clear need to generate more evidence for the best approach to ablation of persistent AF beyond pulmonary vein isolation in the form of adequately powered controlled multi-centre trials.

Atrial fibrillation without comorbidities: Prevalence, incidence and prognosis (from the Framingham Heart Study)

BACKGROUND

The epidemiology of atrial fibrillation (AF) without comorbidities, known as 'lone AF', is uncertain. Although it has been considered a benign condition, we hypothesized that it confers a worse prognosis compared with a matched sample without AF.

METHODS

We described the proportion of AF without comorbidities (clinical, subclinical cardiovascular disease and triggers) among the entire AF sample in Framingham Heart Study (FHS). We compared AF without comorbidities with typical AF, and age-, sex- and cohort-matched individuals without AF, using Cox proportional hazards analysis in relation to combined cardiovascular events (stroke, heart failure, myocardial infarction), and mortality.

RESULTS

Of 10,311 FHS participants, 1,961 were diagnosed with incident AF, among which 173 individuals had AF without comorbidities (47% women, mean age 71±12 years). AF without comorbidities had a prevalence of 1.7% of the entire cohort, and an annual incidence of 0.5 per 1000 person-years. During a median follow-up of 9.7 years after initial AF, 137 individuals with AF without comorbidities (79.2%) died and 141 individuals developed cardiovascular events (81.5%). AF without comorbidities had significantly lower mortality (HR 0.67, 95%CI 0.55-0.81, P < .001) and total cardiovascular events (HR 0.66, 95% CI 0.55-0.80, P < .001) compared with typical AF. However, mortality (HR1.43, 95% CI 1.18-1.75, P < .001) and risk of total cardiovascular events (HR 1.73, 95% CI 1.39-2.16, P < .001) were higher than age-, sex-, and cohort-matched individuals without AF.

CONCLUSIONS

The risk of cardiovascular outcomes and mortality among individuals with AF without comorbidities is lower than typical AF, but is significantly elevated compared with matched individuals without AF.

Myocardial Biopsy In "Idiopathic» Atrial Fibrillation And Other Arrhythmias: Nosological Diagnosis, Clinical And Morphological Parallels, And Treatment

BACKGROUND

The nosological nature of "idiopathic" arrhythmias and the effect of etiotropic and pathogenetic treatment are often unknown.

METHODS AND RESULTS

19 patients (42.6±11.3 years, 9 women) with atrial fibrillation (n = 16), supraventricular (n = 10) and ventricular (n = 4) premature beats, supraventricular (n = 2) and ventricular tachycardia (n = 1), left bundle branch block (n= 2), AV block (n = 2) without structural heart changes. Viruses were identified (polymerase chain reaction, PCR) along with measurement of anti-heart antibodies (AHA) and endomyocardial biopsy (EMB). EMB allowed to establish diagnosis in all patients: infectious-immune myocarditis (n = 11, parvovirus-positive in 1),parvovirus-positive endomyocarditis (n = 1),systemic (n = 2) and myocardial (n = 1) vasculitis,Fabry's disease (n = 1), arrhythmogenic right ventricular dysplasia (n = 1),unspecified genetic cardiomyopathy (n = 2, herpes virus 6 one positive). Level of AHA had the greatest significance for myocarditis diagnostics. All patients with myocarditis/vasculitis had background therapy: acyclovir (n = 10), IV immunoglobulin (n = 2), meloxicam (n = 12), hydroxychloroquine (n = 15), steroids (n = 14, 31.1±12.5 mg/day), azathioprine 150 mg/day (n = 2). Median follow-up was 4 years. Treatment significantly reduced the rate of arrhythmias (8 [5;8] to 3 [1.25;7.75] points); disappearance of bundle branch block was noted.

CONCLUSION

EMB allowed to diagnose immune-mediated inflammatory diseases in 78.9% patients with 'idiopathic' arrhythmias and genetic diseases in 21.1%. Background therapy of myocarditis improved the antiarrhythmic efficiency, and allowed the best premed for interventional treatment.

The Convergent Procedure - A Standardised and Anatomic Approach Addresses the Clinical and Economic Unmet Needs of the Persistent Atrial Fibrillation Population

A standardised treatment management approach is needed to address the escalating worldwide prevalence of atrial fibrillation (AF). The persistent and longstanding persistent AF patient population particularly needs this standardised treatment option to manage their AF. These patients have underlying structural heart disease that result in increased hospitalizations, long-term medical management that increases the cost burden of the healthcare system. Approximately 100 patients have undergone the Convergent Procedure at our center since its introduction 2 years ago, as a treatment option for AF patients. The epicardial and endocardial ablation procedures performed sequentially in a single setting has shown a single procedure success rate of 80%, similar to published success rates at other centers. The epicardial posterior wall isolation silences a majority of known substrates and the endocardial procedure completes the pulmonary vein isolation, creates the cavotricuspid line and provides diagnostic confirmation. The Convergent Procedure should be considered as a first line treatment option for the persistent and longstanding persistent AF patient population who have very limited or no treatment options for the long-term successful management of their AF.

Inherited Structural Heart Diseases With Potential Atrial Fibrillation Occurrence

Inherited cardiac diseases inducing structural remodeling of the myocardium sometimes develop arrhythmias of various kinds. Among these rhythm disturbances, atrial fibrillation is well known to frequently worsen the prognosis of the primary disorder by increasing morbidity and mortality, especially because of a higher rate of heart failure. In this manuscript, we have reviewed the literature on the most important inherited structural cardiac diseases in whose clinical history atrial fibrillation may occur fairly often.

Lone or idiopathic atrial fibrillation, messenger of misery in sight

This editorial refers to 'Gender-related differences in risk of cardiovascular morbidity and all-cause mortality in patients hospitalized with incident atrial fibrillation without concomitant diseases: a nationwide cohort study of 9519 patients' by T. Andersson et al. In order to adequately describe root causes and adverse consequences of apparently idiopathic AF, the requested study population has to be large and be followed for a very long time. Andersson et al. adequately deployed the excellent national Swedish health registries in order to cover the hiatus of aforementioned studies in the current idiopathic AF literature. Considering the notion that patients with idiopathic or lone AF have comparable prospects as AF patients overall but are only caught early in their 'arrhythmia and vascular career', the study by Andersson et al. should trigger physicians to give high priority to exposing predisposing factors or early stages of underlying cardiovascular disease in such a way that preventative measures can be accurately deployed in these patients.

Antiarrhythmic therapy of atrial fibrillation: are we treating too late?

Atrial fibrillation (AF) is associated with increased risk for stroke, heart failure and mortality. The causality between worse prognosis and AF is not clear at this time and AF may just be expression of underlying heart disease that by itself is associated with increased morbidity and mortality. AF is characterized by progression from rare paroxysmal episodes to permanent AF. It has been well recognized that maintenance of sinus rhythm with either antiarrhythmic drugs or catheter ablation is easier to achieve if treatment is established early on. In addition to the established indication of symptomatic improvement, the focus of AF management is shifting to earlier intervention to prevent cardiovascular complications. This concept is currently under investigation in the ongoing EAST trial. Early treatment initiation is desirable from a pathophysiologic perspective. This includes consequent prevention and treatment of AF risk factors, efforts for early diagnosis, and stroke prevention according to the CHA2DS2-VASc score. As long as no data support prognostic advantages with "aggressive" rhythm control therapy it remains reserved for symptomatic patients, since both, medication and catheter ablation, convey a significant risk for complications.

Lone atrial fibrillation: does it exist?

The historical origin of the term "lone atrial fibrillation" (AF) predates by 60 years our current understanding of the pathophysiology of AF, the multitude of known etiologies for AF, and our ability to image and diagnose heart disease. The term was meant to indicate AF in patients for whom subsequent investigations could not demonstrate heart disease, but for many practitioners has become synonymous with "idiopathic AF." As the list of heart diseases has expanded and diagnostic techniques have improved, the prevalence of lone AF has fallen. The legacy of the intervening years is that definitions of lone AF in the literature are inconsistent so that studies of lone AF are not comparable. Guidelines provide a vague definition of lone AF but do not provide direction about how much or what kind of imaging and other testing are necessary to exclude heart disease. There has been an explosion in the understanding of the pathophysiology of AF in the last 20 years in particular. Nevertheless, there are no apparently unique mechanisms for AF in patients categorized as having lone AF. In addition, the term "lone AF" is not invariably useful in making treatment decisions, and other tools for doing so have been more thoroughly and carefully validated. It is, therefore, recommended that use of the term "lone AF" be avoided.

Lone atrial fibrillation - an overview

Atrial fibrillation (AF) sometimes develops in younger individuals without any evident cardiac or other disease. To refer to these patients who were considered to have a very favourable prognosis compared with other AF patients, the term 'lone' AF was introduced in 1953. However, there are numerous uncertainties associated with 'lone' AF, including inconsistent entity definitions, considerable variations in the reported prevalence and outcomes, etc. Indeed, increasing evidence suggests a number of often subtle cardiac alterations associated with apparently 'lone' AF, which may have relevant prognostic implications. Hence, 'lone' AF patients comprise a rather heterogeneous cohort, and may have largely variable risk profiles based on the presence (or absence) of overlooked subclinical cardiovascular risk factors or genetically determined subtle alterations at the cellular or molecular level. Whether the implementation of various cardiac imaging techniques, biomarkers and genetic information could improve the prediction of risk for incident AF and risk assessment of 'lone' AF patients, and influence the treatment decisions needs further research. In this review, we summarise the current knowledge on 'lone' AF, highlight the existing inconsistencies in the field and discuss the prognostic and treatment implications of recent insights in 'lone' AF pathophysiology.

Persistent lone atrial fibrillation: clinicopathologic study of 19 cases

BACKGROUND

The extent to which atrial myocardium is remodeled in patients with persistent lone atrial fibrillation (LAF) is largely unknown.

OBJECTIVE

The purpose of this study was to perform a clinicopathologic investigation in patients with persistent LAF.

METHODS

We characterized structural and molecular remodeling in atrial biopsies from 19 patients (17 males, mean age 49 years) with persistent (>7 days; n = 8) or long-lasting persistent (>1 year; n = 11) LAF who underwent surgical ablation. Atrial tissue from 15 autopsy samples without clinicopathologic evidence of heart disease served as controls.

RESULTS

Morphometric analysis showed cardiomyocyte hypertrophy and greater amounts of myolytic damage and interstitial fibrosis in persistent LAF patients compared to controls (P <.0001). Atrial tissue levels of heme oxygenase-1 and 3-nitrotyrosine were increased in persistent LAF patients (P <.001), consistent with oxidative stress. Levels of superoxide dismutase-2, interleukin-8, interleukin-10, tumor necrosis factor-α, and thiobarbituric acid reactive substance were greater in controls than in persistent LAF patients. Immunoreactive signal for connexin43 was reduced more frequently in persistent LAF patients than controls. There was no correlation between features of structural or molecular remodeling and clinical parameters, including persistent LAF duration.

CONCLUSION

In persistent LAF patients, the atria are modified by structural remodeling and molecular changes of oxidative stress. Tissue changes in persistent LAF appear to occur early after its onset and are qualitatively no different than those observed in patients with atrial fibrillation related to conventional risk factors. These findings suggest that different types of atrial fibrillation are associated with the same spectrum of tissue lesions. Early intervention to restore sinus rhythm in persistent LAF patients may prevent irreversible tissue change, especially interstitial fibrosis.

Comparison of Atrial Fibrillation in the Young versus That in the Elderly: A Review

The incidence and prevalence of atrial fibrillation (AF) are projected to increase significantly worldwide, imposing a significant burden on healthcare resources. The disease itself is extremely heterogeneous in its epidemiology, pathophysiology, and treatment options based on individual patient characteristics. Whilst ageing is well recognised to be an independent risk factor for the development of AF, this condition also affects the young in whom the condition is frequently symptomatic and troublesome. Traditional thinking suggests that the causal factors and pathogenesis of the condition in the young with structurally normal atria but electrophysiological "triggers" in the form of pulmonary vein ectopics leading to lone AF are in stark contrast to that in the elderly who have AF primarily due to an abnormal substrate consisting of fibrosed and dilated atria acting in concert with the pulmonary vein triggers. However, there can be exceptions to this rule as there is increasing evidence of structural and electrophysiological abnormalities in the atrial substrate in young patients with "lone AF," as well as elderly patients who present with idiopathic AF. These reports seem to be blurring the distinction in the pathophysiology of so-called idiopathic lone AF in the young versus that in the elderly. Moreover with availability of improved and modern investigational and diagnostic techniques, novel causes of AF are being reported thereby seemingly consigning the diagnosis of "lone AF" to a rather mythical existence. We shall also elucidate in this paper the differences seen in the epidemiology, causes, pathogenesis, and clinical features of AF in the young versus that seen in the elderly, thereby requiring clearly defined management strategies to tackle this arrhythmia and its associated consequences.