Plasma total testosterone and risk of incident atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

Reduced plakoglobin increases the risk of sodium current defects and atrial conduction abnormalities in response to androgenic anabolic steroid abuse

Androgenic anabolic steroids (AAS) are commonly abused by young men. Male sex and increased AAS levels are associated with earlier and more severe manifestation of common cardiac conditions, such as atrial fibrillation, and rare ones, such as arrhythmogenic right ventricular cardiomyopathy (ARVC). Clinical observations suggest a potential atrial involvement in ARVC. Arrhythmogenic right ventricular cardiomyopathy is caused by desmosomal gene defects, including reduced plakoglobin expression. Here, we analysed clinical records from 146 ARVC patients to identify that ARVC is more common in males than females. Patients with ARVC also had an increased incidence of atrial arrhythmias and P wave changes. To study desmosomal vulnerability and the effects of AAS on the atria, young adult male mice, heterozygously deficient for plakoglobin (Plako+/-), and wild type (WT) littermates were chronically exposed to 5α-dihydrotestosterone (DHT) or placebo. The DHT increased atrial expression of pro-hypertrophic, fibrotic and inflammatory transcripts. In mice with reduced plakoglobin, DHT exaggerated P wave abnormalities, atrial conduction slowing, sodium current depletion, action potential amplitude reduction and the fall in action potential depolarization rate. Super-resolution microscopy revealed a decrease in NaV1.5 membrane clustering in Plako+/- atrial cardiomyocytes after DHT exposure. In summary, AAS combined with plakoglobin deficiency cause pathological atrial electrical remodelling in young male hearts. Male sex is likely to increase the risk of atrial arrhythmia, particularly in those with desmosomal gene variants. This risk is likely to be exaggerated further by AAS use. KEY POINTS: Androgenic male sex hormones, such as testosterone, might increase the risk of atrial fibrillation in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), which is often caused by desmosomal gene defects (e.g. reduced plakoglobin expression). In this study, we observed a significantly higher proportion of males who had ARVC compared with females, and atrial arrhythmias and P wave changes represented a common observation in advanced ARVC stages. In mice with reduced plakoglobin expression, chronic administration of 5α-dihydrotestosterone led to P wave abnormalities, atrial conduction slowing, sodium current depletion and a decrease in membrane-localized NaV1.5 clusters. 5α-Dihydrotestosterone, therefore, represents a stimulus aggravating the pro-arrhythmic phenotype in carriers of desmosomal mutations and can affect atrial electrical function.

Understanding the incidence of atrial fibrillation and stroke in hypertrophic cardiomyopathy patients: insights from Danish nationwide registries

AIMS

The treatment of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) can be challenging since AF aggravates symptoms and increases the risk of stroke. Which factors contribute to the development of AF and stroke in HCM remains unknown. The aim of this study was to determine the incidence of AF and stroke in HCM patients and identify the risk factors.

METHODS AND RESULTS

Using Danish national registries, all HCM patients from 2005 to 2018 were included. The association between HCM, incident AF, and stroke was investigated using multivariable Cox proportional hazards analysis. Cumulative incidences were calculated using the Aalen-Johansen estimator. Among the 3367 patients without prevalent AF, 24% reached the endpoint of incident AF with death as a competing risk. Median follow-up time was 4 years. Atrial fibrillation incidence was equal between sexes and increased for patients with ischaemic heart disease [IHD; hazard ratio (HR) 1.33, 95% confidence interval (CI) 1.08-1.63], hypertension (HT) (HR 1.36, 95% CI 1.14-1.67), and obstructive HCM (HR 1.27, 95% CI 1.05-1.52). Seven per cent developed stroke, with no difference detected stratifying for the presence of AF. Sub-analysis revealed that when AF was treated with oral anticoagulants (OACs), stroke was less likely (HR 0.4, 95% CI 0.18-0.86, P = 0.02). However, 34% of patients were not receiving adequate anticoagulation following AF diagnosis.

CONCLUSION

Obstructive HCM, HT, and IHD were associated with increased risk of AF. Prevalent AF alone was not predictive of stroke; however, AF patients treated with OAC were significantly less likely to develop stroke, suggesting that this development is driven by the protective effect of OAC. Despite this, 34% of patients did not receive OAC.

Testosterone and the risk of incident atrial fibrillation in older men: further analysis of the ASPREE study

Background

A cardiovascular safety trial of testosterone in men with cardiovascular risk factors or disease found no difference in rates of major adverse cardiovascular events (MACE) or death but noted more atrial fibrillation (AF) events in testosterone-treated men. We investigated the relationship between endogenous testosterone concentrations with risk of developing AF in healthy older men.

Methods

Post-hoc analysis of 4570 male participants in the ASPirin in Reducing Events in the Elderly (ASPREE) study. Men were aged ≥ 70 years, had no history of cardiovascular disease (including AF), thyroid disease, prostate cancer, dementia, or life-threatening illnesses. Risk of AF was modelled using Cox proportional hazards regression.

Findings

Median (IQR) age was 73.7 (71.6-77.1) years and median (IQR) follow-up 4.4 (3.3-5.5) years, during which 286 men developed AF (15.3 per 1000 participant-years). Baseline testosterone was higher in men who developed incident AF compared men who did not [17.0 (12.4-21.2) vs 15.7 (12.2-20.0) nmol/L]. There was a non-linear association of baseline testosterone with incident AF. The risk for AF was higher in men with testosterone in quintiles (Q) 4&5 (Q4:Q3, HR = 1.91; 95%CI = 1.29-2.83 and Q5:Q3HR = 1.98; 95%CI = 1.33-2.94). Results were similar after excluding men who experienced MACE or heart failure during follow-up.

Interpretation

Circulating testosterone concentrations within the high-normal range are independently associated with an increased risk of incident AF amongst healthy older men. This suggests that AF may be an adverse consequence of high-normal total testosterone concentrations.

Funding

National Institute on Aging and National Cancer Institute at the National Institutes of Health; Australian Government (NHMRC, CSIRO); Monash University; and AlfredHealth.

Cardiovascular safety of testosterone replacement therapy in men: an updated systematic review and meta-analysis

INTRODUCTION

The cardiovascular (CV) safety of testosterone (T) replacement therapy (TRT) is still conflicting. Recent data suggested a TRT-related increased risk of atrial fibrillation (AF). The aim of this study was to systematic review and meta-analyze CV risk related to TRT as derived from placebo controlled randomized trials (RCTs).

AREAS COVERED

An extensive Medline, Embase, and Cochrane search was performed. All placebo-controlled RCTs reporting data on TRT-related CV safety were considered. To better analyze the role of T on AF, population-based studies investigating the relationship between endogenous circulating T levels and AF incidence were also included and analyzed.

EXPERT OPINION

Out of 3.615, 106 studies were considered, including 8.126 subjects treated with TRT and 7.310 patients allocated to placebo. No difference between TRT and placebo was observed when major adverse CV events were considered. Whereas the incidence of non-fatal arrhythmias and AF was increased in the only trial considering CV safety as the primary endpoint, this was not confirmed when all other studies were considered (MH-OR 1.61[0.84;3.08] and 1.44[0.46;4.46]). Similarly, no relationship between endogenous T levels and AF incidence was observed after the adjustment for confounders Available data confirm that TRT is safe and it is not related to an increased CV risk.

Prediction of atrial fibrillation and stroke using machine learning models in UK Biobank

Objective

Atrial fibrillation (AF) is the most common cardiac arrythmia, and it is associated with increased risk for ischemic stroke, which is underestimated, as AF can be asymptomatic. The aim of this study was to develop optimal ML models for prediction of AF in the population, and secondly for ischemic stroke in AF patients.

Methods

To develop ML models for prediction of 1) AF in the general population and 2) ischemic stroke in patients with AF we constructed XGBoost, LightGBM, Random Forest, Deep Neural Network, Support Vector Machine and Lasso penalised logistic regression models using UK-Biobank's extensive real-world clinical data, questionnaires, as well as biochemical and genetic data, and their predictive performances were compared. Ranking and contribution of the different features was assessed by SHapley Additive exPlanations (SHAP) analysis. The clinical tool CHA2DS2-VASc for prediction of ischemic stroke among AF patients, was used for comparison to the best performing ML model.

Findings

The best performing model for AF prediction was LightGBM, with an area-under-the-roc-curve (AUROC) of 0.729 (95% confidence intervals (CI): 0.719, 0.738). The best performing model for ischemic stroke prediction in AF patients was XGBoost with AUROC of 0.631 (95% CI: 0.604, 0.657). The improved AUROC in the XGBoost model compared to CHA2DS2-VASc was statistically significant based on DeLong's test (p-value = 2.20E-06). In addition, the SHAP analysis showed that several peripheral blood biomarkers (e.g. creatinine, glycated haemoglobin, monocytes) were associated with ischemic stroke, which are not considered by CHA2DS2-VASc.

Implications

The best performing ML models presented have the potential for clinical use, but further validation in independent studies is required. Our results endorse the incorporation of some routinely measured blood biomarkers for ischemic stroke prediction in AF patients.

Drug-induced atrial fibrillation. A narrative review of a forgotten adverse effect

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased morbidity and mortality. There is clinical evidence that an increasing number of cardiovascular and non-cardiovascular drugs, mainly anticancer drugs, can induce AF either in patients with or without pre-existing cardiac disorders, but drug-induced AF (DIAF) has not received the attention that it might deserve. In many cases DIAF is asymptomatic and paroxysmal and patients recover sinus rhythm spontaneously, but sometimes, DIAF persists, and it is necessary to perform a cardioversion. Furthermore, DIAF is not mentioned in clinical guidelines on the treatment of AF. The risk of DIAF increases in elderly and in patients treated with polypharmacy and with risk factors and comorbidities that commonly coexist with AF. This is the case of cancer patients. Under these circumstances ascribing causality of DIAF to a given drug often represents a clinical challenge. We review the incidence, the pathophysiological mechanisms, risk factors, clinical relevance, and treatment of DIAF. Because of the limited information presently available, further research is needed to obtain a deeper insight into DIAF. Meanwhile, it is important that clinicians are aware of the problem that DIAF represents, recognize which drugs may cause DIAF, and consider the possibility that a drug may be responsible for a new-onset AF episode.

Associations of Serum Testosterone and Sex Hormone-binding Globulin With Incident Arrhythmias in Men From UK Biobank

CONTEXT

Sex hormones have been identified as cardiovascular risk factors, whereas the relationship between sex hormones and the risk of arrhythmias in men has not yet been well studied in the prospective cohort study.

OBJECTIVE

To analyze associations of serum testosterone and SHBG concentrations and calculate free testosterone (cFT) with arrhythmias in men.

METHODS

Sex hormones were measured at baseline from UK Biobank. Main outcomes were incidence of atrial fibrillation/flutter (AF), ventricular arrhythmia (VA), and bradyarrhythmia (BA).

RESULTS

Of 173 498 men (aged 37-73 years, followed for 11 years), 11 368 had incident AF, 1646 had incident VA, and 4788 had incident BA. Compared with the third quartiles, the lowest category of serum testosterone was associated with increased risks of AF (hazard ratio [HR], 1.06; 95% CI, 1.00-1.12) and BA (HR, 1.11; 95% CI, 1.02-1.20) after multivariable adjustment, but no VA. Likewise, similar associations were found between cFT values and AF and BA events. Furthermore, higher levels of cFT were associated with increased risks of AF (HR, 1.07; 95% CI, 1.02-1.13) and VA (HR, 1.18; 95% CI, 1.01-1.37). Higher SHBG concentrations were associated with increased risks of AF (HR, 1.44; 95% CI, 1.34-1.54), VA (HR, 1.27; 95% CI, 1.07-1.52), and BA (HR, 1.17; 95% CI ,1.05-1.29).

CONCLUSIONS

Lower levels of testosterone and cFT were associated with increased risk of AF and BA. Higher cFT levels were associated with increased risk of AF and VA. Higher SHBG levels were associated with increased risk of AF, VA, and BA.

Relationships between endogenous and exogenous testosterone and cardiovascular disease in men

In this narrative review, we discuss the evidence about the controversy about the cardiovascular effects of endogenous and exogenous testosterone in men. Prospective cohort studies with follow-up of ~5-15 years generally indicate no association or a possible inverse relationship between serum endogenous testosterone concentrations and composite major cardiovascular events, cardiovascular deaths and overall mortality. Pharmacoepidemiological studies of large databases generally show no association between testosterone therapy and incident major cardiovascular events, and some pharmacoepidemiological studies demonstrate an association with decreased overall mortality. Randomized, placebo-controlled trials indicate that there is no increased incidence of overall major cardiovascular events with 1-3 years of testosterone therapy. These placebo-controlled trials have major limitations including small numbers of participants, short duration of testosterone therapy and follow-up, and lack of systematic adjudication of cardiovascular events. Overall, the evidence indicates that endogenous testosterone concentrations and testosterone therapy at physiological dosages confer no or minimal effects on the incidence of cardiovascular outcomes. There is insufficient evidence to make conclusions about testosterone therapy for patients at high risk of cardiovascular events (e.g., men with recent myocardial infarctions or stroke and men with recurrent idiopathic deep venous thromboses). In general, clinicians should avoid prescribing supraphysiological testosterone therapy to hypogonadal men or men with slightly low to low-normal serum testosterone concentrations and no identified disorder of the hypothalamus-pituitary-testicular axis because of the uncertain cardiovascular risks and the lack of proven health benefits. For most men with bona fide hypogonadism, benefits of testosterone therapy exceed the potential risk of adverse cardiovascular effects.

Connexin Lateralization Contributes to Male Susceptibility to Atrial Fibrillation

Men have a higher risk of developing atrial fibrillation (AF) than women, though the reason for this is unknown. Here, we compared atrial electrical and structural properties in male and female mice and explored the contribution of sex hormones. Cellular electrophysiological studies revealed that action potential configuration, Na+ and K+ currents were similar in atrial myocytes from male and female mice (4–5 months). Immunofluorescence showed that male atrial myocytes had more lateralization of connexins 40 (63 ± 4%) and 43 (66 ± 4%) than females (Cx40: 45 ± 4%, p = 0.006; Cx43: 44 ± 4%, p = 0.002), with no difference in mRNA expression. Atrial mass was significantly higher in males. Atrial myocyte dimensions were also larger in males. Atrial fibrosis was low and similar between sexes. Orchiectomy (ORC) abolished sex differences in AF susceptibility (M: 65%; ORC: 38%, p = 0.050) by reducing connexin lateralization and myocyte dimensions. Ovariectomy (OVX) did not influence AF susceptibility (F: 42%; OVX: 33%). This study shows that prior to the development of age-related remodeling, male mice have more connexin lateralization and larger atria and atrial myocyte than females. Orchiectomy reduced AF susceptibility in males by decreasing connexin lateralization and atrial myocyte size, supporting a role for androgens. These sex differences in AF substrates may contribute to male predisposition to AF.

Strategies for Maintaining Brain Health: The Role of Stroke Risk Factors Unique to Elderly Women

Stroke risk and prevalence increase with advanced age and women tend to be older than men at the time of their first stroke. Advanced age in women confers unique stroke risks that are beyond reproductive factors. Previous reviews and guidelines have largely focused on risk factors specific to women, with a predominant focus on reproductive factors and, therefore, younger to middle-aged women. This review aims to specifically describe stroke risk factors in elderly women, the population of women where the majority of strokes occur, with a focus on atrial fibrillation, hormone therapy, psychosocial risk factors, and cognitive impairment. Our review suggests that prevention and management of stroke risks that are unique or more prevalent in elderly women needs a coordinated system of care from general physicians, general neurologists, vascular and cognitive neurologists, psychologists, cardiologists, patients, and their caretakers. Early identification and management of the elderly woman-specific and traditional stroke risk factors is key for decreasing stroke burden in elderly women. Increased education among elderly women regarding stroke risk factors and their identification should be considered, and an update to the guidelines for prevention of stroke in women is strongly encouraged.

[Testosterone and congestive heart failure]

This article summarizes current information about the interrelation between testosterone concentrations and chronic heart failure (CHF). The authors described key publications that address the prevalence of testosterone deficiency in patients with CHF, the effect of endogenous and exogenous testosterone on the cardiovascular system, the relationship between testosterone levels and the severity and prognosis of CHF, and the efficacy of interventional treatments for CHF.

Circulating sex hormones and risk of atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Sex hormones are associated with many cardiovascular risk factors, but their effects on atrial fibrillation (AF) incidence remain unclear. This systematic review and meta-analysis aimed to evaluate the association of circulating sex hormones with AF risk by pooling available data from observational studies.

METHODS

A systematic literature search for pertinent articles with case-control and cohort designs was conducted via five databases up to 7 July 2021. A meta-analysis with six cohort studies was conducted separately on men and women. Adjusted relative risk (RR) with a 95% confidence interval (CI) was derived by comparing the highest with the lowest levels of a specific sex hormone and by using a random-effect or fixed-effect model. Heterogeneity was tested using the I ² statistic and the Q-test.

RESULTS

A total of six cohort studies and four case-control studies were included. In a meta-analysis of cohort studies, dehydroepiandrosterone sulfate (DHEAS) was associated with a decreased risk of AF in men (RR: 0.729, 95% CI: 0.559-0.952, I ² = 50.0%, P _{-heterogeneity} = 0.157) after combining results from two cohort studies; total testosterone was not associated with any risk of AF in men and postmenopausal women, and AF risk was not associated with estradiol in men after synthesizing available studies.

CONCLUSION

This study indicates that a higher endogenous DHEAS level was associated with a lower AF risk in men, whereas total testosterone and estradiol were not associated with AF risk. Longitudinal studies with multiple monitoring are needed to further promulgate the relationship between various circulating sex hormones and AF risk.

Ventricular Tachyarrhythmia Risk in Paediatric/Young vs. Adult Brugada Syndrome Patients: A Territory-Wide Study

Introduction: Brugada syndrome (BrS) is a cardiac ion channelopathy with a higher prevalence in Asia compared to the Western populations. The present study compared the differences in clinical and electrocardiographic (ECG) presentation between paediatric/young (≤25 years old) and adult (>25 years) BrS patients.

Method: This was a territory-wide retrospective cohort study of consecutive BrS patients presenting to public hospitals in Hong Kong. The primary outcome was spontaneous ventricular tachycardia/ventricular fibrillation (VT/VF).

Results: The cohort consists of 550 consecutive patients (median age of initial presentation = 51 ± 23 years; female = 7.3%; follow-up period = 83 ± 80 months), divided into adult (n = 505, mean age of initial presentation = 52 ± 19 years; female = 6.7%; mean follow-up period = 83 ± 80 months) and paediatric/young subgroups (n = 45, mean age of initial presentation = 21 ± 5 years, female = 13.3%, mean follow-up period = 73 ± 83 months). The mean annual VT/VF incidence rate were 17 and 25 cases per 1,000 patient-year, respectively. Multivariate analysis showed that initial presentation of type 1 pattern (HR = 1.80, 95% CI = [1.02, 3.15], p = 0.041), initial asymptomatic presentation (HR = 0.26, 95% CI = [0.07, 0.94], p = 0.040) and increased P-wave axis (HR = 0.98, 95% CI = [0.96, 1.00], p = 0.036) were significant predictors of VT/VF for the adult subgroup. Only initial presentation of VT/VF was predictive (HR = 29.30, 95% CI = [1.75, 492.00], p = 0.019) in the paediatric/young subgroup.

Conclusion: Clinical and ECG presentation of BrS vary between the paediatric/young and adult population in BrS. Risk stratification and management strategies for younger patients should take into consideration and adopt an individualised approach.

Association of Serum Testosterone and Luteinizing Hormone With Blood Pressure and Risk of Cardiovascular Disease in Middle-Aged and Elderly Men

Background

The age‐related decline in testosterone levels is thought to be of great importance for male aging and cardiovascular diseases. However, data are controversial on whether abnormal sex hormones are linked to the presence of cardiovascular diseases and it is also uncertain how blood pressure modifies the association between testosterone levels and major cardiovascular diseases.

Methods and Results

This is a multicenter, population‐based, cross‐sectional study of 6296 men conducted between 2013 and 2016. Basic information and clinical symptoms were obtained by questionnaires. Blood pressure and plasma levels of total testosterone, sex hormone–binding globulin, luteinizing hormone, and free testosterone were determined in men in a multistage random, cluster sampling in 6 provinces of China. There were 5786 Chinese men (mean [SD] age 55.0 [10.1] years) included after exclusion criteria were applied; 37.2% (2150) of them were diagnosed with hypertension. Total testosterone, free testosterone, and sex hormone–binding globulin were inversely associated with the prevalence of hypertension. Age >65 years or body mass index ≥24 negatively impacted the inverse correlation between testosterone levels and hypertension, whereas smoking and family history of hypertension strengthened the correlation. In participants with grade 2 hypertension, total testosterone was positively associated with the presence of stroke, and luteinizing hormone was also positively correlated with cardiovascular and cerebrovascular diseases.

Conclusions

Lower total testosterone could be a promising risk marker for prevalent hypertension. Both low and high levels of testosterone are associated with greater cardiovascular risk. Primary hypogonadism may be a risk marker for major cardiovascular diseases in men with severe hypertension.

Association of Erectile Dysfunction with Incident Atrial Fibrillation: The Multi-Ethnic Study of Atherosclerosis (MESA)

PURPOSE

Erectile dysfunction has been associated with atrial fibrillation in cross-sectional studies, but the association of erectile dysfunction with incident atrial fibrillation is less well established. This study aimed to determine whether erectile dysfunction is independently associated with incident atrial fibrillation after adjusting for conventional risk factors.

METHODS

We studied 1760 male participants (mean age 68 ± 9 years) from the Multi-Ethnic Study of Atherosclerosis (MESA), who completed self-reported erectile dysfunction assessment at MESA exam 5 (2010-2012). Cumulative incidence of atrial fibrillation was estimated by Kaplan-Meier analysis. Cox proportional hazards regression was used to calculate the unadjusted and adjusted hazard ratios (HR) using 3 models in which variables were added in a stepwise manner. In model 3, HR was adjusted for age, race and ethnicity, education, smoking status, alcohol use, systolic blood pressure, body mass index, diabetes, anti-hypertensive medication use, lipid-lowering medication use, total cholesterol, and estimated glomerular filtration rate.

RESULTS

During the median follow-up of 3.8 (interquartile range, 3.5-4.2) years, 94 cases of incident atrial fibrillation were observed. There was a significant difference between males with and without erectile dysfunction for cumulative incident atrial fibrillation rates at 4 years (9.6 vs 2.9%, P < .01). In the fully adjusted model, erectile dysfunction remained associated with incident atrial fibrillation (model 3; HR, 1.66; 95% confidence interval 1.01-2.72, P = .044).

CONCLUSIONS

Among older male participants in this prospective study, we found that self-reported erectile dysfunction was associated with incident atrial fibrillation.