Atrial Fibrillation in Athletes

Determinants of supraventricular extra beats in elite athletes practicing different sporting disciplines

BACKGROUND

Supraventricular extra beats (SVEB) are frequently observed in athletes but data on significance, prognostic role and correlation with cardiac remodeling are contrasting. It is uncertain whether SVEB may indicate the development of more complex arrhythmias and the need for closer monitoring is undetermined. The aim was to assess the prevalence and clinical significance of BESV in Olympic athletes of different sporting disciplines, evaluating potential correlations with cardiac remodeling and clinical features.

METHODS

We enrolled athletes who participated at 2012-2022 Olympic Games, submitted to physical examination, blood tests, echocardiography and exercise tests, categorized into power, skills, endurance and mixed disciplines.

RESULTS

We studied 1492 elite athletes: 56% male individuals, mean age 25.8 ± 5.1 years; 29.5% practiced power, 12.3% skills, 21% endurance and 37.2% mixed disciplines. At exercise-stress tests, 6.2% had SVEB, mostly single beats. SVEB were not influenced by anthropometrics or blood test results. They were more common in male individuals (77.4 vs. 54.6%, P < 0.0001) and older athletes (27.1 ± 5.7 vs. 25.7 ± 5.1, P = 0.01). In male athletes with SVEB, higher left atrial volumes were observed (24.2 ± 7.3 vs. 22.2 ± 7.1 ml/m2, P = 0.03). No differences were found in terms of sporting discipline: despite larger left atrial dimensions in aerobic disciplines, SVEB rates were similar in different sporting disciplines (6.1% endurance, 6.3% mixed, 5.2% power and 8.7% skills; P = 0.435).

CONCLUSION

SVEB were more common in older, male athletes and associated with higher left atrial volume (especially in male individuals) regardless of sport practiced. Athletes with greater left atrial volume and SVEB are supposed to have higher risk, in middle age, of developing more complex arrhythmias.

Fibrinaloid Microclots and Atrial Fibrillation

Atrial fibrillation (AF) is a comorbidity of a variety of other chronic, inflammatory diseases for which fibrinaloid microclots are a known accompaniment (and in some cases, a cause, with a mechanistic basis). Clots are, of course, a well-known consequence of atrial fibrillation. We here ask the question whether the fibrinaloid microclots seen in plasma or serum may in fact also be a cause of (or contributor to) the development of AF. We consider known 'risk factors' for AF, and in particular, exogenous stimuli such as infection and air pollution by particulates, both of which are known to cause AF. The external accompaniments of both bacterial (lipopolysaccharide and lipoteichoic acids) and viral (SARS-CoV-2 spike protein) infections are known to stimulate fibrinaloid microclots when added in vitro, and fibrinaloid microclots, as with other amyloid proteins, can be cytotoxic, both by inducing hypoxia/reperfusion and by other means. Strokes and thromboembolisms are also common consequences of AF. Consequently, taking a systems approach, we review the considerable evidence in detail, which leads us to suggest that it is likely that microclots may well have an aetiological role in the development of AF. This has significant mechanistic and therapeutic implications.

Italian Cardiological Guidelines (COCIS) for Competitive Sport Eligibility in athletes with heart disease: update 2020

Since 1989, SIC Sport and a FMSI, in partnership with leading Italian Cardiological Scientific Associations (ANCE, ANMCO and SIC) have produced Cardiological Guidelines for Completive Sports Eligibility for athletes with heart disease (COCIS -- 1989, 1995, 2003, 2009 and 2017). The English version of the Italian Cardiological Guidelines for Competitive Sports Eligibility for athletes with heart disease was published in 2013 in this Journal. This publication is an update with respect to the document previously published in English in 2013. It includes the principal innovations that have emerged over recent years, and is divided into five main chapters: arrhythmias, ion channel disorders, congenital heart diseases, acquired valve diseases, cardiomyopathies, myocarditis and pericarditis and ischemic heart disease. Wherever no new data have been introduced with respect to the 2013 publication, please refer to the previous version. This document is intended to complement recent European and American guidelines but an important difference should be noted. The European and American guidelines indicate good practice for people engaging in physical activity at various levels, not only at the competitive level. In contrast, the COCIS guidelines refer specifically to competitive athletes in various sports including those with high cardiovascular stress. This explains why Italian guidelines are more restrictive than European and USA ones. COCIS guidelines address 'sports doctors' who, in Italy, must certify fitness to participate in competitive sports. In Italy, this certificate is essential for participating in any competition.

The Role of Cardiovascular Magnetic Resonance in Sports Cardiology; Current Utility and Future Perspectives

Purpose of review

Cardiovascular magnetic resonance (CMR) is frequently used in the investigation of suspected cardiac disease in athletes. In this review, we discuss how CMR can be used in athletes with suspected cardiomyopathy with particular reference to volumetric analysis and tissue characterization. We also discuss the finding of non-ischaemic fibrosis in athletes describing its prevalence, distribution and clinical importance.

Recent findings

The strengths of CMR include high spatial resolution, unrestricted imaging planes and lack of ionizing radiation. Regular physical exercise leads to cardiac remodeling that in certain situations can be clinically challenging to differentiate from various cardiomyopathies. Thorough morphological assessment by CMR is fundamental to ensuring accurate diagnosis. Developments in tissue characterization by late gadolinium enhancement and T1 mapping have the potential to be powerful additional tools in this challenging clinical situation. Using late gadolinium enhancement, it is also possible to detect non-ischaemic fibrosis in athletes who do not have overt cardiomyopathy. The mechanisms of this fibrosis are unclear; however, it does appear to be clinically important. We also review data on the prevalence of non-ischaemic fibrosis in athletes.

Summary

CMR is a powerful tool to aid in the diagnosis of cardiomyopathy in athletes. It may also have a future role in assessing fibrosis related to long-term participation in sport.

The Competitive Senior Athlete

Clinicians should discuss common health issues of the older population and how medical problems affect their sports performance. Patients with chronic conditions, such as hypertension and diabetes mellitus, benefit from participation in sports. However, special care should be taken to keep the patient healthy and minimize effects of these conditions and their treatments in athletic performance. Another important consideration in the older athlete is fluid ingestion and the increased risk of dehydration. There is evidence that physical exercise reduces pain in osteoarthritis and enhances physical function of affected joints. Older athletes often use multiple medications and dietary supplements; Clinicians should educate patients about possible effects of medications in sports performance.

α-adrenoceptor-mediated enhanced inducibility of atrial fibrillation in a canine system inflammation model

The exact mechanism associated with inflammation and atrial fibrillation (AF) remains unknown. The aim of the present study was to investigate the roles of connexin 43 (Cx43) and a1‑adrenergic receptor (α1‑AR) activation in the pathogenesis of system inflammation‑induced AF. A canine model of chronic low‑grade system inflammation was established by administrating a low dose of lipopolysaccharide (LPS; 0.1 µg/kg) for 2 weeks. Programmed stimulation was applied on the right atrial appendage to determine the effective refractory periods (ERP) and the window of vulnerability (WOV). Tumor necrosis factor α (TNF‑α) and interleukin 6 (IL‑6) levels in plasma and atrial tissue were measured by ELISA. Cx43, Toll‑like receptor 4 (TLR4) and nuclear factor κB (NF‑κB) proteins were analyzed using western blotting or immunohistochemistry. Administration of LPS for 2 weeks increased the concentration of TNF‑α and IL‑6 in the plasma and right atrium. ERP was markedly shortened and cumulative WOV was significantly widened in the LPS group. Following treatment with LPS, the amount of Cx43 protein in the area of intercalated disk increased. In addition, a high‑density of Cx43 in the lateral connection was identified. LPS also induced the activation of NF‑κB in the canine atrium. Administration with the α1‑AR blocker doxazosin prevented the production of LPS‑induced inflammatory cytokine and reversed the enhanced vulnerability to atrial fibrillation. Doxazosin inhibited the LPS‑induced increase in Cx43 protein and heterogeneous distribution, and prevented the activation of NF‑κB. These results indicated that chronic low‑grade system inflammation may increase the inducibility of AF in a canine model. The underlying mechanism may be involved in the LPS‑induced activation of NF‑κB, and the increase in Cx43 expression and lateral distribution via an α1-AR-dependent pathway.

The role of the autonomic nervous system in arrhythmias and sudden cardiac death

The autonomic nervous system (ANS) is complex and plays an important role in cardiac arrhythmia pathogenesis. A deeper understanding of the anatomy and development of the ANS has shed light on its involvement in cardiac arrhythmias. Alterations in levels of Sema-3a and NGF, both growth factors involved in innervation patterning during development of the ANS, leads to cardiac arrhythmias. Dysregulation of the ANS, including polymorphisms in genes involved in ANS development, have been implicated in sudden infant death syndrome. Disruptions in the sympathetic and/or parasympathetic systems of the ANS can lead to cardiac arrhythmias and can vary depending on the type of arrhythmia. Simultaneous stimulation of both the sympathetic and parasympathetic systems is thought to lead to atrial fibrillation whereas increased sympathetic stimulation is thought to lead to ventricular fibrillation or ventricular tachycardia. In inherited arrhythmia syndromes, such as Long QT and Catecholaminergic Polymorphic Ventricular Tachycardia, sympathetic system stimulation is thought to lead to ventricular tachycardia, subsequent arrhythmias, and in severe cases, cardiac death. On the other hand, arrhythmic events in Brugada Syndrome have been associated with periods of high parasympathetic tone. Increasing evidence suggests that modulation of the ANS as a therapeutic strategy in the treatment of cardiac arrhythmias is safe and effective. Further studies investigating the involvement of the ANS in arrhythmia pathogenesis and its modulation for the treatment of cardiac arrhythmias is warranted.