Recommendations for physical activity and recreational sports participation for young patients with genetic cardiovascular diseases

Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part II: ventricular arrhythmias, channelopathies and implantable defibrillators

This consensus paper on behalf of the Study Group on Sports Cardiology of the European Society of Cardiology follows a previous one on guidelines for sports participation in competitive and recreational athletes with supraventricular arrhythmias and pacemakers. The question of imminent life-threatening arrhythmias is especially relevant when some form of ventricular rhythm disorder is documented, or when the patient is diagnosed to have inherited a pro-arrhythmogenic disorder. Frequent ventricular premature beats or nonsustained ventricular tachycardia may be a hallmark of underlying pathology and increased risk. Their finding should prompt a thorough cardiac evaluation, including both imaging modalities and electrophysiological techniques. This should allow distinguishing idiopathic rhythm disorders from underlying disease that carries a more ominous prognosis. Recommendations on sports participation in inherited arrhythmogenic conditions and asymptomatic gene carriers are also discussed: congenital and acquired long QT syndrome, short QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, arrhythmogenic right ventricular cardiomyopathy and other familial electrical disease of unknown origin. If an implantable cardioverter defibrillator is indicated, it is no substitute for the guidelines relating to the underlying pathology. Moreover, some particular recommendations for patients/athletes with an implantable cardioverter defibrillator are to be observed.

Cardiac issues in the young athlete

Young athletes are disproportionately plagued with congenital cardiac disease. Many of these diseases predispose to sudden cardiac death (SCD), a dramatic and tragic outcome for any young athlete. In many cases, conditions that predispose to SCD do not cause symptoms or show signs on examination, making diagnosis of cardiac disease and prevention of SCD difficult. Clinicians should be familiar with common causes of SCD and their symptoms, perform careful evaluations, refer athletes in whom there are concerns, and make sure any concerning findings receive thorough evaluation. Clinicians should also be familiar with and follow recent guidelines on return to play. Unfortunately, most preparticipation examinations are inadequate, due in part to use of inadequate forms. Better forms are available and should replace inadequate ones.

Age- and Training-Dependent Development of Arrhythmogenic Right Ventricular Cardiomyopathy in Heterozygous Plakoglobin-Deficient Mice

Background— Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes sudden death and right ventricular heart failure in the young. Clinical data suggest that competitive sports may provoke ARVC in susceptible persons. Genetically, loss-of-function mutations in desmosomal proteins (plakophilin, desmoplakin, or plakoglobin) have been associated with ARVC. To test the hypothesis that reduced desmosomal protein expression causes ARVC, we studied the cardiac effects of heterozygous plakoglobin deficiency in mice.

Methods and Results— Ten-month-old heterozygous plakoglobin-deficient mice (plakoglobin +/− ) had increased right ventricular volume, reduced right ventricular function, and spontaneous ventricular ectopy (all P <0.05). Left ventricular size and function were not altered. Isolated, perfused plakoglobin +/− hearts had spontaneous ventricular tachycardia of right ventricular origin and prolonged right ventricular conduction times compared with wild-type hearts. Endurance training accelerated the development of right ventricular dysfunction and arrhythmias in plakoglobin +/− mice. Histology and electron microscopy did not identify right ventricular abnormalities in affected animals.

Conclusions— Heterozygous plakoglobin deficiency provokes ARVC. Manifestation of the phenotype is accelerated by endurance training. This suggests a functional role for plakoglobin and training in the development of ARVC.

Advances in congenital long QT syndrome

PURPOSE OF REVIEW

Dramatic advances have been made in understanding of both the genetics and the phenotypic expression of congenital long QT syndrome. This paper reviews recent clinically relevant literature.

RECENT FINDINGS

Long QT syndrome is one of the leading causes of sudden cardiac death. This syndrome, once diagnosed by a clinical profile, has been more clearly defined by specific gene defects causing ion channel abnormalities in the beating heart. Genetic testing for long QT syndrome, once available only through research laboratories, is now commercially available. Diagnosis, risk assessment, and management are increasingly being guided by gene-specific diagnoses. In a family with suspected disease, the genetic test will determine the defect in as many as 75% of subjects. Once the diagnosis is made, the mainstay of therapy continues to be beta-blockers. Implantable cardioverter-defibrillators are indicated in patients at high risk for malignant arrhythmias.

SUMMARY

Long QT syndrome is one of the first cardiovascular diseases to see the dramatic changes that bench research can bring to the clinical arena. Future research is needed to determine the gene defect in the remaining 25% of patients with suspected long QT syndrome and in risk stratification.

Treatment of athletes with cardiac disease or arrhythmias

Ventricular arrhythmias and sudden cardiac death in the athlete are uncommon but extremely visible because of the high profile of amateur and professional athletes. In athletes under the age of 30 years, the incidence of sudden death is low and in most cases occurs in individuals with inherited heart disease. In the older athlete, sudden death is more common and is generally due to arrhythmias in the context of coronary artery disease. Many athletes with aborted sudden death, arrhythmia-related syncope, or high-risk genetic disorders benefit from therapy with implantable cardioverter-defibrillators (ICDs). Although ICD therapy can effectively abort sudden death, implantation of an ICD generally prohibits an individual from all competitive athletics except low-intensity sports. Recommendations for participation in competitive athletics generally follow the recently published 36th Bethesda Conference Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities.

Sudden cardiac death in Athletes

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD), and coronary artery anomalies, each with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have emerged in Europe, where the Italian experience of mandatory annual screening of athletes has been the forerunner in efforts to identify individuals at risk. Ongoing clinical efforts are underway to help define the role of implantable cardioverter defibrillators as a preventive measure in appropriate candidates with HCM or ARVD, as well as methods to limit the potential for SCD as a result of chest blows sustained in sports and other recreational activities by means of chest protectors and special sporting equipment for young athletes.

Cardiovascular management of marfan syndrome in the young

Marfan syndrome is an autosomal-dominant disorder of connective tissue resulting from a mutation in the fibrillin gene. Manifestations of the disorder primarily affect the skeletal, cardiovascular, and ocular systems. The phenotypic manifestations of this disorder can be quite variable. The major cause of morbidity and mortality in this patient population is the cardiovascular manifestations of the disorder: aortic root dilation and dissection. Individuals with this disorder are at risk for catastrophic cardiovascular events, most often as a result of aortic dissection. Although the incidence of dissection in childhood is exceedingly low, the background of a progressively dilating aortic root appears to be the major factor contributing to this risk in adulthood. Therefore, it is beneficial to identify affected individuals as early as possible to institute lifestyle changes and medical therapy in an effort to enhance their long-term outcome. Familial screening, once a case has been identified, and consideration of genetic screening of an affected family may also be helpful. Medical therapy with beta blockers, calcium channel blockers, and/or angiotensin inhibitors has been shown to be somewhat effective in slowing the rate of growth of the aorta. Exciting new data suggest that angiotensin II receptor antagonists may provide an even greater degree of protection from aortic dilatation in this population. Despite medical therapy, patients with Marfan syndrome do have progressive dilatation of their aortic root. The risk of aortic dissection increases with increasing size of the aorta. Prophylactic surgical techniques have been successful in reducing the morbidity and mortality associated with aortic dissection, resulting in a longer average life span in this patient population.

Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee

Improving diet and lifestyle is a critical component of the American Heart Association's strategy for cardiovascular disease risk reduction in the general population. This document presents recommendations designed to meet this objective. Specific goals are to consume an overall healthy diet; aim for a healthy body weight; aim for recommended levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides; aim for normal blood pressure; aim for a normal blood glucose level; be physically active; and avoid use of and exposure to tobacco products. The recommendations are to balance caloric intake and physical activity to achieve and maintain a healthy body weight; consume a diet rich in vegetables and fruits; choose whole-grain, high-fiber foods; consume fish, especially oily fish, at least twice a week; limit intake of saturated fat to <7% of energy, trans fat to <1% of energy, and cholesterol to <300 mg/day by choosing lean meats and vegetable alternatives, fat-free (skim) or low-fat (1% fat) dairy products and minimize intake of partially hydrogenated fats; minimize intake of beverages and foods with added sugars; choose and prepare foods with little or no salt; if you consume alcohol, do so in moderation; and when you eat food prepared outside of the home, follow these Diet and Lifestyle Recommendations. By adhering to these diet and lifestyle recommendations, Americans can substantially reduce their risk of developing cardiovascular disease, which remains the leading cause of morbidity and mortality in the United States.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: screening, diagnosis, and treatment

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disorder characterized pathologically by fatty or fibrofatty replacement and electrical instability of the right ventricular myocardium. Clinical manifestations include structural and functional malformations (fatty infiltration, dilatation, aneurysms) of the right ventricle, ECG abnormalities, and presentation with ventricular tachycardias with left bundle branch block pattern or sudden death. The disease often is familial with an autosomal inheritance. The typical hallmarks of ARVD/C are distributed in the so-called "triangle of dysplasia." The functional and morphologic characteristics are relevant to clinical imaging approaches such as contrast angiography, echocardiography, radionuclide angiography, ultrafast computed tomography, and cardiovascular magnetic resonance imaging. Evident forms of the disease are straightforward to diagnose based on a series of diagnostic criteria proposed by the International Task Force for Cardiomyopathy. However, the diagnosis of early and mild forms of the disease often is difficult. Treatment is directed toward preventing life-threatening ventricular arrhythmias in which radiofrequency ablation and implantable defibrillators play an increasing role. Despite new diagnostic and therapeutic approaches in ARVD/C, uncertainties about the etiology of the disease, the genetic basis, the appropriate diagnosis and therapy, and the clinical course of patients with ARVD/C have resulted in several registries to increase our knowledge of this intriguing disease.

The Congenital Long QT Syndrome and Implications for Young Athletes

The congenital long QT syndrome (LQTS) is caused by cardiac ion channel mutations, which predispose young individuals to sudden cardiac death often related to exercise. The issue of LQTS and sports participation has received significant publicity due to reports of sudden death in young competitive athletes. This article reviews the pathophysiology, clinical characteristics, and management of LQTS in the physically active and athletic population.

Long QT syndrome and short QT syndrome: how to make correct diagnosis and what about eligibility for sports activity

Cardiologists are involved in evaluating the eligibility of athletes to practise competitive sport and they should therefore be able to identify the electrocardiographic markers of long QT syndrome (LQTS) and short QT syndrome (SQTS). An overview of the clinical criteria to perform measurement of QT interval on 12-lead electrocardiogram is provided herein and several instances in which the diagnosis of either LQTS or SQTS may leave the clinician uncertain are discussed. A critical appraisal of current recommendations for eligibility to competitive sport is also provided as well as some of the authors' personal opinions on the practice of recreational activities in patients with abnormal repolarization.

Usefulness and cost effectiveness of cardiovascular screening of young adolescents

OBJECTIVES

This study was conducted to assess the usefulness of a screening system for cardiovascular disease in Kagoshima, Japan, and to compare its cost-effectiveness with that of a similar system reported in the United States.

BACKGROUND

Preparticipation screening of young athletes has been implemented in many countries to prevent sudden death, but sudden death in young nonathletes remains a problem. In Japan, both athletes and nonathletes have been screened for the presence or absence of cardiovascular diseases for more than 20 yr.

METHODS

From 1989 to 1997, all seventh graders in schools in Kagoshima, Japan, were screened for cardiovascular disease using a questionnaire and electrocardiogram before physical examination. They were screened again in the same way 3 yr later. One subject newly diagnosed with cardiovascular disease and recommended to limit athletic participation was defined as "high-risk." Situations leading to cases of sudden death were verified with a report from the school in question.

RESULTS

Of the initial study population, 99% participated in the program every year. A total of 37,807 subjects, including nine high-risk subjects, were evaluated consecutively for 6 yr. Of these nine subjects, six, including three patients with hypertrophic cardiomyopathy, were nonathletes. Three sudden deaths occurred during the study period; one student was from the high-risk group. The cost of this screening system was lower than that reported in the United States.

CONCLUSIONS

Population-based screening for heart disease in this age range is limited by various factors. To analyze the mechanisms of sudden death in adolescents, we, therefore, are in need of a nationwide registry that includes autopsies for all deadly events.

The long QT syndrome family of cardiac ion channelopathies: A HuGE review*

Long QT syndrome (LQTS) refers to a group of "channelopathies"-disorders that affect cardiac ion channels. The "family" concept of syndromes has been applied to the multiple LQTS genotypes, LQT1-8, which exhibit converging mechanisms leading to QT prolongation and slowed ventricular repolarization. The 470+ allelic mutations induce loss-of-function in the passage of mainly K+ ions, and gain-of-function in the passage of Na+ ions through their respective ion channels. Resultant early after depolarizations can lead to a polymorphic form of ventricular tachycardia known as torsade de pointes, resulting in syncope, sudden cardiac death, or near-death (i.e., cardiac arrest aborted either spontaneously or with external defibrillation). LQTS may be either congenital or acquired. The genetic epidemiology of both forms can vary with subpopulation depending on the allele, but as a whole, LQTS appears in every corner of the globe. Many polymorphisms, such as HERG P448R and A915V in Asians, and SCN5A S1102Y in African Americans, show racial-ethnic specificity. At least nine genetic polymorphisms may enhance susceptibility to drug-induced arrhythmia (an "acquired" form of LQTS). Studies have generally demonstrated greater QT prolongation and more severe outcomes among adult females. Gene-gene interactions, e.g., between SCN5A Q1077del mutations and the SCN5A H558B polymorphism, have been shown to seriously reduce ion channel current. While phenotypic ascertainment remains a mainstay in the clinical setting, SSCP and DHPLC-aided DNA sequencing are a standard part of mutational investigation, and direct sequencing on a limited basis is now commercially available for patient diagnosis.

Safety of Sports Participation in Patients with Implantable Cardioverter Defibrillators: A Survey of Heart Rhythm Society Members

Safety of Sports for ICD Patients.

INTRODUCTION

The safety of sports participation for patients with implantable cardioverter defibrillators (ICDs) is unknown, and recommendations among physicians may vary widely. The purposes of this study were to determine current practice among patients with ICDs and their physicians regarding sports participation, and to determine how many physicians have cared for patients who have sustained adverse events during sports participation.

METHODS AND RESULTS

A survey was mailed to all 1,687 U.S. physician members of the Heart Rhythm Society. Among 614 respondent physicians, recommendations varied widely. Only 10% recommended avoidance of all sports more vigorous than golf. Seventy-six percent recommended avoidance of contact, and 45% recommend avoidance of competitive sports. Most (71%) based restrictions on patients' underlying heart disease. Regardless of recommendations, most physicians (71%) reported caring for patients who participated in sports, including many citing vigorous, competitive sports, most commonly cited were basketball, running, and skiing. ICD shocks during sports were common, cited by 40% of physicians. However, few adverse consequences were reported. One percent of physicians reported known injury to patient (all but 3 minor); 5%, injury to the ICD system, and <1%, failure of shocks to terminate arrhythmia. The most common adverse event reported was lead damage attributed to repetitive-motion activities, most commonly weightlifting and golf.

CONCLUSIONS

Physician recommendations for sports participation for patients with ICDs varies widely. Many patients with ICDs do participate in vigorous and even competitive sports. While shocks were common, significant adverse events were rare.

Marfan's syndrome

Marfan's syndrome is a systemic disorder of connective tissue caused by mutations in the extracellular matrix protein fibrillin 1. Cardinal manifestations include proximal aortic aneurysm, dislocation of the ocular lens, and long-bone overgrowth. Important advances have been made in the diagnosis and medical and surgical care of affected individuals, yet substantial morbidity and premature mortality remain associated with this disorder. Progress has been made with genetically defined mouse models to elucidate the pathogenetic sequence that is initiated by fibrillin-1 deficiency. The new understanding is that many aspects of the disease are caused by altered regulation of transforming growth factor beta (TGFbeta), a family of cytokines that affect cellular performance, highlighting the potential therapeutic application of TGFbeta antagonists. Insights derived from studying this mendelian disorder are anticipated to have relevance for more common and non-syndromic presentations of selected aspects of the Marfan phenotype.

Management of pediatric hypertrophic cardiomyopathy

PURPOSE OF REVIEW

As the underlying genetic basis of hypertrophic cardiomyopathy is being characterized, there has been increasing recognition of the wide spectrum and variable evolution of this disease within the pediatric age range. This review outlines recent evidence relevant to the diagnosis, management, and prognosis of hypertrophic cardiomyopathy specific to children and adolescents.

RECENT FINDINGS

Studies of putative causal genes are leading to the discovery of factors affecting the variability of phenotypic expression and possible avenues for new therapies. Nonetheless, the use of genetic testing currently remains for research purposes only. Echocardiography is the primary means for evaluation, with an increasing focus on diastolic performance. Useful prognostic information can be obtained from the safe performance of cardiopulmonary stress testing. Sudden death can occur in children, although the risk factors are likely different than in adults. The role and mechanisms for possible ischemia remain controversial, and likely differ between individuals. Activity restrictions are recommended, with medical therapy reserved for those who are symptomatic. For those with important left ventricular outflow obstruction, surgical myectomy may be indicated, with little current role for alcohol septal ablation. Advances in implantable defibrillators now make this therapy feasible in younger children.

SUMMARY

There are important differences from adults in the approach to the diagnosis and management of hypertrophic cardiomyopathy in children and adolescents. Care regarding prognostication and therapy must be taken given the potential life-long implications.

The Brugada syndrome

Brugada syndrome is a recognized cause of sudden cardiac death worldwide. An inherited ion channel abnormality produces abnormal repolarization leading to characteristic ST-segment elevation in precordial leads V1 to V3 and a pseudo right bundle branch block on electrocardiogram. Only recently has medical therapy and management been defined to allow for athletes to lead healthy lifestyles. This article provides a concise review of the clinical manifestations, pathophysiology, and therapeutic options for the sports medicine team.

The treatment of cardiac causes of sudden death, syncope, and seizure

The treatment for pediatric causes for sudden cardiac death can either be general and supportive or, in 2005, can be much more etiology specific. While antiarrhythmic therapy and activity restriction have been for years the mainstay of therapy, newer technologies such as radiofrequency ablation and automatic implantable cardioverter defibrillators (AICDs) are now more commonly applied for certain disease entities. The evolving role for clinical genetic testing to determine the specific etiology of pediatric sudden cardiac death continues to evolve. Further improvements in risk stratification will allow us to determine which patients are at greatest risk, so that aggressive treatment can be delivered to these subgroups. In the future, there may be gene-specific therapies and/or genetic modification.

Approach to hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a genetic disease characterized by marked left ventricular (LV) hypertrophy. A dynamic LV outflow obstruction is present in approximately 20% of patients. Many affected individuals remain asymptomatic throughout life, others develop heart failure symptoms or atrial fibrillation (AF), and some die suddenly, often young and in the absence of previous symptoms. Stratification of sudden death risk is based on several markers, including a previous cardiac arrest, sustained ventricular tachycardia, family history of sudden death, extreme LV hypertrophy (>/= 30 mm), syncope, nonsustained ventricular tachycardia on Holter, and abnormal exercise blood pressure response. The implantable cardioverter-defibrillator is the most effective treatment for sudden death prevention, and should be considered in patients with either one strong or multiple risk factors. Important symptoms of heart failure develop in a minority of patients, largely as a consequence of diastolic dysfunction, and are usually treated with beta blockers, or verapamil. In patients with LV obstruction and severe symptoms unresponsive to medications, myectomy operation or alcohol septal ablation is indicated for relieving the gradient and improving quality of life. AF develops in approximately 20% of patients. Amiodarone is the most effective medication for preventing AF recurrences. In chronic AF, beta blockers or verapamil are usually effective for heart rate control. The threshold for anticoagulants is low, because even brief AF episodes have a substantial embolization risk.

Long-range silencing and position effects at telomeres and centromeres: parallels and differences

Most of the human genome is compacted into heterochromatin, a form that encompasses multiple forms of inactive chromatin structure. Transcriptional silencing mechanisms in budding and fission yeasts have provided genetically tractable models for understanding heritably repressed chromatin. These silent domains are typically found in regions of repetitive DNA, that is, either adjacent to centromeres or telomeres or within the tandemly repeated ribosomal DNA array. Here we address the mechanisms of centromeric, telomeric and locus-specific gene silencing, comparing simple and complex animals with yeast. Some aspects are universally shared, such as histone-tail modifications, while others are unique to either centromeres or telomeres. These may reflect roles for heterochromatin in other chromosomal functions, like kinetochore attachment and DNA ends protection.

DNA fragmentation in leukocytes following subacute low-dose nerve agent exposure

The objective of the present study was to determine levels of DNA fragmentation in blood leukocytes from guinea pigs by single-cell gel electrophoresis (comet assay) after exposure to the chemical warfare nerve agent (CWNA), soman, at doses ranging from 0.1 LD50 to 0.4 LD50, once per day for either 5 or 10 days. Post-exposure recovery periods ranged from 0 to 17 days. Leukocytes were imaged from each animal, and the images analyzed by computer. Data obtained for exposure to soman demonstrated significant increases in DNA fragmentation in circulating leukocytes in CWNA-treated guinea pigs compared with saline-injected control animals at all doses and time points examined. Notably, significantly increased DNA fragmentation was observed in leukocytes 17 days after cessation of soman exposure. Our findings demonstrate that leukocyte DNA fragmentation assays may provide a sensitive biomarker for low-dose CWNA exposure.