Diagnostic Differentiation Between Arrhythmogenic Cardiomyopathy and Athlete’s Heart by Using Imaging

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of sudden cardiac death (SCD) in youth and athletes. In the last decade, several studies focused on right ventricular (RV) remodeling in athletes and revealed that features of the physiological adaptation of the right heart to training, such as RV dilation, may overlap with those of ARVC. Therefore, a careful multiparametric evaluation is required for differential diagnosis in order to avoid false diagnosis of ARVC or, in contrast, fail to identify the risk of causing SCD. This review summarizes physiological adaptation of the RV to exercise and describes features that could help distinguishing between athlete’s heart and ARVC.     

Canadian Cardiovascular Society/Canadian Heart Rhythm Society Joint Position Statement on the Cardiovascular Screening of Competitive Athletes

Sudden cardiac death (SCD), especially in a young seemingly healthy individual, is a tragic and highly publicized event, which is often followed by a strong emotional reaction from the public and medical community.” Although rare, SCD in the young is devastating to families and communities, underpinning our society’s desire to avoid any circumstances predisposing to the loss of human life during exertion. The Canadian Cardiovascular Society Position Statement on the cardiovascular screening of athletes provides evidence-based recommendations for Canadian sporting organizations and institutions with a focus on the role of routine electrocardiogram (ECG) screening in preventing SCD. We recommend that the cardiac screening and care of athletes within the Canadian health care model comprise a sequential (tiered) approach to the identification of cardiac risk, emphasizing the limitations of screening, the importance of shared decision-making when cardiac conditions are diagnosed, and the creation of policies and procedures for the management of emergencies in sport settings. Thus, we recommend against the routine (first-line or blanket mass performance of ECG) performance of a 12-lead ECG for the initial cardiovascular screening of competitive athletes. Organization/athlete-centred cardiovascular screening and care of athletes program is recommended. Such screening should occur in the context of a consistent, systematic approach to cardiovascular screening and care that provides: assessment, appropriate investigations, interpretation, management, counselling, and follow-up. The recommendations presented comprise a tiered framework that allows institutions some choice as to program creation.     

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.     

Sudden cardiac death in the young: a strategy for prevention by targeted evaluation

The annual incidence of sudden cardiac death (SCD) in the general population is estimated as 1 in a 1,000. Since survival rates from out-of-hospital cardiac arrests are poor, primary prevention is key to reducing the burden of SCD in the community. Prominent causes of SCD include ischaemic heart disease, anomalous coronary arteries, and the primary myocardial diseases: hypertrophic cardiomyopathy, dilated cardiomyopathy, and ar rhythmogenic right ventricular cardiomyopathy (ARVC). In 4% of sudden deaths in the 16-64 age group, post-mortem examination fails to identify a cause, yielding a default diagnosis of sudden arrhythmic death syndrome (SADS). The inherited arrhythmia syndromes (long QT, short QT, and Brugada syndromes, and familial catecholaminergic polymorphic ventricular tachycardia) may be implicated in SADS, owing to their propensity for producing ventricular tachyarrhythmia in the structurally normal heart. Monogenic disorders therefore predominate as causes of SCD in the young. The advent of effective therapies for these diseases, particularly implantable cardioverter defibrillators, has prompted calls for universal screening to enable timely diagnosis of occult cardiac disease. Since prospective cardiac assessment of the general population is not feasible, the solution may be to target high-risk subgroups, namely, patients with cardiac symptoms, relatives of SCD victims, and competitive athletes. The recommended preliminary work-up includes a 12-lead ECG, signal-averaged ECG, transthoracic echocardiogram, exercise test, and ambulatory ECG monitoring. Cardiovascular magnetic resonance is a useful adjunct in patients with suspected ARVC or anomalous coronary arteries. Provocative challenge with a sodium challenge blocker may be of value in unmasking the Brugada syndrome. Identification of disease-causing mutations in affected individuals facilitates cascade screening of families.     

Sudden cardiac death in athletes: the Lausanne Recommendations.

OBJECTIVES: This study reports on sudden cardiac death (SCD) in sport in the literature and aims at achieving a generally acceptable preparticipation screening protocol (PPSP) endorsed by the consensus meeting of the International Olympic Committee (IOC). BACKGROUND: The sudden death of athletes under 35 years engaged in competitive sports is a well-known occurrence; the incidence is higher in athletes (approximately 2/100,000 per year) than in non-athletes (2.5 : 1), and the cause is cardiovascular in over 90%. METHODS: A systematic review of the literature identified causes of SCD, sex, age, underlying cardiac disease and the type of sport and PPSP in use. Methods necessary to detect pre-existing cardiac abnormalities are discussed to formulate a PPSP for the Medical Commission of the IOC. RESULTS: SCD occurred in 1101 (1966-2004) reported cases in athletes under 35 years, 50% had congenital anatomical heart disease and cardiomyopathies and 10% had early-onset atherosclerotic heart disease. Forty percent occurred in athletes under 18 years, 33% under 16 years; the female/male ratio was 1/9. SCD was reported in almost all sports; most frequently involved were soccer (30%), basketball (25%) and running (15%). The PPSP were of varying quality and content. The IOC consensus meeting accepted the proposed Lausanne Recommendations based on this research and expert opinions (http://multimedia.olympic.org/pdf/en_report_886.pdf). CONCLUSION: SCD occurs more frequently in young athletes, even those under the age of 18 years, than expected and is predominantly caused by pre-existing congenital cardiac abnormalities. Premature atherosclerotic disease forms another important cause in these young adults. A generally acceptable PPSP has been achieved by the IOC's acceptance of the Lausanne Recommendations.     

Predicting Sudden Cardiac Death in Genetic Heart Disease

Genetic heart diseases are common causes of sudden cardiac death (SCD) in the young and are typically divided into inherited cardiomyopathies and primary electrical heart diseases. Cardiomyopathies associated with risk of SCD include hypertrophic cardiomyopathy (HCM) and arrhythmogenic cardiomyopathy (ACM). The latter includes arrhythmogenic right ventricular cardiomyopathy (ARVC) as well as ACM primarily affecting the left ventricle, such as lamin cardiomyopathy. Primary electrical diseases more commonly seen in clinical practice include Brugada syndrome (BrS) and long QT syndrome (LQTS). Risk stratification of SCD is a central component of the management of patients with these genetic heart diseases. Numerous risk factors have been identified with variable degrees of scientific evidence. More recently, risk prediction models have been developed to estimate the absolute risk of sustained arrhythmias and SCD, to support clinicians and patients in decision making regarding prophylactic implantable cardioverter-defibrillators (ICDs). This paper provides a practical review of the current literature on risk stratification in ARVC and other ACMs, HCM, BrS, and LQTS, and summarises current recommendations for ICD use.     

Preparticipation athletic screening for genetic heart disease

Sudden cardiac death (SCD) in young athletes is relatively uncommon but tragic when it occurs. Many of these deaths can be prevented by pre-exercise screening to identify cardiac abnormalities and those at high risk. Although recent research has provided much needed information on SCD in athletes, there remain significant gaps in the knowledge needed to determine an optimal screening protocol. This review examines the incidence and demographics of SCD in athletes and the difficulties in determining whether changes in an athlete's heart are due to training or represent a potentially malignant congenital abnormality. Current guidelines for screening and the intense debate over the use of the 12-lead electrocardiogram are discussed. Lastly, the importance of a response plan to an apparent SCD event that includes on-site/on-field automated external defibrillators will be discussed. A case study that illustrates the challenges in screening is presented.     

Sudden cardiac death in heart failure with preserved ejection fraction: a target for therapy?

The incidence and mechanisms of sudden cardiac death (SCD) among patients with heart failure with reduced ejection fraction have been well characterized. Conversely, limited data are available exploring the landscape of SCD in patients with heart failure with preserved ejection fraction (HFpEF). HFpEF is a heterogeneous clinical syndrome of increasing prevalence and is associated with substantial morbidity and mortality. This review will aim to contextualize recent data regarding rates and predictors of SCD in this growing population and to discuss the potential role of pharmacologic and device therapy for prevention of SCD within the at-risk HFpEF subset.     

Atrial fibrillation and its relation to cardiac diseases and sudden cardiac death

Atrial fibrillation (AF) is the most common arrhythmia in adults. Many studies have reported an association between atrial fibrillation and other cardiac diseases including sudden cardiac death (SCD). According to the literature, the prevalence and incidence of atrial fibrillation have been increasing and AF is associated with higher mortality and morbidity. An increased incidence of AF has been described in patients with ischemic heart disease, heart failure, and arterial hypertension. These conditions share some pathophysiological mechanisms with atrial fibrillation, which is, reciprocally, one of their risk factors. As a result, mortality is 2–4-fold higher in individuals with AF. Increased mortality from, and a higher incidence of, ventricular arrhythmias, including ventricular fibrillation (VF), have been found in patients with implantable cardiac defibrillators (ICD), as well as in the general population where AF has been independently related to an up to 3-fold increased risk of cardiac arrest due to VF. The mechanism of action is based on a direct proarrhythmogenic effect of atrial fibrillation, increased cardiac workload, tachycardia-induced ischemia, or heart failure. Risk stratification, optimization of therapy, and screening for subclinical structural heart disease play an important role in the care of patients with atrial fibrillation.     

Sudden cardiac death in athletes

A ‘paradox of sport’ is that in addition to the undisputed health benefits of physical activity, vigorous exertion may transiently increase the risk of acute cardiac events. In general, the risk of sudden cardiac death (SCD) approximately doubles during physical activity and is 2‐ to 3‐fold higher in athletes compared to nonathletes. The incidence of SCD in young athletes is in fact very low, at around 1–3 per 100 000, but attracts much public attention. Variations in incidence figures may be explained by the methodology used for data collection and more importantly by differences between subpopulations of athletes. The incidence of SCD in older (≥35 years) athletes is higher and may be expected to rise, as more and older individuals take part in organized sports. SCD is often the first clinical manifestation of a potentially fatal underlying cardiovascular disorder and usually occurs in previously asymptomatic athletes. In the young (<35 years), SCD is mainly due to congenital/inherited cardiac abnormalities, whilst coronary artery disease (CAD) is the most common cause in older athletes. Cardiac screening including family/personal history, physical examination and resting electrocardiogram (ECG) may identify individuals at risk and has the potential to decrease the risk of SCD in young athletes. Screening including the ECG has a high sensitivity for underlying disease in young athletes, but the specificity needs to be improved, whereas the sensitivity of screening without the use of ECG is very low. The screening modality recommended for young athletes is of limited value in older athletes, who should receive individualized screening with cardiac stress testing for patients with high risk of underlying CAD. As cardiovascular screening will never be able to identify all athletes at risk, adequate preparedness is vital in case of a potentially fatal event at the sporting arena/facility. Firstly, we will review the magnitude of the problem of SCD in athletes of different ages, as well as the aetiology. Secondly, we will focus on how to prevent SCD in athletes of all ages, reviewing cardiovascular screening recommendations as well as emergency preparedness and arena safety.     

Structural pathways and prevention of heart failure and sudden death

We review the macroscopic and microscopic anatomy of myocardial disease associated with heart failure (HF) and sudden cardiac death (SCD) and focus on the prevention of SCD in light of its structural pathways. Compared to patients without SCD, patients with SCD exhibit 5- to 6-fold increases in the risks of ventricular arrhythmias and SCD. Epidemiologically, left ventricular hypertrophy by ECG or echocardiography acts as a potent dose-dependent SCD predictor. Dyslipidemia, a coronary disease risk factor, independently predicts echocardiographic hypertrophy. In adult SCD autopsy studies, increases in heart weight and severe coronary disease are constant findings, whereas rates of acute coronary thrombi vary remarkably. The microscopic myocardial anatomy of SCD is incompletely defined but may include prevalent changes of advanced myocardial disease, including cardiomyocyte hypertrophy, cardiomyocyte apoptosis, fibroblast hyperplasia, diffuse and focal matrix protein accumulation, and recruitment of inflammatory cells. Hypertrophied cardiomyocytes express "fetospecific" genetic programs that can account for acquired long QT physiology with risk for polymorphic ventricular arrhythmias. Structural heart disease associated with HF and high SCD risk is causally related to an up-regulation of the adrenergic renin-angiotensin-aldosterone pathway. In outcome trials, suppression of this pathway with combinations of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, and mineralocorticoid receptor blockers have achieved substantial total mortality and SCD reductions. Contrarily, trials with ion channel-active agents that are not known to reduce structural heart disease have failed to reduce these risks. Device therapy effectively prevents SCD, but whether biventricular pacing-induced remodeling decreases left ventricular mass remains uncertain.     

Long-term prognosis in patients with bifascicular block--the predictive value of noninvasive and invasive assessment

OBJECTIVES: Patients with bifascicular block (BFB) have a high mortality rate. The purpose of the present study was to identify high-risk patients in a BFB population by performing an extensive cardiac evaluation including noninvasive and invasive tests. DESIGN: Population-based study. SUBJECTS: A total of 100 patients with BFB, of whom 41 had a history of unexplained syncope, were prospectively studied. The mean age was 68 +/- 12. All patients were investigated with Holter-monitoring, an exercise test, an echocardiography, and an invasive electrophysiological study. The severity of congestive heart failure (CHF) was assessed by New York Heart Association (NYHA) classification. Patients in NYHA class IV were excluded. INTERVENTIONS: Patients with syncope were recommended prophylactic pacemaker treatment, which was accepted by 31 patients (76%). Main outcome measures. All-cause mortality and sudden cardiac death (SCD). RESULTS: During a median follow-up of 84 months, 33 patients died, of whom 14 in SCD. In a univariate analysis, high age, a previous myocardial infarction, and CHF were associated with a significantly increased risk of all-cause mortality and SCD. In a Cox multiple regression analysis, CHF was the only independent predictor of all-cause mortality and SCD (P < 0.01). CONCLUSION: Patients with BFB have a poor long-term prognosis. The predictive value of noninvasive and invasive investigations is limited. The only independent predictor of all-cause mortality and SCD in this population was the presence of CHF.     

Coronary artery disease in athletes: An adverse effect of intense exercise?

Regular physical exercise is responsible for various health benefits, and is recommended for primary and secondary cardiovascular (CV) prevention. Despite these recognized benefits, various clinical events can occur in athletes, including acute myocardial infarction and sudden cardiac death (SCD); the main cause of SCD in veteran athletes is coronary artery disease (CAD). The relationship between intense exercise training and CAD is controversial, and a U-shaped association has been hypothesized. If this is the case, screening for subclinical CAD in older athletes may be justified, and various different methodologies have been proposed. However, the methodology for screening veteran athletes is not consensual, and several markers of CAD, in addition to clinical CV risk factors, could improve risk stratification in this population. In the present paper we review the published data on CAD in athletes, focusing on the relationship between the dose of exercise and CAD, as well as the implications for pre-participation screening of veteran athletes.     

ICD-Therapie

Sudden cardiac death (SCD) remains the leading common cause for overall mortality in the industrialized world. Although prediction of SCD is considered a necessary prerequisite for its effective prevention and therapy, hard criteria for that goal are difficult to identify. A number of clinical trials were conducted to define the role of implantable cardioverter-defibrillators (ICDs) in preventing SCD. In addition to its undisputed value in secondary prevention of SCD, study results have proven a reduction of mortality through ICDs in patients with both ischemic and non-ischemic cardiomyopathy and a reduced left ventricular ejection fraction (EF). To date, national and international guidelines help us to apply standard ICD indications in patients with structural or hereditary heart diseases that are associated with increased SCD risk. Yet we know that our strategies currently in use for selecting patients who require ICD therapy are imperfect and leave a large number of high-risk patients unprotected. Therefore, the best possible risk assessment should be used in each individual case for optimal SCD prevention without unnecessary device implantation.     

The role of the autonomic nervous system in sudden cardiac death

The autonomic nervous system exerts a modulating effect on the risk of sudden cardiac death (SCD) in the setting of ischemic heart disease. The mechanism by which sympathetic tone increases the risk of ventricular arrhythmias is not known, though regional sympathetic denervation at and apical to the site of transmural infarction may result in regional supersensitivity to circulating catecholamines and play a role in ventricular arrhythmogenesis. [(123)I]MIBG scintigraphy enables noninvasive determination of regional cardiac denervation and may be a useful tool for probing the role of sympathetic nervous system in SCD. Increased vagal tone is generally protective against SCD. Newer tests such as baroreflex slope testing and various techniques for determination of heart rate variability, which provide indices of vagal tone, may have greater predictive value and are powerful tools in assessing the role of autonomic nervous system in SCD.     

Three-Dimensional Echocardiography of Right Heart Pathology

Three-dimensional (3-D) echocardiography uses sequentially acquired tomography echocardiographic data, which is gated to the cardiac cycle, to reconstruct 3-D views of the heart. So far, this technique has been used primarily to evaluate left-sided heart structures. This report focuses on congenital and acquired right-sided heart pathologies that have been visualized by 3-D echocardiography. In addition to reviewing the literature, several representative figures are included illustrating the unique ability of 3-D echo to elucidate complex right heart anatomy. After a brief introduction to the technical aspects of 3-D echocardiography, the discussion centers on evaluation of congenital heart disease and right-sided masses, determination of right ventricular mass and volume, and evaluation of right-sided valvular heart disease. Congenital heart diseases that are reviewed include atrial septal defect (location, size, efficacy of repair), ventricular septal defect, and congenital heart disease in the fetus being evaluated in utero. Evaluation of right-sided masses, including tumors, vegetations, and thrombi, is reviewed. Methods of determining right ventricular volume and mass using 3-D echo are discussed. Evaluation of valvular heart disease, including Doppler analysis of regurgitant flow, is examined. Finally, special attention is given to the perioperative and intraoperative use of 3-D echocardiography for patients with these conditions. The conclusion summarizes the current and potential future uses of 3-D echocardiography.     

It Takes a Village: Multimodality Imaging of Cardiac Amyloidosis

Cardiac amyloidosis (CA) is the buildup and infiltration of amyloid plaque in cardiac muscle. An underdiagnosed form of restrictive cardiomyopathy, CA can rapidly progress into heart failure. CA is evaluated using a multimodality approach that includes echocardiography, cardiac magnetic imaging, and nuclear imaging. Echocardiography remains an essential first-line modality that raises suspicion for CA and establishes functional baselines. Cardiac magnetic imaging provides additional incremental value via high-resolution imaging, robust functional assessment, and superior tissue characterization, all of which enable a more comprehensive investigation of CA. Cardiac scintigraphy has eliminated the need for invasive diagnostic approaches and helps differentiate CA subtypes. Positron emission tomography is the first modality introducing targeted amyloid binding tracers that allow for precise burden quantification, early detection, and disease monitoring. In this review, we highlight the role of several cardiac imaging techniques in the evaluation of CA.     

Pharmacotherapy to reduce arrhythmic mortality

Fatal ventricular arrhythmias and heart failure are the common modes of death in patients with cardiovascular diseases. Intracardiac defibrillator (ICD) implantation reduces arrhythmic mortality to a significant extent in the high risk patient. However, there continues to be a need for effective drug therapy to reduce the arrhythmic and overall mortality in patients with or without an ICD. Although anti-arrhythmic drugs (AAD) appear inferior to ICD, the role of beta-blockers and to an extent amiodarone along with non AAD like angiotensin converting enzyme inhibitors (ACE-I), mineralocorticoid blockers (MRB) and HMG-CoA reductase inhibitors (statins) need to be emphasized. There have been many drug trials and meta-analysis to this effect and we review the role of drugs especially in their ability to reduce arrhythmic mortality and sudden cardiac death (SCD). The focus is on post myocardial infarction (MI) and heart failure patients with a brief overview of role of drugs in channelopathies.     

Arrhythmias and Sudden Cardiac Death in End Stage Renal Disease: Epidemiology,Risk Factors,and Management

Patients with end-stage renal disease (ESRD) are predisposed to heart rhythm disorders resulting in significant morbidity and mortality. Bradyarrhythmia appears to be more prevalent than ventricular tachyarrhythmias. There is also a high incidence of sudden cardiac death (SCD) in this group of patients, which cannot be explained only by traditional cardiac risk factors. The reported incidence and prevalence of arrhythmias and SCD is quite variable mainly because of the different study populations and recording techniques. The mechanism of SCD in patients with ESRD is also not clear. Although traditionally the thinking has been that ventricular arrhythmias are the main contributor to SCD, recent studies with implantable loop recorders have highlighted the role of bradyarrhythmias. The pathophysiological processes resulting in arrhythmia and SCD in patients with ESRD are unique. Some of the risk factors, including dialysate composition, timing, and frequency, are modifiable and hence provide an option for interventions to potentially reduce SCD. In addition, there might be a relationship with the timing of dialysis with SCD tending to occur during the long interdialytic period. Patients with ESRD have a higher likelihood of requiring pacemaker implantation; however, they also have a higher risk of device-related complications. The limited data available regarding the role of the implantable cardioverter defibrillator to prevent SCD in patients with ESRD have shown conflicting results. Future research is needed to develop appropriate risk stratification tools to identify patients who will benefit from such interventions and to assess their safety and efficacy.     

Are women worldwide under-treated with regard to cardiac resynchronization and sudden death prevention?

Implantable cardioverter defibrillators (ICDs) have been demonstrated to improve survival in patients with serious structural heart disease. Likewise, cardiac resynchronization therapy (CRT) has assumed an important role in the treatment of patients with symptomatic heart failure because of its demonstrated value in improving functional class, quality of life, exercise capacity, and survival. However, these clinical trials have all primarily enrolled Caucasian males, raising the question as to whether other important subgroups benefit in a comparable way. Women have lower rates of sudden cardiac death (SCD) compared to men, and event rates lag 10–20 years behind those in men. Among patients with known coronary artery disease, women have one-fourth the risk of SCD found in men. Women with heart failure tend to present at an older age than men, and women more often have heart failure with preserved systolic function, a group in whom prophylactic ICD therapy for the prevention of SCD has not been studied. Despite these differences, analysis of clinical trial results shows that women have similar outcomes with ICD and CRT therapy compared to men. There is a lower percentage of women among device therapy patients both in clinical trials and in practice for reasons that are not clear, but at least some of the difference is likely due to differences in age at presentation and co-morbidities. In fact, device therapy overall appears to be under-utilized in both men and women, when implantation rates are compared to the prevalence of heart failure in the population as a whole.