Preparticipation screening and prevention of sudden cardiac death in athletes: Implications for primary care
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DisclosuresThe authors report no competing interests.
Emily Morse, MSN, APRN, 888 Mount Carmel Avenue, Hamden, CT 06518. Tel: 440-567-5629;Fax: 203-288-5059; E-mail: email@example.com
Purposes: The purposes of this article are to explore the mechanism of sudden cardiac death (SCD) in young athletes and examine how preparticipation screenings help identify precipitating cardiac abnormalities. Electrocardiogram (ECG) testing has been implicated to play an important role in detecting subtle abnormalities that may cause SCD, but the routine implementation of this diagnostic tool remains a debate among experts.
Data sources: This report was compiled by reviewing the scientific literature on SCD in athletes, preparticipation exams, and current screening guidelines using CINAHL, MEDLINE, and PubMed search engines.
Conclusions: Although the American Heart Association guidelines do not include ECG testing for preparticipation screenings, the implementation of routine ECG testing for preparticipation sports physicals is effective in preventing SCD in athletes.
Implications for practice: Primary care providers should be aware of current guidelines for screening patients for heart diseases that predispose them to SCD and their legal obligations to be sure these athletes are safe. The implementation of ECG testing will assist in the decision whether to disqualify an athlete from participation as a result of preexisting cardiac conditions, and ultimately preventing the untimely death of a young athlete.
Sudden cardiac death in athletes
Sudden cardiac death (SCD) resulting from undetected cardiac abnormalities in athletes is a tragic and potentially avoidable event. There is overwhelming evidence that exercise can trigger ventricular arrhythmias and cardiac arrest in individuals with preexisting heart conditions, even in well-conditioned young athletes (Corrado, Basso, & Thiene, 2012). The vast majority of these sudden deaths are caused by previously unidentified and asymptomatic underlying cardiovascular conditions. SCD has sparked debate among experts in cardiology for many years and is the topic of a Bethesda Conference, a consensus conference held by the American College of Cardiology Foundation. The 36th Bethesda Conference (BC no. 36) held in 2004 resulted in the publication of a report outlining eligibility recommendations for competitive athletes with cardiovascular abnormalities (Maron & Zipes, 2005).
The current American Heart Association (AHA) guidelines for participation in competitive sports are limited to a history and physical examination and are not mandated by law. In Italy, however, all athletes who participate in competitive sports are required by law to have a preparticipation screening that focuses on identifying asymptomatic cardiac abnormalities and includes a 12-lead electrocardiogram (ECG), as described by the European Society of Cardiology (ESC) Consensus recommendations (Pelliccia, Zipes, & Maron, 2008). Italy is the only country to implement mass ECG screening and require it by law. Rates of SCD in athletes prior to the implementation of the screening program in 1971 were estimated to be 1 in 25,000, decreasing to 2.3 in 100,000 by 1996 (Corrado, Basso, Pavei, Michieli, Schiavon, & Thiene, 2006).
Many studies report vastly different incidences of SCD within different populations and age groups. Data are limited in the United States as a result of a lack of a mandatory reporting system for juvenile sudden death, and most studies rely solely on surveys, media reports, and insurance claims (Drezner, 2008). A summary of key studies reporting SCD incidence in young athletes in the United States and Italy is shown in Table 1. Despite the discrepancies in the overall incidence of SCD, one common finding across studies is that the incidence of SCD in athletes affects males much more often than females at a ratio ranging from 5:1 to 9:1 (Drezner, 2008). Black athletes are also affected more commonly than other races, and football and basketball are the most common sports associated with SCD (Maron, Doerer, Haas, Tierny, & Mueller, 2009).
Table 1. Incidence of SCD in athletes
|United States||High school and college 13–24 years||1983–1993||National athletic association reports and newspapers||1:300,000||Van Camp, Bloor, Mueller, Cantu, and Olson (1995)|
| ||High school 13–19 years||1985–1997||Catastrophic insurance claims||1:200,000||Maron, Gohman, and Aeppli (1998)|
| ||College||1999–2005||Retrospective survey||1:67,000||Drezner, Rogers, Zimmer, and Sennett (2005)|
| ||High school and college 12–23 years||1980–2005||Electronic resources and media reports||1:50,000||Maron, Doerer, Haas, Tierny, and Mueller (2006)|
|Italy||12–35 years||1979–1982||Regional registry for juvenile sudden death||1:25,000||Corrado et al. (2006)|
Exercise and the healthy heart
SCD is more likely to occur during exercise than at rest; however, regular exercise decreases the overall risk of cardiac death (Crawford, 2007). Extensive conditioning often causes structural remodeling in the heart of an athlete and can affect rhythm and electrical conduction. Electrical changes can include sinus bradycardia, first-degree atrioventricular block, and early repolarization. The physiological adaptation of the autonomic nervous system can cause this early repolarization and result in increased vagal tone and withdrawal of sympathetic activity (Corrado & McKenna, 2007). Premature ventricular beats are not uncommon in athletes and are usually asymptomatic and considered benign (Heidbuchel et al., 2006). While this arrhythmia frequently occurs with underlying heart disease, in the absence of a comorbid cardiac condition, there are usually no adverse outcomes in athletes with premature beats (Biffi et al., 2002).
The structural changes often involve thickening of the left ventricular (LV) wall that can mimic hypertrophic cardiomyopathy (HCM) on diagnostic examinations, but it is possible to differentiate between these changes and others suggesting cardiac abnormalities that increase the risk of SCD. The remodeling of cardiac structures that results from extensive exercise produces abnormal ECGs in up to 80% of highly trained athletes and is often consistent with LV hypertrophy (LVH; Corrado & McKenna, 2007). A short period of deconditioning (about 3 months restriction from exercise) may decrease LV wall thickness by 2–5 mm and will distinguish training-induced hypertrophy from the pathologic hypertrophy of HCM (Maron, 2005).
Pathophysiology of SCD
The cardiovascular conditions triggering SCD in athletes vary in their prevalence in different cultures. Most of the literature is based on U.S. and Italian data. For competitive athletes younger than 35 years of age in the United States, the leading cause of SCD is HCM, which accounts for 36% of cases. Other causes include congenital coronary artery anomalies (17%), indeterminate LVH-possible HCM (8%), myocarditis (6%), arrhythmogenic right ventricular cardiomyopathy (ARVC; 4%), and ion channel disorders (3%; Maron et al., 2007). In Italy, however, the leading cause of SCD in athletes is ARVC (Corrado, Basso, & Thiene, 2000). Coronary atherosclerosis accounted for 18.4% of the SCD cases, anomalous origin of a coronary artery had a 12.2% incidence, and HCM was present in only 2% of victims. The common final pathway of SCD in athletes is the result of ventricular tachyarrhythmias. The aforementioned pathologies predispose the athlete's heart to these potentially fatal arrhythmias and ultimately cause cardiac death (Heidbuchel et al., 2006).
HCM is the most common genetic cardiac disease, inherited as an autosomal dominant trait, and occurring in the general population with a prevalence of 1:500 (Maron, 2002). However, Basavarajaiah and colleagues (2008) argued that the prevalence of HCM in “elite athletes” (elite status was based on achievements in the arena) is extremely rare. They screened 3500 asymptomatic athletes between 14 and 35 years of age, all competing in the regional level and 60% at the national level, and found that only 3 (0.09%) athletes had morphology that could be considered mild HCM and after further diagnostic testing none could be definitively diagnosed with HCM. This is not to say that HCM should not be screened for, but suggests that the functional changes that result from HCM may naturally select out individuals from elite athletics.
Findings that suggest HCM may include a heart murmur, family history, an abnormal ECG (increased precordial or limb lead voltages, alterations in ST segments, T-wave inversion, or deep and narrow Q waves), or new cardiac-related symptoms such as shortness of breath on exertion, dizziness, and/or syncope. ECG abnormalities may be significant but do not reliably reflect the severity of disease (Maron, 2001). The gold standard for diagnosing HCM is with two-dimensional echocardiography to identify a thickened LV wall (>12 mm) in the absence of a dilated chamber (Maron, 2002).
Arrhythmogenic right ventricular cardiomyopathy
Many different cardiac conditions can be grouped as ARVCs and share a common pathology of structural right ventricular fibro-fatty replacement of the myocardium (Heidbuchel et al., 2006), resulting in a thin and dilated right ventricular wall. In about 50% of cases, this disease has been shown to be genetically inherited as an autosomal dominant trait with incomplete penetrance (Corrado et al. 2000). ARVC leads to arrhythmias that are exacerbated during exercise and, although it is rare in the United States, it should be considered during cardiovascular screenings of athletes. Early diagnosis in the absence of symptoms is often difficult and the initial presentation in 30% of patients is syncope (Pigozzi & Rizzo, 2008). In 50%–90% of patients with ARVC, the resting 12-lead ECG reveals abnormalities that may include T-wave inversion, right bundle branch block, or prolongation of the QRS complex in the right precordial leads, among others (Corrado et al., 2000).
Congenital coronary artery anomalies
Normal coronary artery anatomy for the majority of individuals includes a left main coronary artery and a right coronary artery that originate at their respective sinuses of Valsalva. A diagnosis of anomalous coronary artery origin is considered when any deviation from this normal anatomy occurs and this may cause SCD in individuals by causing transient myocardial ischemia during vigorous exercise (Baggish & Thompson, 2007). This diagnosis in a young athlete should be suspected when the individual presents with symptoms of exercise-induced myocardial ischemia, such as exertional chest pain, exercise intolerance or syncope, or palpitations. Coronary artery angiography has traditionally been considered the gold standard for diagnosis, but newer noninvasive techniques, such as magnetic resonance imagery and computed tomography, are replacing angiography. ECG and stress tests have not been shown to detect these anomalies accurately.
Arrhythmias and ion channelopathies
Premature ventricular beats, commonly originating in the right ventricular outflow tract, are not an uncommon finding in the athletic population and are usually asymptomatic and considered benign (Heidbuchel et al., 2006). While this arrhythmia frequently occurs with underlying heart disease, in the absence of a comorbid cardiac condition, there generally are no adverse outcomes in athletes with premature beats (Biffi et al., 2002). Nonsustained ventricular arrhythmias (three or more consecutive beats greater than 120 bpm) or sustained ventricular tachycardia (greater than 30 s) often suggest an underlying disease and require cardiovascular evaluation with echocardiography to exclude these pathologies (Heidbuchel et al., 2006). Long QT syndrome is caused by ion channel mutations in cardiac fibers and can be congenital or acquired. This condition predisposes the individual to potentially fatal torsades de pointes and ventricular fibrillation (Heidbuchel et al., 2006). Brugada syndrome is a genetic condition that results in the loss of function of sodium channels, causing elevated ST segments, and subsequent ventricular arrhythmias (Brugada, Benito, Brugada, & Brugada, 2009). Preexcitation syndrome, or Wolff-Parkinson-White syndrome, is caused by abnormal conduction resulting in the premature activation of the ventricular myocardium (Mark, Brady, & Pines, 2009).
History and physical examination
A comprehensive personal and family history can help to identify potential risk factors for underlying cardiac conditions or SCD for an athlete. Some cardiac abnormalities, such as HCM and long QT syndrome, are potential hereditary conditions and identifying any diagnosed relatives may prompt further investigation. Incidents such as unexplained sudden death of a first-degree relative would be a “red flag” for the clinician to pursue a potential underlying cardiovascular condition in the patient. Personal history of chest pain, excessive shortness of breath, and syncope are some examples of positive findings for possible abnormalities. Specifically, exercise-related syncope may indicate LV outflow tract obstruction, arrhythmias, or congenital coronary anomalies and require special testing (Giese, O’Connor, Brennan, Depenbrock, & Oriscello, 2007). The AHA recommends the 12-point screening questionnaire for cardiovascular screening that is outlined in Table 2.
Table 2. Twelve-point AHA consensus panel recommendations for preparticipation athletic screening
|Family history|| 1. Premature sudden cardiac death|
| || 2. Heart disease in surviving relatives less than 50 years old|
|Personal history|| 3. Heart murmur|
| || 4. Systemic hypertension|
| || 5. Fatigue|
| || 6. Syncope/near-syncope|
| || 7. Excessive/unexplained exertional dyspnea|
| || 8. Exertional chest pain|
|Physical examination|| 9. Heart murmur (supine/standing)|
| ||10. Femoral arterial pulses (to exclude coarctation of aorta)|
| ||11. Stigmata of Marfan syndrome: typical physical findings include tall, thin stature with increased arm span-to-height ratio, and increased lower-to-upper body segment ratio (Glorioso & Reeves, 2002)|
| ||12. Brachial blood pressure measurement (sitting)|
Many experts in the field claim that the exclusive implementation of history and physical examination in preparticipation screenings is unable to decrease the risk of SCD in young athletes. Wilson et al. (2008) screened over 1000 young athletes using history, physical examination, and a resting 12-lead ECG to determine the efficacy of these screening methods to detect cardiac conditions that increase the risk of SCD. They concluded that the use of family history and personal symptom questionnaires is inadequate for these purposes. In one study examining SCD in 134 deceased young athletes, the exclusive use of physical examination and standard medical history indicated cardiac disease in only 3% of the subjects and <1% received a definitive diagnosis (Maron et al., 1996).
The ECG is used to detect evidence of underlying disorders, such as HCM, ARVC/dysplasia, dilated cardiomyopathy, long QT syndrome, Brugada syndrome, preexcitation syndrome, and manifestations of premature atherosclerotic coronary disease (Moss, 2007). Measuring the QT interval allows the clinician to use concrete guidelines to assist in diagnosing cardiac abnormalities. Both resting and stress ECG testing may be used and can help differentiate normal from abnormal physiologic changes in the athlete's rhythm.
Two-dimensional echocardiography is used to detect congenital structural abnormalities including valvular disease, aortic root dilation, and LV dysfunction or enlargement related to myocarditis and dilated cardiomyopathy (Maron, Douglas, Graham, Nishimura, & Thompson, 2005). The leading cause of SCD in young athletes in the United States is HCM, so echocardiography is of specific interest to this population as a screening tool because it is the primary imaging test used to diagnose this cardiac abnormality.
Wyman, Chiu, and Rahko (2008) successfully screened a large number of collegiate athletes using echocardiography during yearly physical examinations in a timely and cost-effective manner. Although this study demonstrated that echocardiograms could be implemented during routine preparticipation screenings, nationwide funding and availability of equipment and trained personnel remain obstacles for this and all types of preparticipation screening.
When clinically indicated, several other diagnostic tests are available for select patients. These include both noninvasive and invasive procedures, such as cardiac magnetic resonance imaging, stress testing, long-term Holter ECG monitoring, implanted loop recording, tilt table examination, and electrophysiologic testing with stimulation (Maron et al., 2005). DNA testing is also available for known familial conditions such as Marfan syndrome, certain ion channel disorders, and long QT syndrome; however, diagnoses continue to be made through clinical testing. The high cost and limited availability of these genetic tests preclude them for the routine screening of young athletes (Maron et al., 2005).
Data for the cost-effectiveness of ECG use in preparticipation screenings are limited. Chaitman (2007) argued that as a result of the lack of research and the high cost of tests, implementing universal ECG screening for all competitive athletes is not feasible to do in a cost-effective manner. Most arguments against the use of ECGs in screening focus on a high rate of false positives and follow-up testing. Chaitman (2007) suggested that healthcare money might be better used for the more prevalent health conditions of adolescence and young adulthood such as diabetes mellitus and obesity.
On the other hand, others (Corrado et al., 2012; Wheeler, Heidenreich, Froelicher, Hlatky, & Ashley, 2010) argued that not only is cardiac-focused preparticipation screening with an appropriately interpreted ECG cost-effective when compared to no screening, but that screening with a history and physical alone is, in fact, not cost-effective. This is as a result of the low sensitivity and specificity of these exams. According to Myerburg and Vetter (2007), as a result of the large number of cardiac conditions that have a genetic component, the screening and diagnosis of these abnormalities through the use of ECGs in adolescents and young adults may result in subsequent identification of affected family members, thus resulting in an overall cost-effectiveness of the ECG and decrease in morbidity and mortality.
The data for echocardiogram screening cost-effectiveness are even more limited than for the ECG. One study that focused on screening for HCM in high-level athletes concluded that routine use of echocardiogram screening is not cost-effective, mainly as a result of the very small numbers of participants with abnormal morphology (0.09%) following initial echocardiogram screening (Basavarajaiah et al., 2008).
The literature overwhelmingly shows that the relationships between sports medicine, cardiology screenings, and the law are not only complex but are continuously evolving. The law generally states that the provider is required to adhere to standards of good medical practice and comply with the current guidelines, such as the AHA and American College of Cardiology's BC no. 36 recommendations. The provider's duty to the patient is to protect his or her well-being while avoiding unnecessary exclusion from competition (Paterick, Paterick, Fletcher, & Maron, 2005). There have been many malpractice and negligence suits filed against schools, colleges, physicians, and hospitals following the sudden death of a young athlete. Alternatively, the prominent case of Knapp v Northwestern University came about when an athlete diagnosed with HCM was disqualified from competition by physicians (Maron, Mitten, Quandt, & Zipes, 1998). This student based his case on the fact that he was being discriminated against on the basis of a medical disability and had the right to chose whether or not he wanted to risk his health by competing. The court upheld the University's decision to disqualify the athlete in this case. There are many issues to consider when discussing the medical-legal aspects of preparticipation screening, including the difficulty in diagnosing cardiac abnormalities, individualization of care, and ethical “quality-of-life” considerations.
Current guidelines and recommendations
The current AHA recommendations for personal and family history and physical examination are outlined in Table 2, and a positive finding for any one or more items is sufficient to refer for cardiovascular evaluation (Maron et al., 2007). The BC no. 36 outlines individual sports and their relative risk to patients with various cardiovascular diseases at specific severities. Selected cardiovascular conditions, clinical exclusion criteria, and sports permitted by the BC no. 36 are compared to the ESC recommendations in Table 3. The BC no. 36 also includes the levels of static (isometric) and dynamic (involving movement, such as running or swimming) exercise that are required to participate in each sport. These different types of exercise should be taken into account when evaluating how much physical exercise an individual with a specific condition can safely tolerate (Crawford, 2007).
Table 3. Selected cardiovascular abnormalities and differences in BC no. 36 and ESC recommendations for sports participation
|Gene carriers without phenotype (HCM, ARVC, dilated cardiomyopathy, ion channel diseases)||All sports||Only recreational sports|
|Long QT syndrome||> 0.47 s in males, > 0.48 s in females; only low-intensity competitive sports||> 0.44 s in males, > 0.46 s in females; only recreational sports|
|Marfan syndrome||If aortic root < 40 mm, no magnetic resonance, no familial sudden death; low- to moderate-intensity competitive sports allowed||Only recreational sports|
|Premature ventricular complexes||If no increase in premature ventricular complexes or symptoms that occur with exercise, all competitive sports allowed||If no increase in premature ventricular complexes, couplets, or symptoms that occur with exercise, all competitive sports allowed|
|Nonsustained ventricular tachycardia||If no cardiovascular disease, all competitive sports allowed||If no cardiovascular disease, all competitive sports allowed|
| ||If cardiovascular disease present, only low-intensity competitive sports* allowed||If cardiovascular disease present, only recreational sportsa allowed|
The standards for obtaining medical clearance for sports participation of high school athletes are established by the state, local districts, or sometimes the Department of Education and are not regulated by the National Federation of State High Schools. The responsibility of obtaining medical clearance is generally left to the athletes to seek a healthcare provider themselves, and there are no certification guidelines in place for the providers who perform the screenings (Maron et al., 2007). Parental verification is needed for the personal and family medical history of school-aged athletes. Colleges and universities generally maintain their own system of preparticipation screenings using team physicians and trainers, as well as campus health clinics. The National Collegiate Athletic Association has mandated that collegiate athletes in all divisions are required to have an evaluation by a qualified physician prior to practicing and competing that includes 10 of the 12 AHA items, omitting Marfan stigmata and history of fatigability (Maron et al., 2007).
Many institutions have recruited other types of providers to perform preparticipation screenings of athletes because of reduced costs associated with nurse practitioners (NPs), physician assistants, nurses, and athletic trainers, as compared to physicians (Crawford, 2007). A study examining U.S. high school screening protocols found that legislation in several states had increased the number and variety of clinicians who were performing preparticipation screening exams, including chiropractors and naturopathic clinicians (Glover, Glover, & Maron, 2007).
The ESC and International Olympic Committee both recommend standard 12-lead ECG screening of athletes prior to participation in competitive sports, in addition to a comprehensive history and physical examination. Since 1982, Italy has mandated by law that all participants in organized team or individual sports must obtain medical clearance by a certified sports medicine physician that includes history, physical, and 12-lead ECG evaluation. This program has decreased the annual number of SCD cases by almost 90% by identifying and disqualifying athletes with previously undetected cardiac conditions (Corrado et al., 2006).
Conclusions and implications for practice
It seems clear that implementing ECG screening along with a detailed history and physical examination can reduce and potentially eliminate SCD in young athletes with previously undiagnosed cardiac conditions. Current guidelines need to be reevaluated and should include the routine use of ECG screening. The Italian screening program not only demonstrates that this method is effective, but also shows that the implementation of such a program is possible on a national scale. Preparticipation screening does not clearly meet all of the World Health Organization (WHO) screening criteria because of the relatively low incidence of SCD; however, the WHO recognizes diseases with potentially grave prognoses for screening (Papadakis & Sharma, 2009). SCD obviously falls within this realm and actions need to be taken on the national level to enforce more thorough screening of athletes. These preparticipation examinations must be performed by well-trained clinicians, including primary care NPs who are qualified to detect abnormalities in a history, physical, and ECG, leaving the specialists available for appropriate referrals when indicated. Although cost is a big issue in this debate, Wheeler's analysis demonstrates that adding an ECG to routine screenings is actually more cost-effective than history and physical alone for detecting cardiac abnormalities (Wheeler et al., 2010). Additionally, implementing more NPs rather than physicians for preparticipation screenings would offset some of the cost of adding ECG screenings.
Whether or not ECG screening becomes a routine test for athletes in the United States, the responsibility of the primary care NP performing preparticipation examinations is to be familiar with current AHA guidelines, be able to detect any abnormalities, and refer appropriate athletes to a specialist. As always, individualization of care must be in the forefront of any clinician's mind when evaluating a patient. As primary care providers NPs may be the first (or only) line of defense in preventing SCD in young athletes.