Q&A: Sudden death and sports
Charles Berul, MD
What causes sudden death during athletic activities?
The vast majority of sudden deaths are caused by cardiac events,
with the remainder secondary to pulmonary causes such as asthma
and anaphylaxis, or neurovascular congenital abnormalities such
as aneurysms. Most sudden cardiac deaths in the young occur during
or immediately following school sports, and nearly 90 percent
occur in the presence of a teacher or coach.
How common is exercise-associated sudden death?
Among healthy children, sudden death while participating in sporting
events is quite rare. Although uncommon, it attracts disproportionate
attention from the media. In the United States, there are approximately
15 million school-age students and 100 to 200 reported pediatric
sudden deaths per year, roughly calculating to one to two children
per 100,000 annually. Sudden cardiac death during sports typically
occurs in healthy, previously asymptomatic children and young
adults.
Is it feasible or effective to screen healthy young athletes
to detect those at risk?
The challenges of screening young athletes relate mainly to the
difficulties in differentiating normal variations from true pathological
markers of cardiac risk. Controversial issues include the accuracy
of presymptomatic diagnostic testing and the cost-effectiveness
of widespread pre-participation athletic screening evaluations.
How can care providers screen young athletes for risk factors?
The most effective means is evaluation by each child's primary
care provider. Inquiring about pertinent symptoms will often be
the most valuable diagnostic aid in identifying the rare, at-risk
individual. Specific symptoms to inquire about include a history
of syncope, chest pain, palpitations, dizziness or rapid heart
rate. In particular, these symptoms become even more concerning
when correlated with exercise. Candid discussions are also necessary
regarding legal and illicit drug use, alcohol, caffeine, smoking,
and medications including prescription and over-the-counter drugs,
health and nutritional supplements, and anabolic steroids. As
some of the cardiac substrates for sudden death are hereditary,
a family history will also be consequential. A family history
of congenital heart disease, arrhythmias, sudden death or inherited
cardiac diseases (e.g., cardiomyopathies, long QT syndromes, Marfan
syndrome) will markedly increase the level of suspicion. Such
a family history justifies a more intense diagnostic assessment.
During the physical examination of a young athlete, the care
provider should assess vital signs, symmetry of 4-extremity pulses,
perfusion, weight and body habitus, and general overall health
and fitness. Cardiac auscultation by the pediatrician or other
primary care provider should include determination of the presence
of murmurs, rubs, or clicks, and assuring a normal splitting and
intensity of the S2 component of the heart sounds.
When do I need a subspecialist?
I recommend referral to a pediatric cardiologist if the primary
evaluation findings include a concerning medical history, family
history, physical or other potential risk factors, or in the case
of exercise-associated symptoms or serious-sounding symptoms at
rest.
What does a pediatric cardiologist/electrophysiologist do?
We have the task of determining whether the referred patient
has an identifiable substrate for sudden cardiac death. He or
she obtains a more organ-system-directed personal cardiovascular
history and family history, and performs a cardiac-specific physical
examination.
An ECG is relatively inexpensive and helpful for assessment of
heart rate, rhythm, axis, conduction intervals, ischemia, infarction,
and chamber size estimation. However, athletes may have ECG findings
that overlap with pathologic abnormalities. In particular, a well-conditioned
aerobic athlete may have sinus bradycardia, ectopic atrial or
junctional escape rhythm, first- or second-degree atrioventricular
block, intraventricular conduction abnormalities, premature atrial
and ventricular contractions and/or exaggerated voltages suggestive
of ventricular hypertrophy. These findings may be normal variants
for the young athlete, and are sometimes difficult to differentiate
from cardiac diseases.
A chest X-ray may reveal a generous-appearing cardiac silhouette,
due to the relatively larger size of an athlete's heart.
Imaging studies, such as echocardiography or magnetic resonance,
are useful to assess intracardiac anatomy, chamber dimensions,
and ventricular function. Exercise testing may be helpful for
the correlation of exercise-associated symptoms, assessment of
exercise intolerance, or for provocation (or suppression) of arrhythmias,
conduction block, or exercise-induced ischemia. More invasive
diagnostic studies are less frequently needed, and may be indicated
based in part upon the history, physical examination and noninvasive
evaluation.
Will pre-screening prevent sudden cardiac death?
Unfortunately, rare sporting catastrophes such as commotio cordis
due to blunt chest wall impact cannot be anticipated by pre-participation
screening. This is almost always fatal and occurs in normal children
who are hit in the chest with an object (e.g., baseball, hockey
puck or knee) during a vulnerable period of the cardiac action
potential.
Are certain individuals and families more vulnerable to sudden
death during sports?
There are patients with congenital heart diseases and cardiomyopathies
that are particularly prone to development of arrhythmias and
sudden death during exertion. These individuals can potentially
be identified prior to sports participation, and should be given
restriction guidelines or advised of specific exercise and sporting
limitations. Inherited hypertrophic cardiomyopathy patients are
especially vulnerable to exercise-associated sudden death, and
this disease is the leading cause of sudden cardiac death under
age 35 in the United States.
There are multiple causes of QT prolongation on an ECG, including
congenital and acquired long QT syndromes (see sidebar), but they
can both result in sudden cardiac death during exercise. Typically,
the congenital forms present during childhood, and the acquired
forms may present during either childhood or adulthood, depending
mainly on the inciting factors. Other electrical myopathies besides
long QT syndrome, such as Brugada syndrome and arrhythmogenic
right ventricular dysplasia, involve abnormalities in cardiac
ion channel function, leading to ventricular arrhythmia vulnerability.
Increased emotional and physical stress, as well as enhanced hormonal
and catecholamine responses, associated with sports are likely
triggers for the susceptible heart.
Where do we go from here?
Identification of at-risk individuals among a large population
of young athletes is a challenge, particularly for primary care
providers, who must attempt to identify patients with suspicious
medical or family histories, or physical findings in order to
selectively and accurately refer at-risk athletes for further
subspecialty evaluation, diagnostic testing and possible activity
restriction. The goal is to allow athletes full participation
in activities without endangering their safety. This balance is
precarious and requires careful attention to specific details
and warning signs, such as exercise-associated symptomatology,
and detection of familial cardiac diseases.
Who should people contact for more information or to refer
a patient?
The Division of Electrophysiology within the Cardiology Department
at Children's Hospital Boston has six physicians and four
nurses who specialize in pediatric cardiac rhythm disorders. Outpatient
programs are available in Boston and at satellite outreach clinics,
including Lexington. You can also contact me directly at charles.berul@cardio.chboston.org.
