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Risks and Benefits of Exercise Reviewed in AHA Statement CME/CE

News Author: Shelley Wood
CME Author: Désirée Lie, MD, MSEd

Complete author affiliations and disclosures, and other CME information, are
available at the end of this activity.

Release Date: May 3, 2007; Valid for credit through May 3, 2008
Credits Available
Physicians - maximum of 0.25 AMA PRA Category 1 Credit(s)™ for physicians;
Family Physicians - up to 0.25 AAFP Prescribed credit(s) for physicians;
Nurses - 0.25 nursing contact hours (None of these credits is in the area of
pharmacology)

All other healthcare professionals completing continuing education credit for
this activity will be issued a certificate of participation.
Physicians should only claim credit commensurate with the extent of their
participation in the activity.

from Heartwire — a professional news service of WebMD

May 3, 2007 — A scientific statement released by the American Heart Association
(AHA) aims to put the risks and benefits of exercise "in perspective." According
to first author and Co-Chair Paul D. Thompson, MD, FAHA, many clinicians may be
familiar with information summarized in the statement, but having that
information compiled in a single document should help them make decisions and
answer questions in their day-to-day practices.

In particular, the statement addresses the potential adverse cardiovascular
events that can be triggered by exercise, how these events arise, and how often
they occur and in whom, and provides strategies for reducing complications.
Although the statement does not provide step-by-step guidance for dealing with
different groups or scenarios, it does synthesize a lot of information from a
range of exercise-related documents, and directs clinicians to those documents,
where appropriate.

The statement is published online in the April 27 Published Ahead of Print issue
and in the May print issue of Circulation.
Exercise Beneficial in Most, but Not All

A key point, said Dr. Thompson, is that doctors and allied healthcare
professionals, while advocating regular physical activity, must keep in mind
that some patients may not benefit from exercise. "We always talk about the fact
that exercise and physical activity has benefits, and that in adults, even if
they have mild underlying heart disease or coronary atherosclerosis, the
benefits of exercise outweigh the risks, and that's where most of the evidence
lies," he explained. "But as we mention in this statement, some situations
aren't improved by vigorous exercise, things like hypertrophic cardiomyopathy
and anomalous coronary arteries. That's pretty obvious when you think about it,
but it's an addition that hasn't been made before. The simple point that some
doctors and cardiologists should take from this is that there are some groups
who simply don't benefit from being engaged in vigorous exercise."
A Compilation of Helpful Information

The statement reviews the well-established pathological causes of cardiac events
in younger vs older adults: in people younger than 40 years, hereditary or
congenital abnormalities are typically the cause of exercise-related events,
whereas in people older than 40 years, coronary disease is the most common
underlying cause. But, as the authors point out, habitual physical exercise has
been shown to reduce the risk for events in most people, even those with occult
disease, and cardiac rehabilitation appears to reduce the risk for coronary
heart disease (CHD) death in people with diagnosed disease. This holds true even
though vigorous exercise increases the risk for an event during exercise or soon
after. "No evidence suggests that the risks of physical activity outweigh the
benefits for healthy subjects. Indeed, the converse appears to be true,"
Thompson and colleagues write.

To heartwire, Dr. Thompson highlighted other parts of the statement that he
believes will be particularly helpful to clinicians.

"This statement is a good compilation of things people ask about frequently,
such as morning versus afternoon exercise. So it's a useful document for doctors
who talk to patients. When patients say, 'I heard it's more dangerous to
exercise in the morning,' this goes through the fact that there is a theoretical
consideration of that, but very little data to support it. We come down on the
side that it's more important for individuals to exercise regularly than it is
that they worry about morning versus evening."

Another example, he said, is whether different types of exercise are more
harmful than others — another topic covered in the statement. "We talk about the
fact that snow-shoveling has been repeatedly associated with increased
cardiovascular events and probably elicits a higher cardiovascular stress than
other activities," Dr. Thompson said.

Other topics covered in the statement include identification of prodromal
symptoms, preparing fitness personnel and exercise facilities for cardiovascular
emergencies, and preparticipation screening.

Dr. Thompson has disclosed research grants from Merck, Pfizer, AstraZeneca, and
Kos Pharma. Complete disclosure information for Dr. Thompson and the other
authors is available in the original article.

Circulation. Published online April 27, 2007.

2007;115:2358-2368.

The complete contents of Heartwire, a professional news service of WebMD, can be
found at www.theheart.org, a Web site for cardiovascular healthcare
professionals.
Learning Objectives for This Educational Activity
Upon completion of this activity, participants will be able to:

* Describe the risk for sudden cardiac death associated with exercise.
* Describe the American Heart Association recommendations for reducing risk
in patients who exercise.

Clinical Context

According to the authors of the current statement, habitual physical activity
reduces CHD events but vigorous activity can increase the risk for sudden
cardiac death and acute myocardial infarction in susceptible persons,
particularly those who are least habitually active. This review of the AHA in
collaboration with the American College of Sports Medicine examines the evidence
for screening individuals before exercise programs and the value of training
emergency personnel for sports events, and compares the risk for sudden cardiac
death according to age and risk factors.
Study Highlights

* Vigorous exercise is defined as an absolute exercise work rate of at
least 6 metabolic equivalents, which approximates the energy equivalent of
activities such as jogging.
* In individuals younger than 30 or 40 years, the most frequent underlying
factors for sudden cardiac death are pathologic congenital cardiovascular
abnormalities and myocarditis.
* Ventricular arrhythmias are most often the immediate cause of death
except for Marfan syndrome, in which aortic rupture is often the proximate
cause.
* In young adults with predisposing conditions such as hypertrophic
cardiomyopathy or anomalous coronary arteries, the risk from vigorous physical
activity is likely to exceed the benefits.
* The incidence of sudden cardiac death in young adults has been estimated
at 0.9 and 2.3 per 100,000 for nonathletes and athletes, respectively.
* In older adults, studies in 2 US states estimated hourly death rate has
been shown to be 7.6 to 25 times higher during exertion than during leisurely
activities.
* The relative risk was greatest among the least vs the most active men.
* In older individuals who die during vigorous exercise, CHD is the most
frequent underlying cause.
* Vigorous physical activity may cause coronary thrombosis by worsening
mild plaque fissure.
* For patients with CHD, the relative risk for cardiac arrest during
vigorous exercise has been documented at 6 to 164 times greater vs without
exertion.
* Vigorous exertion transiently increases the risk for acute myocardial
infarction and sudden cardiac death, especially among habitually sedentary
persons.
* Soon after vigorous exercise, the risk for acute myocardial infarction
may be 50 times higher for habitually inactive persons vs the most active
individuals.
* Over time, regular physical activity reduces CHD events.
* Acute myocardial infarction and sudden cardiac death among adults and
sudden death among nonathletes with hypertrophic cardiomyopathy are more
frequent during early morning hours.
* Sudden death and cardiac arrest among young athletes occur primarily in
the afternoon and early evening, associated with training and competition.
* The incidence of both acute myocardial infarction and sudden death is
greatest in those habitually least physically active; no strategies have been
adequately studied to evaluate their ability to reduce exercise-related acute
cardiovascular events.
* Observational studies suggest that regular exercise to maintain fitness
confers protection against CHD death.
* The AHA recommends preparticipation screening of high school and college
athletes and screening at 2- to 4-year intervals.
* Preparticipation screening of athletes aged 12 to 35 years, including
electrocardiograms, has been associated with a 90% decrease in sudden death from
3.6 to 0.4 deaths per 100,000 athletes.
* Those with risk factors for CHD should receive preparticipation screening
before beginning an exercise program.
* The US Preventive Services Task Force states that insufficient evidence
is available to evaluate the value of exercise testing before exercise programs,
but the AHA and American College of Sports Medicine recommend exercise testing
before vigorous exercise in persons with known cardiovascular disease.
* Prodromal symptoms are more common among those who experience sudden
cardiac death, and attention should be paid to athletes with cardiac complaints.
* The AHA recommends that coaches and trainers be trained in
cardiopulmonary resuscitation and participants in fitness facilities should be
screened for heart disease.
* Active individuals should modify their exercise programs in response to
variations in capacity, habitual activity, and the environment.

Pearls for Practice

* Vigorous exercise confers a risk for sudden death among nonathletes,
young adults with structural heart disease, and older adults with cardiovascular
risk factors.
* Preexercise screening is recommended for young athletes and those with
cardiovascular risk, and athletes with prodromal cardiac symptoms should be
assessed for sudden cardiac death risk.

(Continued at http://www.medscape.com/viewarticle/555986?src=mp )