Philly Marathon deaths raise questions
DR LEWIS MAHARAM
Monday, November 21, 2011
Dear Running Doc:
Given the two deaths at the Philadelphia marathon this past weekend, please fill me in why young people can have heart attacks. Im really worried I'll be the next one. What can I do? Stephen L. Great Neck, NYC.
Thanks for writing, Stephen. Whenever a runner goes down, we get this same question. My office telephone has been ringing off the hook and I've been getting tons of letters in the wake of the tragedy in Philadelphia in which two runners went down: Their identities haven't been released yet, but a police spokesman said one was a 21-year-old Asian male and the other was a 40-year-old white male.
As I said in my first column for the Daily News, asking the the right questions is the first step in understanding any issue:
What is “sudden cardiac death” and what is its incidence?
Physicians define “sudden death” in young athletes (women as well as men, ages 35 and younger) as a nontraumatic, nonviolent, unexpected death due to cardiac causes within one hour of the onset of symptoms.
One study estimated that the incidence of sudden cardiac death in unscreened men during exercise is 1 in 280,000 per year. In studies of the risk of death in marathons, it's been estimated that one death would occur in 50,000-88,000 marathon finishers.
In a study I published with Dr. Steve Van Camp in 2004, we found that the risk in distances between 10-K and half-marathon was significantly lower: 3.1 deaths per million finishers. There have also been reports of one sudden cardiac death per 4,000-26,000 in active men; 56X greater risk during exercise in sedentary men and only 5X greater risk during exercise in active men.
What is an enlarged heart?
Exercise causes normal blood flow and electrical changes seen on an EKG. During intense aerobic exercise, the oxygen consumption of muscle tissue increases and cardiac output must rise to meet the demands. Over time, aerobic training results in increased left ventricular mass, decreased resting heart rate, increased ventricular stroke volume, and increased cardiac output, among other effects. This is called an “Athlete’s Heart” — it is normal and nothing to worry about.
But there are enlarged heart conditions that can lead to sudden death. Although more than 20 pathologic entities have been identified as causes of sudden death in young athletes, a few lesions are responsible for most of these deaths that are reported:
Hyperpertrophic Cardiomyopathy
Although rare in the general population (0.1% to 0.2% prevalence), this is the most common cause of sudden cardiac death in young athletes It is inherited and 60% of individuals with this have an affected first-degree relative. On autopsy, patients with hypertrophic hearts are found to have a larger-than-normal heart with a distinctively enlarged left ventricle. Hypertrophy of the ventricular septum is often disproportionate to that of the left ventricular free wall, an asymmetry not seen in the “athlete's heart.” In addition to the increased size, the asymmetric thickening of the septum may act as an obstruction to the flow of blood into the aorta during pumping. Microscopic changes include abnormalities of the small arteries and "myocardial disarray," a bizarre arrangement of muscle cells with diffuse interstitial fibrosis.
The hallmark physical examination finding is a murmur that decreases in intensity with the athlete lying down. This contrasts with functional outflow murmurs common in athletes, which increase in intensity with lying down. Approximately 90% of patients with hypertrophic hearts have abnormal EKG results. In many, but not all, cases, this can be diagnosed by echocardiographic findings.
Despite the above information, individuals may present with sudden cardiac death as their first and only symptom of a hypertrophic heart.
Coronary Artery Abnormalities
A variety of inherited coronary artery abnormalities combine to represent the second leading cause of sudden death in young athletes. Only about one third of affected individuals are thought to be symptomatic (experiencing angina, syncope, or shortness of breath with exercise) before sudden death. The mechanism of sudden death in all cases here is thought to be an arrhythmia (abnormal heart rhythm) triggered by heart tissue ischemia or infarction (heart attack). Some cases may be suspected on echocardiography, but a definitive diagnosis is made by coronary angiography, computed tomography, or magnetic resonance imaging.
Myocarditis Acute
myocarditis is an inflammatory condition of infectious origin. Coxsackie B virus causes more than 50% of all cases, but a variety of causes have been implicated. Symptoms are often overshadowed or preceded by symptoms of viral illness such as vomiting, fever, nausea, diarrhea, and muscle aches. However, many individuals are asymptomatic, and again sudden death may be the only presenting sign. The infected myocardium becomes inflamed, creating an unstable site where a potentially terminal arrhythmia may arise. In other cases, involvement of the conduction system may lead to a fatal heart rhythm as well.
Marfan Syndrome
Marfan syndrome is an inherited connective tissue disorder occurring in about 1 in 10,000 people. Affected individuals are at increased risk for sudden death as the result of progressive dilatation of the aortic root, ending in complete dissection or bleeding internally.
The diagnosis of Marfan syndrome is based on a good physical exam (although genetic testing may be appropriate in families with several affected members). Clinical features include tall stature, long and thin limbs, an arm span substantially greater than height, diminished upper body-to-lower body ratio, and a long, thin face.
Electrophysiologic Abnormalities
Abnormalities of the conduction system may lead to fatal cardiac arrhythmias. Their incidence is likely underreported since autopsy findings may be inconclusive. Approximately 60% of patients present with symptoms related to physical activity or strong emotional response, primarily fainting, seizures, or heart palpitations. One third of previously "healthy" young adults present with sudden death. The mechanism of death is a fatal arrhythmia. The EKG results are abnormal in nearly all affected individuals. Treatment generally involves betablocker medication (sometimes with permanent cardiac pacing or internal defibrillator) and avoidance of intense physical exertion.
Other Causes A number of illicit drugs have also been implicated in sudden death. Cocaine abuse may cause local ischemia and infarction due to clamping down of the blood vessels, whereas inhalant use has resulted in fatal arrhythmias. Additional deaths have also been linked to performance-enhancing agents such as erythropoietin, diet medications and anabolic steroids.
So is pre-screening useful?
Yes Stephen, there is no substitute for a yearly physical exam by your primary physician. And if there is a suspected anomaly, referral to a cardiologist for further investigation is warranted. It is interesting to note that in Italy, where healthcare is universal and everyone gets full pre-screening, the rates of sudden cardiac death are no different than in the USA where not everyone gets pre-screened. This tells us that we, as a scientific community, do not yet have an accurate way to predict this tragic outcome.
What can you do?
Exercising is still far better than stopping. We know that active individuals are far healthier and have a better chance of surviving a cardiac event than our sedentary friends. What you can do to help you and your physician decide how much exercise is good for you is be aware of the following:
* Investigate your family history and be aware of any cases of sudden cardiac death in your family. This is the best predictor. Help your doctor to help you by knowing your history.
* Be aware of your body. Report to your doctor immediately chest pain or abnormal shortness of breath that comes on with exercise or in your training.
* Keep your cholesterol level within a good profile. Don't be afraid of taking a statin pill to lower your cholesterol if recommended by your physician. Keeping those coronaries clean is important.
* Follow your doctor's advice. Once you have a respected doctor, resist doctor searching for the answer you want to hear. We all do this. Realize, it may be the wrong answer.
***
Lewis G. Maharam is the author of the Running Doc's Guide to Healthy Running and medical director of the Rock 'n' Roll Marathon series and the Leukemia & Lymphoma Society's Team in Training program. He is past president of the New York Chapter of the American College of Sports Medicine. Learn more at runningdoc.com.
http://articles.nydailynews.com/2011-11-20/news/30423444_1_lewis-g-maharam-marathon-deaths-marathon-medical-directors
No comments:
Post a Comment