Is Comprehensive Screening Good Enough to Detect Sudden Cardiac Death?
Posted Sep 28 2008 11:25am
Is comprehensive heart screening sufficient for young people who are engaging in aggressive exercises such as Marathon running, military training, etc? Should they also undergo additional testing with treadmill exercise and echocardiography (cardiac ultrasound)?
What is sudden cardiac death? As defined by American Heart Association, sudden cardiac death (SCD) or cardiac arrest is the sudden, abrupt loss of heart function in a person who may or may not have diagnosed heart disease. It just occurs immediately or shortly after the symptoms appear.
Every year, sudden cardiac death causes about 166,200 deaths among adults in the United States before reaching a hospital or emergency room.
For people below the age of 35, SCD has many causes. Not all of these causes are due to cardiac problems and only some of these can be detected by screening. Patients who die suddenly are commonly caused by cardiovascular disease, in particular, coronary heart disease (CAD), but it rarely happens to younger age group.
No doubt treadmill ECG stress testing can be used to detect CAD. Nevertheless, it does have its own limitations. For example, it has a false positive result of 10 to 20 percent. In other words, if CAD occurs in 1 per 1,000 people screened, out of 25,000 persons tested, 25 might have CAD. This means that 2,500 to 5,000 might have false positive stress results, and these people have to undergo further testing, such as nuclear imaging and coronary angiography, which may have other risks such as radiation exposure.
It is unjustified to place such a big percentage of people to these risks, as this would certainly outweigh the benefit of detecting a few with CAD. Obviously, stress testing should only be used for those at higher risk such as older men or those with significant risk factors for heart disease.
For youngsters, a more common cause of SCD is hypertrophic cardiomyopathy (HCM). It is an inherited condition with abnormal thickening of the heart muscle. People with HCM will show ECG abnormalities.
In fact, adding ECG to a history and physical examination in athletes, and referring only those with ECG abnormalities for more tests was proved to be an effective mean to minimize the risk of SCD due to HCM. Such approach has also been shown by studies in Italy and endorsed by the International Olympic Committee and European Society of Cardiology.
Meanwhile, prevention and control of risk factors like diabetes, high cholesterol, hypertension (high blood pressure), obesity, and smoking through healthy lifestyles should be encouraged to reduce SCD.