Diurnal hypercapnia in patients with obstructive sleep apnea syndrome.

We thank Dr. RuDusky for his comments. He raises important issues in dealing with young adults, having to do with the lack of a standardized criterion for age inclusion. Family history of premature coronary artery disease is considered positive if it was diagnosed in a first-degree relative at age 55 or younger for men, and age 65 or younger for women. As premature coronary artery disease becomes more appreciated, it will become necessary to have a consistent definition, as Dr. RuDusky suggests. A second issue concerns the unfortunate presentation of myocardial infarction in the very young. In the very young population that Dr. RuDusky discusses, myocardial infarction may occur in the absence of angiographically proven coronary artery disease. The differential diagnosis may include thromboembolism, metabolic and endocrine disorders, illicit drug use, coagulopathies, or infections. However, there are disease processes separate from coronary artery disease, as angiography fails to reveal underlying atherosclerotic lesions. Our study deals with people with coronary artery disease in whom the clinical presentation occurred at an early age. Traditionally, it has been thought that myocardial infarctions are relatively rare at this age. Another difference between our population and the population that Dr. RuDusky talks about is that our subjects have high rates of traditional risk factors, including hypertension, smoking, obesity, and a family history of premature coronary artery disease. Our message is that young adults with cardiovascular risk factors are at risk for early presentation of myocardial infarction. Contrary to popular belief, a normal lipoprotein profile in a young adult with risk factors does not imply freedom from coronary artery disease. Concerning novel risk factors, we believe it is important to understand all contributing causes of coronary artery disease. However, sufficient evidence exists to support the aggressive management of all modifiable risk factors. Ironically, most of these risk factors are preventable in the first place. Yet we do poorly in controlling them. We must not necessarily wait for new answers to start taking premature coronary heart disease seriously. A good beginning is to translate what is already known into clinical practice, focusing on elimination of all modifiable risk factors.