The study is to commence on March 1st 2001 and is to be completed within 2-5 years. The targeted number of patients to be enrolled is 15,000. All patients undergoing cardiac catheterization or have had a heart catheterization within one year, coming in for outpatient appointments, or have scheduled cardiac CT scans or CT scans performed within one year of scheduled blood draw, will be eligible to be enrolled. Patients inclusion criteria are as follows, once informed consent is obtained: