The study follows up 1,000 asymptomatic high-risk survivors from the South Bay Heart Watch population recruited in 1990-1992 (n = 1,461) and studied with EBCT in 1992-1993 (n = 1,309). The primary objective is to examine the effects of baseline risk factors and measures of calcium metabolism on changes in the amount of coronary calcium in this asymptomatic high-risk adult cohort. This observational study has the following specific aims, as follow: 1) relating demographic factors and traditional risk factors to progression in coronary artery calcification (CAC) score over time; 2) relating serum markers of calcium metabolism to changes in CAC score; and 3) relating baseline CAC score and changes in CAC score to left ventricular dysfunction and intervening coronary events.