The study was renewed in 1996 through June, 2000. During the initial funding period studies were conducted on the relationship to primary cardiac arrest of dietary intake of long chain n-3 polyunsaturated fatty acids from seafood. The investigators are now extending the population-based, case-control study to determine whether the dietary intake of trans-fatty acids derived from partially hydrogenated unsaturated fatty acids measured through a biomarker are directly associated with the risk of primary cardiac arrest. Cases of PCA who were attended by paramedics in King County, Washington are identified. Demographically similar controls are identified from the same community using random digit dialing. Blood specimens from both previously identified and newly identified cases (collected by paramedics in the field) and controls are analyzed for red cell membrane total trans-fatty acid levels. This serves as a biomarker of dietary trans-fatty acid intake.