['Raised triglyceride-rich lipoproteins significantly increase the risk for cardiovascular disease. Variation in the activity of the enzyme lipoprotein lipase (LPL), which is crucial in the removal of these lipoproteins, may therefore modulate this risk.', 'Postheparin levels of LPL activity and mass were measured in a large cohort of male coronary artery disease patients participating in the Regression Growth Evaluation Statin Study (REGRESS), a lipid-lowering regression trial. In addition, the relationships between LPL activity and mass and severity of angina pectoris according to the NYHA classification and silent ischemia on 24-hour ambulatory ECG monitoring were assessed. Patients in different LPL activity quartiles and mass had different severities of angina; a total of 47% of patients in the lowest LPL quartile reported class III or IV angina. In contrast, only 29% in the highest activity quartile (P:=0.002) had severe angina. These parameters were supported by ambulatory ECG results, for which the total ischemic burden in the lowest LPL activity quartile was 36. 5+/-104.1 mm x min compared with 14.8+/-38.8 mm x min in the highest quartile of LPL activity (P:=0.001). LPL activity levels were strongly correlated with LPL mass (r=0.70, P:<0.0001). A significant association between the LPL protein mass and NYHA class (P:=0.012) was also demonstrated.'] Is lipoprotein lipase activity associated with severity of angina pectoris . REGRESS Study Group?