One of the most objective clinical manifestations of coronary disease is cardiac infarction. Two main pathological processes may be implicated in its pathogenesis: first, the degree of disease in the vessel wall, and secondly, the presence of disease within the arterial lumen in the form of an occluding thrombus. Because of this potentially dual pathogenesis, there is a distinct possibility that any of the lipid abnormalities associated with the development of cardiac infarction, e.g. a high serum cholesterol level, could be relevant either to the degree of disease in the vessel wall, or alternatively to thrombosis itself, for occluding or near-occluding thrombi are found in over 90 per cent of recent infarcts (Mitchell and Schwartz, 1963). We have, therefore, made an attempt to assess the relationships between the amount of the various macroscopic types of coronary artery disease and age, diastolic blood pressure, heart weight, post-mortem serum cholesterol, and total coronary artery area. These findings are presented and discussed.
SUBJECTS AND METHODSDuring the years 1962-63 we studied the coronary arteries of 206 patients (122 male, 84 female) dying in the Royal Adelaide Hospital, South Australia. This unselected necropsy sample initially comprised all cases including traumatic deaths presenting for necropsy examination on Wednesdays and alternate Sundays, but throughout the latter part of the study consecutive patients were admitted to the series. For each of these patients, the age, sex, and blood pressure levels were abstracted from the hospital in-patient notes when available. Wherever there was doubt as to the validity of the pressure records thus obtained, as in cases with heemorrhage, cardiac infarction, or strokes, an attempt was made to detennine representative values from either the hospital out-patient notes, or from the patients' private medical attendants. In 15 of the 206 patients, valid pressure records were not available from the above sources.Post-mortem Serum Cholesterol. Total serum cholesterol was determined using modifications of the methods of Zlatkis, Zak, and Boyle (1953), and Zak (1957). A standard volume of serum (0X2 ml.) was heatextracted with an alcohol-acetone mixture and aliquots of this extract were evaporated to dryness. This residue was dissolved in glacial acetic acid, and the colour developed by the addition of a mixture of ferric chloride in sulphuric acid. Blood was removed from the heart while in situ with a 20 ml. syringe inserted in the right atrium, care being taken to avoid any dilution of the blood with serous fluid from the pleural or pericardial cavities. In 5 of the 206 patients the blood became gelatinous and would not separate on centrifugation.Fifteen of the 206 patients had a previous serum cholesterol estimation, at intervals ranging from several hours to two years before death. In Fig. 1, these ante-and post-mortem cholesterol levels are compared. The post-mortem levels are on the average 33 mg./100 ml. higher than the ante-mortem levels, and the cor-*