FACTORS INFLUENCING MORTALITY AND MYOCARDIAL-INFARCTION AFTER CORONARY-ARTERY BYPASS-GRAFTING

Although the mortality for coronary artery bypass graft surgery has de clined, some categories of patients are still recognized as being at g reater risk. Because the mortality, even for most patients with risk f actors, is less than 10%, evaluating this risk and any improvement ari sing from changing techniques requires thousands of cases. The need fo r these large patient numbers makes the evaluation of changes difficul t. Even when other risk factors are accounted for in the mortality est imate, the patient's age remains an important factor, although there i s no obvious reason why this should be so. Similarly, female sex is we ll recognized as a risk factor. However, the tendency for women to hav e a smaller body surface area and corresponding smaller arterial diame ters may be the explanation. Perfusion time appears to have a strong i nfluence on mortality after it exceeds about 90 minutes, and a similar influence on myocardial infarction also appears to be present. The in creased risk of myocardial infarction with unstable angina may relate to disruption of the normal endothelial vasodilatation caused by nitri c oxide.