Coronary bypass surgery. An overview.

During the ten year history of coronary bypass surgery the initially unacceptable high operative mortality has dropped to 1--2%. Of the twin targets of the procedure, alleviation of disabling angina and improvement in the prognosis, the former seems to have been achieved and is universally accepted. Several series with repeated exercise tests show that about 70% of the patients gain definite benefit; a high proportion of these patients become entirely asymptomatic. Reestablishment of effective coronary perfusion via the grafts seems to be the key factor in this response. However, several other factors, such as perioperative infarction, psychogenic effects, cardiac denervation, and changes in left ventricular function, are also involved. There is still disagreement about the effect of bypass surgery on life expectancy. It is not, in fact, known with certainty whether prognosis is improved, although coronary bypass surgery does not appear to be inferior to medical management in terms of prolonging life span. It has also been established that there is an improvement in prognosis after bypass surgery for patients with obstruction of the left main coronary artery, while the fairy favourable prognosis of patients with single vessel disease can hardly be improved. Available data from randomized series consisting of the whole range of patients with coronary heart disease are either quantitatively or qualitatively insufficient by present standards. Accordingly, new data will eventually afford the evidence needed for drawing firm conclusions about the final value of coronary bypass surgery in improving the prognosis of coronary heart disease.