PROGNOSTIC IMPLICATIONS OF ASYMPTOMATIC CARDIAC ISCHEMIA

The Oslo Ischemia Study was initiated between 1972 and 1975 in 2,014 m en (age, 40-59 years), with the aim of detecting previously unknown an d unsuspected coronary heart disease. Of the men who were eligible, 86 % participated and were apparently free from cardiovascular disorders. Following a positive symptom-limiting bicycle test, 109 of the men un derwent diagnostic coronary angiography and 105 were evaluable; the an giograms were normal in 36 and pathologic in 69. Nineteen of the men w ith pathologic angiograms had mild angina on the exercise test, while 50 (72%; 2.5% of total study population) remained completely asymptoma tic. During a mean follow up of 15 years, 14 of the 50 completely asym ptomatic men died (12 suddenly, 1 of whom had angina pectoris for 5 ye ars). Eighteen of the surviving 36 men remained completely asymptomati c and free from signs of coronary artery disease, other than exercise- induced ST-segment depression. One man had ECG signs of a previous myo cardial infarction, on the annual follow up; chest pain as a first pre senting symptom was observed in a further 17 of 36 survivors. Repeat a ngiography was performed in 22 men who experienced either chest pain o r worsening symptoms following exercise test; of these, 14 underwent c oronary bypass surgery and are still alive. The data appear to refute a 'wait-and-see' policy among subjects with asymptomatic cardiac ische mia. It is concluded that medical or surgical intervention can affect prognosis in the asymptomatic or mildly symptomatic phase of coronary artery disease. Further trials are in progress to evaluate if prognosi s can be improved by effective anti-ischemic intervention.