EVALUATION OF THE PROGNOSIS OF MYOCARDIAL -ISCHEMIA BY THALLIUM SCINTIGRAPHY

Thallium scintigraphy holds a unique position amongst the methods avai lable for evaluating the prognosis of coronary patients : it enables q uatification of underperfused myocardium and evaluates already constit uted ventricular damage (irreversible necrosis) and areas at risk of f uture coronary events (viable but ischemic myocardium). In a series of 1 926 patients who underwent exercise stress or dipyridamole Thallium myocardial scintigraphy for angina pectoris and followed up fort an a verage of 34 months, the following features were observed : the long-t erm prognosis in patients with normal myocardial scintigraphy (715 pat ients) was identical to that of a normal population of the same age (0 .11 % cardiovascular deaths per year) whereas the cardiovascular morta lity was 15 times higher in cases with a pathological scintigraphy : f inally, the long-term prognosis (cadiovascular deaths, infarcts or sec ondary revascularisation) was directly related to the severity of the initial lack of Thallium putake. This method was used to assess the pr ognosis and evaluate the myocardial ischaemia in 75 patients who under went complete surgical revascularisation fort ischaemia, 50 of whom ha d previous myocardial infarction : all patients had at least one arter ial bypass graft : 39 % of the myocardium was underperfused before rev ascularisation ; this procedure reduced by 80 % (p < 0.0001) the zones of reversible underperfusion but also zones of irreversible underpefu ssion by 17 % (p = 0.04). The results were particularly impressive in patients who underwent revascularisation with an arterial pedicle (lef t and right internal mammary, gastroepiploic alone or in association) as 91 % of the ischemic territories recovered on-average 13 days after revascularisation. It may be suggested that the improvement in functi onal status and survival of these patients, obtained by these differen t methods of antiischemic therapy, is directly related to the degree o f regression of this ischaemia.