[Exercise test coupled with thallium-201 myocardial scintigraphy after a primary posterior wall infarct. Apropos of 123 patients subjected to coronarography].

The following investigations were performed in 123 patients (118 men and 5 women) with an average age of 51 +/- 6 years, between the 3rd and 6 week after primary posterior infarction, a standard exercise stress test on a bicycle ergometer coupled with Thallium 201 myocardial scintigraphy, followed by coronary angiography in the following 15 days. The object of these investigations was to detect severe stenosis (greater than 70%) of the left anterior descending artery and 50% stenosis of the left main stem. Thirteen investigations could not be interpreted because of a submaximal exercise stress test which did not attain 85% of the theoretical maximal heart rate. The sensitivity of exercise stress testing was 73% and that of myocardial scintigraphy 71%. On the other hand, the specificity of scintigraphy was 94% compared to 68% for exercise stress testing. The predictive value of a positive scintigraphy was 88% compared to 47% for stress testing. However, the predictive value of a negative test was similar with both techniques (87% for exercise stress testing, 90% for scintigraphy). When all the positive results were considered, the sensitivity was 93% but the specificity only 66%. The simplest and most rational way of exploiting the information provided by these investigations is to combine the results: when they are concordant they indicate the true diagnosis in 90% of cases. Discordant results pose a more difficult problem with myocardial scintigraphy being the more reliable: its positive predictive value was 71% when exercise stress testing was negative; its negative predictive value was 87% when exercise stress testing was positive.(ABSTRACT TRUNCATED AT 250 WORDS)