Q. Corelation of ST Depressoin with Coronary Angiography?
Various investigators considered 1 mm of horizontal or downsloping ST depression to denote a positive test and used from 50-75 per cent cross sectional narrowing as a significant coronary lesion. From the data available at this time the following statements regarding average correlations between catheterization data and maximal stress testing seem in order if ST-segments are taken as the only marker for coronary ischaemia.
1) Men with single vessel disease and significant coronary narrowing of 70 per cent of luminal diameter have about 50 to 60 per cent chance of an abnormal test result.
2) Men with two-vessel disease have a 65 per cent chance of an abnormal test result.
3) Men with three-vessel disease have a 78 per cent chance of an abnormal test result.
4) Men with left main disease have an 85 per cent chance of an abnormal test result.
5) Men admitted for evaluation of chest pain who are over age 45 with 1.0 mm ST-segment depression have a 90 per cent chance of having coronary disease or evidence of significant left ventricular dysfunction.
6) Men in the above category with 1.5 mm of ST depression have a 94 to 95 per cent chance of having coronary disease or evidence of significant left ventricular dysfunction.
7) Men over age 45 with 2.0 mm or more ST-segment depression have a 98 per cent chance of having coronary disease or evidence of significant left ventricular dysfunction.