Q. Show Upsloping ST-Segment?

There are few subjects in exercise literature that has generated more controversy than the significance of up sloping ST-segments. The up sloping ST-segment is considered to indicate ischaemia if, at 80 msec after the J point, the segment is 1.5 mm below the baseline level of the PQ Junction. Junctional changes with very steep up sloping segments are probably not pathological.

The physiological basis for the observed  ECG abnormalities is complex and may be multifactorial. The magnitude of the stenosis  in an artery, estimated by angiography may not accurately predict the amount of restriction in  flow, especially when spasm may be induced by exercise. There has been general agreement however, that an increased magnitude of ST-segment depression usually denotes an increased degree of ischaemia. Ekelund reported an almost a three fold increase in cardiac events in patients with the so called strongly positive stress test (ST depression of 2 mm or more). Current criteria accept 1.5 mm of depression of 0.08 msec from the J point even if the ST-segment slopes upward.
 
Mason and associates in the study of a relation observed that reducing the depression of the ST-segment to 0.5 mm increased the sensitivity to 84 per cent but decreased the specifity to 57 per cent. They found that the ST-segments alone at maximum exercise correlated best with an increased LV filling pressure in 90 per cent of patients.