This is seen due to

In a patient taking digoxin. The ST-T complexes here are 'scooping' - consistent with a digitalis 'effect'. In the digitalis effect, the ST segments are often likened to a 'reverse tick' or to the shape of Dali's moustache The impoant learning point here is that the digitalis 'effect' does not necessarily mean toxicity. These ECG features can often be seen when digoxin levels are within the therapeutic range.