ECG 1 (Above) was recorded from an aysmptomatic 79-year old female with hypertension, for which she was taking an ACE inhibitor and a diuretic. ECG 2 (below – apologies for the size, please zoom if you can) was recorded two months later as part of a routine assessment for cancer surgery. Is there any significant difference between the two ECGs? If so, what might be the explanation?