- Patients with symptoms presumed secondary to STEMI lasting at least 20 minutes and accompanied by ECG evidence >2 mm of ST elevation in 2 or more contiguous precordial leads or in 2 or more limb leads;or > 1mm ST elevation in 2 or more limb leads coupled with >1 mm ST depression in 2 or more contiguous precordial leads such that the total ST deviation is >4 mm; or presumed new left bundle branch block