The ECG findings vary considerably, depending importantly on four major factors: (1) the duration of the ischemic process (acute versus evolving or chronic) ; (2) its extent (large versus small) ; (3) its topography (anterior versus inferior-posterior and right ventricular) ; (4) the presence of other underlying conditions (e.g. LBBB, WPW or pacemaker pattern) that can mask or alters the classic pattern.