Duration and amplitude of Diagnostic Q Waves: at least 40 milliseconds in duration, at least 25% the amplitude of the following R wave and they must occur in two adjacent or contiguous leads. If not all criteria are met, the Q waves are non-diagnostic. Marked ST elevation in the same area is consistent with a recent MI. If it persists and is present in an older infarction, it is associated with a wall motion abnormality or an aneurysm.

Anterior infarcts are associated with diagnostic Q waves in at least 2 of the anterior leads, V2,3,4. The lesion and/or thrombus that caused it usually occurred in the proximal left anterior descending coronary artery. Since it involves a large portion of the LV mass often a wall motion abnormality can be appreciated on physical exam. Anterior MI's are more likely to be complicated by shock or CHF than other patterns.

If this is a new pattern and the patient is presenting with typical ischemic chest pain and ST elevation, then ASA and thrombolysis should be given as soon as possible unless there is a contraindication. Palpation of the precordium can reveal a wall motion abnormality (displaced PMI with sustained lift). These patients usually should be placed on a beta-blocker for at least 2 years after their MI occurred. ACE inhibitors are indicated in those with documented LV dysfunction. ACE inhibitors can cause a cough, hyperkalemia and renal dysfunction requiring a switch to a long acting nitrate and hydralazine.