Sinus rhythm is present at a rate of about 75/min. Note the loss of R waves, with frank Q waves in leads V1 to V4 in concert with ST elevations in V2 to V5/V6, as well as more subtly in leads I and aVL. Marked left-axis deviation is present with a normal QRS duration consistent with left anterior fascicular block (LAFB). The patient had sustained a very recent ST-elevation/Q wave anterior myocardial infarction (MI). Cardiac catheterization revealed three-vessel disease with a 90% mid-left anterior descending coronary artery "culprit" lesion that was successfully treated with a percutaneous coronary intervention procedure.
With permission, from Nathanson LA, McClennen S, Safran C, Goldberger AL. ECG Wave-Maven: Self-Assessment Program for Students and Clinicians. https://ecg.bidmc.harvard.edu.
