Dynamic Left Ventricular Outflow Tract Obstruction in Acute Myocardial Infarction With Shock Cause, Effect, and Coincidence

Case presentation: A 70-year-old white woman with a prior history of tobacco abuse, emphysema, and recent pneumonia presented to an outside emergency room with brief episodes of dull chest pressure recurring over 5 days. Because the current episode was not relieved after 4 hours, and because her ECG showed ST elevation up to 3 mm in V2 through V6, she was given heparin and nitroglycerin infusions and was transferred to the University of Missouri. On admission to our hospital, she was pain-free with stable vital signs. Her examination was remarkable for a grade 2/6 systolic ejection murmur in the left third intercostal space. An ECG showed Q waves in V1 through V3. Echocardiography revealed significant left ventricular (LV) dysfunction, ejection fraction of 35% with systolic anterior motion (SAM) of the anterior mitral leaflet, and moderate mitral regurgitation (MR; Figure 1). LV outflow tract (LVOT) gradients were not quantified owing to MR Doppler contamination. Her maximum troponin was 5 ng/mL, and brain natriuretic peptide was 190 pg/mL. Catheterization showed normal coronaries with anteroapical akinesia and LV dysfunction with an ejection fraction of 30%. Figure 1. Apical 4-chamber view showing SAM of anterior mitral leaflet. LA indicates left atrium. The patient became hypotensive after catheterization, with systolic pressures between 70 and 85 mm Hg. Dopamine infusion did not improve blood pressure, and the murmur increased to grade 3/6 intensity. Atrial fibrillation developed with a ventricular rate of 150 bpm. Dopamine was discontinued, and intravenous amiodarone converted the …