Coronary Artery Disease - STEMI Case #11

A 56-year-old female presents with shortness of breath, nausea and diaphoresis. She has had some “heartburn” for the last 2 days. She is afebrile with a blood pressure of 120/80 mm Hg, heart rate of 70 beats per minute and respirations 22 per minute. There is an S4 heart sound present, no murmurs and clear lungs on examination. Chest X-ray is clear. Her ECG is below:


She is treated with standard medical therapy using aspirin, clopidogrel, low molecular weight heparin, a beta-blocker, nitrates for chest pain and oxygen. Her blood pressure suddenly drops to 80/40 mm Hg. Lung exam remains clear, and she is chest pain free. Emergent left heart catheterization is performed, revealing a totally occluded proximal right coronary artery with thrombus. This is treated with primary percutaneous coronary intervention. Left ventricular angiography shows an ejection fraction of 45% with inferior hypokinesis. Right heart catheterization shows small V waves in the pulmonary capillary pressure tracing, normal right heart pressures, a right atrial saturation of 65%, right ventricle 64% and pulmonary artery 68%. Her right atrial pressure is 20 mm Hg, right ventricle 40/10 mm Hg and pulmonary artery 35/12 mm Hg. Her systemic pressure remains 80/40, even after PCI. Which of the following is the likely cause of of her hemodynamic instability?

A. Acute mitral regurgitation

B. Acute left ventricular free wall rupture

C. Acute ventricular septal defect

D. Right ventricular infarction

E. Cardiogenic shock from acute left ventricular systolic dysfunction