A 68-year-old woman with a history of anterior wall myocardial infarction 2 days ago is admitted with acute dyspnea and hypotension. On examination, BP is 82/50 mmHg, HR 110/min, JVP elevated at 10 cm H₂O, lungs show bilateral crackles, and extremities are cold and clammy. Echocardiography shows severely reduced left ventricular ejection fraction (LVEF 20%) with global hypokinesis. Lactate is 3.8 mmol/L. What is the primary pathophysiologic mechanism responsible for this patient's shock state?