Cardiogenic shock: a lethal complication of acute myocardial infarction.
Cardiogenic shock is a serious complication of myocardial infarction (MI) that affects approximately 7% of MI patients, accounting for the majority of all deaths related to acute infarction. Shock is typically the result of a massive amount of damage to the left ventricular myocardium; its defining characteristics are hypotension (systolic blood pressure [SBP] of 90 mm Hg or less, or in chronically hypertensive patients a drop in SBP of 30 mm Hg or more) and hypoperfusion. Shock occurs more frequently in ST-segment elevation MI (STEMI) patients than in non-STEMI patients. Revascularization, either with angioplasty or coronary bypass graft surgery, is associated with better outcomes than intensive medical therapy in patients with shock. Adjunctive therapies include vasopressor therapy, mechanical ventilatory support, and intra-aortic balloon pump counterpulsation (IABP). IABP can stabilize some patients and may make revascularization safer. Other adjunctive therapies being investigated include improved mechanical support devices, induction of systemic hypothermia, use of supersaturated oxygen, and, as medical therapy, administration of L-NMMA.