A 58-year-old man with acute myocardial infarction develops hypotension, cool extremities, and reduced urine output despite adequate fluid resuscitation. Which is the most common type of shock in this clinical scenario?

Explanation

## Cardiogenic Shock in Acute MI **Key Point:** Cardiogenic shock is the most common cause of in-hospital mortality in acute myocardial infarction, occurring in 5–10% of acute MI cases. It results from severe left ventricular dysfunction with cardiac output insufficient to maintain tissue perfusion. ### Clinical Features in This Case - Hypotension (SBP < 90 mmHg) - Cool extremities (peripheral vasoconstriction due to sympathetic activation) - Oliguria (reduced renal perfusion) - Inadequate response to fluid resuscitation (distinguishes from hypovolemic shock) ### Pathophysiology 1. Acute loss of ventricular contractility (>40% of LV mass infarcted) 2. Reduced cardiac output → systemic hypoperfusion 3. Compensatory sympathetic activation → increased afterload → further reduction in cardiac output (vicious cycle) 4. Tissue hypoxia and metabolic acidosis ### Hemodynamic Profile in Cardiogenic Shock | Parameter | Value | | --- | --- | | Cardiac Index | < 2.2 L/min/m² | | PCWP (Pulmonary Capillary Wedge Pressure) | > 18 mmHg | | SVR (Systemic Vascular Resistance) | Elevated (> 1200 dyne·s·cm⁻⁵) | | Urine Output | < 0.5 mL/kg/hr | **High-Yield:** In acute MI, cardiogenic shock indicates extensive myocardial necrosis and carries a mortality rate of 50–80% despite revascularization. Early recognition and intervention (PCI, intra-aortic balloon pump, inotropic support) are critical. **Clinical Pearl:** The key distinguishing feature is that fluid resuscitation worsens the condition (increases PCWP and pulmonary edema) rather than improving perfusion—unlike hypovolemic shock where fluids restore perfusion. [cite:Robbins 10e Ch 4]