After successful reperfusion of an acute myocardial infarction, echocardiography shows regional systolic dysfunction that persists for several days despite restoration of coronary flow and absence of irreversible injury. In contrast, chronic hypocontractile but viable myocardium in a stenosed territory recovers function after bypass grafting. These two states are termed, respectively:

• A Hibernation and stunning
• B Chronic ischemic heart disease and myocardial fibrosis
• C Ischemic preconditioning and no-reflow phenomenon
• D Stunning and hibernation ✓

Explanation

Stunning is transient post-ischemic dysfunction that persists after reperfusion despite viability, caused by oxidative stress and calcium handling abnormalities. Hibernation is a chronic downregulation of contractile function in response to reduced perfusion, preserving viability so that function recovers after revascularization. Preconditioning refers to protection conferred by brief prior ischemia, the no-reflow phenomenon describes failure of microvascular reperfusion, and chronic ischemic heart disease with fibrosis implies irreversible loss of myocytes.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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