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"Hibernating" myocardium: asleep or part dead?
Insights
Chronic left ventricular dysfunction may not always be "hibernating" myocardium. Nontransmural infarction independently impacts dysfunction, affecting diagnostic accuracy for myocardial viability and recovery after reperfusion.
Area of Science:
- Cardiology
- Cardiac Imaging
- Myocardial Viability
Background:
- Chronic ischemic left ventricular dysfunction is often assumed to be "hibernating" myocardium, implying functional recovery post-reperfusion.
- Diagnostic techniques like dobutamine stress echocardiography aim to identify "viable" myocardium with reported accuracies of 70-85%.
Discussion:
- This review questions the universal "hibernating" hypothesis, highlighting that chronic dysfunction can stem from transmural and nontransmural infarction.
- Nontransmural infarction's independent contribution to chronic dysfunction may confound assessments of myocardial viability.
- The severity of dysfunction influences functional recovery, suggesting multifactorial causes beyond simple hibernation.
Key Insights:
- Nontransmural infarction plays an independent role in chronic left ventricular dysfunction.
- Current diagnostic methods for hibernating myocardium may overestimate viability due to confounding infarction.
- Functional recovery post-reperfusion is variable and influenced by the specific causes of dysfunction.
Outlook:
- Further research is needed to differentiate the impact of nontransmural infarction from hibernating myocardium.
- Refining diagnostic techniques is crucial to accurately predict functional recovery in ischemic cardiomyopathy.
- Understanding the distinct roles of infarction and hibernation will improve therapeutic strategies for chronic left ventricular dysfunction.
Abstract:
Chronic ischemic dysfunction of the left ventricle is commonly presumed to represent "hibernating" myocardium. The implication of this assumption is that with successful reperfusion, systolic function will improve. Several diagnostic techniques including dobutamine stress echocardiography have been used to detect "viable" myocardium in the setting of chronic left ventricular dysfunction. Predictive accuracies of 70% to 85% have been reported for identifying myocardium that recovers function. Recovery of function has been variable and often dependent on the severity of dysfunction. All current models have presumed that chronically dysfunctioning myocardium is "hibernating." Obviously, in the chronic setting, dysfunction may have many causes and include components of transmural and nontransmural infarction as well as hibernating myocardium. This review focuses on the independent role that nontransmural infarction may play in chronic dysfunction and suggests its impact on diagnostic techniques used to identify hibernating myocardium.