Hibernating myocardium: is there evidence for chronic flow reduction?

Area of Science:

• Cardiology
• Nuclear Medicine
• Medical Imaging

Background:

• Myocardial hibernation is characterized by reduced contractility and potential recovery after revascularization.
• The chronicity of reduced myocardial perfusion in inducing hibernation remains controversial.
• Hibernating myocardium refers to dysfunctional but viable heart muscle.

Purpose of the Study:

• To review the clinical literature for evidence of chronically reduced myocardial perfusion in hibernating myocardium.
• To assess the methodology of studies investigating myocardial perfusion, viability, and function in hibernating myocardium.

Main Methods:

• A systematic search of clinical studies involving patients with hibernating myocardium and revascularization.
• Review of 93 studies assessing contractile function, myocardial viability, and perfusion.
• Analysis of measurement frequency and timing of perfusion, viability, and function assessments before and after revascularization.

Main Results:

• Contractile function was assessed before revascularization in 97.8% of studies and after in 91.4%.
• Myocardial viability was assessed before revascularization in 71% of studies and after in 20.4%.
• Myocardial perfusion was measured before revascularization in 73.1% of studies but only 30.1% after, with no studies performing multiple pre-revascularization perfusion measurements.

Conclusions:

• There is a lack of evidence in the current clinical literature to support the hypothesis of chronically reduced myocardial perfusion in hibernating myocardium.
• The absence of systematic, serial perfusion measurements before revascularization limits conclusions about its chronicity.
• Further research with serial perfusion assessments is needed to clarify the role of chronic perfusion reduction in myocardial hibernation.