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The multifarious spectrum of ischemic left ventricular dysfunction: relevance of new ischemic syndromes
1Ischaemic Heart Disease Research Unit for the Medical Research Council, University of Cape Town, Medical School, South Africa.
Insights
Ischemic heart disease is more complex than previously thought, encompassing new syndromes like silent ischemia, stunning, hibernation, and preconditioning. These conditions, often linked to ischemia and reperfusion, can coexist in patients, forming a mixed post-infarct syndrome.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Ischemic Heart Disease Research
Background:
- Ischemic heart disease (IHD) is evolving beyond traditional definitions like angina and myocardial infarction.
- New syndromes such as silent ischemia, stunning, hibernation, and preconditioning have emerged, all related to ischemia and reperfusion.
- These syndromes represent a more complex understanding of IHD.
Purpose of the Study:
- To describe the newly identified ischemic syndromes: stunning, hibernation, and preconditioning.
- To explore the nature of ischemic left ventricular (LV) dysfunction in post-infarct patients.
- To propose a unifying concept for overlapping IHD conditions in post-infarct patients.
Main Methods:
- Review and synthesis of existing knowledge on ischemic syndromes.
- Clinical observation and characterization of post-infarct LV dysfunction.
- Conceptual framework development for mixed ischemic syndromes.
Main Results:
- Stunning involves post-reperfusion mechanical dysfunction with recovery.
- Hibernation presents as contractile dysfunction with good recovery upon reperfusion.
- Preconditioning offers protection against subsequent ischemic events.
- Ischemic LV dysfunction can be systolic, diastolic, or mixed, potentially influenced by calcium regulation.
- A 'mixed post-infarct ischemic syndrome' is proposed, encompassing various new syndromes and LV dysfunction.
Conclusions:
- Ischemic heart disease is a complex entity involving multiple overlapping syndromes.
- Stunning, hibernation, and preconditioning are key ischemia-reperfusion related syndromes.
- A mixed post-infarct ischemic syndrome, including LV dysfunction and new syndromes, is a relevant clinical concept.
Abstract:
Ischemic heart disease, once limited to a number of well defined entities such as angina of effort, unstable angina, and myocardial infarction, must now be regarded as a much more complex and elusive entity. Silent ischemia was the first of the new ischemic syndromes to be described. Recently, three further new syndromes have been added, namely stunning, hibernation and preconditioning. All three have one common theme--they can be related to ischemia and reperfusion. In stunning, there is post-reperfusion mechanical dysfunction that recovers. In hibernation, there is prominent contractile dysfunction, apparently out of proportion to the reduction in coronary flow, and the recovery upon reperfusion is good. In preconditioning, severe ischemia followed by reperfusion protects against subsequent ischemia which may modify the severity of ischemic damage in the other ischemic syndromes. Ischemic LV dysfunction as found in post-infarct patients and in the absence of any simple relation to reperfusion, can be either diastolic or systolic or both in nature. In ischemic LV diastolic dysfunction without major systolic dysfunction, calcium antagonists may be appropriate therapy which could point to a role for abnormalities in the regulation of cytosolic calcium. It is proposed that there is potentially a mixed post-infarct syndrome, which may comprise one or more of the new ischemic syndromes (silent ischemia, stunning, hibernation, and preconditioning), as well as a varying degree of systolic and/or diastolic dysfunction. The basis of the systolic dysfunction is, at least in part, post-infarct LV remodeling. Several of these entities could overlap in the same patient. The term "mixed post-infarct ischemic syndrome" is suggested to describe this condition.