Clinical implications of coronary microvascular dysfunction in patients with non-obstructive coronary artery disease
Alice Benedetti1, Gianluca Castaldi1, Paul Vermeersch1
1HartCentrum, Antwerpen Hospital Network (ZNA) Middelheim, Antwerp, Belgium.
Insights
Coronary microvascular dysfunction (CMD) is a key cause of angina in patients without obstructive coronary artery disease (CAD). Assessing microvascular function is crucial for prognosis and management in these individuals.
Area of Science:
- Cardiology
- Vascular Biology
- Diagnostic Imaging
Background:
- Coronary angiography reveals no obstructive coronary artery disease (CAD) in over 60% of patients presenting with angina or myocardial ischemia.
- Coronary microvascular dysfunction (CMD) is increasingly recognized as a significant cause of these symptoms, distinct from epicardial obstruction.
- Two endotypes of CMD exist: structural (low coronary flow reserve [CFR], high microvascular resistance [MVR]) and functional (low CFR, normal MVR).
Purpose of the Study:
- To review the definition, prevalence, and clinical implications of different forms of CMD.
- To discuss the technical aspects of invasive assessment for CMD.
- To highlight the importance of microvascular function assessment in patients with non-obstructive CAD.
Main Methods:
- Review of current evidence on CMD definition, prevalence, and clinical impact.
- Discussion of invasive assessment techniques, including thermodilution and continuous thermodilution.
- Analysis of prognostic significance of CMD in patients with no obstructive CAD.
Main Results:
- Nearly half of patients with non-obstructive CAD exhibit signs of CMD.
- Both structural and functional CMD are associated with a worse prognosis, including increased mortality and major adverse cardiovascular events (MACE).
- Thermodilution is an established invasive method for coronary physiology evaluation; continuous thermodilution offers direct measurement of flow and resistance but requires further clinical investigation.
Conclusions:
- Microvascular function assessment should be considered in patients with angina and no obstructive CAD.
- CMD significantly impacts prognosis in this patient group.
- Further research is needed to fully integrate novel techniques like continuous thermodilution into clinical practice.
Abstract:
More than 60% of patients undergoing coronary angiography present no coronary artery disease (CAD). Angina and myocardial ischemia are classically determined by epicardial vascular obstruction, but coronary microvascular dysfunction (CMD) may also represent a possible cause for these phenomena. Two endotypes of CMD have been recognized, with two different pathophysiological mechanisms: structural CMD, characterized by low coronary flow reserve (CFR) and high microvascular resistance (MVR) values; and functional CMD, characterized by low CFR and normal MVR values. According to the present data, almost half of patients with non-obstructive CAD have shown signs of CMD. For this reason, further investigations for microvascular function assessment should be considered when evaluating no-CAD patients complaining of angina or presenting signs of myocardial ischemia. The thermodilution method is currently becoming a widespread invasive technique due to its feasibility and high reproducibility for coronary physiology evaluation. Furthermore, a recently introduced technique - called continuous thermodilution - allows for direct measurement of absolute coronary flow and resistances. The role of this brand-new technique in the clinical scenario is however still to be fully investigated and its use is at present limited to research purposes only. Among no-CAD patients, both structural and functional CMD are related to a worse prognosis in term of mortality and major adverse cardiovascular events (MACE). In this review, we will discuss the present evidence supporting the definition, prevalence and clinical implication of the different forms of CMD and the technical aspects of its invasive assessment.
