Abstract
Up to 40% of patients evaluated for angina/ischemia have non-obstructive coronary arteries, referred to as ANOCA when angina is the presenting symptom and INOCA when objective ischemia is documented. The 2024 ESC Chronic Coronary Syndromes guideline introduces a Class I, Level B recommendation for performing invasive coronary angiography when invasive functional assessments are available to confirm or exclude obstructive coronary artery disease or ANOCA/INOCA, even if non-invasive testing yields an uncertain diagnosis. Despite the absence of epicardial stenosis, these patients frequently suffer from recurrent angina, reduced quality of life, and excess cardiovascular risk. Coronary microvascular dysfunction and vasospastic angina are the two dominant endotypes. A comprehensive invasive coronary function testing protocol, combining fractional flow reserve or instantaneous wave-free ratio with coronary flow reserve, the index of microcirculatory resistance (bolus thermodilution), and the emerging minimal microvascular resistance (continuous thermodilution), allowing for detailed physiological characterization. This expanded diagnostic framework enables the subclassification of coronary microvascular dysfunction into structural and functional endotypes, thereby facilitating personalized therapy and enhancing prognostic accuracy. Acetylcholine provocation further identifies endothelial or vasospastic components, completing a precision endotyping approach that guides risk-stratified therapy.
This narrative review synthesizes global evidence and provides a pragmatic roadmap relevant to health systems such as Vietnam’s, where anatomical strategies still predominate. We summarize epidemiology, pathophysiology, diagnostic algorithms, therapeutic implications, and research priorities, highlighting future directions and collaborative opportunities to responsibly expand access to invasive coronary physiology while maintaining patient safety and scientific rigor.