Functional coronary angiography (FCA) is a novel modality for assessing the physiology of coronary lesions, going beyond anatomical visualization by traditional coronary angiography. FCA incorporates indices like fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR), which utilize pressure measurements across coronary stenoses to evaluate hemodynamic impacts and to guide revascularization strategies. In this review, we present traditional and evolving modalities and uses of FCA. We will also evaluate the existing evidence and discuss the applicability of FCA in various clinical scenarios. Finally, we provide insight into emerging evidence, current challenges, and future directions in FCA.
Keywords: coronary artery disease; coronary microvascular disease; fluid dynamics; functional coronary angiography; provocation testing.
Functional coronary angiography is a technique that combines detailed imaging of the coronary arteries with assessments of how well they function, helping physicians evaluate both large and small arteries in the heart. Unlike traditional angiography, functional coronary angiography uses advanced methods to measure the impact of any abnormalities, without needing extra invasive procedures. This approach is especially useful for patients who have cardiac symptoms but don't show significant blockages on standard tests. Functional coronary angiography is increasingly used to guide treatment decisions, ensuring patients receive the right care while avoiding unnecessary interventions. Functional Coronary Assessment primarily enhances coronary artery disease management by integrating various techniques to measure the hemodynamic significance of coronary lesions, guiding treatment decisions, and improving outcomes. The gold-standard Fractional Flow Reserve, along with alternatives like instantaneous wave-free ratio, resting-full cycle ratio, and diastolic pressure ratio, provides precise lesion severity assessments, reducing unnecessary interventions and enabling tailored revascularization strategies. Emerging technologies like Ultrasound-based fractional flow reserve and Optical Flow Ratio (OFR) offer promising, less invasive alternatives, while tools such as Coronary Flow Reserve and Index of Microvascular Resistance expand FCA's diagnostic scope to microvascular dysfunction and ischemia without obstructive coronary artery disease. FCA also plays a key role in personalized revascularization strategies, from routine management to high-risk, improving clinical decisions, reducing adverse events, and enhancing survival across diverse patient groups.In this review, we present traditional and evolving uses of functional coronary angiography by evaluating its broad applicability across a variety of clinical indications.