Coronary Physiology: Delivering Precision Medicine?

Abstract

Coronary physiological assessment is now widely used to assess epicardial coronary lesions in cath lab. Based on clinical evidence, fractional flow reserve (FFR) is the gold standard method to select whether epicardial coronary lesions need revascularization. While additional epicardial indexes, such as instantaneous wave-free ratio (iFR), are also used for revascularization decision-making, several indexes are now also available to explore the coronary microcirculation. Therefore, coronary physiological assessment now allows to explore the entire coronary tree and offer the potential of precision medicine for patients affected by coronary artery disease (CAD). This paper will provide review of the epicardial and microvascular indexes available for the assessment of coronary physiology. More specifically, the already demonstrated contributions of these indexes in the management of CAD and the role they could play in precision medicine will be reviewed with special emphasis on chronic coronary syndrome.

Keywords: coronary microcirculation dysfunction; coronary physiology assessment; precise medicine.

Fig. 1.

Proposition of utilization of coronary physiology assessment to precise medicine. CFR, Coronary flow reserve; FFR, fractional flow reserve; HMR, Hyperaemic Microvascular Resistance; HSR, Hyperaemic Stenosis Resistance; iFR, instantaneous wave-free ratio; IHDVPS, Instantaneous Hyperemic Diastolic Velocity Pressure Slope; IMR, Index of Microcirculatory Resistance; MRR, Microvascular Resistance Reserve; PPG, Pullback pressure gradient; Pzf, Zero-Flow Pressure; QFR, Quantitative Flow Ratio; RRR, Resistive reserve ratio; WIA, Wave Intensity Analysis.

Fig. 2.

Schematic illustration of the use of pullback index by FFR, iFR and QFR to characterize a coronary lesion. FFR, fractional flow reserve; iFR, instantaneous wave-free ratio; QFR, Quantitative Flow Ratio.