Role of coronary physiology in the contemporary management of coronary artery disease

Table 1 Advantages and disadvantages of the different coronary physiology indices

	Advantages	Disadvantages
FFR	Clear "cut-off" value Clinically validated Can be used in a wide range of patients Accounts for collateral circulation	Requires administration of vasodilator Risk of coronary artery injury Relatively expensive
IMR	True measure of microcirculatory resistance independent of epicardial coronary disease A tool to potentially predict prognosis in acute patients	Requires administration of vasodilator The full extent of clinical utility is currently unknown
CFR	A tool to potentially predict prognosis in acute patients	Value is affected by both epicardial disease and microvasculature The full extent of clinical utility is currently unknown Influenced by hemodynamics

FFR: Fractional flow reserve; IMR: Index of microcirculatory resistance; CFR: Coronary flow reserve.