Physiological assessment of coronary artery disease (CAD) has become one
of the cornerstones of decision making for myocardial
revascularization, with a large body of evidence supporting the benefits
of using fractional flow reserve and other pressure-based indexes for
functional assessment of coronary stenoses. Furthermore, physiology
allows the identification of specific vascular dysfunction mechanisms in
patients without obstructive CAD. Currently, more than 10 modalities of
functional coronary assessment are available, although the overall
adoption of these physiological tools, of either intracoronary or
image-based nature, is still low. In this paper the authors review these
modalities of functional coronary assessment according to their timing
of use: outside the catheterization laboratory, in the catheterization
laboratory prior to the percutaneous coronary intervention (PCI), and in
the catheterization laboratory during or after PCI. The authors discuss
how the information obtained can be used in setting the indication for
PCI, in planning and guiding the procedure, and in documenting the final
functional result of the intervention. The advantages and limitations
of each modality in each setting are discussed. Furthermore, the key
value of intracoronary physiology in diagnosing mechanisms of
microcirculatory dysfunction, which account for the presence of ischemia
in many patients without obstructive CAD, is revisited. On the basis of
the opportunities generated by the multiplicity of diagnostic tools
described, the authors propose an algorithmic approach to physiological
coronary investigations in clinical practice, with the key aims of:
1) avoiding unneeded revascularization procedures; 2) improving
procedural PCI and long-term outcomes in patients with obstructive CAD;
and 3) diagnosing vascular dysfunction mechanisms that can be
effectively treated in patients with NOCAD. The authors believe that
such structured approach may also contribute to the wider adoption of
available technologies for functional assessment of patients with CAD.
