Incremental prognostic value of coronary flow reserve assessed with single-photon emission computed tomography

Excerpt

The diagnostic and prognostic values of stress myocardial perfusion imaging (MPI) is well established with SPECT1-12 and more recently with PET or PET-CT imaging.13-15 Conventional MPI identifies local reductions in perfusion relative to the best ventricular wall, where the maximum value is presumed to be normal. However, this technique is known to underestimate the extent or severity of multi-vessel coronary disease, when the maximum value does not represent normally perfused myocardium.16,17 In contrast, myocardial perfusion measured on an absolute scale (mL/min/g) permits the assessment of stress-to-rest perfusion or vasodilator reserve without the assumption of a normal reference region, first demonstrated with PET imaging by Gould et al18 In this way, the stress perfusion scan is interpreted relative to the individual’s normal resting state, using the patient as their own control. The clinical value of absolute perfusion or myocardial blood flow (MBF) measurements has been reported extensively using dynamic PET imaging with ¹⁵O-water and ¹³N-ammonia in patient populations such as diabetes, hypertension, hyperlipidemia, smoking, syndrome X, non-compaction, takotsubo, hypertrophic ,and dilated cardiomyopathies. The impact of invasive fractional flow reserve (FFR) imaging to direct PCI and improve patient outcome has recently been reported using FFR measurements in a prospective randomized controlled trial.19 …