Let’s functionalize the myocardial flow reserve

Excerpt

Quantitative myocardial blood flows (MBF) by PET are entering the practice of nuclear cardiology. Flow responses to pharmacologic vasodilation measured in absolute units together with myocardial flow reserves (MFR) have improved the detection of functionally obstructive coronary artery disease, especially in patients with multivessel disease. They also have become powerful predictors of major adverse cardiac events (MACE) including cardiac death, nonfatal myocardial infarction, acute coronary syndrome and hospital admission for heart failure. Applied globally to the myocardium, vasodilator-stimulated flows probe the responsiveness of the entire coronary circulation and provide a measure of its overall vascular health. The “global myocardial flow reserve (MFR)” as the ratio of global hyperemic to rest MBF therefore reflects the composite effects of coronary morphological and functional alterations that exert resistance to increases in coronary flow. A benchmark value of 2.0 for the MFR has emerged from multiple follow up investigations in patients after PET MPI and flow measurements, a threshold value that discriminates between high and low risk of cardiac death and of MACE.^1‐3 …