Regional versus global PET function and perfusion computations for detecting cardiac ischemia

1636 Objectives: Because myocardial ischemia is not only produced by arterial stenosis but also by diffuse epicardial coronary disease \u0026 microvascular coronary disease, coronary flow capacity (CFC) has been advanced as an approach to categorize the severity of left ventricular (LV) ischemia by PET myocardial blood flow (MBF) measurements. The objective of this investigation was to compare global versus regional CFC computations for identifying pts with cardiac ischemia. Methods: Data were examined retrospectively for 231 pts evaluated for known/suspected CAD who underwent rest \u0026 regadenoson-stress82Rb PET/CT. Rest \u0026 stress absolute MBF \u0026 myocardial flow reserve (MFR = stress MBF/rest MBF) were quantified from first-pass 82Rb PET time activity curves. CFC categorized the 3 main arterial territories (LAD, LCX \u0026 RCA) from regional MFR \u0026 stress MBF values, according to a proposed classification system(J Am Coll Cardiol 2018;72:2642-62), based on which we defined “abnormal CFC” as either moderately reduced (MFR \u003e 1.27-1.60 \u0026 stress MBF \u003e 0.83-1.09 ml/g/min) or severely reduced (MFR ≤ 1.27 \u0026 stress MBF ≤ 0.83 ml/g/min). These same criteria were used to categorize overall global LV CFC. Relative perfusion values, including summed stress score (SSS), were assessed for each arterial territory by applying gender-specific 82Rb normal limits. Global SSS was computed as the sum of the 3 territorial SSS values. Asynchrony was assessed as systolic phase contraction bandwidth (BW), the % of the R-R interval spanning 95% of LV contractions. BW was assessed both globally \u0026 regionally for each of the 3 main arterial territories. A subgroup of 106 pts also had x-ray contrast arteriography. Their angiograms were reviewed at a core lab by expert cardiologists, who quantified coronary artery stenosis by planimetry. Results: Inter-rater agreement of global CFC values with maximum regional CFC values demonstrated “good agreement” (κ = 0.78). Categorizing the 231 pts by abnormal global CFC \u0026 any abnormal individual regional CFC agreed significantly (χ2 = 128.4, p 4 \u0026 those with abnormal regional CFC (Δ = 5%, p = 0.13), but more pts had global SSS \u003e 4 than had abnormal global CFC (Δ = 29%, p 70% was similar when identified by any abnormal regional CFC (Δ = 2%, p = 0.63), but more pts had an arterial stenosis \u003e 70% than had abnormal global CFC (Δ = 23%, p Conclusions: Anatomic (\u003e70% stenosis) \u0026 functional (regional perfusion abnormalities \u0026 LV asynchrony) evidence of myocardial ischemia correspond more closely to regional than global abnormalities of CFC. This suggests that territorial, rather than global, CFC values may potentially have greater value for identifying risk for future cardiovascular events.