Coronary circulatory function with increasing obesity: A complex U‐turn

Abstract

Aims:The aim of this investigation was to explore and characterize alterations in coronary circulatory function in function of increasing body weight with medically controlled cardiovascular risk factors and, thus, "metabolically" unhealthy obesity. Materials and Methods:We prospectively enrolled 106 patients with suspected CAD but with normal stress-rest myocardial perfusion on 13 N-ammonia PET/CT and with medically controlled or no cardiovascular risk factors. 13 N-ammonia PET/CT concurrently determined myocardial blood flow (MBF) during pharmacologically induced hyperaemia and at rest. Based on body mass index (BMI), patients were grouped into normal weight (BMI: 20.0-24.9 kg/m 2 , n = 22), overweight (BMI: 25.0-29.9 kg/m 2 , n = 27), obese (BMI: 30.0-39.9 kg/m 2 , n = 31), and morbidly obese (BMI ≥ 40kg/m 2 , n = 26). Results:Resting MBF was comparable among groups (1.09 ± 0.18 vs. 1.00 ± 0.15 vs. 0.96 ± 0.18 vs.. 1.06 ± 0.31 ml/g/min; p = .279 by ANOVA). Compared to normal weight individuals, the hyperaemic MBF progressively decreased in in overweight and obese groups, respectively (2.54 ± 0.48 vs. 2.02 ± 0.27 and 1.75 ± 0.39 ml/g/min; p < .0001), while it increased again in the group of morbidly obese individuals comparable to normal weight (2.44 ± 0.41 vs. 2.54 ± 0.48 ml/g/ min, p = .192). The BMI of the study population correlated with the hyperaemic MBF in a quadratic or U-turn fashion (r = .34, SEE = 0.46; p ≤ .002). Conclusions:The U-turn of hyperaemic MBF from obesity to morbid obesity is likely to reflect contrasting effects of abdominal versus subcutaneous adipose tissue on coronary circulatory function indicative of two different disease entities, but needing further investigations.

Post COVID‐19 syndrome with impairment of flow‐mediated epicardial vasodilation and flow reserve

“… 7 Regional MBFs of the three main myocardial vascular territories subtended to the left anterior descending artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) were averaged on a polar map, and the resulting mean MBF of the LV was defined as global MBF. 7 Following, longitudinal flows, MBFs in the mid and mid‐distal myocardial segment of the LV corresponding to the vascular territories of the LAD (segments: 7–8 and 13–14), LCx (segments: 11–12 and 16), and RCA (segments: 9–10 and 15) were determined. 11 Basal segments (LAD: 1–2, LCx: 5–6, and RCA: 3–4) and the apical segment (LAD: 17), however, were not included for this analysis owing to a possible count variability induced by the membranous septum, by a certain variability in locating the last apical slice, and by partial volume errors resulting from object size at the apex.…”

“…Accordingly, patients with a SDS ≥2, suggestive of hemodynamically obstructive CAD lesions, were excluded from study analysis. For quantification of myocardial blood flow in ml/g/min, left ventricular (LV) contours and input function region were obtained automatically with minimal operator intervention using Corridor4DM software (Cardiac; 4DM PET CFR) version 2016 (INVIA Medical Imaging Solutions, Ann Arbor, MI) 7 . Regional MBFs of the three main myocardial vascular territories subtended to the left anterior descending artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) were averaged on a polar map, and the resulting mean MBF of the LV was defined as global MBF 7 .…”

“…Following the topogram used to determine the axial field of view and a low-dose CT scan (120 kV, 30 mA) for attenuation correction, 13 N-ammonia PET determined myocardial perfusion and MBF in mL/min/g with serial image acquisition and a two-compartment tracer kinetic model during regadenoson-stimulated hyperemia and at rest, respectively. 7,11 PET image acquisition was performed during regadenoson-stimulated hyperemia (0.4 mg intravenous bolus injection over 10 and 20 s interval) was started immediately following injection of ≈370 MBq 13 Nammonia as a bolus followed with immediate infusion of 10 ml saline solution over 30 sec (0.33 ml/sec) via fusion pump (e.g. Aitecs Syringe Pump) and also 40 min later at rest for a total duration of 10 min list-mode PET data Solutions, Ann Arbor, MI).…”

“…5 Assessment of left-ventricular (LV) myocardial blood flow (MBF) during pharmacologically stimulated hyperemia, at rest and the resulting myocardial flow reserve (MFR) with positron emission tomography (PET) is used clinically to evaluate for the presence of coronary microvascular dysfunction as potential functional substrate for microvascular angina. [7][8][9] Such noninvasively obtained information on hyperemic MBFs and MFR is also known to provide important prognostic information in patients with and without clinically-manifest coronary artery disease, ischemic and nonischemic cardiomyopathy. 8,10 More recently, PET flow assessment of an abnormal decrease in MBF from the base to the apex of the left ventricle during hyperemic flows, a so-called longitudinal flow gradient, has been applied to provide more detailed information on functional and/or structural alterations of epicardial artery in individuals with cardiovascular risk.…”

“…Assessment of left‐ventricular (LV) myocardial blood flow (MBF) during pharmacologically stimulated hyperemia, at rest and the resulting myocardial flow reserve (MFR) with positron emission tomography (PET) is used clinically to evaluate for the presence of coronary microvascular dysfunction as potential functional substrate for microvascular angina 7–9 . Such noninvasively obtained information on hyperemic MBFs and MFR is also known to provide important prognostic information in patients with and without clinically‐manifest coronary artery disease, ischemic and nonischemic cardiomyopathy 8,10 .…”