Myocardial perfusion and oxidative metabolism in healthy subjects: sex-specific insights from vasodilatory stress 11C-acetate PET.

Abstract

Background: ¹¹C-acetate positron emission tomography (PET) enables simultaneous quantification of myocardial blood flow (MBF) and oxidative metabolism; however, sex-specific normative data under vasodilator stress remain insufficiently defined. We aimed to characterize these parameters in healthy individuals.

Results: Eighteen healthy individuals (9 males and 9 females, age/sex-matched; median age 43 years [range 34-65]) with normal echocardiography and no underlying cardiovascular disease underwent one-day rest-stress dynamic ¹¹C-acetate PET with adenosine. Median stress MBF was 2.73 (2.24-3.11) mL/min/g and rest MBF 0.99 (0.82-1.14) mL/min/g. Stress kmono was 0.074 (0.063-0.082)/min, and rest kmono was 0.061 (0.050-0.068)/min. External cardiac work, total myocardial oxygen consumption (MVO₂), and MEE were 4.24 (3.75-5.54) × 10⁵ mL·mmHg/min, 16.5 (14.9-20.9) mL/min, and 17.7% (14.0-24.2%), respectively. Compared to males, females exhibited significantly higher corrected rest MBF (1.14 vs. 0.96 mL/min/g, p = 0.032), stress kmono (0.078 vs. 0.070 /min, p = 0.005), and total MVO₂ (17.6 vs. 15.5 mL/min, p = 0.003). Despite similar external cardiac work, myocardial external efficiency was significantly lower in females (15.5% vs. 20.3%, p = 0.009). MBF and oxidative metabolism were positively correlated in both sexes.

Conclusions: This study assesses reference ranges and demonstrates significant sex-based differences in myocardial perfusion and oxidative metabolism using vasodilatory stress ¹¹C-acetate PET. These findings provide a valuable physiological framework for assessing perfusion-metabolism abnormalities in clinical practice.