Females have higher myocardial perfusion, blood volume and extracellular volume compared to males - an adenosine stress cardiovascular magnetic resonance study

Knowledge on sex differences in myocardial perfusion, blood volume (MBV), and extracellular volume (ECV) in healthy individuals is scarce and conflicting. Therefore, this was investigated quantitatively by cardiovascular magnetic resonance (CMR). Healthy volunteers (n=41, 51% female) underwent CMR at 1.5T. Quantitative MBV [%] and perfusion [ml/min/g] maps were acquired during adenosine stress and at rest following an intravenous contrast bolus (0.05mmol/kg, gadobutrol). Native T1 maps were acquired before and during adenosine stress, and after contrast (0.2mmol/kg) at rest and during adenosine stress, rendering rest and stress ECV maps. Compared to males, females had higher perfusion, ECV, and MBV at stress, and perfusion and ECV at rest (p<0.01 for all). Multivariate linear regression revealed that sex and MBV were associated with perfusion (sex beta -0.31, p=0.03; MBV beta -0.37, p=0.01, model R-2=0.29, p<0.01) while sex and hematocrit were associated with ECV (sex beta -0.33, p=0.03; hematocrit beta -0.48, p<0.01, model R-2=0.54, p<0.001). Myocardial perfusion, MBV, and ECV are higher in female healthy volunteers compared to males. Sex is an independent contributor to perfusion and ECV, beyond other physiological factors that differ between the sexes. These findings provide mechanistic insight into sex differences in myocardial physiology.