Investigating the association of cardiovascular risk factors to baseline breath-hold heterogeneity of myocardial oxygenation- a study using oxygenation-sensitive cardiovascular magnetic resonance

Abstract Background Myocardial oxygenation changes observed with Oxygenation-Sensitive Cardiovascular Magnetic Resonance (OS-CMR) during vasoactive breathing manoeuvres are a validated marker for coronary vascular function across multiple cardiovascular pathologies. Previous literature has measured myocardial oxygenation markers derived from a prolonged breath-hold following paced hyperventilation. This study aimed to assess myocardial oxygenation responses during a brief breath-hold, without hyperventilation, as a marker for vascular function associated with cardiovascular risk factors. Purpose To assess the utility of OS-CMR with a brief breath-hold to identify markers of vascular function associated with cardiovascular risk factors. Methods This was a cross-sectional, single-centre study recruiting sex- and age-matched healthy controls and individuals with metabolic risk factors (≥3) but no overt cardiovascular disease. All subjects underwent an OS-CMR exam on a 3T Signa Premier scanner, including a brief breath hold (10s). Myocardial contours were generated using an automated algorithm of a certified software, while signal intensity parameters were extracted using a custom Python script. The script also calculated heterogeneity as defined by myocardial signal entropy, i.e. the inter-pixel standard deviation in images across the cardiac cycle. T tests with Bonferroni correction were used to evaluate between-group differences, and multiple linear regression analyses within each group were used to explore the association of risk factors with heterogeneity. Results 34 healthy controls (50% female, mean age 55±10 years) and 34 at-risk individuals (50% female, mean age 55±10 years) were studied. Myocardial signal entropy across the baseline breath-hold was significantly reduced in the at-risk group (124±7.49) compared to healthy controls (136±5.7, p