Does hemoglobin concentration independently affect resting and stress myocardial blood flow or myocardial flow reserve in patients with chronic coronary syndromes?
Hemoglobin concentration affects resting but not stress myocardial blood flow, suggesting stress MBF is a more reliable measure of maximal coronary flow capacity than MFR in patients with anemia.
BACKGROUND: Anemia is a prognostic factor in chronic coronary syndromes (CCS), but its impact on quantitative myocardial perfusion and potential sex differences remains unclear. We investigated whether hemoglobin concentration (Hb) independently affects resting and stress myocardial blood flow (MBF) or myocardial flow reserve (MFR). METHODS: O-water positron emission tomography (PET) and had available Hb data. PET parameters included resting and stress MBF, MFR, and forward stroke volume index (FSVi), calculated by dividing cardiac index derived from the indicator dilution technique by heart rate. Multivariable regression and mediation analyses were performed to determine the independent influence of Hb. RESULTS: = .66). In mediation analysis, the association between Hb and resting MBF was mainly direct, with partial mediation by FSVi only in females, and no mediation by heart rate or SBP. Hb was not associated with stress MBF in any sex (P ≥ .17). Anemia was associated with a higher proportion of low MFR (<2.5) despite normal stress MBF (20.9% vs. 9.3%, P = .004). CONCLUSIONS: Hemoglobin concentration affects resting myocardial blood flow but not stress MBF, indicating stress MBF may serve as a more robust and reliable measure of maximal coronary flow capacity than MFR, particularly in patients with anemia.
Svanström et al. (Thu,) studied this question.