Abstract
BACKGROUND: Within normal variation, higher haemoglobin (Hb) levels are associated with unhealthier body composition, adverse metabolism and cardiovascular disease (CVD)-related mortality. Global longitudinal strain (GLS) is a direct, well validated and reproducible echocardiographic measure for the evaluation of cardiac contractile function, providing additional prognostic value for prediction of a variety of cardiac events. This study investigated the relation between Hb levels and cardiac function measures, including GLS, in a Finnish midlife population. MATERIALS AND METHODS: Echocardiography was carried out in a subpopulation of the Northern Finland Birth Cohort 1966 at age of 46 (n = 1155). GLS was available for n = 796. Subjects with diabetes, severe cardiac diseases, echocardiographic abnormalities, heart rate ≥85 bpm during echocardiography or Hb level outside the Finnish reference intervals (117-155 g/L for females and 134-167 g/L for males) were excluded from the analysis. The study population included 635 subjects (46% males). The data were analysed in Hb tertiles and in multivariable linear regression models. RESULTS: The highest Hb tertile had adverse anthropometric and metabolic parameters compared to other Hb tertiles. Of the studied echocardiographic parameters, the highest Hb tertile had the highest left ventricular mass (LVM, p < .01), LVM index (LVMi, p < .05), LV end-diastolic volume (LVEDV, p < .05), posterior wall thickness (PWT, p < .001), relative wall thickness (RWT, p < .05) and the lowest absolute GLS (p < .001) but no difference in LV ejection fraction (LVEF) was observed between the Hb tertiles. In linear models, when adjusted for covariates, Hb levels were associated positively and independently with GLS (B = 0.153 [0.071; 0.235]) and LVM (B = 0.272 [0.193; 0.350]). CONCLUSIONS: Higher Hb levels are associated with an adverse metabolic and inflammatory profile and more adverse cardiac function measures, including GLS, in both sexes in midlife.