Is hyperdynamic circulation a hallmark of obesity?

Background: Obesity is a major contributor to cardiovascular disease. Although altered central hemodynamics have been reported in obesity, studies are few, small, and limited to specific populations, leaving these changes underrecognized. This study investigates the association between body mass index (BMI) and central hemodynamics in a large cohort of adult patients admitted for medical reasons. We hypothesized that higher BMI is associated with increased cardiac index (CI) and reduced systemic vascular resistance (SVR), reflecting a hyperdynamic circulatory state. Methods: This is a cross-sectional study of adults admitted to the Emergency Department at a large tertiary care hospital in Copenhagen, Denmark during 2019–2023. Patients were evaluated by physical examination and laboratory testing. Hemodynamic measurements, including CI and SVR, were estimated within 24 hours of admission using the non-invasive and continuous pulse wave analysis by Finapres® NOVA. The relationship between BMI, CI, and SVR were investigated using linear regression models. Results: Of 942 participants (mean age 64 years; 44% female), 187 had obesity (BMI ≥ 30 kg/m²). Compared to participants without obesity, participants with obesity had 16% higher CI and 23% lower SVR (p < 0.0001). In linear regression models, BMI was positively associated with CI (p = 0.0001) and inversely with SVR (p = 0.0102). Each 5 kg/m² increase in BMI corresponded to a 7.7% rise in CI and a 12.7% decrease in SVR (p < 0.0001). Conclusion: Higher BMI is significantly associated with increased CI and decreased SVR, indicating a hyperdynamic circulatory state in obesity. These findings suggest a potential hemodynamic mechanism linking obesity to cardiovascular risk. Clinical trial registration: ClinicalTrials.gov (NCT03934775).