Aortic flow is associated with aging and exercise capacity

Abstract

Aims: Increased blood flow eccentricity in the aorta has been associated with aortic (AO) pathology, however, its association with exercise capacity has not been investigated. This study aimed to assess the relationships between flow eccentricity parameters derived from 2-dimensional (2D) phase-contrast (PC) cardiovascular magnetic resonance (CMR) imaging and aging and cardiopulmonary exercise test (CPET) in a cohort of healthy subjects.

Methods and results: One hundred and sixty-nine healthy subjects (age 44 ± 13 years, M/F: 96/73) free of cardiovascular disease were recruited in a prospective study (NCT03217240) and underwent CMR, including 2D PC at an orthogonal plane just above the sinotubular junction, and CPET (cycle ergometer) within one week. The following AO flow parameters were derived: AO forward and backward flow indexed to body surface area (FFi, BFi), average flow displacement during systole (FDs_avg), late systole (FDls_avg), diastole (FDd_avg), systolic retrograde flow (SRF), systolic flow reversal ratio (sFRR), and pulse wave velocity (PWV). Exercise capacity was assessed by peak oxygen uptake (PVO₂) from CPET. The mean values of FDs_avg, FDls_avg, FDd_avg, SRF, sFRR, and PWV were 17 ± 6%, 19 ± 8%, 29 ± 7%, 4.4 ± 4.2 mL, 5.9 ± 5.1%, and 4.3 ± 1.6 m/s, respectively. They all increased with age (r = 0.623, 0.628, 0.353, 0.590, 0.649, 0.598, all P < 0.0001), and decreased with PVO₂ (r = -0.302, -0.270, -0.253, -0.149, -0.219, -0.161, all P < 0.05). A stepwise multivariable linear regression analysis using left ventricular ejection fraction (LVEF), FFi, and FDs_avg showed an area under the curve of 0.769 in differentiating healthy subjects with high-risk exercise capacity (PVO₂ ≤ 14 mL/kg/min).

Conclusion: AO flow haemodynamics change with aging and predict exercise capacity.

Registration: NCT03217240.

Keywords: 2D phase-contrast; Aortic flow; Cardiopulmonary exercise testing; Flow displacement; Haemodynamics.