MR augmented cardiopulmonary exercise testing—a novel approach to assessing cardiovascular function

The purposes of this study were: (1) to evaluate feasibility and acceptability of MRI augmented cardiopulmonary exercise testing (MR-CPET) in healthy adults and (2) to test whether peak values obtained at conventional and MR-CPET correlate and to demonstrate variation in peak oxygen consumption (VO₂) relates to both peak cardiac output (CO) and peak oxygen extraction (ΔcO₂). Seventeen healthy adults underwent CPET and MR-CPET using an MR compatible ergometer and CPET system customised for MR use. Continuous aortic flow measurement used a validated UNFOLD-SENSE spiral phase contrast magnetic resonance (PCMR) sequence.Fifteen of 17 volunteers completed exercise; exclusions were due to claustrophobia and inability to effectively master exercise technique. Measures of acceptability were lower but still satisfactory for MR-CPET.There were strong correlations between conventional and MR-CPET for peak VO₂ (r = 0.94, p < 0.001); VCO₂ (r = 0.87, p < 0.001) and VE (r = 0.88, p < 0.001).Multiple linear regression analysis demonstrated peak CO and ΔcO₂ were independent predictors of peak VO₂ measured during MR-CPET (β = 0.73 and 0.38 p < 0.0001) and conventional CPET (β = 0.78, 0.28 p < 0.0001).MR-CPET is feasible, acceptable and demonstrates physiology not apparent with conventional CPET. MR-CPET allows differentiation of the contributions of CO and ΔcO₂ to variation in peak VO₂. We believe that this will be useful in understanding the origin of reduced exercise capacity in cardiac disease. (note)