Interrelationship Between Cardiopulmonary Exercise Testing Indices and Markers of Subclinical Cardiovascular Dysfunction in Those with Type 2 Diabetes—An Observational Cross-Sectional Analysis

<b>Purpose</b>: While peak oxygen uptake (V.O_2peak) is the gold standard method for assessing exercise tolerance, there is a tendency for underestimation. Several other cardiopulmonary exercise testing (CPET) variables may provide additive prognostic value beyond V.O_2peak alone. The aim of this study was to examine if alternative CPET indices of exercise tolerance are (a) impaired in people with T2D and (b) independently associated with measures of cardiovascular structure and function measured via echocardiography and cardiac MRI. <b>Methods</b>: Participants with type 2 diabetes (T2D) and healthy controls underwent cardiac magnetic resonance imaging, transthoracic echocardiography, and a CPET. Multiple linear regression was used to determine the relationship between indices of exercise tolerance and markers of cardiovascular structure and function. <b>Results</b>: A total of 84 people with T2D and 36 healthy volunteers were included in the analysis. All CPET outcomes were worse in those with T2D vs. the controls. Three CPET outcomes were associated with markers of cardiovascular structure and function: V.O₂ recovery with mean aortic distensibility (β = 0.218, <i>p</i> = 0.049); heart rate recovery with early filling velocity on transmitral Doppler/early relaxation velocity (β = -0.270, <i>p</i> = 0.024), left ventricular mass/volume ratio (β = -0.248, <i>p</i> = 0.030) and mean aortic distensibility (β = 0.222, <i>p</i> = 0.029); and V.O₂ at the ventilatory threshold with myocardial perfusion reserve (β = 0.273, <i>p</i> = 0.018). <b>Perspective</b>: These lesser-used CPET indices could be used to identify which people with T2D are at elevated risk of progression to symptomatic heart failure. However, larger longitudinal studies are required to confirm these findings and their potential clinical application.