Cardiopulmonary Exercise Testing Combined With Stress Echocardiography for the Evaluation of Myocardial Dysfunction...

In pediatric cardiology, stress echocardiography is rarely used, even though it is an established tool for investigating myocardial dysfunction due to coronary insufficiency, a threat in children after arterial switch operation (ASO) or Kawasaki disease (KD). This study combines stress echocardiography with cardiopulmonary exercise testing in this cohort.

The participants in this study were recruited from a cohort of patients after ASO or KD. An age- and sex-matched control group was recruited from university students and school children from nearby schools. All undertook a cardiopulmonary exercise testing either on a tilt-recline cycle ergometer or on a treadmill with intermittent echocardiography. The echocardiographic examination consisted of global longitudinal strain measurements of the left ventricle as parameters of left ventricular function. In addition to the standard cardiopulmonary exercise parameters (peak oxygen consumption, peak heart rate, O2pulse, oxygen uptake efficiency slope, V˙E/V˙CO2-slope, and others), the behavior of the O2pulse before and after the end of exercise was evaluated.

Overall, 43 participants were recruited (20 ASO, mean age: 14.7 y, 8 females; 10 KD, mean age: 15.0 y, 3 females; 13 controls, mean age: 15.7 y, 5 females). The patients after ASO showed a significantly lower peak cardiopulmonary function (V˙O2peak: 39.6 vs 45.9 mL/kg/min) than the control group. When combined (KD and ASO patients), the first ventilatory threshold as well as the decline of the O2pulse during recovery were significantly lower than in the control group. There were no differences with respect to the echocardiographic parameters.

The lower peak oxygen consumption observed in the ASO group point to a lower cardiopulmonary function. The lower oxygen consumption at first ventilatory threshold can be an indicator of poorer endurance. Even though the ventricular function recorded using echocardiography showed no significant decrease, the slower recovery of the O2pulse during recovery could point to an impairment in cardiac output during exercise as the O2pulse is a surrogate parameter of cardiac output at peak exercise.