Abstract
Background: Cardiovascular magnetic resonance imaging (CMR) represents the gold standard for routine examination of cardiac function and structure evaluation at rest and during exercise as well. Conventional stress CMR includes drug administration to increase heart rate (HR). The recently developed MR-conditional cardio stepper (CS) could be an alternative for real time stress CMR. So far, no data on cardiorespiratory responses exist for this device. Thus, this study evaluated cardiorespiratory responses to exhaustive testing on the CS compared to cycle and treadmill ergometry.
Methods: Forty-six healthy participants (24 men, 22 women, age: 31.4 ± 8.9 yrs, height: 174.8 ± 7.2 cm, weight: 70.3 ± 9.4 kg) performed three incremental exercise tests to volitional failure in a randomized crossover trial.
Results: Maximal values using the CS were significantly lower when compared to cycle and treadmill ergometry (HRmax: 170 ± 13 vs. 186 ± 9 vs. 190 ± 11 bpm, respectively; p<0.05, maximal oxygen uptake: 2971 ± 772 vs. 3531 ± 1023 vs. 3849 ± 1013 ml/min, respectively; p<0.05 and exercise duration: 539 ± 130 vs. 745 ± 157 vs. 710 ± 128 sec, respectively; p<0.05).
Conclusions: Although cardiorespiratory responses are not maximal when using the CS, the target heart rate, i.e. >85% of HRmax, for a stress CMR can be achieved.