Peak exercise-to-recovery changes in biventricular volumes and function assessed by exercise cardiovascular magnetic...

Exercise cardiovascular magnetic resonance (Ex-CMR) assesses cardiac function under physiological stress. Imaging during continuous in-bore exercise reflects peak physiology but is challenging, prone to motion artefacts and patient discomfort. Exercise performed outside the scanner followed by rapid post-exercise imaging improves feasibility and image quality, but the time course of ventricular volume recovery after exercise cessation remains poorly defined. We compared biventricular Ex-CMR measurements during steady-state peak exercise with those acquired sequentially after exercise termination.

Ten healthy adults [24 (21-31) years; 8 female] underwent Ex-CMR on a 3T system. Biventricular volumes were assessed using a free-breathing, electrocardiogram-triggered, highly accelerated multi-slice cine sequence with compressed sensing and deep learning-based reconstruction. Short-axis stacks were acquired at rest, during two steady-state peak exercise acquisitions, and at three sequential post-exercise timepoints, with the first recovery scan beginning 10-15 s after cessation. Linear mixed-effects models evaluated recovery categorically and as a function of elapsed time. Differences between repeated peak acquisitions were small [left ventricular (LV) end-diastolic volume +1 ± 3 mL; LV end-systolic volume -4 ± 7 mL]. Immediately after cessation (13 ± 2 s), biventricular volumes remained unchanged vs. peak (all P = 1.00). Significant recovery-related changes emerged by 54 ± 9 s and were present for all parameters by 99 ± 18 s. Linear modelling showed LV stroke volume declining 2.1 mL (-1.9%) per 10 s, with similar right-ventricular trends. Post-exercise acquisitions showed higher diagnostic quality and fewer artefacts than in-bore imaging.

Biventricular volumes measured immediately after exercise closely approximate peak physiology, whereas recovery changes occur rapidly and linearly thereafter. Rapid post-exercise acquisition offers a practical surrogate for peak measurements while improving image quality.