Assessing exercise cardiac reserve using real-time cardiovascular magnetic resonance

Background: exercise cardiovascular magnetic resonance (excmr) has great potential for clinical use but its development has been limited by a lack of compatible equipment and robust real-time imaging techniques. we developed an excmr protocol using an in-scanner cycle ergometer and assessed its performance in differentiating athletes from non-athletes. methods: free-breathing real-time cmr (1.5t aera,siemens) was performed in 11 athletes (5 males; median age 29 [iqr: 28-39] years) and 16 age- and sex-matched healthy volunteers (7 males; median age 26 [interquartile range (iqr): 25-33] years). all participants underwent an in-scanner exercise protocol on a cmr compatible cycle ergometer (lode bv,the netherlands),with an initial workload of 25w followed by 25w-increment every minute. in 20 individuals,exercise capacity was also evaluated by cardiopulmonary exercise test (cpet). scan-rescan reproducibility was assessed in 10 individuals,at least 7 days apart. results: the excmr protocol demonstrated excellent scan-rescan (cardiac index (ci): 0.2 ± 0.5l/min/m2) and inter-observer (ventricular volumes: 1.2 ± 5.3ml) reproducibility. ci derived from excmr and cpet had excellent correlation (r = 0.83,p < 0.001) and agreement (1.7 ± 1.8l/min/m2). despite similar values at rest (p = 0.87),athletes had increased exercise ci compared to healthy individuals (at peak exercise: 12.2 [iqr: 10.2-13.5] l/min/m2 versus 8.9 [iqr: 7.5-10.1] l/min/m2,respectively; p < 0.001). peak exercise ci,where image acquisition lasted 13-17 s,outperformed that at rest (c-statistics = 0.95 [95% confidence interval: 0.87-1.00] versus 0.48 [95% confidence interval: 0.23-0.72],respectively; p < 0.0001 for comparison) in differentiating athletes from healthy volunteers; and had similar performance as vo2max (c-statistics = 0.84 [95% confidence interval = 0.62-1.00]; p = 0.29 for comparison). conclusions: we have developed a novel in-scanner excmr protocol using real-time cmr that is highly reproducible. it may now be developed for clinical use for physiological studies of the heart and circulation. © 2017 the author(s).