A novel protocol to calculate non-invasive cardiac energetics using exercise MRI

Abstract Introduction Cardiac power would be an objective, quantitative, and clinically useful assessment of cardiac function but is not used because it requires simultaneous ventricular pressure and volume data. Furthermore, research studies of cardiac power neglect exercise, which is precisely when patients with cardiovascular disease experience symptoms and limitations. Purpose To develop a novel experimental and computational modelling methodology to quantify cardiac power during exercise MRI in healthy volunteers, establishing a baseline for patient assessments. Methods Seven healthy volunteers were recruited. Cardiac MRI images were acquired at rest and three incremental levels of exercise. Exercise levels were determined at a fixed interval of the max HR (220-age) minus resting HR. At each state, short-axis stack (SAX), coronary sinus (CS) flow and chamber views were acquired. Figure one shows the schematic of the planned exercise test. Non-invasive BP was taken from a brachial sphygmomanometer and the pressure reconstructed using an assumed elastance. Changes in energetics were compared to trends in literature. Results ESV decreased and ESP increased with exercise intensity, in line with relative changes from multigated blood pool studies (ESV: 59±17 ml, 61±18 ml, 50±18 ml, 37±14 ml*; ESP: 102±8 mmHg, 109±9 mmHg, 113±11 mmHg, 124±15 mmHg, *significant to P