A 62-year-old man undergoes left ventricular pressure-volume loop analysis during cardiac catheterisation. Before an intervention, his end-diastolic volume is 140 mL and his end-systolic volume is 60 mL. After a sudden rise in aortic pressure from 100 to 140 mmHg, end-diastolic volume is 142 mL and end-systolic volume is 82 mL, with no change in the slope of the end-systolic pressure-volume relation. Which mechanism best explains these findings?
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