Abstract 15207: Stroke Volume and Cardiac Index at Exercise as Measured by Cardiac Magnetic Resonance Predicts Metabolic Exercise Performance
Background: Single ventricle pts with Fontan palliation are known to have decreased exercise (Ex) performance. However, mechanisms of this limitation are still poorly understood. We wished to study the relationship between ventricular performance and Ex capacity in Fontan pts using a cardiac magnetic resonance (CMR) Ex protocol.
Methods: Fontan pts who previously had standard graded metabolic Ex testing (MET) to evaluate metrics at peak Ex and anaerobic threshold (AT), underwent a resting CMR that included both segmented short axis cine images and real-time (RT) cine imaging to quantify end-diasotlic (EDV), end-systolic (ESV), and stroke (SV) volumes, ejection fraction (EF) and indexed ventricular output (CI). Pts then underwent a graded Ex protocol on a supine ergometer to achieve the heart rate associated with AT on prior MET. Real-time measurements were repeated immediately after Ex. Resting RT and segmented data were compared using intraclass correlation. VO2 at AT and peak Ex were indexed to body weight and compared with resting and Ex volumetric data using Pearson correlation.
Results: 30 pts age 16.2 years (range 12.7-41.9) had a mean EF of 67% (47-85%) at rest and 74% (53-87%) at Ex (p<0.001). There was excellent agreement between segmented and RT resting EDV (ICC=0.95, p<0.001), ESV (ICC=0.92, p<0.001), and EF (ICC=0.87, p<0.001). There was significant correlation between VO2 at AT and 1) RT Ex SV (top figure), 2) CI at Ex (bottom figure) and 3) change in CI from rest to Ex (r=0.42, p=0.029). There was no significant correlation between EDV, ESV, or EF at rest or Ex with any MET parameter.
Conclusions: We present preliminary data demonstrating that real time cine imaging by CMR can characterize single ventricle performance at rest and exercise. In addition, we show that MET performance at AT correlates with SV and CI at Ex, as well as change in CI. This suggests Ex CMR better predicts exercise capacity than resting data in single ventricle pts.
- © 2013 by American Heart Association, Inc.