Abstract 2915: The Usefulness of Exercise Stress Tissue Velocities in Predicting Cardiopulmonary Performance in Cardiac Patients and Healthy Individuals
Background Myocardial function determines tissue oxygen delivery and thus exercise capacity. The relationship of myocardial wall motion and oxygen uptake during exercise needs further study.
Methods Forty six subjects (28 male) were studied: healthy (n = 17, age 43+/20 yrs), heart failure (CHF) (n - 17, age 76+/8 yrs, NYHA III/IV) and atrial fibrillation (AF) (n = 12, age 73+/9 yrs). Exercise testing was performed using a cycle ergometer. Apical pulsed wave tissue velocity traces for the anterior, inferior, septal and lateral walls were taken at the mitral annulus (GE System V). Longitudinal systolic myocardial velocities for the left ventricle were averaged for rest (rVel) and peak exercise (pVel). Peak oxygen uptake (VO2 peak) was measured using a Jaeger Oxycon system. Changes in myocardial velocities (ΔVel) and oxygen uptake (ΔVO2) from rest to peak exercise were calculated.
Results Significant differences between groups were found for rVel, pVel, ΔVel, VO2 peak and ΔVO2 (p < 0.001). Significant relationships using linear regression were found between rVel and VO2 peak (r2 = 0.489, p < 0.001), pVel and VO2 peak (r2 = 0.790, p < 0.001), ΔVel and VO2 peak (r2 = 0.760, p < 0.001), ΔVel and ΔVO2 (r2 = 0.759, p < 0.001). Multiple regression analysis showed pVel to be the best predictor of VO2 peak (see figure⇓). pVel but not LVEF or ΔVel showed a significant (p < 0.05) relationship with pVO2 in the healthy and AF groups but not CHF.
Conclusion Contractile reserve as measured by exercise peak systolic tissue velocity can be used as a marker for VO2 peak and exercise capacity in healthy individuals and AF patients. This relationship was not seen in the heart failure patients with limited contractile reserve.