Abstract 12315: Which is More Important as a Cause for Exercise Intolerance, Chronotropic Incompetence or Left Ventricular Diastolic Dysfunction?
Exercise intolerance is generally considered to be associated with left ventricular (LV) diastolic dysfunction (DD). Chronotropic incompetence (CI) which is common in patients with cardiovascular disease also produces exercise intolerance. Accordingly, we investigated which parameter is more explainable for exercise intolerance in patients with preserved LV ejection fraction.
Methods: We studied 360 subjects who referred to exercise stress testing for clinical reasons (age 66.0±13.8 years; male 59.4%). All patients had preserved LV ejection fraction (>50%). Patients who were taking β-blockers were excluded. We evaluated the patients with standardized cardio-pulmonary exercise testing (CPX) including the analysis for oxygen uptake at peak exercise (peak VO2). Before testing, we performed comprehensive Doppler echocardiography including the measurements of early diastolic transmitral flow velocity (E) and mitral annular velocity during early diastole (e’). Chronotropic response index ≤80% was defined as CI. The E/e’ ratio>13 was defined as DD.
Results: Peak VO2 significantly correlated with the E/e’ ratio (r=-0.16, p=0.003), age (r=-0.55, p ≤0.001), female gender (r=-0.31, p≤0.001), body mass index (r=-0.22, p ≤0.001), and maximum reached heart rate (r=0.57, p ≤0.001). Patients without CI (n=194) had significantly higher peak VO2 than those with CI (n=166) (23.5±6.4 vs 19.3±5.7, ml/kg/min, p≤0.001). However, there were no significant differences in the E/e’ ratio between patients with CI and without CI (7.5±2.4vs7.7±2.6, p=0.36). In multiple logistic regression analysis, age (OR 6.1, 95%CI 3.4-11.0, p≤0.001), female gender (OR 5.8, 95%CI 3.1-10.9, p≤0.001), body mass index (OR 3.7, 95%CI 1.8-7.8, p≤0.001), DD (OR 3.8, 95%CI 1.1-13.2, p=0.03), and CI (OR 3.3, 95%CI 1.8-5.8, p≤0.001) significantly contributed to exercise intolerance.
Conclusions: CI may be related to exercise intolerance independently of LV DD. Both CI and DD are the crucial factors to explain exercise intolerance in patients with preserved LV ejection fraction.
- © 2013 by American Heart Association, Inc.