ABSTRACT
BACKGROUND: The aim of this study was to assess contractile reserve (CR) in patients with severe aortic regurgitation (AR), and potential clinical applications of CR in minimally symptomatic patients. METHODS AND RESULTS: Symptom-limited treadmill exercise echocardiography was performed in 58 asymptomatic or mildly symptomatic patients with chronic severe AR (male 69%, 50±14 years). Patients with increased ejection fraction (EF) after exercise were denoted as having CR (+) and those without increased EF were categorized as CR (-). CR (+) was found in 31 and CR (-) in 27 patients. Compared with CR (+), the CR (-) group had lower EF, larger effective regurgitant orifice, regurgitant volume, left ventricular (LV) end-diastolic dimension, LV end-systolic dimension (LVESD), and LV mass index. On multiple logistic regression analysis LVESD index (LVESDI; odds ratio -0.354, P<0.0001) was an independent predictor of CR. One-third of patients with LVESD >50mm, however, were found to be CR (+), while one-third of patients with smaller LVESD were CR (-). CONCLUSIONS: Although CR is best related to baseline resting LVESDI, one-third of patients were found to have discordance between the presence of CR and the LV dimension recommended for aortic valve replacement (AVR) in minimally symptomatic patients with severe AR, suggesting that exercise test may be able to further stratify the current guideline for AVR.