Abstract 19080: Peak Exercise Capacity is a Poor Indicator of Functional Capacity for Patients Supported by a Continuous Flow Left Ventricular Assist Device
Introduction: Six minute walk distance (6MWD) has been shown to be linearly related to peak oxygen uptake (VO2) during maximal exercise for patients suffering from heart failure (HF); however, this relationship in patients supported by left ventricular assist devices (CF-LVAD) is not well understood.
Hypothesis: CF-LVADs readily support sub-maximal exercise such as walking, but this improvement is not accompanied by increased maximal exercise capacity due to relatively fixed cardiac output assistance provided by the LVAD.
Methods: Forty patients with HF and 29 patients supported by LVADs performed a 6-minute walk test and a maximal cardiopulmonary exercise test.
Results: The peak VO2 was linearly correlated with 6MWD in both HF (r=0.58, p<0.001) and LVAD patients (r=0.53, p=0.003). While the slopes were similar, b=0.025 and b=0.029 for CHF and LVAD, respectively, patients with HF had a greater peak VO2 than patients supported by LVADs who achieved the same 6MWD. CF-LVAD patients walked approximately 80 meters more than HF patients in a 6-minute walk test for any given peak VO2.
Conclusions: For any given peak VO2, patients supported by LVAD may have a greater functional capacity than HF patients. Peak VO2 should not be used as an outcome variable in clinical trials assessing functional capacity after LVAD implantation.
- © 2013 by American Heart Association, Inc.