LVAD Pump Speed Increase is Associated With Increased Peak VO2 and Lower Cardiogenic Exercise Limitation

BACKGROUND: In patients affected by hearth failure (HF) one of the major determinants of quality of life is functional limitation during effort. Oxygen uptake at peak exercise (VO2 peak) assessed through cardiopulmonary test (CPET) is nowadays a strong prognostic predictor in HF and it is also commonly used to monitor patients\u2019 functional status. As per present literature, a change of speed in left ventricular assistance device (LVAD) at rest causes a variation in CO, but is not related to better exercise capacity. In the present analysis, we tested the hypothesis that the change of pump speed during exercise in patients wearing LVAD might be associated with a better exercise performance. METHODS: We enrolled 16 HF patients (100% males, mean age 63.8\ub18.3 years) all wearing LVAD (Jarvik 2000). Each patient performed on different days two maximal workload CPETs, one at LVAD speed 3 (basal speed CPET) and one performed increasing the LVAD speed during exercise from 3 to 4 and then to 5, respectively at 30 and 60% of total workload previous gain at basal CPET (increased speed CPET). Before and after each test, pulmonary function test and diffusion lung capacity with carbon dioxide and nitric oxide (DLCO-DLNO) were performed. RESULTS: Comparison between basal speed and increased speed CPETs reveals a higher VO2 peak from 11.9\ub12.7 to 12.8\ub12.4 ml/Kg/min (p<0.01), confirmed also assessing peak VO2 as absolute or % of predicted value. Peak VO2 increased in absence of significative changes in heart rate and peak workload. VO2/work relationship increased from 9.4\ub11.8 to 10\ub11.6 mk/Kg/min/watt (p<0.01), which confirms lower cardiogenic limitation to exercise. On the other hand, no differences were observed in anaerobic threshold, ventilatory parameters during exercise and DLCO-DLNO analysis. CONCLUSIONS: In patients wearing LVAD, a LVAD pump speed increase during exercise leads to a better functional performance mainly related to an improvement of cardiogenic limitation to exercis