Ventilatory Efficiency and Oscillatory Breathing As Clinical Markers of Surgical Outcomes in Heart Failure

Abstract

BackgroundVentilatory efficiency (Ve/VCO2) and oscillatory breathing (OB) during exercise have been shown to be important predictors of long‐term survival in patients with chronic systolic heart failure (CHF). However, the status of Ve/VCO2 and OB in patients after undergoing heart transplant (HT) or left ventricular assist device (LVAD) implant is less clear. The aim of this study was to assess the outcomes of HT or LVAD implantation on Ve/VCO2 and OB. We hypothesized that Ve/VCO2 and OB are improved (i.e. decreases in Ve/VCO2 slope and breathing interval variability) after HT and LVAD and that these changes correlate with improved exercise tolerance (6 minute walk).MethodsCardiopulmonary exercise test (CPET) data were retroactively analyzed for Ve/VCO2 slope and OB (coefficient of variability of breath interval) during progressive treadmill exercise from eight CHF patients: HT (n=4), and LVAD (n=4). Sample size was restricted due to insufficient CPET data in most HT/LVAD patient records at the time of analysis.ResultsWe found that Ve/VCO2 was reduced in three patients in each group after the intervention [LVAD: 38 ± 6.1(SD) before vs. 34 ± 3 after (6 % improvement) n =4] [HT: 45 ± 17 before vs. 35 ± 6 after (12 % improvement) n= 4]. The reduction in Ve/VCO2 in the three patients from each group correlated with a reduction in exercise OB. One patient in each group exhibited increased Ve/VCO2 and OB after the intervention. Overall, the direction and magnitude of the change in Ve/VCO2 correlated well with changes in OB for all patients (r2 = 0.70). There also was a correlation between improved VE/CO2 or OB and improved exercise tolerance (increased distance walked in 6 min).ConclusionsVe/VCO2 and OB were improved after LVAD or HT implant in the majority of CHF patients tested and correlated with improved exercise tolerance. Patients will be followed to determine long‐term survivability. Further analysis as additional CPET data becomes available will give a more complete picture of the efficacy of these measurements as diagnostically relevant markers of improved ventilatory function and long‐term outcomes in LVAD and HT patients.Support or Funding InformationNIH PO1‐HL62222