A significant number of patients with heart failure (HF) present with both diminished self-reported quality of life and perceived functional capacity. The Minnesota Living with HF Questionnaire (MLWHFQ) and the Duke Activity Status Index (DASI) are two validated and reliable tools that have been frequently used to quantify quality of life and functional capacity in this chronic disease population [1,2]. Previous research by our group has demonstrated that peak oxygen consumption (VO 2 ) is significantly correlated with both the MLWHFQ and DASI in HF patients [3,4]. Conversely, the VE/VCO 2 slope, an established marker of ventilatory efficiency in HF patients, is not associated with quality of life [4] and seemingly no information is available on its relationship to perceived functional capacity. Exercise oscillatory ventilation (EOV) has garnered great attention in recent years, demonstrating a robust ability to predict increased risk for adverse events and reflect disease severity [5,6]. To our knowledge, we are unaware of any previous investigation that has assessed the relationship between EOV and self-reported quality of life or perceived functional capacity, which is the purpose of the present study.Forty-six patients (33 males; mean age = 50 ± 14 years, mean left ventricular ejection fraction = 26.6 ± 10.7%) underwent cardiopulmonary exercise testing (CPX) using a conservative treadmill protocol. The ventilatory expired gas analysis system (SensorMedics Vmax29, Yorba Linda, CA) was calibrated before each test according to manufacturer specifications. Ten-second averaged minute ventilation data during rest and the entire exercise test was plotted using Microsoft Excel software (Microsoft, Seattle, WA). Exercise oscillatory ventilation was defined as an oscillatory pattern at rest that persisted for ≥60% of the exercise test at an amplitude of ≥15% of the average resting value [5]. Peak VO 2 was defined as the highest 10-second averaged value during CPX. Minute ventilation and VCO 2 values, acquired from the initiation of exercise to peak, were input into spreadsheet software (Microsoft Excel, Microsoft Corp., Seattle, WA) to calculate the VE/VCO 2 slope via least squares linear regression (y= mx + b, m = slope). Immediately prior to testing, all subjects completed the MLWHFQ and DASI. For the MLWHFQ, the ⁎ Corresponding author at: Physical Therapy Program, (R. Arena).overall, physical sub-score (sum of questions 2, 3, 6, 7,11,12, and 13), and psychosocial/symptomatology sub-score (sum of remaining questions) were determined. The DASI score was expressed in mlO 2 kg −1 min −1 . Institutional board approval was obtained and all subjects signed a written informed consent.Statistical analysis was performed using SPSS 19.0 (SPSS, Chicago, IL). Unpaired t-testing assessed differences in MLWHFQ and DASI scores according to the presence or absence of EOV. Unpaired t-testing was also used to assess differences in age, peak VO 2 and the VE/VCO 2 slope according EOV status. Receiver operating characteristic (ROC) curve...
