Heart Rate and Respiration During Activity Measured by an Implanted Device Correlate well with those Measured by a CPX Machine

IntroductionHeart Failure (HF) is classified in part by severity of symptoms such as fatigue and shortness of breath experienced during exertion. Physiologic variables associated with these symptoms, such as heart rate (HR) and respiratory rate (RR) measured during activity, could be useful to monitor disease progression. In the PRE-SENSE study, physiologic response to activity (PRA) measured from an implanted device were compared to data from external cardiopulmonary exercise testing equipment (CPX) during a graded exercise test.MethodsPatients (n=71) with a COGNISTM cardiac resynchronization therapy defibrillator were enrolled. The device was enabled to run the PRA algorithm, which continuously identifies steady-state activities based on accelerometer (XL) and captures HR and RR during these periods. HR and RR were also collected by CPX equipment. Linear least-squares regressions of end-stage averages of CPX HR and RR vs. XL were obtained in each patient. Linear interpolation was then performed to determine CPX HR and RR at the same XL levels as the device-based PRA. Linear regression was performed between device- and CPX-based PRA to assess level of agreement.ResultsFifty-nine patients (62±10 y.o., 63% male, LVEF 32±12%) attained XL of 60 mG (corresponding to 1.5 miles per hour walk) during exercise test. Average slopes and R-Square from linear regression comparison of CPX vs PRA at fixed XL levels are listed below.ConclusionsTable 1Linear regression comparison of HR and RR interpolated to fixed XL levels by PRA (Y) vs CPX (X)Activity Level (XL, mG)Heart RateRespiratory RateR-SquareSlopeR-SquareSlope00.7980.8420.5840.505100.8390.8550.6240.529200.8750.8690.6600.560300.9040.8820.6880.594400.9240.8820.6880.594500.9350.9050.7240.669600.9380.9130.7330.705 Open table in a new tab IntroductionHeart Failure (HF) is classified in part by severity of symptoms such as fatigue and shortness of breath experienced during exertion. Physiologic variables associated with these symptoms, such as heart rate (HR) and respiratory rate (RR) measured during activity, could be useful to monitor disease progression. In the PRE-SENSE study, physiologic response to activity (PRA) measured from an implanted device were compared to data from external cardiopulmonary exercise testing equipment (CPX) during a graded exercise test.