Inspiratory Capacity and NT-pro BNP Predict Key Cardiopulmonary Exercise Results but not Six-Minute Walk Test distance in Older Patients with Heart Failure

Abstract

Introduction Heart failure (HF) affects more than five million people, half of whom are at least 75 years old. Peak oxygen consumption (VO2peak), Ventilatory efficiency (VE/VCO2 slope) and the Six-Minute Walk test (6MWT) are powerful prognostic indicators and are useful for monitoring the therapeutic efficacy of symptom and disease management. Cardiopulmonary Exercise testing (CPX) and/or the 6MWT are often not performed as a part of symptom assessment and management in older adults with HF, presumably due to cost, comorbidities and/or potential frailty. NT-pro BNP, NYHA classification, and inspiratory capacity are all easily obtainable in an office setting and may correlate with VO2peak, the VE/VCO2 slope, Peak cardiac output (Qpeak) and/or 6MWT. Hypothesis NT-pro BNP, NYHA classification, and/or inspiratory capacity predict VO2peak, the VE/VCO2 slope, Qpeak, and/or 6MWT. Methods Twenty-three patients (73.6 + 4.5 years old) with HF underwent assessment and determination of NYHA classification status, venipuncture, inspiratory capacity measurement, and performed the 6MWT and CPX per standardized protocol, (Qpeak measured via acetylene washin method). VO2peak, VE/VCO2 slope and Qpeak were recorded during the CPX. Results The strongest relationships were between inspiratory capacity and Qpeak, and between NT-pro BNP and the VE/VCO2 slope. There was a moderate relationship between inspiratory capacity and VO2peak and between NT-pro BNP and VO2peak. Inspiratory capacity and NT-pro BNP combined explained 42% of the variance in VO2peak (adjusted R2 = 0.42, F (2, 20) = 8.82, p Conclusion NT-pro BNP and inspiratory capacity can, either alone or combined, explain between 42% and 59% of variance in key exercise measurements. Both measurements are obtainable in the office setting for monitoring the therapeutic efficacy of symptom and disease management. Moreover, inspiratory capacity has the potential to be measured by older adults in their home.