Relationship of Resting B-type Natriuretic Peptide Level to Cardiac Work and Total Physical Work Capacity in Heart Failure Patients

In Brief PURPOSE Plasma B-type natriuretic peptide (BNP) levels obtained at rest have been previously shown to be correlated with the global functional capacity measures of peak oxygen uptake (V̇O2peak) and the minute ventilation/carbon dioxide (VE/V̇CO2) slope. The purpose of this study was to assess the relationship of the plasma BNP level to the rate-pressure product (RPP) as an indicator of central or cardiac work capacity. METHODS Twenty-two subjects (12 men), mean age 57 ± 12 years, diagnosed with heart failure (8 ischemic/14 nonischemic) were recruited. All subjects were stable on optimal medical therapy for at least 1 month. Blood samples for BNP level analysis were obtained at rest. Subjects underwent a symptom-limited treadmill exercise test using a ramping protocol while V̇O2, heart rate (HR), and blood pressure (BP) were monitored. Correlation analyses were conducted to assess the relationship of BNP level to RPP level, V̇O2peak, VE/V̇CO2 slope, end-tidal CO2 pressure (PETCO2), and left ventricular ejection fraction (LVEF). RESULTS Resting BNP levels were significantly correlated with RPP levels (r = −0.69). The BNP level and the RPP level were correlated with V̇O2peak (r = −0.63 and r = 0.66, respectively) and VE/V̇CO2 slope (r = 0.53 and r = −0.54, respectively). The RPP level but not the BNP level was correlated with PETCO2 (r = 0.57). Neither BNP nor RPP levels were well correlated with LVEF (r = −0.26 and r = 0.14, respectively). DISCUSSION The results of this study suggest that resting plasma BNP level may be a useful clinical measure for evaluating both global functional capacity and myocardial specific work capacity in individuals with heart failure. The relationship of plasma B-type natriuretic peptide (BNP) level to rate-pressure product (RPP) level as an indicator of central (cardiac) work capacity in patients with heart failure was assessed. The BNP level was similarly correlated with the RPP level, peak oxygen uptake, and minute ventilation/carbon dioxide slope, suggesting its usefulness in assessing global and myocardial work.