Abstract 19271: Resting and Post Exercise Serum Brain Natriuretic Peptide Levels Do Not Help Differentiate Heart Failure With Normal Ejection Fraction From Respiratory Limitation and Deconditioning in Patients Aged Over 60 Years

Introduction: Although diagnosis of HFnEF based on elevated resting LV diastolic pressure necessarily results in associated elevation in plasma BNP, several groups have shown that resting LVEDP may be a poor indicator of patients with a cardiac cause for exercise limitation, because of the profoundly dynamic nature of diastolic function on exercise, wrongly diagnosing cardiac limitation in some and missing others. We therefore evaluated the use of both resting and exercise BNP in the prediction of the cause of exercise limitation breathlessness in a community population of patients aged over 60. Hypothesis: Exercise BNP would better distinguish patients with normal LVEF who had a cardiac vs non cardiac cause for exercise limitation. Methods: We measured bedside BNP levels before exercise, at peak exercise, and 15 minutes after a maximal cardio-pulmonary exercise test (CPEX), in 70 elderly (over 60 years) breathless subjects (NYHA ≥2b) and in 42 healthy and 28 hypertensive-but otherwise healthy subjects. All had prior echocardiogram showing LVEF >50% and no significant valve disease. Results: The breathless subjects were classified into HFnEF, respiratory limitation and deconditioning, based on CPEX. There was no statistically significant difference in BNP levels between the three groups at rest, peak exercise and 15 minute post exercise. Furthermore, ROC curves analysis showed while BNP levels could distinguish HFnEF and healthy subjects, there was no clear distinction between the HFnEF and hypertensive groups. Conclusion: Resting, peak-exercise or post-exercise BNP levels do not help identify the cause of breathlessness in an elderly population with normal ejection fraction.