Introduction:
Around 920000 people in the UK are affected by chronic heart failure (CHF), mainly due to an ageing population(1). High cardiac sympathetic drive and release of the sympathetic co-transmitter neuropeptide-Y (NPY) are significant features of CHF(2), and resting venous NPY levels are well known to be associated with morbidity and mortality(3), but how the NPY levels change during exercise and how this correlates with functional capacity is unknown.
Method:
We sought to establish the dynamics of circulating NPY levels in heart failure patients and compare these with indices of performance and cardiac function linked to long-term prognosis. Cardiopulmonary exercise testing (CPET) is an established method of quantitative assessment of exercise performance via measurement of ventilation, oxygen consumption (V̇O2) and carbon dioxide production. CPET is applied in the heart failure population where the quality of life and exercise capacity are inextricably linked. Patients at least 6 months post cardiac resynchronisation therapy (CRT) device implantation underwent CPET with venous blood sampling at rest, peak exercise, and recovery as part of the device based synchronized biventricular (SyncAV) study (n=15). Patients' CPET performance measures were compared to the venous serum NPY levels at the rest, peak and recovery. Data is expressed as mean±standard deviation.
Results:
15 heart failure patients (9 males and 6 females, age 70.3±10 years, ejection fraction 29±7 % pre-CRT and 44±7 % post-CRT, p<0.00001). NPY levels increased significantly from baseline to peak exercise (40.08±6.90 to 93.46±42.13 pg/ml, p=0.0004) and remained elevated during recovery (to 86.84±44.60 pg/ml, p=0.002). The peak (r=0.58, p=0.02), and recovery (r=0.56, p=0.03) NPY levels as well as the ability to increase NPY from baseline (r=0.53, p=0.04) significantly correlated with heart rate recovery at 1 minute, but not with peak V̇O2 (r=0.38, p=0.16).
Conclusion:
In heart failure patients, the ability to increase NPY levels on exertion correlates with heart rate recovery, a known prognostic indicator for mortality.