Brain natriuretic peptide facilitates severity classification of stable chronic heart failure with left ventricular dysfunction

New York Heart Association (NYHA) classification is popularly used to evaluate severity of stable chronic heart failure. Since this evaluation depends on subjective symptoms such as dyspnoea or fatigue with exertion, it is not expected to provide a precise reflection of physiologic abnormality. Useful objective indices to evaluate severity of heart failure are peak oxygen uptake (Vo2) and minute ventilation–carbon dioxide output (VE–Vco2) slope, which are derived from cardiopulmonary exercise testing,1 but the required methodology is complex and may not be widely available. Previous studies have shown that plasma brain natriuretic peptide (BNP), a cardiac hormone secreted mainly by cardiac ventricles, increases in chronic heart failure and correlates with haemodynamic abnormalities such as left ventricular dysfunction.2 Although measurement of plasma BNP has been thought of as a simple way to diagnose heart failure,2 it has not been revealed how well plasma BNP concentration predicts severity of heart failure. If exercise tolerance could be shown to correlate with plasma BNP concentration in heart failure, it would enhance this measurement’s value in evaluating heart failure severity. In this study we investigated the relation between plasma BNP concentration and exercise tolerance in patients with chronic stable heart failure. Patients with stable chronic heart failure (neither diuretics nor inotropic drug were changed within two weeks before the study and more than …