Described are methods for diagnosing a cardiac disease, particularly an acute cardiac event, in a patient presenting with symptoms of acute cardiac decompensation, comprising the steps of (a) measuring, typically in vitro, the level of NT-proBNP (N-terminal brain natriuretic peptide) or a variant thereof in a sample from the patient, (b) measuring, typically in vitro, the level of NIT-proANP (N-terminal atrial natriuretic peptide) or a variant thereof in a sample from the patient, (c) combining the information of the measured levels of NT-proANP and NT-proBNP, wherein an increased level of NT-proANP in presence of a non-increased or weakly increased level of NT-proBNP indicates the presence of an acute cardiac event, or wherein an increased level of NT-proANP in presence of a highly increased level of NT-proBNP indicates the presence of a chronic cardiac disease. The methods also allow distinguishing an acute cardiac event from decompensation of a chronic cardiac disease. Described also are corresponding kits and to methods of treatment of cardiac diseases.