The invention relates to pimobendan for use in a method of reducing the heart size and/or delaying the onset of clinical symptoms in a patient suffering from asymptomatic (occult, preclinical) heart failure, preferably congestive heart failure, due to mitral valve disease (MVD), and/or delaying the onset of heart failure, preferably congestive heart failure, in a patient suffering from asymptomatic (occult, preclinical) heart failure, preferably congestive heart failure, due to mitral valve disease (MVD), wherein the patient is preferably a mammal, more preferably a human, a dog, a cat or a horse, and most preferably a dog.本發明係關於匹莫苯坦(pimobendan)，其係用於在患有由二尖瓣疾病(MVD)所致之無症狀(隱發性，臨床前)心臟衰竭，較佳充血性心臟衰竭的患者中減小心臟大小及/或延遲臨床症狀之發作，及/或在患有由二尖瓣疾病(MVD)所致之無症狀(隱發性，臨床前)心臟衰竭，較佳充血性心臟衰竭的患者中延遲心臟衰竭、較佳充血性心臟衰竭之發作的方法中，其中該患者較佳係哺乳動物，更佳係人類、狗、貓或馬，且最佳係狗。
