His height was 161 cm and body weight was 83 kg. Blood pressure was 110/60 mm Hg. The fasting blood glucose was 107 mg/dl and HbA1c was 6.3%. The chest x-ray showed cardiomegaly with a cardiothoracic ratio of 0.67 (figure 1A). ECG, as shown in video 1, revealed a diffused hypokinetic left ventricle with markedly dilated left ventricle dimension (end-diastole: 95 mm) and reduced EF (0.11). The coronary angiogram was normal. A myocardial biopsy revealed that over 50% of cardiomyocytes were replaced by fibrosis (figure 2). An implantable cardioverter-defibrillator was implanted. Due to the typical facial appearance and thickening of hands, he was referred to the endocrinology department. The plasma level of GH was 8.2 ng/ml and IGF-1 was 504 ng/ml. MRI demonstrated a macroadenoma in the pituitary. Thus, he was diagnosed as acromegaly.

He was treated with octreotide long-acting-release (LAR) for 8 months. Thereafter, he underwent trans-sphenoidal surgery in January 2009 (figure 3).

It is reported that heart failure due to acromegalic cardiomyopathy was improved after normalisation of plasma GH and IGF-1 levels in some cases,^4–6 although there were also other cases in which the cardiac dysfunction was irreversible.⁷ In the former cases, the fibrosis of the cardiomyocytes was moderate.^{4 5} Furthermore, while myocardial damage such as infiltration of inflammatory cells disappeared after treatment, the interstitial fibrosis remained unchanged in both cases.^{4 5} Based on these data, it has been suggested that acromegalic cardiomyopathy with severe fibrosis has a poor prognosis. However, the criteria for the cure of acromegaly with medicine or surgery could differ among studies, and it is not clear whether plasma GH and IGF-1 levels were normalised completely in the cases in which cardiac dysfunction was not improved. Direct effects of GH and IGF-1 on cardiomyocytes as well as increases in circulating plasma volume have been implicated in the pathogenesis of the acromegalic cardiomyopathy.^{8 9} While it is shown that there were no differences in cardiomyocyte histology between acromegalic and idiopathic cardiomyopathy,¹⁰ the residual cardiomyocytes were reportedly reconstituted after normalisation of plasma GH and IGF-I levels in the case of acromegaly.^{4 5} Although we have not conducted a biopsy after treatment, drastic changes in cardiac function were probably due to the improvement in function of the residual cardiomyocytes in our case. It should be also emphasised that such drastic changes only occurred after surgery when plasma GH and IGF-I levels decreased to normal levels. Thus, it is also demonstrated that normalisation of plasma GH and IGF-1 levels was mandatory to improve acromegalic cardiomyopathy as has been suggested.¹¹ Since effective treatment of acromegaly reportedly did not necessarily improve long-term survival,¹² a careful follow-up of cardiac function is needed in our case.