The temporary drop of serum octreotide concentration deteriorated ventricular tachycardia in an acromegalic patient.

Acromegaly is frequently accompanied by left ventricular hypertrophy (LVH) which causes ventricular dysfunction. Ventricular arrhythmia is one of the important complications in acromegalic patients. Hypertrophic cardiomyopathy (HCM) is characterized by LVH with a nondilated chamber. About 10 % of HCM evolve into dilated phase of HCM, which is associated with an increased incidence of ventricular tachycardia (VT). However there is no report about a combination of dilated phase of HCM and VT in acromegalic patients. Octreotide is a somatostatin analog that has been used for medical therapy for acromegaly. We herein report that the first case of the change of serum octreotide concentration affected the control of VT, which was induced by dilated phase of HCM. A 56-year-old Japanese man was referred to our hospital for treatment of acromegaly. The patient was diagnosed the dilated phase of HCM with sustained VT. The frequency and severity of VT were gradually ameliorated by subcutaneous octreotide injection. However VT was deteriorated when its injection was changed to octreotide long-acting release (LAR) injection. The temporary drop in serum octreotide concentration was known at the transition from subcutaneous injection to LAR injection. This clinical course gives us the important information that subcutaneous octreotide injection for two weeks should be necessary to keep serum octreotide concentration when switing to octreotide LAR administration in acromegalic patients with severe arrhythmia.