IGF1 and acromegaly: The pathogenesis of arrhythmias in acromegaly appears to be multifactorial, involving the effects of IGF-1 (direct positive inotropic effect on cardiac myocytes by increasing Ca2+ availability to myofilaments) [60], cardiac structural changes (left ventricular hypertrophy, collagen deposits in cardiac tissues, and fibrosis) [42,43,44], and electrophysiological alterations (increased QT interval variability) [61].