A 57-year- old lady came with chief complaints of fatigue. On fuher questioning, she reveals that she has gained 5 kg weight in one month. She has been taking L-thyroxine for hypothyroidism since 10 years and fairly controlled. Recently she was staed on an anti-arrhythmic drug for treatment of his cardiac condition. The symptoms staed after sta of this drug. Most likely anti-arrhythmic drug she was prescribed is?