Hi Thank you for sharing with HCM I read your query and understand your concern First you have to be calm because cardiac frequence is called as normal till 120 The old cardiac infarct can generate atrial fibrillation so you need to be carefullbto monitaore your cardiac rhythm If atrial fibrillation is diagnosed you should start anticoagulation Thyroid dysfunction can cause cardiac rhythm disorder but as you said your hormonal value are normal I don t think that thyroid is responsible for your tachycardia Anyway I don t see reason for you too worry too much as your parameters are normal Wish you good health and fast recovery Feel free to contact me further questions or queries Regards Dr Drilona Kenga Cardiologist