Hello there, thanks for the good question and I am sorry to hear you are experiencing symptoms and very worried. Apparently beta-blocker is not working very well in your case and this medication can not prevent serious conditions as you are worried about. I think you should see an electrophysiologist (specialized cardiologist in dealing with long QT syndrome) as soon as possible and seek the possibility of ICD placement to prevent sudden death. If the ventricular ectopies can not be managed medically, they can be ablated by the electrophysiologist. I would definitely seek their professional opinion ASAP.
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