Hello! Welcome and thank you for asking on HCM! Regarding your concern, i would explain that your symptoms seem to be related to anxiety associated with the reduce of Zapiz. You should know that Zapiz is a benzodiazepine, which can help control anxiety and the reducing of the doses could be associated to exacerbation of the symptoms. But a cardiac arrhythmia can not be excluded too. So I recommend consulting with your GP for a careful physical examination, a resting ECG, a chest x ray study and some blood lab tests : - complete blood count - thyroid function tests ( some changes in thyronorm may be needed) - blood electrolytes. If the above tests result normal, the most probable cause would remain a panic attack. In such case, you should discuss with your attending physician on the possibility of making some changes to your actual therapy, to help you control better your anxiety. Hope to have been helpful! Greetings! Dr. Iliri