I recommend that you discuss your symptoms with your cardiologist
. It sounds like the initial workup when you went to the hospital was to rule out a blood clot in the lungs, or pulmonary embolus, which is what the CT scan
likely was for, and to rule out a heart attack or other major problem with the structure and function of the heart, which is what the echo and cardiac catheterization
were for. The fact that these tests all came back normal is really good news, but it sounds like the symptoms are still persistent and require additional evaluation.
The sensation of fluttering in the chest is most concerning for an abnormal heart rhythm, which might be intermittent and therefore might not have been picked up during your hospitalization. Consultation with your cardiologist, explaining to them that these symptoms are ongoing, would be the first step. They may want to perform some additional monitoring of your heart's electrical rhythm, which might include wearing a monitoring device at home for a while in the hopes of capturing one of these events.
It might also be necessary to consider other conditions which can cause the sensation of palpitations, including a problem with the thyroid gland, or a problem with panic attacks.