Shortness of breath at rest, exercise at 160bpm does not make it worse, maybe a little better. had lung ct scan, lung function and echocardiogram norm?

Sleep apnea maybe?: are you overweight? do you think you may have sleep apnea and get tired in the day too with little rest? iit may be a good idea to get a night time pulse oximeter test ordered by your PCP or a sleep study place to see if you desaturate at night. it can cause SOB and even chest pain as there is lack of oxygen to the organs. if it is that, you can get a cpap machine at night.

Hard to say: The good news is that you probably ruled out serious conditions by the test you have done. Irregular heart rhythm Asthma, allergic reaction, anxiety or panic attack can sometimes cause shortness of breath at rest. Any palpitations, wheezing or cough?

Likely: A nasal problem, possibly deviated septum, less likely polyps. Do you have a history of nasal trauma? When you exercise, do you mouth breath which would explain why exercise doesn't make you short of breath because you don't breathe through your nose. See an ENT = ear, nose, throat MD. HRS, MD, FACC. www.thepmc.org