Chronic pericarditis. pain greatly increased during trip to higher elevation. a strange coincidence or can pain increase w altitude?

More work: At higher elevation the heart has to work a little harder to keep your body oxygenated. More work for the heart means more friction in the pericardium. The pain may be due to something other than your pericarditis so if you have any other symptoms such as swelling, shortness of breath, dizziness, nausea or sweating, please go be evaluated immediately.

Yes: At higher altitude partial pressure of oxygen is relatively low. So, at high altitude every one developed hypoxia. Our body compensate it by increase breathing & heart rate. A person with chronic heart or lung condition unable to do so resulting a new chest pain or worsening previous symptoms. In your case chronic pericarditis symptoms will worsen & you should use extra O2 at high altitude

Yes: Higher altitudes mean more fluid in your pericardium and lungs due to lower atmospheric pressures. Slower ascent and taking Diamox (acetazolamide) before ascent may help