Controlled paroxysmal afib and controlled hypertension. would these conditions alone affect the immune system of an otherwise healthy, physically fit person?

No but some meds for them might.Discuss with your Dr. By hypertension control we like to see home BP less than 135/80 or lower. Take BP each AM before meds. Ask about low blood K as can re related to both HBP and A fib. Go to hyperaldosteronism@groups.io for more info on a problem that can cause both at the same time.

Not aware of any effects on the immune system. But both abnormalities need to be well controlled to prevent future long term problems.