Your ankles can also swell as a reaction to medication, retaining water. I have had swollen ankles for years. Every time I've had EKGs they have been fine. Pretty much everything has been tested that could swell my ankles and nothing has been found. I am talking 20+ years. They first got swollen as after a bad reaction to a birth control pill and then never really went down (of course I had pregnancy soon after) and then onto psych meds 3 weeks postpartum. I nursed on Zoloft as it was seen OK to breastfeed on it back then, and my weight dropped into the 90s, couldn't keep any weight on while nursing, and still I had swollen ankles. I have also had to quit taking a lot of psych meds including Vraylar because of increased swelling in my feet & ankles.