@scamp At this point we can't even be sure your chest sensations are heart related, but you could always get an EKG if you wish to rule it out.
I would just focus on getting plenty of heart supporting nutrients in your diet. Potassium, magnesium, selenium, vitamins C, D, & E. Make sure you're keeping PTH suppressed with plenty of calcium and/or low phosphate. Those are the main supporters of general cardio health.
Endocrine issues, like estrogen dominance, can also be a problem, the "staircase effect" that Albert Szent-Gyorgyi talked about. Androgens and Progesterone stabilize the heart's rhythm, whereas estrogen promotes heart failure pathology by creating weaker faster beats. The heart begins to work twice as hard for smaller results.