I believe it is the associated symptoms of subclinical hypothyroidism that contribute to the risk of congestive heart failure. Hypertension, tendancy to gain weight, poor circulation and hormonal imbalance and a lowered immune response, were all symptoms that I had, as well as hypothyroidism.
I have dealt with all of these symptoms and conditions with iodine, herbal and mineral supplements, and a change of diet. Last tests showed vast improvements to all areas. It is certainly doable without needing to resort to thyriod medication.