Welcome to the forum, Dide.
Your husband is very likely hypothyroid but if this is his first abnormal TSH result his GP may want to retest in 2-3 months just incase it is a non-thyroidal illness or virus raising his TSH.
If he is hypothyroid he will need Levothyroxine to replace the low thyroid hormone. As your husband has had a heart attack and doesn't appear to be in good health he will probably be started on a low dose of 25mcg. Dose can be adjusted in 25mcg increments every 6-8 weeks until he is optimally medicated with TSH around 1.0.
If your husband's GP decides to prescribe Levothyroxine immediately your husband should take it with water 1 hour before, or 2 hours after, food and drink, 2 hours away from other medication and supplements, and 4 hours away from calcium, iron, vitamin D supplements, magnesium and oestrogen.
It takes 7-10 days for Levothyroxine to be absorbed before it starts working and it will take up to six weeks to feel the full impact of the dose. Symptoms may lag behind good biochemistry by several months.
Your husband should have a follow up thyroid test 6-8 weeks after starting Levothyroxine. Arrange an early morning and fasting (water only) blood draw when TSH is highest, and take Levothyroxine after his blood draw.