Levothyroxine replacement in ischaemic hea disease Hypothyroidism and ischaemic hea disease are common conditions that often occur together. Although angina may remain unchanged in severity or paradoxically disappear with restoration of metabolic rate, exacerbation of myocardial ischaemia, infarction and sudden death are recognised complications of levothyroxine replacement, even using doses as low as 25 mg per day. In patients with known ischaemic hea disease, thyroid hormonereplacement should be introduced at low dose and increased veryslowly under specialist supervision. It has been suggested that T3 has an advantage over T4, since T3 has a shoer half-life and any adverse effect will reverse more quickly, but the more distinct peak in hormone levels after each dose of T3 is a disadvantage. Coronary intervention may be required if angina is exacerbated by levothyroxine replacement therapy Ref - davidsons 23e p641