Oral levothyroxine is contraindicated in patients with an acute myocardial infarction. All levothyroxine dosage formulations are cardiostimulatory and should be used with great caution in patients with angina pectoris or other preexisting cardiac disease, including uncontrolled hypertension, cardiac arrhythmias, coronary artery disease, or a previous myocardial infarction; do not use levothyroxine therapy in patients with heart disease and nontoxic diffuse goiter or nodular thyroid disease if the serum TSH concentration is suppressed. Many authorities recommend lower initial dosages and slower titration of thyroid hormones in patients with heart disease. If adverse cardiac symptoms develop or worsen, reduce or withhold levothyroxine and cautiously restart at a lower dose. Over-treatment with thyroid hormones may cause cardiac stimulation and lead to increased heart rate, cardiac wall thickening and increased cardiac contractility, which may precipitate angina or cardiac arrhythmias. Concomitant administration of levothyroxine with sympathomimetic agents in patients with coronary artery disease may precipitate coronary insufficiency and associated symptoms. Patients with coronary artery disease who are receiving thyroid hormones may be at a higher risk for developing arrhythmias, particularly during surgery.[53562]