Thyroid Dysfunction and Cardiovascular Outcomes

Author: K.Hristozov, M.Siderova, A.Penev

Abstract: 

Thyroid dysfunction has well-characterized deleterious effects on the cardiovascular system. Hyperthyroidism is known to induce many cardiovascular events such as tachycardia, systolic hypertension and predisposition to dysrrhythmias, especially atrial fibrillation. Hypothyroidism causes hypercholesterolemia, coronary heart disease and heart failure. In order to determine the relationship between thyroid dysfunction and cardiovascular outcomes, we performed a retrospective study including 1156 patients admitted to the Coronary Care Unit (CCU) of our hospital for a period of 2 years (2003 and 2004). Fifty-four of them, mean age 56 years, had thyroid disease. 16 patients were hyperthyroid due to: Graves’disease – 7 patients (43,8 %), toxic multinodular goiter – 4 patients (25 %), toxic adenoma – 2 patients (12,5 %), Amiodarone induced thyrotoxicosis – 2 patients (12,5 %) and thyrotoxicosis factitia in 1 patient (6,3 %). All 16 hyperthyroid patients suffered with paroxysmal atrial fibrillation. An attempt for pharmacological cardioversion was made in 14 cases with success in 11 of them and 3 remaining arrhythmic with ventricular rate control; electrocardioversion was performed successfully in 1 case; one patient died in the ward. 20 patients were hypothyroid: 12 after thyroid surgery (60 %), 7 with Hashimoto’s thyroiditis (35 %), 1 after subacute thyroiditis (5 %). Among the hypothyroid patients 16 had coronary heart disease, 4 sufferred myocardial infarction (with 3 deaths), 8 with chronic heart failure. The remaining 18 patients were euthyroid with underlying diffuse goiter (9 patients), nodular goiter (6 patients), Hashimoto’s thyroiditis (3 patients). Our results showed that the main cause for cardiovascular hospitalization of hyperthyroid patients is atrial fibrillation (100% of the studied patients with hyperthyroidism).

 

Observing the hypothyroid patients we confirmed the well known prevalence of acute coronary incidents among them. The study results also showed that the death rate from MI in hypothyroid patients is over 4 times the death rate from MI in our hospital.

 

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