Cardiovascular Manifestations of Primary Hypothyroidism


ABSTRACT:BACKGROUND:Primary hypothyroidism accounts for 90 to 95 %of all cases of hypothyroidism. Thyroid hormone deficiency increases systemic vascular resistance, decreases contractility and slow the heart rate .OBJECTIVE: To investigate cardiac changes in primary hypothyroidism.METHODS:In this prospective study 36 patients with untreated primary hypothyroidism were compared with 30 healthy persons. Cardiovascular evaluation of all subjects had been made both clinically and by the following studies :Chest X-Ray, electrocardiography, serum lipid and Echocardiography.RESULTS::The main cardiac manifestations of hypothyroidism were: Easy fatigability( 88.9 %(, exertional dyspnea )75%o),obesity or gaining weight( 66.7 %(, sinus bradycardia ) 47.2 %(and peripheral edema(11.1 %(Electrocardiography showed sinus bradycardia in( 47%( low QRS voltage in )33.3%( , flat or inverted T wave(27.8%), prolonged QT interval )19.5%), first degree heart block in( 19.5 %(.Echocardiography showed the following :a decrease in global systolic function, asymmetric sepalhypertrophy in )91.6%) Pericardial effusion in )38.8%).Low QRS voltage was found to be related to thyroxin level and age of the patient .No correlation was found between heart rate and thyroxin level.CONCLUSION:Primary hypothyroidism accompanied by significant changes in cardiovascular system which may explain the development of premature coronary artery disease in these patients.