Effects of L-Thyroxine treatment on QTc interval of overt hypothyroid female patients.

Introduction-In overt hypothyroid patients mostly the left ventricular dysfunction is seen, which is due to slowed myocardial relaxation. Also the ECG finding includes QTc interval prolongation, which is an index of the inhomogeneity of ventricular repolarization. Many previous studies concluded that prolongation in ventricular repolarization time is due to decreased serum T3 and elevated serum TSH levels in overt hypothyroid patients. Thus, the aim of this study was to test the hypothesis that L-Thyroxine treatment changes the QTc interval of overt hypothyroid patients. Material and Methods-The study included newly diagnosed 38 female volunteers of overt hypothyroidism. All patients were checked with a lead-II ECG before and after 3 months of L-thyroxine treatment and QTc interval was noted. Results-There was significantly improvement in the thyroid profile and QTc interval after L-Thyroxine treatment in overt hypothyroid patients. Conclusion-In overt hypothyroid patients, decrease in thyroid hormone level leads to ventricular inhomogeneity, but subsequent replacement of L-thyroxine therapy may reduce risk of ventricular arrhythmias. [ABSTRACT FROM AUTHOR]