Ventricular repolarization changes during thyrotropin releasing hormone test

We investigated the ventricular repolarization changes during thyrotropin-releasing hormone (TRH) test in 20 euthyroid healthy subjects. TSH elevation was observed in 14 subjects (age: 29±5 years). TSH increased at 20 min (baseline: 1.91±1.18 μU/ml vs. 20 min: 13.7±7.2 μU/ml, P<0.0001) and slightly decreased at 40 min (baseline vs. 40 min: 11.6±6.7 μU/ml P<0.0001). Many dispersions prolonged at 20 and 40 min (P<0.05). At baseline, 20 and 40 min, positive linear correlations were observed between TSH levels and TTd and TTcd. These data shows that ventricular repolarization and regional inhomogeneity of ventricular repolarization increase during the TRH test. Neural and receptor-mediated mechanisms on repolarization kinetics of myocardial cells may act on this effect.