Mental stress may induce QT-interval prolongation and T-wave notching.

Background: The effects of active and passive mental stress (PMS) on the QT interval were studied by using an intraindividual regression method of QT-interval correction for heart rate.

Methods: Thirty healthy males (age 21.2 +/- 1.

Acute effects of cigarette smoking on the QT interval in healthy smokers.

This study assesses the effect of a first cigarette smoked in the morning on the QT interval duration in healthy habitual smokers after not smoking overnight. This study demonstrates that although after cigarette smoking the QT(Bc) values increase, the QT(Fc) and QT(Lc) values remained unchanged, and an increased sympathetic response was evident. The discrepancies between the results seen by different QT correction formulas emphasize the importance of selecting an accurate method for heart rate correction when evaluating and interpreting alterations in QT values.