Prolonged QT interval is associated with the generation of life-threatening arrhythmias and sudden death. However, neither the relation between QT duration and heart rate, nor the association between mental stress and QT time has been clarified.
Aim: The relationship between QT duration and smoking, cardiovascular reactivity, and mental stress as well as newer methods of QT correction were studied.
Methods: In six laboratory experiments 166 volunteers were studied. Smoking, treadmill exercise, mental arithmetic and videogame were applied as stressors. Besides fixed formulae, study and subject-specific QT correction methods were also used.
Results: 1. Bazett formula is not appropriate to compare QT durations. 2. Acute smoking has no effect on QT time. 3. QT changes are related to cardiovascular reactivity. 4. Mental stress may induce QT prolongation. 5. Bifid T waves often develop during mental and isometric stress.
Conclusions: New methods for QT correction are more reliable than preformed formulae. QT prolongation and bifid T waves may be the links between mental stress and life threatening arrhythmias.