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 +/- 1.8 years) performed a mental arithmetic for 1 minute, which was considered as active mental stress (AMS) because of the performance requirement. A 1-minute unpleasant video clip was used for PMS. Two baseline and two (an early and a late) ECGs were prepared in both mental stress periods. The individual QT-RR relationship was assessed by linear regression analysis of 7-15 (11.0 +/- 1.9) controlled QT-RR data pairs, also obtained from ECGs gained during a successive set of 9 isometric stretching exercises.


RESULTS
Heart rate has increased significantly at both measurements in response to AMS (P < 0.0001), but not in response to passive stress. QTc significantly prolonged early in AMS (P = 0.0004), then normalized by the end of the period. During PMS, no significant QTc changes were observed. The evolution of bifid T waves was noted in 14 subjects: 8 presented bifid T waves during both AMS and exercise, and 6 during only exercise.


CONCLUSIONS
AMS and PMS elicit different cardiovascular reactions. Our results indicate that changes in the autonomic tone, probably abrupt sympathetic predominance, may cause QTc prolongation and bifid T waves. This suggests that besides stress quality and intensity, the dynamics of stress application and perception also influence repolarization.
Andrássy
Gábor
G
Department of Cardiology, Saint Francis Hospital, Budapest, Hungary. andrassy.gabor@t-online.hu
Szabo
Attila
A
Ferencz
Gyöngyvér
G
Trummer
Zsófia
Z
Simon
Eszter
E
Tahy
Adám
A
D000328:Adult; D004562:Electrocardiography; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008133:Long QT Syndrome / Q000503:physiopathology*; D008297:Male; D013315:Stress, Psychological / Q000503:physiopathology*