The effect of acute psychological stress on QT dispersion in patients with coronary artery disease.
BACKGROUND
An acute psychological stress can precipitate ventricular arrhythmias and sudden cardiac death in patients with coronary artery disease (CAD). However, the physiologic mechanisms by which these effects occur are not entirely clear. Mental stress-induced myocardial ischemia occurs in a significant percentage of the CAD population. It is unknown if the proarrhythmic effects of psychological stress are mediated through the development of myocardial ischemia.


OBJECTIVE
To examine the effects of psychological stress on QT dispersion (QTd) among CAD patients and whether these effects are mediated via the development of myocardial ischemia.


METHODS
Psychological stress was induced using a public speaking task. Twelve-lead electrocardiograms (ECG) were recorded at rest, during mental stress, and during recovery. QTd was calculated as the difference between the longest and the shortest QT interval in the 12-lead ECG. Rest-stress myocardial perfusion imaging was also performed to detect mental stress-induced myocardial ischemia.


RESULTS
Mental stress induced a significant increase in QTd compared to the resting condition (P < 0.001). This effect persisted beyond the first 10 minutes of recovery (P < 0.001). QTd was significantly associated with the development of mental stress ischemia with ischemic patients having significantly higher QTd during mental stress than nonischemic patients (P = 0.006). This finding remained significant after controlling for possible confounding factors (P = 0.01).


CONCLUSIONS
An acute psychological stress induces a significant increase in QTd, which persists for more than 10 minutes after the cessation of the stressor. This effect seems to be, at least partially, mediated by the development of mental stress-induced myocardial ischemia.
Hassan
Mustafa
M
Division of Cardiology, Department of Medicine, University of Florida, Gainesville, Florida, USA. mustafa.hassan@medicine.ufl.edu
Mela
April
A
Li
Qin
Q
Brumback
Babette
B
Fillingim
Roger B
RB
Conti
Jamie B
JB
Sheps
David S
DS
D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000175:diagnosis*; D003324:Coronary Artery Disease / Q000150:complications* / Q000175:diagnosis*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D013315:Stress, Psychological / Q000150:complications* / Q000175:diagnosis*