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Repolarization Changes Induced by Mental Stress in Normal Subjects and Patients with Coronary Artery Disease: Effect of Nitroglycerine

From the Department of Cardiology, The Hatter Institute and Centre for Cardiology, University College London Hospitals (P.T., P.S.); Department of Cardiac and Vascular Sciences, St Georges, University of London (V.N.B.); and Department of Cardiological Investigation, The Whittington Hospital (G.Y., S.Y., D.P.), London, United Kingdom.

Address correspondence and reprint requests to Dr Peter Taggart, Department of Cardiology, The Hatter Institute and Centre for Cardiology, University College London Hospitals, Grafton Way, London WC1E 6DB, UK. E-mail: peter.taggart{at}uclh.org

Objectives: Mental stress can significantly affect ventricular repolarization, which could potentially trigger arrhythmias. We compared the effect of mental stress on repolarization indexed by the amplitude and area of the T wave in patients with coronary artery disease (CAD) and healthy subjects.

Methods: Fourteen healthy controls (11 M, mean age 42 years) and 14 patients with stable CAD (12 M, mean age 64) underwent a mental stress protocol consisting of mental arithmetic followed by a speech (5 minutes each), which was performed on two occasions following either nitroglycerine (NTG) or placebo. Multiple 12-lead electrocardiograms were acquired and repolarization was analyzed using automatically measured T wave amplitude (T_amp) and area (T_area).

Results: When preceded by placebo the overall effect of mental stress, whether induced by arithmetic or speech, was significantly different in CAD patients compared with controls, with a decrease in T_amp and T_area in controls and an increase in patients; e.g., change in T_amp during arithmetic –20 ± 3 µV in controls versus 4 ± 2 µV in patients, p < .001, and during speech –9 ± 3 µV in controls versus 7 ± 1 µV in patients, p < .001. Following NTG, the effect of stress on repolarization was similar in the 2 groups, with a reversed effect, i.e., decrease instead of increase in T_amp and T_area in CAD patients.

Conclusions: The effect of mental stress on ventricular repolarization is significantly different in CAD patients compared with healthy controls. These differences are considerably reduced by NTG.

Key Words: electrocardiogram • ventricular repolarization • mental stress • nitroglycerine

Abbreviations: CAD = coronary artery disease; ECG = electrocardiogram; NTG = nitroglycerine; T_amp = maximal amplitude of the T wave; T_area = total area under the T wave.