Introduction: Mental Stress-Induced Myocardial Ischemia (MSIMI) can occur in patients with coronary artery disease (CAD) during acute mental stress challenge and is associated with an increased risk of adverse cardiovascular events. Adverse dynamic changes in repolarization with stress may also be particularly important when assessing risk of MSIMI.
Hypothesis: In subjects with CAD, dynamic ECG repolarization changes during stress and recovery are associated with MSIMI.
Methods: We studied 419 individuals with CAD who underwent mental stress challenge via a standardized speech stressor. Digital 12-lead ECGs were collected at baseline during resting , 1 minute after speech started, immediately after speech, and during recovery (5 minutes after speech ended). Repolarization metrics, including QRS-T angle, T-axis, ST depression, and T wave area were quantified in all 12 leads. Heart rate was also included. Subjects with baseline artifact were excluded. Changes amongst baseline, stress, and recovery were analyzed. Forward selection with alpha=0.01 was used to help guide the final model. MSIMI was assessed via Tc99m myocardial perfusion imaging (read by experienced clinicians).
Results: The mean (SD) age was 56 (10), 38% were women, and 17% had MSIMI. The most significant predictors of MSIMI, based on the multivariate model, are summarized in the table. The C-statistic was 0.73, but reduced to 0.71 after leave-one-out cross validation. Goodness of fit was adequate. No significant race or gender differences were noted.
Conclusion: Baseline and dynamic ECG repolarization changes in recovery (but not peak stress) contribute to MSIMI classification, and may be useful for risk stratification of arrhythmia risk due to emotional triggers. While the mechanisms regarding the relationship of MSIMI and ECG metrics during recovery are unknown, they could be due to hysteresis phenomena and/or known autonomic changes during recovery from stress.