Key result
Exercise-induced sympathetic activation linked to increased myocardial repolarization dispersion and steeper QTe/RR slopes.
Why the study?
Temporal dispersion of myocardial repolarization plays an important role in sudden cardiac death risk stratification, but the influence of heart rate, the autonomic nervous system, and controlled breathing on repolarization markers needed evaluation.
Does exercise-induced sympathetic activation influence time- and frequency-domain markers of myocardial repolarization dispersion in healthy subjects?
Observational (n=21)
Does exercise-induced sympathetic activation influence time- and frequency-domain markers of myocardial repolarization dispersion in healthy subjects?
Heart rate and sympathetic activity during exercise influence time-domain markers of myocardial repolarization dispersion in healthy subjects without altering spectral components.
Exercise effects on repolarization dispersion in healthy subjects may inform arrhythmia mechanisms; leaves open prospective validation before clinical use.
Background/aim Recently, data from temporal dispersion of myocardial repolarization analysis have gained a capital role in the sudden cardiac death risk stratification. Aim of this study was to evaluate the influence of heart rate, autonomic nervous system, and controlled breathing on different myocardial repolarization markers in healthy subjects. Method Myocardial repolarization dispersion markers from short‐period (5 minutes) electrocardiogram (ECG) analysis (time and frequency domain) have been obtained in 21 healthy volunteers during the following conditions: free breathing (rest); controlled breathing (resp); the first 5 minutes of postexercise recovery phases (exercise Peak ), maximum sympathetic activation; and during the second 5 minutes of postexercise recovery phases (exercise Recovery ), intermediate sympathetic activation. Finally, we analyzed the whole repolarization (QTe), the QT peak (QTp), and T peak ‐ T end intervals (Te). Results During the exercise Peak , major part of repolarization variables changed in comparison to the rest and resp conditions. Particularly, QTe, QTp, and Te standard deviations (QTe SD , QTp SD , and Te SD ); variability indexes (QTeVI and QTpVI), normalized variances (QTeVN, QTpVN, and TeVN); and the ratio between short‐term QTe, QTp, and Te variability RR (STV QTe/RR , STV QTp/RR, and STV Te/RR ) increased. During exercise Recovery , QTp SD ( P < .05), QTpVI ( P < .05), QTeVN ( P < .05), QTpVN ( P < .001), TeVN ( P < .05), STV QTe/RR ( P < .05), STV QTp/RR ( P < .001), and STV Te/RR ( P < .001) were significantly higher in comparison to the rest. The slope between QTe (0.24 ± 0.06) or QTp (0.17 ± 0.06) and RR were significantly higher than Te (0.07 ± 0.06, P < .001). Conclusion Heart rate and sympathetic activity, obtained during exercise, seem able to influence the time domain markers of myocardial repolarization dispersion in healthy subjects, whereas they do not alter any spectral components.
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Piccirillo et al. (2020) conducted an observational in Healthy subjects (n=21). Exercise and controlled breathing vs. Rest (free breathing) was evaluated on Myocardial repolarization dispersion markers. Exercise-induced sympathetic activation increased time-domain markers of myocardial repolarization dispersion, with QTe/RR slopes (0.24) significantly higher than Te/RR slopes (0.07, P<0.001).
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