Plasma potassium concentration and cardiac repolarisation markers, Tpeak–Tend and Tpeak–Tend/QT, during and after exercise in healthy participants and in end-stage renal disease (original) (raw)

2022, European Journal of Applied Physiology

The cardiac T-wave peak-to-end interval (Tpe) is thought to reflect dispersion in ventricular repolarisation, with abnormalities in Tpe associated with increased risk of arrhythmia. Extracellular K + modulates cardiac repolarisation and since arterial plasma K + concentration ([K + ]) rapidly increases during and declines following exercise, we investigated the relationship between [K + ] and Tpe with exercise. Methods Serial ECGs (Tpe, Tpe/QT ratio) and [K + ] were obtained from 8 healthy, normokalaemic volunteers and 22 patients with end-stage renal disease (ESRD), at rest, during and after exhaustive exercise. Results Post-exercise [K + ] nadir was 3.1 ±0.1, 5.0 ±0.2 and 4.0 ±0.1 mmol.L-1 (mean ± SEM) for healthy participants and ESRD patients before and after HD, respectively. In healthy participants, compared to pre-exercise, recovery-induced low [K + ] was associated with a prolongation of Tpe (110 ±8 vs. 87 ±5 ms, respectively, p=0.03) and an increase in Tpe/QT ratio (0.28 ±0.01 vs. 0.23 ±0.01, respectively, p=0.01). Analyses of serial data revealed [K + ] as a predictor of Tpe in healthy participants (β =-0.54 ±0.11, p=0.0007), in ESRD patients (β =-0.72 ±0.1, p < 0.0001) and for all data pooled (β =-0.64 ±0.52, p = 0.0007). The [K + ] was also a predictor of Tpe/QT ratio in healthy participants and ESRD patients. Conclusions Tpe and Tpe/QT ratio are predicted by [K + ] during exercise. Low [K + ] during recovery from exercise was associated with increased Tpe and Tpe/QT, indicating accentuated dispersion of ventricular repolarisation. The findings suggest that variations in [K + ] with physical exertion may unmask electrophysiological vulnerabilities to arrhythmia.