Fig. 5.

Plots of mean ± SEM (a) (dV/dt)_max, (b) AP latency and (c) time to 90% AP recovery (APD₉₀) and (d) AP wavelength for APs obtained in response to S2 stimuli (i) through the range of coupling intervals explored, reducing from 89 ms to 30 ms. Panel (ii) for each provides a comparison of these values at the beginning and termination of the pacing protocol, corresponding to a refractory outcome or the onset of sustained arrhythmia. The symbols denote significant differences between each pair, obtained from post hoc Tukey testing, which was conducted if the ANOVA indicated a significant outcome. Single, double and triple symbols denote p < 0.05, p < 0.01 and p < 0.001 respectively.