Figure 4
CL patterns preceding the maximum APD dispersion. (A) Three previous CLs (CLn−3 − CLn−2 − CLn−1) preceding ΔAPDmax in LMC, LQT1, and LQT2 (n = 10 stimulation protocols from 5 hearts per group). Note that long-short-long CL patterns precede ΔAPDmax in LQT2 (paired t-test between CLn−2 and CLn−1, p = 0.0017), while no clear pattern was found in LMC (p = 0.1836) or LQT1 (p = 0.2084). (B) Correlation analysis of alternating CL and APD dispersion in random stimulation protocol. CL difference (ΔCL = CLn−1 − CLn−2) vs. APD dispersion (σAPD) shows a clear positive association in LQT2, unlike LMC & LQT1. Correlation coefficient between APD dispersion (σAPD) and ΔCL in LQT2 greater than others under random stimulations (slope = 0.00797 ± 0.00237 in LMC, 0.0022 ± 0.0037 in LQT1, and 0.02218 ± 0.00759 in LQT2 n = 4 hearts each. p = 0.039, 0.012, and 0.003 in LMC VS. LQT1, LMC VS LQT2 and LQT1 VS. LQT2 respectively, Student’s t-test where appropriate). APD dispersion of LQT2 is more dependent on CL difference. (C) Correlation of CL difference (ΔCL = S2S3 − S1S2) with APD dispersion (σAPD) in S1S2S3 Protocol replicating short-long CL pattern. In LQT2, there is a positive relationship (slope = 0.035 ± 0.020, n = 4 hearts) between short-long cycle and APD dispersion (σAPD), but of much smaller size in LMC (slope = 0.003 ± 0.003, n = 4 hearts, p = 0.02 LQT2 VS. LMC, Student’s t-test where appropriate).
