Figure 4. Amplification of Rate-Dependent APD Alternans in Paroxysmal AF Prior to AF.
This patient (LA diameter 39 mm, LVEF 59 %) showed (A) No APD alternans at CL 500 ms; (B) APD alternans at CL 300 ms; (C) marked AP Alternans at CL 250 ms(phase II/III shape), during 3:1 AV conduction prior to AF initiation. Asterisk indicates far-field AF activation or an after-depolarization triggering AF. (D) APD restitution slope was >1 at its maximum, but <1 at APD alternans onset. (Key: as figure 2).