Figure 4: Examples of atrial decremental evoked potentials (DeEP) in response to extraistimulus testing with a drive train (S1) at 600 ms and extrastimulus (S2) at 20 ms above the refractory period, with a multipolar catheter placed at multiple regions with the atrium. DeEP positive sites may showed marked latency of activation (A), EGM fractionation (B) or a combination of the two (C).