High‐density mapping of de novo focal atrial tachycardias using a new software: Protected low‐voltage areas by zones of conduction delay

Background The pathophysiological mechanism of focal atrial tachycardias (AT) remains obscure. Methods Fifteen patients (6 males, age 45 ± 18) with focal AT underwent high-density activation mapping using a new software called extended early-meets-late (EEML). Results Irrespective of the arrhythmia mechanism, low bipolar voltage fractionated signals (0.14 ± 0.10 mV) were seen at the earliest activation site. The mean low-voltage area (LVA) at the earliest activation site was 3.2 ± 1.0 cm2. EEML mapping revealed zones of conduction delay at the borders of LVAs. Conclusions LVAs protected by zones of slow conduction appears to play an important role in the initiation and maintenance of focal ATs.