A system adapted to detect one or more conduction gaps in a pulmonary vein of a patient, the system including a device configured to receive or obtain a plurality of pulmonary vein recordings in respect of said patient, each pulmonary vein recording being representative of electrical signals detected or predicted at respective electrodes or between respective pairs of electrodes located or simulated within said pulmonary vein, a device configured to determine a respective activation time for each of said plurality of pulmonary vein recordings and generating curve data representative of said activation times, and a device configured to determine the presence of one or more conduction gaps by identifying one or more respective earliest activation times.
