Flecainide-induced AV dyssynchrony and atrial latency progression in a patient with a dual-chamber pacemaker.

Prudence should be exercised when initiating flecainide therapy, particularly in pacemaker-dependentpatients, who may be at risk for increasedthresholds, inconsistent capture, and latency. In the setting of apparentcapture latency, changing to AAI mode may both confirm the diagnosis andprovide a symptomatic benefit.