Question - What are the most prominent EKG findings associated with toxicity of the drug flecainide?
Answer - One study notes: “Upon review of the data, two morphologically distinct patterns emerged based upon the duration of the QRS interval. In patients with flecainide toxicity and QRS duration less than or equal to 200 ms, the ECGs were more likely to show RBBB, visible P waves (p = 0.03), and shorter QT (p = 0.02) and QTc intervals (p = 0.004). Conversely, in patients with QRS duration greater than 200 ms, the ECGs were more likely to show LBBB, loss of P waves, a northwest axis (p = 0.01), and longer QT and QTc intervals.” (Valentino MA et al. Flecainide toxicity: A case report and systematic review of its EKG patterns and management. 2017 Cardiovasc Toxicol 17:260-266)