Atrial fibrillation - QT interval and catheter ablation.

Letter to the editor 1, authored by Linda Mann

The recent article about atrial fibrillation1 states that the QT interval should be closely monitored, and sotalol is relatively contraindicated in patients with chronic renal impairment. How do we monitor QT interval in atrial fibrillation when it is not measurable?

Linda Mann, General practitioner

YourDoctors, Sydney

Letter to the editor 2, authored by Paul Salmon

Great article on atrial fibrillation1a, but why is there no mention of cryoablation when radiofrequency ablation was mentioned?

Paul Salmon, Radiologist

Sydney

Deep Chandh Raja, one of the authors of the article, comments:

In response to Linda Mann’s query, we suggest measuring the QT interval in atrial fibrillation as an average over five ventricular beats. This has been shown to correspond very closely to the QT interval of the same patients in sinus rhythm, when corrected for heart rate.1b A heart rate correction formula (e.g. Bazett’s) should be used, however there is no robust evidence to show superiority of one particular formula over the other.1b

With regards to the query from Paul Salmon about catheter ablation, there are different sources of energy for catheter ablation – radiofrequency energy, cryotherapy and pulsed field ablation.2b Radiofrequency energy continues to remain the widely practised mode of catheter ablation, although radiofrequency energy and cryotherapy have similar efficacy rates. Pulsed field ablation or electroporation has recently shown promising results in the first-in-human trials.2b