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Impaired myocardial blood flow in atrial fibrillation

To the Editor, We have read with great interest the article entitled “Class 1C Antiarrhythmic Drugs in Atrial Fibrillation and Coronary Artery Disease” by Pantlin et al in the latest issue of the journal. We would like to thank the authors for filling the scientific gap in this topic. The authors have stated the safety of class 1C antiarrhythmic use in patients with atrial fibrillation (AF) and occult coronary artery disease. In the case of uncontrolled heart rates in AF, rate‐related ST depression is generally seen without significant coronary stenosis, indicating the most possible underlying mechanism of supply‐demand imbalance. Some imaging modalities such as positron emission tomography and magnetic resonance imaging can accurately quantify myocardial blood flow (MBF) of patients with AF and no significant coronary stenosis in both baseline and stress conditions, regardless of heart rate. It has been shown that baseline MBF is significantly lower in patients with AF compared with patients in sinus rhythm. Also, stress MBF is significantly lower in patients with paroxysmal or persistent AF (as in the current study, 1.7 ± 0.7 and 1.5 ± 0.6 mL/g/min using positron emission tomography) compared with patients in sinus rhythm. No improvement of these impaired MBF characteristics in patients with AF who underwent catheter ablation was detected when compared with preablation values even in patients with no recurrence. In other words, MBF is impaired in patients with AF who have no significant coronary stenosis and, restoration of sinus rhythm is insufficient to reverse this impairment.