Myocardial Ischemia due to Rapid Atrial Fibrillation Revealed Using the Instantaneous Wave-Free Ratio A Case Report

Instantaneous wave-free ratio (iFR) is a non-hyperemic coronary physiological index measured during the diastolic wave-free period. Although atrial fibrillation (AF) with beat-to-beat fluctuations can occur during diastole, the feasibility of iFR measurements during AF has previously been demonstrated. However, the effects of coronary circulation during AF on iFR measurements remain unknown. In addition, the pathophysiology of ischemia due to AF tachycardia requires further elucidation. We report a unique case of myocardial ischemia due to rapid AF, as indicated by the iFR pullback measurement and beat-to-beat analysis. When planning revascularization in patients with rapid AF, the ability of iFR to reflect ischemic stress due to AF tachycardia should be considered.