Tachycardia Is Associated With Lower And Not Higher Left Atrial And Ventricular Filling Pressures

Background: It is a common concern that higher heart rates (HR) reduce coronary flow due to a shortened diastolic interval and increase left atrial and ventricular filling pressures. Translational studies also suggest that tachycardia leads to cardiomyocyte sodium retention that causes incomplete relaxation. These paradigms were tested. Methods: In eleven patients in sinus rhythm who underwent radiofrequency ablation for paroxysmal atrial fibrillation coronary sinus flow was measured by intra-cardiac ultrasound. Coronary sinus (CS) blood samples were collected at baseline and with atrial pacing at 125 bpm to assess myocardial metabolism and sodium handling. Left atrial pressures (LAP) and end-diastolic pressures (LVEDP) were recorded at the baseline heart rate (BL) and with atrial pacing at 95 and 125 bpm. Results: Seven men and 4 women were studied (age 61±9 years, ejection fraction 61±3%). Mean HR at baseline was 68±9 bpm. Compared to baseline, CS flow increased substantially with pacing at 125 bpm (in ...