Left Atrium Reservoir Function Modulation in Patients With Atrial Fibrillation: A Randomized Digoxin Versus Beta Blocker Study

Atrial fibrillation (AF) is responsible of significant morbidity and mortality. Management of signs and symptoms of heart failure generated by AF is at the center of the latest European recommendations . Mechanisms by which these symptoms are generated are very poorly understood. Heart rate control is one of the recommended strategies but remains poorly codified and generally follows the preferences and experiences of each local center. The European guidelines propose at least 4 molecules for heart rate control without emitting preferences for one molecule over the other due to the lack of robust randomized studies. Recently, a study comparing digoxin vs ß-blockers showed the superiority of digoxin in decreasing symptoms despite a comparable action on heart rate. On the other hand, the reservoir function of the left atrium (LA) has taken a central role in assessing signs of left heart failure and monitoring filling pressures . Other studies have demonstrated the association of left atrium reservoir strain with these symptoms .

It is commonly accepted that ß blockers decrease AF-related symptoms by a negative chronotropic effect thanks to their blocking action on the sympathetic system. While the action of digoxin on symptoms goes through a positive inotropic effect thanks to the increase in intracellular calcium .

However, the impact of these two molecules on the function of the left atrium has never been investigated. Our diagnostic hypothesis is that in addition to their action on heart rate, the improvement of symptoms noted by using b blockers and digoxin during the treatment of AF would go through an improvement LA reservoir function . The superiority of digoxin in the reduction of symptoms compared to ß blockers would be due to a greater improvement in reservoir function and this thanks to the increase in myocardial intracellular calcium.