Abstract

Objective: To investigate the effects of digoxin on left atrial (LA) function in patients with congestive heart failure and dilated left atria.

Patients: 30 patients with enlarged left atrium (maximum LA diameter > 4 mm) caused by heart failure (New York Heart Association functional class III or IV) were studied before and after treatment with digoxin (0.25 mg orally for 12 days). Digoxin was also administered to 30 normal participants who served as controls.

Main outcome measures: LA active (AEF) and passive emptying fractions (PEF), reservoir fraction (RF), kinetic energy (KE), and mean velocity of circumferential atrial fibre shortening (Vcf) were calculated from echocardiographic measurements of LA volumes and transmitral Doppler flow velocities at baseline and on the third, sixth, eighth, and 12th day after digoxin administration.

Results: LA AEF, PEF, RF, KE, and Vcf were significantly lower in patients than in controls (p < 0.001). LA AEF, PEF, RF, KE, and Vcf increased significantly both in patients and controls after digoxin administration (p < 0.001). This increase was greater in patients than in controls (p < 0.001). KE was linearly correlated with LA volume at the onset of atrial systole in all participants. The slope and the intercept of this relation were significantly increased after digoxin both in patients and in controls (p < 0.001).

Conclusions: LA performance is impaired in patients with heart failure. Dilated atria manifest atrial failure. Digoxin improves LA performance and LA contractility both in dilated and in normal atria. The effects of digoxin on LA contractility are augmented in the failing atria compared with the normal atria.