Favorable effects of oral digoxin therapy on the left ventricular performance in patients with artificial pacemakers.

The contribution of atrial systole in the left ventricular (LV) function and the effects of oral digoxin maintenance therapy on the LV function were evaluated noninvasively in patients who had artificial pacemakers but no clinical manifestation of congestive heart failure (NYHA Class I). Diastolic dimension (Dd), ejection time (ET), and stroke volume were constant in 8 patients without P waves on their electrocardiograms, but in 20 patients with P waves they were variable from beat to beat because of the variation of the PR intervals which caused them to reach their maximum values when the PR intervals were 160 to 200 msec. Ten out of the 28 patients were given 0.25 mg of digoxin daily for 10 days. Dd did not change significantly, but the ET and the systolic dimension were significantly shortened (P < 0.001). Posterior wall excursion, ejection fraction, and mean posterior wall velocity were significantly increased (P < 0.001). It is concluded that (1) atrial contraction is important to the LV function in patients with artificial pacemakers, and (2) that favorable effects on the LV function can be obtained by a small dose of digoxin administered to the patients who had artificial pacemakers but no congestive heart failure.