Effects of digoxin on exercise capacity and right ventricular function during exercise in chronic airflow obstruction

Area of Science:

• Cardiology
• Pulmonology
• Exercise Physiology

Background:

• Patients with chronic airflow obstruction (CAO) often exhibit impaired right ventricular function.
• The efficacy of digoxin in improving exercise capacity and right ventricular function in this population is not well-established.

Purpose of the Study:

• To evaluate the effects of oral digoxin on exercise capacity (VO2 max) and right ventricular (RV) pump function during exercise in patients with stable CAO and abnormal RV function.
• To assess changes in ejection fractions (RVEF, LVEF) at rest and during exercise.

Main Methods:

• A randomized, double-blind, placebo-controlled, cross-over study involving 12 patients with stable CAO.
• Patients received oral digoxin (0.25 mg/day) or placebo for two weeks, followed by cross-over.
• Exercise tests and gated equilibrium radionuclide angiography were performed to measure VO2 max and ejection fractions.

Main Results:

• All patients presented with abnormal right ventricular function (low resting RVEF or subnormal exercise response).
• Digoxin did not significantly increase resting or exercise RVEF.
• Small, non-significant increases in exercise duration, maximum workload, and VO2 max were observed with digoxin. Only the increase in oxygen-pulse (O2-P) was statistically significant (p < 0.05).

Conclusions:

• Oral digoxin does not significantly improve exercise capacity in severe chronic airflow obstruction with impaired right ventricular function.
• Digoxin does not significantly improve right ventricular ejection fraction at rest or during supine submaximal exercise in this patient group.