Serial serum digoxin concentrations and quantitative electrocardiographic changes.

Four elderly female patients in sinus rhythm and with mild congestive cardiac failure were treated with digoxin and studied over a 6-month period. There were significant linear correlations between serum digoxin concentrations and several quantitative electrocardiographic (ECG) parameters. T-wave amplitude was the most important ECG variable. ECG changes reverted to baseline values when digoxin was discontinued. These findings suggest that quantitative ECG changes are potentially useful in clinical and research situations involving digitalis glycosides.