Effects of maintenance digoxin therapy on systolic time intervals and serum digoxin concentrations.

or 0.5 mg/day for alternate two-week periods without a loading dose. Control data were obtained both before and after the four weeks of treatment. After 13 days treatment with digoxin, 0.5 mg/day, there was a significant decrease in total electromechanical systole corrected for heart rate (QS2i), pre-ejection period (PEP), pre-ejection period corrected for heart rate (PEP,) and PEP/left ventricular ejection time (LVET). After the thirteenth dose of 0.25 mg/day there was significant shortening of PEP1 and PEP/LVET. Shortening of QS2i correlated significantly with SDC 24 hours after the thirteenth dose of 0.5 mg. These data suggest that after 13 days of treatment with 0.25 and 0.5 mg/day of digoxin, a positive inotropic effect occurs as reflected by STI shortening. A greater effect was recorded with the 0.5 mg dose.