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Spontaneous variability of ventricular function in patients with chronic heart failure. The Western Enoximone Study
1Department of Medicine, University of California, Los Angeles School of Medicine.
Purpose:
The spontaneous variation of the left and right ventricular ejection fractions (LVEF and RVEF) was evaluated in patients with chronic heart failure receiving only digoxin and diuretics over a 12-week interval.
Patients And Methods:
Fifty-one patients with stable heart failure were studied with radionuclide angiography. A baseline evaluation and a 12-week follow-up study were performed. Heart failure therapy consisted of digoxin and diuretics alone during this time.
Results:
The mean baseline LVEF (n = 51) was 27.2 +/- 9.5 (range: 7 to 50) and the LVEF after 12 weeks was 27.6 +/- 9.7 (range: 11 to 53; p = NS versus baseline). Mean RVEF (n = 19) was 31.9 +/- 11.3 at baseline and 30.3 +/- 11.3 (range: 14 to 50; p = NS versus baseline) after 12 weeks. Although there was no significant change in mean LVEF or RVEF in this group of patients, individual patients demonstrated considerable spontaneous variation. Individual LVEF values changed from 0 to 26 ejection fraction percentage points (mean of individual changes = 5.6 +/- 5.5). Individual RVEF determinations over the 12-week period varied by 0 to 15 percentage units (mean = 5.6 +/- 4.9). Thirty-five percent of patients had an absolute change in LVEF greater than 5 and 37% of patients had an absolute change of RVEF greater than 5. Even after deletion of the two worst outliers from the LVEF and RVEF data, a change in LVEF greater than 13 and a change in RVEF greater than 11% units were necessary to exclude spontaneous variation as a likely cause for the observed changes (95% confidence limits). No relationship between a change in the individual patient's LVEF or RVEF was found when these values were compared with exercise time, systolic or diastolic blood pressure, heart rate, or degree of baseline left or right ventricular dysfunction.
Conclusion:
In patients with heart failure, large (greater than 5) spontaneous changes in LVEF and RVEF may be seen in over one third of patients during a 12-week period. This variability should be considered when the ejection fraction is used as an index of improved or worsened cardiac function. The use of the LVEF and RVEF to assess interventions or therapy for heart failure should be interpreted with caution.