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Measurement of left ventricular ejection fraction after acute myocardial infarction. A serial cross sectional
Insights
Significant changes in left ventricular ejection fraction (LVEF) after myocardial infarction (MI) indicate complications. A decrease greater than 0.1 in LVEF suggests infarct extension or reinfarction, while smaller changes may reflect natural variability.
Area of Science:
- Cardiology
- Medical Imaging
Background:
- Left ventricular ejection fraction (LVEF) is a key indicator of cardiac function post-myocardial infarction (MI).
- Assessing changes in LVEF can help identify complications and predict outcomes after acute MI.
Purpose of the Study:
- To evaluate the correlation between changes in LVEF and clinical complications in patients following their first acute MI.
- To determine the threshold for significant LVEF changes indicative of adverse cardiac events.
Main Methods:
- Biplane cross-sectional echocardiography was used to measure LVEF in 65 patients with first acute MI.
- LVEF was assessed on day 1, day 3 (30 patients), and at 3 months (35 patients).
- Reproducibility of LVEF measurement was tested in 20 outpatients.
Main Results:
- A decrease in LVEF >0.1 between days 1 and 3 correlated with infarct extension.
- A decrease in LVEF >0.1 between day 1 and 3 months indicated reinfarction or left ventricular aneurysm development.
- Changes in LVEF between 0.05 and 0.1 were not consistently linked to complications and may reflect measurement variability.
Conclusions:
- Changes in LVEF exceeding 0.1 are clinically significant and associated with adverse events after acute MI.
- Smaller LVEF changes (0.05-0.1) may be attributed to spontaneous variation or method reproducibility limits.
- Echocardiographic assessment of LVEF is valuable for monitoring post-MI complications.
Abstract:
Left ventricular ejection fraction was assessed by biplane cross sectional echocardiography in 65 patients with a first acute myocardial infarction on the first day. In 30 patients (group 1) measurements were repeated on the third day and in another 35 patients (group 2) at three months. Changes in ejection fraction of 0.05 or less were arbitrarily called insignificant. In group 1 only two patients showed a decrease of more than 0.1 between days 1 and 3, and both had an enzymatically confirmed infarct extension. The remaining patients had no complications. In group two 11 patients had decreases of more than 0.1 between day 1 and three months: three of them had an enzymatically confirmed reinfarction (perioperative in one) and four a possible reinfarction, and in two an angiographically confirmed left ventricular aneurysm developed. In two no complications occurred. The other complications that occurred were an enzymatically confirmed but small reinfarction, an angiographically confirmed but circumscript aneurysm, and an uncomplicated bypass operation in one patient each. These three patients had a small increase (between 0.05 and 0.1) in ejection fraction. Reproducibility of the method of measuring the ejection fraction was assessed concurrently in 20 outpatients with a previous myocardial infarction who were studied twice on the same day (with a 30 minute interval) by two different observers. The mean absolute difference in ejection fraction between the paired observations was 0.036 +/- 0.023 with a range of 0 to 0.07. Thus only changes in ejection fraction of more than 0.1 correlate with clinically recognised complications. Changes between 0.05 and 0.1 may be due to spontaneous variability or to the limited reproducibility of the method.