The review compared the diagnostic accuracy of echographic methods (Simpson's rule, wall motion index, visual assessment) with contrast or radionuclide ventriculography for the assessment of left ventricular systolic function. The conclusion that echocardiography provides moderately accurate assessments appears reliable.

To evaluate evidence for the accuracy of three echocardiographic methods (Simpson's rule, wall motion index, and subjective visual assessment) in comparison with radionuclide or contrast ventriculography in the assessment of left ventricular ejection fraction (LVEF).

MEDLINE was searched for studies published up to 2000; the search terms were given. Additional studies were sought from the reference lists of retrieved studies and reviews. Non-English language papers were not eligible for inclusion unless their English abstract provided relevant results.

Study designs of evaluations included in the review

The study designs eligible for inclusion were not specified. The studies had to report the agreement of the index text result and the reference standard.

Specific interventions included in the review

Studies of the geometric algorithm 'Simpson's rule', the mean score 'wall motion index' and subjective visual assessments through experienced observers in echocardiography were eligible for inclusion in the review. The review was restricted to 2-dimensional transthoracic echocardiography.

Reference standard test against which the new test was compared

Studies using single or biplane contrast ventriculography and radionuclide ventriculography as the reference standards were eligible for inclusion.

Participants included in the review

Studies of predominantly adults undergoing an assessment of LVEF for the diagnosis and management of cardiac disorders were eligible for inclusion. The participants in the included studies had various cardiac disorders: ischaemic heart disease, myocardial infarction, dilated cardiomyopathy and regional wall motion abnormalities.

Outcomes assessed in the review

Studies reporting correlation coefficients or Bland-Altman limits of agreement were eligible for inclusion. The included studies provided further information on bias and inter- and intra-observer variability.

How were decisions on the relevance of primary studies made?

The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.

The authors did not state that they assessed validity.

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction. The reviewers extracted the correlation coefficient, the Bland-Altman agreement, a bias measure (systematic under- or overestimation of LVEF), and inter- and intra-observer variability where available. For some of the included studies, the reviewers were able to derive the Bland-Altman agreement from the data in the original studies.

How were the studies combined?

Details of the available outcomes in the individual studies were tabulated and summarised narratively. The range and the median of the Bland-Altman agreement method and the bias measure were presented for the three index tests.

How were differences between studies investigated?

The results of the studies were displayed according to the type of index test analysed. Differences between the index tests, sources of heterogeneity between study samples (including patient selection, echogenicity and disease spectrum), technical equipment and rater variability were highlighted.

Forty-three studies were included in the review. Thirty-two studies evaluated Simpson's rule (n=1,679), 10 evaluated the wall motion index (n=658) and 8 evaluated subjective visual assessment (n=476). Five of the included studies evaluated more than one echocardiography method.

Twenty-five studies provided the Bland-Altman measure.

Simpson's rule (28 comparisons in 21 studies): the 95% confidence intervals (CIs) ranged from LVEF +/- 7% to +/- 25% (median +/- 18%).

Wall motion index (4 comparisons in 3 studies): the 95% CIs ranged from LVEF +/- 13% to +/- 20% (median +/- 16%).

Subjective visual assessment (4 comparisons, 4 studies): the 95% CIs ranged from LVEF +/- 16% to +/- 24% (median +/- 19%).

None of the methods systematically under- or overestimated the LVEF.

Echocardiography provides a moderately accurate assessment of the left ventricular systolic function, although there may be some patients in whom the level of accuracy is inadequate. The findings of the review have important implications for the investigation of heart failure and for the reporting of echocardiography.

The inclusion criteria and searches for the review were targeted, building on older and non-systematic reviews. The search could possibly have incorporated more systematic searches of conference abstracts to limit publication bias. This 2003 review used only studies that were retrieved up to 2000. In addition, there was limited information on the review process itself (e.g. how the studies were selected, what was done to minimise selection bias)

Although studies that reported solely a correlation as a measure of agreement were eligible for inclusion, the review made little use of the data. Only the actual correlation coefficients for the included studies were reported; information about the kind of coefficient (e.g. Pearson, intra-class correlation) and the significance level were missing and were not investigated further. A rationale for the preference of the Bland-Altman measure was given.

The conclusions with regard to the accuracy of echographic methods appear reliable, but there was a wider evidence base for Simpson's rule than the wall motion index and visual assessment.

Practice: The authors stated that a descriptive grading system is proposed to identify borderline patients for whom more diagnosis is needed. If echocardiography is used alone, 'borderline dysfunction' should be taken as an LVEF of less than 40%.

Research: The authors stated that it is important to develop standards for the performance and the reporting of echocardiography.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.