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Tissue Doppler E′ to detect diastolic dysfunction from quantitative echo: a Z-score of E′ preferable to raw E′ velocities
  1. H Yadav,
  2. B Unsworth,
  3. K Medlow,
  4. R Baruah,
  5. B Wasan,
  6. J Mayet,
  7. DP Francis
  1. Imperial College NHS Trust, London, UK

Abstract

Introduction Despite their potential as a sensitive measure of ventricular performance, tissue Doppler velocities vary with normal ageing. This is inconvenient for non-specialists to interpret, and makes it difficult to use as an entry criterion for clinical studies. Age-adjusted tissue Doppler Z-scores may avoid these disadvantages and be more discriminant for myocardial impairment than raw velocities.

Methods We conducted a metaregression of studies reporting age-specific normal tissue Doppler velocities to determine a consensus formula for Z-scores (nine studies, 1990 patients), which we then tested in an independent study at our institution. We then compared Z-scores head-to-head with raw velocities in their ability to distinguish a fresh set of 81 healthy subjects from groups in whom subtle ventricular dysfunction may be expected: 50 patients with dilated cardiomyopathy, 50 with aortic regurgitation and 50 with mitral regurgitation.

Results Discriminant capacity, assessed by the area under the receiver operator characteristic curves, was higher for Z-scores than for raw velocities in each patient group. At the septal angle of the mitral annulus: dilated cardiomyopathy (DCM) 0.95 versus 0.92 (p = 0.03), aortic regurgitation (AR) 0.83 versus 0.78 (p = 0.02), mitral regurgitation (MR) 0.85 versus 0.81 (p = 0.04). At the lateral angle: DCM 0.94 versus 0.88 (p = 0.005), AR 0.92 versus 0.83 (p = 0.001), MR 0.87 versus 0.85 (p = 0.31).

Abstract 069 Figure 1

Where the healthy controls from our centre lie on the meta-regression model of E′ with age at the septal angle of the mitral annulus. The dark line represents weighted linear regression of 1990 patients from nine studies. Solid error bars represent 1 SD. Dashed error bars represent 2 SD, ie, the 95% limits of the distribution expected from the metaregression.

Abstract 069 Figure 2

Receiver operator characteristic (ROC) curve analysis for raw velocities versus Z-scores: septal angle ROC curves for tissue Doppler imaging raw velocities and Z-scores in detection of myocardial disease over age-matched controls. In all cases, the area under the ROC curve is significantly higher for Z-scores than raw velocities.

Conclusion Z-scores of tissue Doppler velocities are better able than raw velocities to detect myocardial impairment in valve or heart muscle disease. Calculation needs only raw velocity and age. Tissue Doppler Z-scores might be used to create a new, sensitive, definition of ventricular dysfunction, and may make it easier for non-specialists to interpret reports.

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