The lack of a reliable quantitative measurement analysis package for regional left ventricular wall motion is not new.
The lack of a reliable quantitative measurement analysis package for regional left ventricular wall motion is not new. Throughout the early 1980s, when the preferred method of evaluating left ventricular function was radionuclide ventriculography, multiple regional wall motion algorithms were tried. Qualitative (visual) analysis was limited by the relatively poor quality of the studies, but in the end, qualitative analysis remained the preferred, though limited, method.
Here we are, 20 years later, with additional higher quality imaging modalities to assess regional left ventricular function, and it appears that the methodology continues to outstrip the analysis. Hoffman and colleagues analyzed resting regional function by 4 different methods: cineventriculography, cardiac magnetic resonance imaging, unenhanced echocardiography, and contrast-enhanced echocardiography. Considerable interobserver variability and lack of accuracy were seen with all imaging modalities, although contrast echocardiography had the highest interobserver agreement and was the most accurate.
It would be interesting to review the data on interobserver agreement according to regional site, as one would imagine that anterior wall abnormalities would be more easily and more reliably detected. It would also be interesting to compare accuracy to thallium studies, as detection of a wall motion abnormality may also be dependent on the size of the ischemic or infarcted area. Small areas may be influenced more (masked) by surrounding normally functioning myocardium. Because smaller infarcts would be more common in the inferior or posterior wall, it would not be surprising to see relatively low accuracy and high variability. Larger areas of nonfunctioning myocardium may more commonly occur in the anterior-septal region, be easier to detect, and have higher levels of agreement.
The poor agreement among these high-tech studies is disappointing but is not unexpected and does not necessarily mean that the use of these techniques combined with exercise will also be as limiting. Exercise studies are based on a comparison between resting and stress studies with direct visualization of the images side to side. A in regional wall motion between studies is likely easier to detect and far more accurate than the reading of a resting study alone.
Finally, this high variability and low accuracy should spur further investigation into analyses that are as good as the imaging modalities. Combination perfusion and functional imaging may be the most accurate determinant of regional abnormalities. Perfusion/functional imaging should not be difficult with emerging imaging modalities. A crude variation has been available for years with gated thallium studies.