Myocardial viability assessment: poor correlation between electromechanical cardiac mapping and positron emission tomography in severe coronary artery disease.

BACKGROUND: An intracardial electromechanical mapping system has recently been introduced which offers the ability to perform on-line myocardial viability assessment in the catheterisation laboratory. Only a small number of studies have been performed to validate this potentially very useful technique. AIM: We sought to assess the correlation between viability assessment performed with both positron emission tomography (PET) and electromechanical cardiac mapping (EMM) in patients suffering from severe coronary artery disease, since PET is considered the golden standard in myocardial viability assessment.
METHODS: Patients undergoing both EMM and PET analysis were systematically scanned for viability assessment. EMM analysis was performed for both linear local shortening and unipolar voltage. PET analysis consisted of dipyridamole stress and fluoro-deoxy-d-glucose (FDG) measurements. All data were converted to nine-segment bull's-eye maps to allow comparison. One single operator analysed all the data, blinded for clinical status.
RESULTS: 34 patients suffering from severe coronary artery disease underwent both PET and EMM analysis. In total 253 EMM segments had more than four contact points and could be used for analysis. Unipolar voltage showed a trend towards lower values in infarcted segments; however, linear local shortening did not show any correlation.
CONCLUSION: In this study viability assessment by EMM did not correspond with PET analysis. Although the advantage of having some form of online myocardial assessment is evident, operators should bare in mind that the quantitative EMM measurements are not an absolute substitute for nuclear imaging.