Noninvasive localization of accessory pathways in patients with Wolff-Parkinson-White syndrome with the use of myocardial Doppler imaging

This study sought to examine the diagnostic accuracy of noninvasive predict ion of accessory pathway localization in patients with manifest Wolff-Parki nson-White syndrome with the use of myocardial Doppler imaging as a new non invasive mapping procedure. Myocardial Doppler imaging measures myocardial velocities and therefore can determine the site of earliest ventricular act ivation in patients with accessory bypass tracts. Twenty-five patients with manifest preexcitation were studied with the use of pulsed wave and M-mode myocardial Doppler imaging for the evaluation of the shortest electromecha nical time interval in 9 basal myocardial segments. The new diagnostic test was compared with 3 electrocardiographic algorithms. An invasive mapping p rocedure served as reference standard. Abnormally short electromechanical t ime intervals were found in preexcited segments (27 +/- 12 ms vs 64 +/- 27 ms). Myocardial Doppler imaging correctly localized 84% of the accessory pa thways and electrocardiographic algorithms only 48% to 60% of cases. Noninv asive prediction of accessory pathway localization by myocardial Doppler im aging is accurate and proved to be superior to prediction based on electroc ardiographic algorithms.