MYOCARDIAL WORK IN VENTRICULAR PREEXCITATION

Background: Ventricular preexcitation alters electromechanical activation sequence and may induce left ventricular (LV) contractile discoordination and pathologic remodelling in selected cases.
Aim: To evaluate LV myocardial work before and after accessory pathway (AP) ablation in patients with WPW preexcitation and to compare them to normal controls.
Methods: 20 paediatric pts. with the WPW syndrome/pattern underwent myocardial work evaluation using speckle tracking echocardiography before and 24hrs. after catheter ablation (N=17/20 pts.) and were compared to 20 healthy individuals. 3D electroanatomical mapping system EnSite Precision™ was used to localize APs during EP study.
Results: Before ablation LV ejection fraction (EF; mean 53.8 vs 59.2 %, P=0.004) and global work efficiency (WE; median 92.5 vs 95.0 %, P<0.001) were lower in patients vs controls. Global WE correlated negatively with QRS duration (P=0.028) and delta to R interval (P=0.002). Segmental WE increased with distance from AP insertion from median 87.0 % at AP location to 98.0 % in distant segments (P<0.001). After successful ablation both LV EF and global WE tended to normalize. Segmental WE was almost equally distributed among LV segments.
Conclusions: Ventricular preexcitation induces significant LV myocardial work inefficiency in segments adjacent to AP which correlates with the degree of preexcitation and tends to normalize early after ablation. The amount of wasted work may be considered when assessing the potential for pathologic LV remodelling or discussing the indication for prophylactic ablation.