Effects of epicardial versus transvenous left ventricular lead placement on left ventricular function and cardiac perfusion in cardiac resynchronization therapy: A randomized clinical trial
Myocardial perfusion scintigraphy (MPS) studies in patients without coronary artery disease and LBBB have shown myocardial perfusion defects due to pacemaker stimulation,6 and has been validated for assessment of LV volumes and ejection fraction.8 Other smaller trials have shown that decreased contractile force is due to regional perfusion abnormalities and abnormal myocardial glucose metabolism in CHF patients, which improves after CRT.9 Optimal LV lead position in patients undergoing device implantation for BIV pacing is crucial to achieve a maximum effect on hemodynamics. Ideal lead placement is often hampered by unfavorable coronary sinus (CS) anatomy, high pacing threshold in case of fibrosis and phrenic nerve stimulation. Due to this difficulties, up to 30% of TV LV lead placements fail or result in limited or no clinical response.11 Even with the use of multipolar LV electrodes, clinical nonresponse due to suboptimal lead positioning remains a clinically relevant problem. Epicardial (EPI) LV lead placement through a small lateral thoracotomy or using thoracoscopic techniques might overcome these obstacles and limitations. Surgical EPI LV lead placement could be performed at a position anticipated to be the optimal site (with maximal dyssynchrony), which may have a more favorable effect on myocardial perfusion. EPI LV lead placement has been shown to be both safe as well as feasible.12 In most institutions, this technique is either performed if TV placement fails, or as concomitant treatment if an elective thoracotomy is planned for another indication. Possibly, a surgical EPI approach for LV lead placement in CHF patients scheduled for CRT could yield better results with a greater number of responders to CRT than the conventional TV approach. Data on the comparison of TV versus EPI LV lead placement in matters of improvement in left ventricular function are limited and are mostly observational nonrandomized trials; randomized data are lacking. To adjudicate the proper position of EPI LV lead placement, there is need for randomized trials performing a head to head comparison with TV placement. With this trial we attempt to elucidate whether there is a place for EPI lead placement as first line therapy.
In this randomized trial we hypothesize that surgical EPI lead placement is superior to the conventional TV approach in improving LV function and myocardial perfusion.