Midtveisevaluering - Håvard Keilegavlen

Impact of the left ventricular lead on the efficacy of Cardiac Resynchronization Therapy for heart failure

by PhD-Candidate Håvard Keilegavlen

Abstract: 

Cardiac resynchronization therapy (CRT) provides improved cardiac performance and clinical outcome in heart failure patients with wide QRS complex. Non-optimal position of the left ventricular (LV) pacemaker lead is a major reason for inferior response to CRT. The ability to reach the desired position, the rate of lead dislodgements, occurrence of phrenic nerve stimulation and clinical outcome are affected by properties of the LV leads. The aims of this PhD project are to examine the impact of different LV leads and in particular a novel bipolar LV lead with a side helix for active fixation.

In the first article we presented the result from a prospective non-randomized trial of 106 patient who received a CRT-pacemaker with the novel active fixation LV lead. We showed that the lead has abilities to be placed in target vein segments over a wide range of vein anatomies. The average LV pacing threshold at implant was low, remained stable at follow-up and no late dislodgements were observed.

In the subsequent trial that is the basis for article 2 and 3, the objective is to compare the active fixation LV lead and a quadripolar passive LV lead. We performed a randomized and blinded trial that included 63 patients scheduled for CRT implantation. The latest contracting LV segment was identified as target segment by radial strain speckle-tracking echocardiography. In article 2, we compared the electrical performance and the ability to achieve a stable proximal position in a coronary vein located concordant to target segment. We found low and stable pacing capture thresholds, but no significant differences between the  leads. The active fixation did not facilitate a more proximal position of the stimulating electrode nor a higher grade of concordance to the target LV segment. In the third article we will present the clinical outcome in terms of improvement of cardiac performance and clinical symptoms and evaluate factors that influence the outcome.