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Targeted LV Lead Implantation Strategy for Non-LBBB
Quick Takes
- Among patients with heart failure and non-LBBB conduction delay, LV lead placement based on electrical delay in the LV region (QLV) did not result in improved outcomes compared with the anatomical approach.
- In the study, the reported responder rate was on the order of 60-70% in both pacing arms; there was no nonpacing group for comparison.
Study Questions:
What are the clinical outcomes between an increased electrical delay in the left ventricular region (QLV)-based LV lead implantation approach (QLV arm) and anatomical implantation approach (control arm) in patients with non-left bundle branch block (non-LBBB)?
Methods:
Subjects were randomized in a 2:1 ratio between a QLV-based implantation approach and anatomical implantation approach and were implanted with a St. Jude Medical quadripolar cardiac resynchronization therapy (CRT) defibrillator system. The primary endpoint was the clinical composite score after 12 months of follow-up.
Results:
A total of 248 subjects were enrolled. The study analyzed 191 available subjects at 12 months of follow-up (128 QLV arm, 63 control arm). Of these, 39 subjects (26 in the QLV arm and 13 in the control arm) had heart failure events (eight cardiac deaths and 31 heart failure hospitalizations). Aside from New York Heart Association functional class, there were no other significant differences in baseline characteristics between the two arms. The responder rate at 12 months measured by the clinical composite score was 67.2% in the QLV arm and 73.0% in the control arm (p = 0.506).
Conclusions:
There was no observable difference in outcome between the QLV-based implantation approach and the conventional anatomical implantation approach following LV lead placement.
Perspective:
Some patients with non-LBBB activation pattern appear to benefit from CRT. The main challenge is proper patient selection among those with various forms of interventricular delay, as well as the most optimal placement of the lead, rendering the field of CRT in non-LBBB patients somewhat controversial. In the present study, the authors attempted to use local electrical delay in reference to the beginning of the QRS (QLV) as a means of optimizing the LV lead placement. The study failed to show a difference between this approach and the standard anatomic approach. One possible reason for this failure is that a significant portion of the patients (44%) had relatively short QRS intervals (from 120-149 msec), which is known to be associated with poorer response in CRT patients. Another factor impacting the results of the study is the fact that the ultimate location of the lead placement was not significantly different between the QLV-guided approach and the traditional anatomic approach. Unfortunately, there was no sham pacing group in whom LV pacing would be OFF.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure
Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Bundle-Branch Block, Cardiac Resynchronization Therapy, Death, Sudden, Cardiac, Defibrillators, Heart Failure, Heart Ventricles, Secondary Prevention, Treatment Outcome, Vascular Diseases
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