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LV Lead Location and Long-Term Outcomes in CRT Patients
Study Questions:
What are the long-term clinical outcomes of all-cause mortality and heart failure (HF) in patients with cardiac resynchronization therapy-defibrillator (CRT-D) by left ventricular (LV) lead location?
Methods:
This was a substudy of the long-term follow-up of the MADIT-CRT (Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy) trial. The LV lead location was classified in 797 patients with CRT-D: 569 patients with left bundle branch block (LBBB) and 228 with non-LBBB. Leads were classified into apical (n = 83) and nonapical (n = 486), with the nonapical LV leads further categorized into anterior (n = 99) and posterior/lateral (n = 387) within LBBB. All-cause mortality and HF events were assessed using Kaplan-Meier and Cox analyses.
Results:
In CRT-D patients with LBBB, posterior/lateral LV lead location was associated with a significant reduction in long-term all-cause mortality (hazard ratio [HR], 0.54; 95% confidence interval [CI], 0.37-0.79) and HF events (HR, 0.44; 95% CI, 0.33-0.60) compared to an implantable cardioverter-defibrillator (ICD) only. An anterior LV lead location was associated with a significant reduction in HF events compared to an ICD only (anterior: HR, 0.50; 95% CI, 0.30-0.82); however, no association with mortality reduction was observed from CRT-D versus an ICD only. CRT-D was not associated with improved outcomes in non-LBBB patients, regardless of LV lead location.
Conclusions:
In mild HF patients with LBBB and a CRT-D, lateral/posterior and anterior LV lead locations are similarly associated with reduction in the risk of HF or death compared to ICD alone. Mortality benefit derived from CRT-D is associated only with patients with lateral/posterior LV lead location. An apical LV lead location should be avoided due to the early risk of death whenever possible.
Perspective:
The results of this analysis are consistent with prior reports. The key message is that posterior/lateral location is associated with better outcomes, including mortality reduction, and that apical placement of CRT lead is detrimental. Anterior location was associated with improved outcomes, but not mortality benefit. Non-LBBB patients did not experience clinical benefit from CRT-D with any LV lead locations. A significant imitation of this and other reports in this area is that the lead location is never randomized, so it does not imply causality. LV lead locations are influenced by available coronary sinus branches and the presence of scar, which itself may be responsible for the observed outcomes.
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Cardiac Resynchronization Therapy, Cardiac Resynchronization Therapy Devices, Cicatrix, Coronary Sinus, Defibrillators, Implantable, Heart Failure, Outcome Assessment, Health Care, Secondary Prevention
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