Mortality and Quadripolar vs. Bipolar LV Leads in CRT
How does the survival from all-cause mortality, lead deactivation, and lead replacement compare between quadripolar versus bipolar leads?
Using nationwide data from device implant registration records of a single manufacturer, the authors identified patients with a de novo cardiac resynchronization therapy with defibrillation (CRT-D). Patients were followed for up to 24 months. Left ventricular (LV) lead types (quadripolar Quartet [St. Jude Medical] LV lead or bipolar LV lead) were compared in regard to death, LV lead replacement, and LV lead deactivation.
Among 23,570 patients (mean age, 69.5 years; 28% female; median follow-up time, 1.14 years), 18,406 had quadripolar and 5,164 had bipolar LV leads. The quadripolar and bipolar groups had 5.04 and 6.45 deaths per 100 patient-years, respectively (p < 0.001). After multivariate adjustment, the quadripolar lead was associated with a lower risk of deactivation (hazard ratio [HR], 0.62; p = 0.002), replacement (HR, 0.67; p < 0.001), and death (HR, 0.77; p < 0.001).
In this observational study of CRT-D devices, use of a quadripolar, compared to a bipolar LV lead, was associated with a reduction in LV lead deactivation, replacement, and mortality.
The introduction of the quadripolar LV lead has been a major advancement in CRT. The four LV electrodes now allow pacing from a multitude of vectors. The additional vectors play a host of functions. This includes the avoidance of phrenic nerve stimulation; potentially increased lead stability with deeper advancement of the lead in a coronary sinus tributary, while maintaining the ability to pace from mid to basal lateral LV wall; and a decreased risk of LV lead replacement, reducing exposure to potential complications of lead or device revisions. The findings make a lot of sense, but the mortality benefit claim remains hypothetical due to the observational character of the present study, and lack of relevant clinical data. The ongoing limitation of CRT remains anatomically restricted ability to deploy the pacing electrode in the most optimal location for each patient.
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