Bipolar left ventricular pacing is associated with significant reduction in heart failure or death in CRT-D patients with LBBB
Introduction
Cardiac resynchronization therapy (CRT) is an efficient treatment modality to improve clinical symptoms and to reduce heart failure (HF) hospitalizations in patients with mild to severe HF, reduced left ventricular ejection fraction (LVEF), and wide QRS.1, 2, 3, 4, 5, 6 CRT has also been shown to reduce all-cause mortality.2, 4 The beneficial effects of CRT are attributed to the successful electrical and mechanical resynchronization of ventricles, resulting in improvement in left ventricular (LV) systolic function and reversal of adverse remodeling, called LV reverse remodeling.7, 8
The Multicenter Automatic Defibrillator Implantation Trial – Cardiac Resynchronization Therapy (MADIT-CRT) has shown significant benefit in the time to first HF hospitalization or death, whichever came first, in patients with mild symptoms of HF, reduced LVEF, and prolonged QRS duration who have received cardiac resynchronization therapy with defibrillator (CRT-D).1 The results were confined to patients with a left bundle branch block (LBBB) electrocardiogram (ECG) pattern.9 We have also suggested that CRT-D reduces the risk of ventricular tachyarrhythmias (VTA), especially in those with LBBB.9
LV lead pacing polarity is a modifiable parameter in most cases. Bipolar LV leads offer the ability to pace from the distal pole only, proximal pole only, and bipolar pacing, often reducing the incidence of diaphragmatic stimulation.10 One study has also demonstrated that the pacing vector changes the ventricular activation sequence and alters the electromechanical parameters of the paced ventricle.11 There have been limited data to further explore the long-term clinical significance of LV lead pacing polarity. As a result, we hypothesized that pacing polarity may play a role in ventricular response to resynchronization and could be associated with significant differences in clinical outcomes.
Therefore, the aim of our study was to determine the association between LV lead pacing polarity and (1) HF events or death, (2) death alone, and (3) VTA, in patients enrolled in MADIT-CRT, receiving a CRT device with implanted cardioverter-defibrillator (ICD), by LBBB ECG morphology.
Section snippets
Study population
The design, protocol, and results of the MADIT-CRT study have been published previously.11, 12 Briefly, 1820 patients with ischemic cardiomyopathy (New York Heart Association [NYHA] functional class I or II) or nonischemic cardiomyopathy (NHYA functional class II only), LVEF of less than 30%, and a prolonged QRS duration >130 ms were randomized to receive CRT-D or ICD therapy in a 3:2 ratio. All eligible patients met the guideline criteria for ICD.13 Patients with certain clinical
Clinical characteristics of patients
Among the 969 patients in this study, 421 patients had True Bipolar LV pacing while the remainder (n = 548) had Unipolar/Extended Bipolar LV pacing. Baseline clinical characteristics of patients by programmed LV pacing polarity are listed in Table 1. Patients programmed to True Bipolar pacing more often had nonischemic cardiomyopathy and LBBB ECG pattern at baseline and they were more likely from a non-US center compared to patients programmed to Unipolar/Extended Bipolar pacing.
Relationship between left ventricular pacing polarity and death or heart failure event
Among patients
Discussion
In our study, we demonstrate that patients with LBBB and CRT-D with True Bipolar LV lead pacing polarity have a significantly lower risk of all-cause mortality and HF/death compared to those with Unipolar/Extended Bipolar LV pacing. Our findings were consistent in patients with ischemic and nonischemic etiology of cardiomyopathy and independent of LV lead location.
LV lead pacing polarity is a nonstandardized, provider-driven selection largely made at the time of implantation or soon thereafter.
Conclusion
In mild HF patients with LBBB and CRT-D, True Bipolar LV pacing is associated with a significantly lower risk of HF/death and all-cause mortality compared to patients with Unipolar/Extended Bipolar LV pacing.
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Cited by (11)
Quadripolar versus bipolar leads in cardiac resynchronization therapy: An analysis of the National Cardiovascular Data Registry
2020, Heart RhythmCitation Excerpt :Notably, the rates of device-related infection in the overall cohort and in the CMS-linked matched cohort are low, which is in accordance with a recently published trial that evaluated differences in device-related infection among patients randomized to either conventional or incremental antibiotic coverage with reported 1-year hospitalization for device-related infection ranging between 0.78% and 1.23%.18 In an analysis of patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy, BP LV lead pacing has been associated with reduction in all-cause mortality rate (hazard ratio 0.46; 95% CI 0.24–0.88; P = .020) and combined all-cause mortality and CHF rates (hazard ratio 0.68; 95% CI 0.46–1.00; P = .048) in comparison to UP lead pacing in patients with left bundle branch block.19 The use of UP leads has reduced since the introduction of QP leads, from 2610 leads in 2014 to 720 leads in 2015 (Figure 2).
Capture threshold of bipolar and unipolar pacing of left ventricle via coronary sinus branch: longitudinal study
2023, Frontiers in Cardiovascular MedicineTrue bipolar or extended bipolar left ventricular pacing is associated with better survival in cardiac resynchronization therapy patients
2020, PACE - Pacing and Clinical Electrophysiology
The MADIT-CRT study was supported by a research grant from Boston Scientific, St Paul, Minnesota, to the University of Rochester School of Medicine and Dentistry. Drs Jamé and Kutyifa contributed equally to the design of the study, data analyses, and manuscript preparation. Clinical Trial Registration: http://clinicaltrials.gov/ct2/show/NCT00180271.
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Sina Jamé, MD, Valentina Kutyifa, MD, PHD, MSc, FHRS are co-first authors.