Elsevier

Heart Rhythm

Volume 12, Issue 8, August 2015, Pages 1762-1769
Heart Rhythm

Characterization of ventricular activation pattern and acute hemodynamics during multipoint left ventricular pacing

https://doi.org/10.1016/j.hrthm.2015.04.029Get rights and content

Background

Multipoint left ventricular (LV) pacing (MultiPoint Pacing [MPP], St Jude Medical, Sylmar, CA) in a single coronary sinus branch has been introduced as a novel means of cardiac resynchronization therapy (CRT). It is speculated that MPP improves LV function by capturing a larger LV tissue area, resulting in uniform wavefront propagation throughout the ventricles, in comparison to conventional biventricular pacing (BIV).

Objective

The purpose of this study was to evaluate MPP by means of contact mapping and hemodynamic measures to understand the underlying mechanisms and effects.

Methods

Ten patients with non–ischemic cardiomyopathy (mean age 69 ± 9 years; 6 men (60%); New York Heart Association heart failure class II or III; QRS duration 173 ± 20 ms; LV ejection fraction 27% ± 5%) received a CRT-defibrillator capable of MPP. After the implantation procedure, an acute pacing protocol was implemented, including 2 BIV and up to 9 MPP interventions. In all pacing interventions, LV electrical activation patterns and hemodynamics (dP/dtmax) were evaluated, and for each patient, both the resulting measures were compared between MPP and BIV interventions.

Results

Compared with BIV, MPP resulted in an increase in LV dP/dtmax (30% ± 13% vs 25% ± 11%; P = .041), a reduction in QRS duration (22% ± 11% vs 11% ± 11%; P = .01), and a decrease in total endocardial activation time (25% ± 15% vs 10% ± 20%; P = .01). MPP resulted in a larger capture of LV mass during the first 25 ms (35% ± 22% vs 16% ± 8%; P = .005) and during the first 50 ms (78% ± 27% vs 60% ± 23%; P = .03) of pacing, suggesting a quicker wavefront propagation throughout the left ventricle.

Conclusion

In this acute study, MPP in CRT improved both endocardial and surface electrical parameters and hemodynamics in comparison with BIV.

Introduction

In patients suffering from heart failure with electrical dyssynchrony, as detected by surface electrocardiogram (ECG), cardiac resynchronization therapy (CRT) has proved to exert positive effects. CRT restores the contractile function and improves exercise tolerance and quality of life1, 2, 3 in addition to promoting reverse remodeling and reducing mortality.4, 5 However, about a third of patients receiving CRT do not obtain any clinical improvement. A few recent studies have suggested that simultaneous multisite pacing delivered by 2 left ventricular (LV) leads placed in 2 coronary sinus (CS) branches may improve response to CRT.6, 7, 8 More recent studies using MultiPoint Pacing (MPP) from a single CS branch with a quadripolar LV lead (Quartet, St Jude Medical, Sylmar, CA) have demonstrated that MPP exerts favorable acute hemodynamic effects,9, 10 reduces echocardiographic dyssynchrony,11 and improves mid-term and long-term outcomes.12 However, little is known about the effects of MPP on the activation sequence of the left ventricle and its relationship to acute hemodynamics. We set out to examine the underlying mechanisms of MPP in improving the electrical activation pattern and acute hemodynamics.

Section snippets

Study population

This study enrolled consecutive patients meeting the inclusion and exclusion criteria at a single investigational center. The study population consisted of patients with the following characteristics: ≥18 years old indicated for a CRT implant approved by European Society of Cardiology/European Heart Rhythm Association (ESC/EHRA) guidelines, non–ischemic etiology, New York Heart Association heart failure class II or III, LV ejection fraction (EF) ≤35%, typical left bundle branch block (LBBB) or

Patients’ demographic characteristics and procedural data

The study was carried out in 10 patients (6 men, 60%). Table 2 lists their demographic and clinical characteristics (age, sex, baseline EF, New York Heart Association heart failure class, basal QRSd, QRS morphology, QRS axis, and total procedure time). No complications were recorded during the implantation or mapping procedures except for 1 inguinal hematoma. The LV lead was positioned in the posterior (1, 10%), posterolateral (2, 20%), lateral (5, 50%), anterolateral (1, 10%), and anterior (1,

LV activation pattern and hemodynamic response to pacing

This is the first study to evaluate the effect of MPP on the LV activation pattern and hemodynamics in the same patient population. The activation pattern reveals that MPP is able to recruit a greater portion of the left ventricle, generating a flat wavefront, to which a higher conduction velocity is associated15; this leads to a reduction in activation times and QRSd in comparison with traditional BIV. At the same time, it improves cardiac contractility, as evaluated by means of the increase

Conclusion

MPP improved hemodynamic parameters, QRSd, and activation patterns in at least one of the settings tested. These findings on the effects of CRT on patient outcomes may have important implications. Long-term follow-up and the outcomes of these patients will help confirm our findings.

Clinical Perspectives

Nonresponse to cardiac resynchronization therapy is still an issue for ≈30% of the patients, and efforts to reduce this number should be pursued. MultiPoint Pacing may play a role in addressing

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