Left Ventricular Lead Placement in Cardiac Resynchronization Therapy: Where and How?

Fakhar Zaman Khan; Munmohan Singh Virdee; Simon Patrick Fynn; David Paul Dutka

Disclosures

Europace. 2009;11(5):554-561. 

In This Article

Abstract and Introduction

Abstract

Cardiac resynchronization therapy (CRT) offers proven benefit to patients with refractory symptomatic chronic heart failure (New York Heart Association Class III or IV), severe left ventricular (LV) systolic dysfunction (LV ejection fraction <35%), and LV dyssynchrony (QRS width >120 ms). Cardiac resynchronization therapy has the potential to improve survival and functional capacity, reduce hospital admissions, and promote LV reverse remodelling. Although difficult to truly evaluate, up to 30% of patients do not attain symptomatic benefit. Factors associated with a poor outcome include inappropriate patient selection, inadequate device programming, presence of myocardial scar, and suboptimal LV lead placement. Left ventricular dyssynchrony is an important determinant of CRT response, although at present no reliable single measure to identify patients beyond QRS width has been identified. In this review, we discuss the effect of LV lead placement to pace the region of maximal dyssynchrony, the impact of total scar burden on response, and the relationship between LV lead position and localized scar. Consideration is also given to prospectively defining placement of the LV lead including surgical epicardial lead positioning.

Introduction

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients receiving continuing symptoms, despite optimal medical therapy (New York Heart Association Class III or IV), severe left ventricular (LV) systolic dysfunction [left ventricular ejection fraction (LVEF) <35%], and LV dyssynchrony (QRS width >120 ms). Cardiac resynchronization therapy also reduces decompensation and requirement for hospitalization and facilitates improved LV reverse remodelling.[1–8] The number of patients who do not respond is difficult to define but up to 30% do not attain symptomatic benefit due to inappropriate selection for CRT, presence of myocardial scar, suboptimal LV lead position, and inadequate post-implant device programming. Although LV dyssynchrony is an important determinant of CRT response, there is presently no reliable single measure to identify patients beyond prolonged QRS duration.[9] This review will address the question of pre-implant assessment to direct placement of the LV lead in regions of maximal dyssynchrony, the impact of total scar burden on response, and the relationship between the LV lead position and localized scar. Consideration is also given to prospectively targeting LV leads using pre-implantation imaging and the role of surgical lead placement in challenging cases.

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