Cardiac resynchronization therapy: current state of the art: cost versus benefit.

Abstract

An overwhelming amount of evidence from prospective randomized controlled trials supports the clinical efficacy and safety of cardiac resynchronization therapy (CRT) in patients with moderate or severe heart failure and ventricular dyssynchrony.1–6 As noted below, CRT makes heart failure patients feel better, improves cardiac structure and function, and reduces all-cause as well as heart failure morbidity and mortality. Thus, there may be a clinical mandate for use of CRT in many patients with chronic heart failure. This notion raises important questions about the clinical application of this therapy. For example, will the availability of CRT change our current clinical approach to heart failure patients? Will it lead to new research advances? Will CRT patients also require an implantable cardioverter defibrillator (ICD) to optimize outcomes? Will the clinical benefits of these therapies justify the costs? Patients with left ventricular (LV) systolic dysfunction and dilation, with or without clinical signs or symptoms of heart failure, frequently have ventricular conduction delays.7 In such patients, this is usually manifested as a left bundle-branch block (LBBB). This type of conduction abnormality is generally associated with delayed depolarization and contraction of the lateral LV free wall (Figure 1), whereas the interventricular septum exhibits a normal (early) contraction resulting in paradoxical septal motion. Figure 1. Ventricular activation sequence in narrow vs prolonged QRS duration failing hearts. A, 3D activation sequence recorded with 3D mapping system (EnSite 3000, Endocardial Solutions) in a patient with dilated cardiomyopathy, heart failure, and QRS duration of 95 ms. The activation breakthrough point was located in the septal region of the left ventricle. From this site, the activation immediately propagated to the anterior and lateral walls as indicated by the arrow. The basal region of the left ventricle was the last activated. B, In contrast, in a patient with a QRS …