Cardiac resynchronization therapy in New York Heart Association class IV heart failure: it is all about selection.

In recent years, cardiac resynchronization therapy (CRT) has emerged as an important therapeutic strategy in patients with advanced heart failure. It has become common practice to use CRT in combination with implantable cardioverter-defibrillator (so-called CRT-D) in patients with impaired left ventricular systolic function and New York Heart Association (NYHA) class III symptoms.1 Evidence is also mounting regarding the potential benefit of CRT in delaying disease progression in patients with symptomatic heart failure.2,3 However, the role of CRT and CRT-D is less clear in patients with very advanced heart failure, especially in those with NYHA class IV symptoms (those with symptoms at rest and worsening with exertion). In fact, 5% of all heart failure subjects enrolled in large multicenter mortality device trials fulfilled this category.4 Although there has been increasing debate over this issue,5–7 patients in the intensive care unit requiring inotropic and mechanical support are still not considered suitable candidates for CRT or CRT-D “salvage” therapy.8 Some patients with very advanced, refractory heart failure are ambulatory, however; in these patients, neither cardiac transplantation nor permanent mechanical support devices are appropriate or imminent. Many of these patients are still considered as approaching “stage D heart failure,” in which they can be best characterized by experiencing end-stage disease refractory to optimal medical therapy. Even now, we have few data in such patients because they have been systematically excluded or avoided in most CRT trials, perhaps because of a presumed shortened lifespan.