[Electrotherapy of cardiac failure]

Intracardiac conduction disturbances, mostly manifested as a left bundle branch block (LBBB), are common findings in cardiac failure and associated with a poor prognosis. LBBB is a marker of disease progression and also leads to worsened cardiac hemodynamics by dyssynchronous contraction that can accelerate progression of the underlying disease. Cardiac resynchronization therapy (CRT) can reduce the negative effects of these disturbances leading to improvement in hemodynamics and long-term improvement in cardiopulmonary exercise tolerance, reduction of left ventricular volumes and functional mitral regurgitation. Prospective multicenter studies, such as the CARE-HF and COMPANION trials have demonstrated reduced mortality with CRT or combined treatment with defibrillator capability (CRT-D). Thus, CRT has been adopted in the current guidelines of cardiology societies. Nevertheless, there are a number of open issues with CRT, such as the high number of non-responders or the value of CRT in patients with atrial fibrillation, narrow QRS complex and mild cardiac failure or asymptomatic left ventricular dysfunction. In addition, the question whether every CRT patient needs a device with defibrillating capabilities is not fully resolved, at least for patients with dilative cardiomyopathy.