title: Cardiac resynchronization therapy: results, challenges and perspectives for the future.
abstract: Heart failure (HF) is considered as an epidemic and affects 2% of the population in the Western world. About 15-30% of patients with HF and reduced ejection fraction (HFrEF) also have prolonged QRS duration on the surface ECG, most commonly as a result of left-bundle branch block (LBBB). Increased QRS duration is a marker of a dyssynchronous activation, and subsequent contraction, pattern in the left ventricle (LV). When dyssynchrony is superimposed on the failing heart it further reduced systolic function and ultimately worsens outcome. During the past 15 years several randomized controlled clinical trials have documented that resynchronization of the dyssynchronous failing heart with a biventricular pacemaker - cardiac resynchronization therapy (CRT) - which can restore a more synchronous activation and contraction pattern. This translates in halted or reversed disease progression and improved clinical outcome, including reduced mortality. In this review, we will discuss several aspects of CRT including mechanisms of dyssynchrony and resynchronization in the failing heart, evidence of CRT efficacy derived from clinical trials and current challenges in CRT including patient selection and optimization of therapy delivery. Last, we will discuss future perspectives including the role of CRT to prevent adverse events in patients with an indication for antibradycardia pacing, the role of leadless pacing in the CRT setting as well as a new clinical arena where dyssynchrony and resynchronization may be important.
authors: a Department of Medicine, Karolinska Institutet , Solna , Stockholm , Sweden.|b Department of Cardiology , Karolinska University Hospital , Solna , Stockholm , Sweden.
authors: Marcus
authors: M
authors: Ståhlberg
authors: a Department of Medicine, Karolinska Institutet , Solna , Stockholm , Sweden.|b Department of Cardiology , Karolinska University Hospital , Solna , Stockholm , Sweden.
authors: Frieder
authors: F
authors: Braunschweig
authors: a Department of Medicine, Karolinska Institutet , Solna , Stockholm , Sweden.|b Department of Cardiology , Karolinska University Hospital , Solna , Stockholm , Sweden.
authors: Fredrik
authors: F
authors: Gadler
authors: a Department of Medicine, Karolinska Institutet , Solna , Stockholm , Sweden.|b Department of Cardiology , Karolinska University Hospital , Solna , Stockholm , Sweden.
authors: Lars
authors: L
authors: Mortensen
authors: a Department of Medicine, Karolinska Institutet , Solna , Stockholm , Sweden.|b Department of Cardiology , Karolinska University Hospital , Solna , Stockholm , Sweden.
authors: Lars H
authors: LH
authors: Lund
authors: a Department of Medicine, Karolinska Institutet , Solna , Stockholm , Sweden.|b Department of Cardiology , Karolinska University Hospital , Solna , Stockholm , Sweden.
authors: Cecilia
authors: C
authors: Linde
mesh_terms: D000200:Action Potentials; D000818:Animals; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000401:mortality / Q000639:trends*; D058409:Cardiac Resynchronization Therapy Devices / Q000639:trends*; D004059:Diffusion of Innovation; D004867:Equipment Design; D005544:Forecasting; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate; D006801:Humans; D020127:Recovery of Function; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: Heart failure; cardiac resynchronization therapy; pacing