title: Reversible left bundle branch block should be mentioned in cardiac resynchronization therapy; A clinical case report.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) is a medical device to help cardiac synchronized contractility by electrical impulses. Improvement of symptoms and left ventricular systolic function, reducing hospital admissions and mortality in patients with moderate to severe heart failure are the main benefits of administration of cardiac resynchronization therapy.
  
  
  METHODS
  In this article, we describe a case of heart failure and left bundle branch block (LBBB) who was candidate for cardiac resynchronization therapy; but after managing hyperkalemia, left bundle branch block resolved, ejection fraction increased and cardiac resynchronization therapy implantation was canceled.
  
  
  CONCLUSIONS
  Exclusion of treatable causes is the first important step before any interventions. Now there is an important question; is cardiac resynchronization therapy effective in patients with heart failure and transient or intermittent left bundle branch block?
authors.affiliation: Associate Professor, Tehran Heart Center AND Department of Cardiology, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Vasheghani-Farahani
authors.affiliation: Resident, Tehran Heart Center AND Department of Cardiology, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Masih
authors.initials: M
authors.lastname: Tajdini
authors.affiliation: Resident, Tehran Heart Center AND Department of Cardiology, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Abolfazl
authors.initials: SA
authors.lastname: Mohsenizadeh
authors.affiliation: General Practitioner, Department of Radiology, Massachusetts General Hospital, Boston, MI.
authors.forename: Seyed Mohammad Reza
authors.initials: SM
authors.lastname: Hosseini
keywords: Cardiac Resynchronization Therapy; Hyperkalemia; Reversible Left Bundle Branch Block