Reversible left bundle branch block should be mentioned in cardiac resynchronization therapy; A clinical case report.

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. CASE REPORT: 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. CONCLUSION: 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?