Table 2.

ESC Guidelines - Recommendations for cardiac resynchronizatin therapy directly or upgrade from a conventional pacing system in patients with heart failure and formal indication for cardiac pacing therapy.

Recommendation	Class	Level of evidence
1. Upgrade of conventional PM or ICD CRT is indicated in HF patients with	I	B
LVEF <35% and a demand for high percentage of ventricular pacing who persist in the NYHA functional class
III or IV even with optimized medical treatment
2. CRT in a direct way CRT should be considered in patientis with HF, depressed LVEF and a demand for high percentage of ventricular pacing under risk of worsening od HF symptoms	IIa	B

PM=pacemaker; ICD=mplantable cardioverter defibrillator; CRT=cardiac resynchronization therapy; HF=heart failure; LVEF=left ventricular ejection graction; NYHA=New York Heart Association. Brignole M, Auricchio A, Baron-Esquivias G, Bordachar P, Boriani G, Breithardt OA, et al.^[3]