i
Class I indications for cardiac resynchronization therapy for reducing the risk of HF hospitalization and reducing the risk of premature death:
- CHF + NYHA Class II persisting despite optimal pharmacotherapy + sinus rhythm + LBBB QRS morphology + QRS duration of > 0,13 s + LVEF < 30% + patients in whom expected survival time with good functional status is > 1 year,
- CHF + NYHA Class III - IV persisting despite optimal pharmacotherapy + sinus rhythm + LBBB QRS morphology + QRS duration of > 0,12 s + LVEF < 35% + patients in whom expected survival time with good functional status is > 1 year.

Class IIa indications for cardiac resynchronization therapy for reducing the risk of HF hospitalization and reducing the risk of premature death:
- CHF + NYHA Class II persisting despite optimal pharmacotherapy + sinus rhythm + non-LBBB QRS morphology + QRS duration of > 0,15 s + LVEF < 30% + patients in whom expected survival time with good functional status is > 1 year,
- CHF + NYHA Class III - IV persisting despite optimal pharmacotherapy + sinus rhythm + non-LBBB QRS morphology + QRS duration of > 0,15 s + LVEF < 35% + patients in whom expected survival time with good functional status is > 1 year.