The study tested the usefulness of cardiopulmonary exercise test (CPET) in selection of potential responders to CRT.

Cardiac resynchronization therapy (CRT) is an acknowledged therapy of selected patients with heart failure (HF). One of the unresolved problems is high percentage of non-responders to CRT, reaching 40%. No single parameter, helpful in identifying non-responders prior to CRT implantation, was found.

The study included patients with HF of ischemic or non-ischemic etiology, in NYHA class II-IV, EF≤35% and QRS≥120ms. All the patients had CRT implanted. Clinical evaluation, CPET and NT-proBNP levels measurement were performed before CRT implantation and after 3-6 months. Improvement in HF symptoms of one or more NYHA class correlated with two-years survival. It was used as the criterion of positive response to CRT.

Inclusion Criteria:

• HF in class III or IV according to New York Heart Association (NYHA) in the course of ischemic (ICM) or non-ischemic cardiomyopathy (NICM), QRS complex duration ≥ 120ms, EF ≤35% and dilatation of the left ventricle diastolic diameter >55mm (LVdD), according to the ESC guidelines in 2007
• HF in NYHA class II, LBBB with QRS complex duration ≥ 150 ms according to the guidelines update in 2010
• optimal pharmacotherapy of HF in the period of three months prior to the study entry.
• the expected survival of the patient > 1 year.

Exclusion Criteria:

• severe chronic obstructive pulmonary disease (FEV1 <30%)
• inability to perform a stress test on a treadmill

The study comprised 122 patients qualified for CRT-D and followed-up for five years after CRT implantation. Patients were qualified for CRT-D based on the guidelines of the European Society of Cardiology in 2007 and its update in 2010.