The aim of this study is to evaluate the effects of heart rate optimization and guided A-V and V-V delay from color Doppler echocardiography, in subjects affected by heart failure with reduced ejection fraction and CRT-D device wearers who did not respond to device implantation in clinical, electrophysiological, and other terms.

Inclusion Criteria:

1. Patient must be 18 to 85 years of age inclusive, at the time of signing the informed consent form;
2. Heart failure with ventricular ejection fraction left <45%;
3. Presence of CRT-D devices in a non-responder patient for cardiac resynchronization
4. NYHA >II;
5. Resting heart rate <65 beats per minute;
6. Biventricular pacing >97%.

Exclusion Criteria:

1. Age <18 and >85 years;
2. Insufficient functional capacity to complete the tests required by the research protocol;
3. Permanent Atrial Fibrillation

Subjects affected by heart failure with reduced ejection fraction and CRT-D device wearers, who did not respond to the implantation of the device in clinical and electrophysiological terms.