Background:

Cardiac resynchronization therapy (CRT) is indicated in patients who often present cardiac remodeling due to dilata tion and contractile dyssynchrony. CRT contributes to reverse remodeling which is associated with reduced mortality and heart failure (HF) hospitalizations. Improvements in intraventricular conduction with decreased ventricular activation time have also been observed. The quantification of reverse electrical remodeling has been underused as a parameter of response, and there are few reports on its association with the clinical-structural response.

Objective:

To analyze intraventricular reverse electrical remodeling as a parameter of response to CRT in living individuals.

Methods:

We included patients implanted at least 6 months ago. A deactivated stimulation ECG (post-CRT intrinsic QRS, iQRS) was obtained, and by means of transthoracic echocardiography (TTE), the left ventricular ejection fraction (LVEF), the left ventricular end-diastolic diameter (LVEDD) and the presence of mitral regurgitation were defined. Patients were classified according to their clinical-structural response. Electrical remodeling was characterized by comparing pre- and post-CRT QRS duration and assessing QRS changes (ΔiQRS) between groups.

Results:

A total of 23 patients were included, 39% of which showed a >10 msec decrease in iQRS. We observed a ΔiQRS of -9.3±20.7 msec in responders, and 11.25±18.9 msec in non-responders (p=0.027), more marked in hyper-responders (ΔiQRS: -14.44±17.40 msec, p=0.026). Women with pre-CRT QRS ≥150 msec showed a significant decrease in iQRS (p=0.0195).

Conclusion:

Reverse electrical remodeling was found in 39% of the patients under CRT. We noted a significant relationship between ΔiQRS and clinical-structural response, higher in hyper-responders. Women with wider pre-CRT QRS showed more marked reverse electrical remodeling. This parameter is accessible and easy to read in outpatient visits.