# Usefulness of Cardiac Resynchronization Therapy Optimization Using Combined Electrocardiography and Echocardiography

## TL;DR

This study shows that combining echocardiography with electrocardiography improves the effectiveness of heart therapy in patients who don't fully respond to electrocardiography alone.

## Contribution

The study demonstrates that echocardiography-based adjustments can further improve cardiac resynchronization therapy when electrocardiography alone is insufficient.

## Key findings

- TTE adjustments significantly improved left ventricular ejection fraction and reduced septal flash.
- ECG optimization alone improved LV dyssynchrony in 36 patients, while 29 required additional TTE adjustments.
- Patients needing TTE adjustments had a higher QRS width after TTE-based optimization than after ECG-based optimization.

## Abstract

Introduction

Optimization of cardiac resynchronization therapy (CRT) using a 12-lead electrocardiogram (ECG) alone may not sufficiently improve left ventricular (LV) function in all cases. Therefore, we aimed to investigate whether additional optimization using transthoracic echocardiography (TTE) could further enhance CRT efficacy.

Methods

Sixty-five patients who underwent CRT implantation between March 2018 and July 2022 at Sakakibara Heart Institute, Japan, were included in this study. Data were collected at three points: before optimization (point A), after ECG-based optimization (point B), and after TTE-based adjustments (point C).

Results

The mean age was 74±11 years (male: 78.4%). The PR interval was significantly prolonged at points B and C compared with that at point A. The QRS width narrowed significantly at point B (119±20 ms vs. 137±20 ms, p<0.01) but increased at point C (124±20 ms), approaching point A levels. Thirty-six patients achieved LV dyssynchrony improvement with ECG optimization alone, whereas 29 required TTE adjustments for further improvement. Patients needing TTE optimization had higher QRS width at point C than at point B. TTE adjustments significantly improved LV ejection fraction (28.1±6.8% to 31.5±8.0%, p=0.01) and reduced septal flash (46.2% to 15.4%, p=0.04). The need for TTE adjustments was similar to the usage of CRT devices with and without auto-adjustment functions.

Conclusion

TTE-based optimization enhances LV function and synchrony in cases where ECG-based adjustments alone are insufficient, highlighting the importance of TTE evaluation in CRT optimization.