# Interaction of left ventricular size with the outcome of cardiac resynchronization therapy in Japanese patients

## TL;DR

This study found that a higher QRS duration to left ventricular size ratio is linked to better survival in heart failure patients undergoing cardiac resynchronization therapy.

## Contribution

The study introduces the QRSd/LVEDV ratio as a potential new index for selecting patients for cardiac resynchronization therapy.

## Key findings

- Patients with a QRSd/LVEDV ratio ≥0.67 had better survival than those with a ratio <0.67.
- No significant difference in the primary endpoint was observed between different QRSd groups.
- The QRSd/LVEDV ratio may help identify patients who benefit more from cardiac resynchronization therapy.

## Abstract

We analyzed the influence of the QRS duration (QRSd) to LV end‐diastolic volume (LVEDV) ratio on cardiac resynchronization therapy (CRT) outcomes in heart failure patients classified as III/IV per the New York Heart Association (NYHA) and with small body size.

We proposed the hypothesis that the QRSd/LV size ratio is a better index of the CRT substrate.

We enrolled 114 patients with advanced heart failure (NYHA class III/IV, and LV ejection fraction >35%) who received a CRT device, including those with left bundle branch block (LBBB) and QRSd ≥120 milliseconds (n = 60), non‐LBBB and QRSd ≥150 milliseconds (n = 30) and non‐LBBB and QRSd of 120−149 milliseconds (n = 24).

Over a mean follow‐up period of 65 ± 58 months, the incidence of the primary endpoint, a composite of all‐cause death and hospitalization for heart failure, showed no significant intergroup difference (43.3% vs. 50.0% vs. 37.5%, respectively, p = .72). Similarly, among 104 patients with QRSd/LVEDV ≥ 0.67 (n = 54) and QRSd/LVEDV < 0.67 (n = 52), no significant differences were observed in the incidence of the primary endpoint (35.1% vs. 51.9%, p = .49). Nevertheless, patients with QRSd/LVEDV ≥ 0.67 showed better survival than those with QRSd/LVEDV < 0.67 (14.8% vs. 34.6%, p = .0024).

Advanced HF patients with a higher QRSd/LVEDV ratio showed better survival in this small‐body–size population. Thus, the risk is concentrated among those with a larger QRSd, and patients with a relatively smaller left ventricular size appeared to benefit from CRT.

Advanced HF patients with a higher QRS duration (QRSd)/LV end‐diastolic volume (LVEDV) ratio showed better survival in this small‐body–size population. Thus, the QRSd/LVEDV might serve as a relatively simple index to improve patient selection for cardiac resynchronization therapy in patients with mid‐wide QRSd.