# Dynamic assessment of myocardial contractile dysfunction and its recovery after IVIG treatment in a murine model of Kawasaki disease using high-resolution speckle-tracking echocardiography

## TL;DR

This study uses high-resolution imaging to show that IVIG treatment improves heart function in a mouse model of Kawasaki disease.

## Contribution

The study introduces high-resolution speckle-tracking echocardiography as a sensitive tool for assessing myocardial dysfunction in KD and evaluating IVIG's effects.

## Key findings

- IVIG treatment significantly prevents myocarditis and vasculitis in the KD mouse model.
- Longitudinal strain recovers to normal levels in IVIG-treated mice by day 56.
- High-resolution STI detects myocardial dysfunction earlier and more accurately than conventional echocardiography.

## Abstract

Myocarditis is a common feature of acute Kawasaki disease (KD) and a major contributor to myocardial contractile dysfunction, which can be alleviated by timely intravenous immunoglobulin (IVIG) treatment. However, the effects of KD on myocardial systolic function and the impact of IVIG on myocardial recovery are not well understood in animal models. This study aims to explore whether left ventricular systolic dysfunction occurs in a KD mouse model and to evaluate the potential benefits of IVIG in mitigating myocardial contractile impairment using high-resolution speckle-tracking imaging (STI).

We utilized a Lactobacillus casei cell-wall extract (LCWE)-induced murine model of KD vasculitis to assess the effects of IVIG treatment on myocardial dysfunction. Histological analyses and speckle-tracking strain imaging were performed to evaluate myocardial function during the progression of KD-induced vasculitis and myocarditis.

IVIG treatment significantly prevented both myocarditis and vasculitis. Conventional echocardiographic analyses showed differences in ejection fraction between the KD and control groups 14 days after LCWE injection, regardless of IVIG treatment. Notably, both the KD and KD + IVIG groups exhibited reduced longitudinal strain (LS) as early as 3 days post-injection compared to the control group. While LS remained decreased in the KD group throughout the disease progression, the KD + IVIG group showed a recovery to normal LS levels by day 56. At 14 and 28 days post-LCWE injection, LS in the KD group was significantly lower than in the KD + IVIG group. LS was negatively related to myocarditis scores (r = −0.94, P < 0.001).

Myocardial contractile dysfunction resulting from myocarditis occurs in the KD mouse model and can be improved with IVIG treatment. High-resolution STI offers a more sensitive and accurate method for assessing myocardial dysfunction and the effects of cardioprotective treatments compared to conventional echocardiography.