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.

Background: 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). Methods: We utilized a Results: 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, Conclusions: 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.