P2.035: Impact of IVIG Timing on Left Ventricular Longitudinal Strain in Kawasaki Disease with Giant Coronary Artery Aneurysms

Background: Kawasaki disease (KD) is a medium-sized vessel vasculitis and is the leading cause of acquired heart in children. Timely intravenous immunoglobulin (IVIG) administration reduces the risk of developing coronary artery aneurysms (CAA). Left ventricular function, particularly myocardial deformation in the course of disease is understudied. Standard therapy includes timely intravenous immunoglobulin (IVIG), which reduces the risk of developing coronary artery aneurysms (CAA). We hypothesized that left ventricular longitudinal strain (LVLS) improves from admission to follow-up and that earlier IVIG administration is associated with greater LVLS improvement.

Methods: This is a single-center study that examined patients with KD and giant CAA (GCAA) (Z-score ≥10) at our institution from 2005-2023. The timing of IVIG was based on the date of fever onset. Patients receiving multiple IVIG courses, steroids, or additional anti-inflammatory therapies were included. LVLS was measured offline via 2D echocardiography on apical 4-chamber views fully profiling the LV at time of admission, discharge, GCAA diagnosis (which occurred either during initial admission or following discharge, but prior to follow-up) and follow-up at 6-12 months. Mann-Whitney tests were used to evaluate differences between LVLS on admission and follow-up. Spearman correlations were used to evaluate associations between the time from fever onset to IVIG infusion and both LVLS and left ventricular ejection fraction (LVEF) across time points. Univariable linear regressions examined associations between LVLS at admission and follow-up.

Results: 24 patients were included (Table 1). LVLS was significantly lower at admission [19.3% (17.1 - 21.2)] compared to follow-up [22.4% (20.1–23.2)], showing a progressive improvement over time. Specifically, LVLS at follow-up was, on average, 2.34% higher than at admission (β = 2.36, 95% CI: 0.09 to 4.63, p = 0.041, Figure 1). There was no correlation between the time from fever onset to IVIG administration and the absolute values of LVLS at admission (p = 0.06) or follow-up (p = 0.8).

LVEF values during the acute phase were not significantly different from those at follow-up: 65% (60.3–67) at admission, 69% (59–72.7) at discharge, 64.2% (60–72) at GCAA diagnosis, and 67.3% (64.7–70.4) at follow-up. However, a significant negative correlation was found between the time from fever onset to IVIG infusion and LVEF at discharge (ρ = –0.62, p = 0.015), suggesting that longer delays in treatment were associated with relatively reduced LVEF, although still within normal range.

Conclusion: In our cohort of patients with KD and GCAA, LVLS was reduced during the acute phase but improved by follow-up. Although lower LVEF at discharge was associated with longer timing in therapy initiation, LVLS recovery was not influenced by the timing of IVIG administration. These findings highlight the importance of timely IVIG infusion; however, no significant associations were observed between IVIG timing and LVLS recovery in our cohort.