Background Kawasaki Disease Shock Syndrome (KDSS) has been defined as a rare manifestation of Kawasaki Disease (KD) characterized by systolic hypotension or clinical signs of poor perfusion that requires fluid support and occasionally vasoactive drugs.

Objectives To describe the incidence, the main clinical presentation, echocardiographic, laboratory findings, goal treatment and clinical outcomes of KDSS compared with KD patients randomly chosen in a case-control study.

Methods We examined data of 84 children with KD diagnosis, admitted to the Institute of Child and Maternal Health-IRCCS Burlo Garofolo–of Trieste and Anna Meyer Children Hospital of Firenze from 2004 to 2013. Case group and control group included patients with and without KDSS respectively. We compared the following variables: sex, age, type of KD (classic, atypical or incomplete), clinical manifestations, cardiac involvement, laboratory findings, therapy administered and response to treatment.

Results Five out of 84 patients with KD (5,9%) met the criteria for KDSS. Four of them were male and the median age of onset was 25 months (5-139). All patients with KDSS had hypotension or clinical signs of hypoperfusion and/or clinical signs of heart failure. Comparing case and control groups: one of the 5 cases vs 23 of 79 controls had an incomplete form of disease; atypical manifestations of KD were more frequent in the case-group especially major abdominal involvement, which occurred in 60% vs 11%; patients with KDSS had more often higher values of C-reactive protein [median 27,8 (23,26-96) vs 9,11 (5,46-16,2) (p=0,004)], lower Hemoglobin levels [median 8,1 (7,1-9,5) vs 11 (10,2-11,9) (p=0,003)], had more often hyponatriemia, 80% vs 15%, hypoalbuminemia, 60% vs 10%, evidence of consumptive coagulopathy, 40% vs 0% and increase in cardiac troponins, 80% vs 5% (p=0,000). KDSS group presented a more frequent cardiac involvement, but not more severe coronary abnormalities, among KDSS patients 3/5 had coronary artery involvement (thickening, dilatation or aneurysm) vs 13/79, but none of the 3 cases with coronary involvement developed permanent aneurysm vs 2 of 13 in the control group; echocardiographic alterations were more frequent in patients with KDSS: 3 of 5 cases vs 3 of 79 had reduced ejection fraction (p=0,002), 2 of 5 vs 2 of 79 had areas of infarction or ischemia and 2 of 5 vs 3 of 79 showed cardiac dyskinesia. Regarding therapy, 3 of 5 cases presents Intravenous Immunoglobulin resistance compared with 23 of 79 controls, all KDSS cases received volume resuscitation and 2 received infusions of vasoactive agents. None of the 5 cases was fatal.

Conclusions As demonstrated by other studies, subjects with KDSS were more likely to have laboratory findings consistent with greater inflammation and to have higher rates of cardiac involvement. However most cardiovascular alterations resolved promptly with therapy. In fact, compared with previous studies, our patients with KDSS had a better prognosis, probably explained by an earlier diagnosis, aided by the presence of most of clinical diagnostic signs of KD, and therefore resulting in more timely treatment.

Disclosure of Interest None declared