An 8 year old boy was diagnosed with Kawasaki disease, having been ill for 7 days. Echocardiography revealed a fusiform aneurysm of 7 millimetres diameter on his right coronary artery (panel a), and two saccular aneurysms on his left anterior interventricular artery (LAD) (panel b), the larger measuring 13 millimetres (panel c). The patient received intravenous immunoglobulin at 2 grams per kilogram over 12 hours on the 7th and 9th days, high-dose Aspirin at 80 milligrams per kilogram per day, and anticoagulation with fractionized heparin, switching to Warfarin on the 9th day. He responded with resolution of his fever, and a drop in inflammatory markers. Echocardiography was repeated on the 8th and 9th days, with identical measurements of the aneurysms. On the 9th day, he developed acute chest pain, and went into pulseless cardiac arrest. Resuscitation, including pericardial drainage at which haemorrhagic fluid was obtained, was unsuccessful. At post-mortem examination, the echocardiography findings were confirmed, with rupture of the larger aneurysm on his left interventricular artery (LAD) (panel d). As far as we know, this is the first case reported in the literature where daily echocardiographic examinations showed no progressive dilation of an aneurysm, yet rupture occurred after clinical and biochemical response to three days of standard treatment.

Figure 1