Imaging the delayed complications of childhood Kawasaki disease

Abstract

This review will discuss the long-term complications of Kawasaki disease with a particular focus on imaging surveillance of the coronary arteries in adolescence and adult life. The relative advantages and disadvantages of each modality will be illustrated with practical examples, demonstrating that, in many cases, a multimodality imaging strategy may be required.

Keywords: CMR; IVUS; Kawasaki disease; OCT; PET; cardiac CT; cardiovascular magnetic resonance; intravascular ultrasound; optical coherence tomography; positron emission tomography.

Figure 1.. Evidence of acute thrombus in LAD seen on echocardiography.

A) Thrombus (asterisk) within the proximal portion of the large LAD aneurysm. B) Accelerating narrowed diastolic flow jet around the peripheral rim of the thrombus. LAD, left anterior descending.

Figure 2.. Circumflex territory infarct.

A) Nuclear SPECT perfusion study demonstrating a largely fixed infero-lateral defect on polar map. B,C) Late gadolinium enhancement reveals a non-transmural scar (white arrows) in the same area. D) Black-blood CMR shows circumflex aneurysms with thrombus (asterisks). E) Angiogram confirms Cx aneurysms with poor distal flow.

Figure 3.. Stress perfusion CMR in right coronary artery stenosis.

A,D) Calcific cast of RCA (arrow) is noted prior to contrast injection. B,C) Note that the contrast column does not touch the vessel edge outlined by the calcium, consistent with the presence of laminar thrombus. A focal tight mid RCA stenosis is present (arrow). E) Area of hypoperfusion (arrow) in the basal infero-septum on dipyridamole stress CMR. F) Whole heart coronary MRA of RCA corresponding to image in C – there is good correlation for aneurysm morphology, but note that the RCA distal stenosis is less well visualized due to inferior spatial resolution of CMR compared to conventional angiography.

Figure 4.. Stress perfusion CMR in the context of collateralization.

A,B) A zone of subendocardial hypoperfusion is evident in the RCA territory (arrows, top panels). Note the lack of underlying scar on the corresponding LGE images (bottom panels). C) Cardiac CTA shows a long segment of irregular and hypo-enhanced RCA suspicious for diffuse disease with high-grade stenoses. D) Coronary angiography in fact shows RCA occlusion with extensive bridging collaterals from proximal to distal RCA forming a ‘woven’ vessel. Further collateralization is seen from the Cx to the distal RCA (arrow, bottom panel). Extensive collateralization like this may reduce the size of the perfusion defect (as here) and the true ischemic burden can be difficult to judge. This young woman wished to get pregnant and went ahead without revascularization after Bruce protocol treadmill stress echo where she managed 13 METS of activity without symptoms, ECG changes or wall motion abnormality.

Figure 5.. Progressive thrombus deposition in Kawasaki aneurysms.

A) Late gadolinium enhancement (LGE) acquired in 2010 demonstrates a small rim of thrombus (arrow) in the more distal of 2 sequential Cx aneurysms. B) Repeat in LGE in 2012 reveals increased thrombus burden in this aneurysm (white arrow) and new layers of thrombus in the more proximal aneurysm (black arrows). The patient had not been compliant with anticoagulation during this period. C & D) Mid ventricular short-axis and 2-chamber LGE sequences demonstrate partial thickness infarction (arrows) in the basal to mid inferior and inferolateral walls extending into the inferoseptal wall related to embolism into this dominant circumflex coronary artery.

Figure 6.. Cardiac CT vs catheter correlation.

A-C) Conventional angiographic views display 2 giant aneurysms in the RCA. D,E) Curved multiplanar reformats from cardiac CT data set demonstrate good correlation and more clearly depict wall calcification and lack of mural thrombus. F) Volume-rendered image from a cardiac CT data set represents an alternative visual method for displaying CT findings.

Figure 7.. Progression of plaque.

A) Initial coronary CT demonstrates subtle soft plaque/vessel wall thickening (white asterisks) in the proximal LAD. B) Calcium score, 3 years later, now shows new overlying calcification (black asterisks) implying mineralization secondary to chronic low-grade inflammation. Statin therapy should be considered for all KD patients although the level of evidence for treatment is weak.

Figure 8.. Dipyridamole stress CTA.

A-C) Basal, mid and apical short axis reconstructions of a stress CT data set demonstrating an LAD territory perfusion defect in a Kawasaki patient with LAD aneurysm and prior occlusion.

Figure 9.. Coronary stasis.

Multiple frames are shown from the left coronary injection of a conventional angiogram. A large saccular proximal LAD aneurysm is outlined. Note the extreme delay before contrast fully opacifies the distal LAD at frame 150 from the start of injection. It is this intra-coronary stasis that accounts for the high thrombotic risk in this patient population, even on anticoagulants.

Figure 10.. Pseudo-thrombus at catheterization.

A) Right coronary injection demonstrates a large proximal aneurysm with an apparent central oval lucency (white asterisk). This was interpreted as a ball-valve thrombus in this young man with chest pain symptoms. B) Same-day coronary CT acquired 1 minute after injection shows completely uniform iodine intensity within the aneurysm (black asterisk), confirming the absence of any real thrombus – indicating that the catheter finding was the result of swirling flow and incomplete mixing of blood and iodine immediately after injection.

Figure 11.. Optical coherence tomography.

(A & E) Coronary angiogram demonstrating mild atherosclerotic disease. (B & F) OCT examination of these coronary arteries demonstrating normal intima-media where * demonstrates muscular media. (C & G) Angiography demonstrating coronary arteries many years after Kawasaki disease. OCT examination of these arteries demonstrates destroyed intima-media structure that is replaced by thick fibrosis (D) and disintegrated muscular layer (H). (I) Longitudinal reformatted OCT image of the same coronary artery demonstrated aneurysmal and stenotic segments along its length.

Figure 12.. A hierarchical approach to testing in complicated adult Kawasaki disease.

Newly referred adults - with a history of Kawasaki disease in childhood - are staged with up to 3 levels of investigation. Level 1: Coronary CTA is performed first. If there is no evidence of coronary involvement (or no worse than only mild dilatation), no further investigation is required. If there is evidence of aneurysm or stenosis further testing is required. Level 2: The precise test chosen should depend upon availability and local expertise. If embolic infarction from aneurysmal thrombus is suspected, then CMR is often the most revealing test. Where the selected level 2 test is equivocal, we often proceed to an alternative level 2 test for confirmation. When there remains residual doubt, or if a level 2 test is positive, we proceed to the next step. Level 3: Invasive coronary angiography with or without hemodynamic assessment of severity of stenosis by FFR. While OCT and IVUS may be useful to assess stent deployment, percutaneous coronary intervention is often a poorer choice than bypass surgery for the majority of Kawasaki patients, given the variability in cross-sectional diameter of involved segments.