Evaluation of coronary artery lesions in children with Kawasaki disease by coronary angiography

Abstract

Background

Coronary angiography (CAG) plays a critical role in the detailed anatomical assessment of coronary artery lesions (CALs) during the early recovery phase of Kawasaki disease (KD) in children. However, its practical experience and reported outcomes in pediatric populations remain limited.

Objective

To summarize the coronary angiographic features and evaluate the safety and feasibility of CAG in children with KD complicated by CALs.

Methods

We retrospectively analyzed the clinical and angiographic data of 15 consecutive children with KD complicated by CAL (KD-CAL) who underwent CAG during the recovery phase (3–6 months after disease onset) at our center between June 2020 and June 2024. Preoperative transthoracic echocardiography was performed for CAL assessment, followed by selective CAG under general anesthesia. Procedural parameters, lesion characteristics, and clinical outcomes were systematically reviewed.

Results

All 15 children (median age 1.5 years) successfully completed CAG without immediate complications. A total of 21 CALs were identified, predominantly located in the left main stem (38.1%, 8/21) and the proximal left anterior descending branch (38.1%, 8/21). Lesion distribution included small aneurysms/dilatations (47.4%), medium aneurysms (31.6%), and giant aneurysms (21.0%). CAG detected one case of coronary stenosis with collateral vessel formation and one case of intra-aneurysmal thrombosis, both missed by preoperative echocardiography. No significant differences were observed in aneurysm dimensions (inlet, widest, outlet diameters, and length) or in Z-scores between echocardiography and CAG (all P > 0.05). Median fluoroscopy time was 3.1 min, radiation dose-area product was 42 Gy·cm², and contrast volume was 1.5 mL/kg. During a median follow-up of 33 months, no coronary events occurred.

Conclusion

In children with high-risk KD-CAL, invasive coronary angiography (CAG) is a safe and feasible procedure that provides superior anatomical detail for detecting critical complications such as stenosis and thrombosis. Echo-cardiography remains the first-line modality for aneurysm sizing and serial monitoring. However, for comprehensive coronary assessment following echocardiography, CT coronary angiography (CTCA) is the preferred non-invasive imaging standard. Invasive CAG should be reserved for selected high-risk or complex cases where it provides decisive anatomical and functional information to guide definitive management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-026-06567-2.

Introduction

Kawasaki disease (KD) is a leading cause of acquired heart disease in children worldwide, with its most serious acute complication being coronary artery lesions (CALs), occurring in 5% to 20% of untreated cases [1]. While intravenous immunoglobulin (IVIG) has significantly reduced CAL incidence, approximately 15% of children still develop persistent coronary abnormalities, including dilation, aneurysms, stenosis, occlusion, and in rare cases, myocardial infarction or sudden death [2, 3]. Therefore, precise evaluation of KD-CAL is paramount for formulating individualized treatment and long-term follow-up strategies.

In the assessment of coronary artery aneurysms secondary to Kawasaki disease, echocardiography serves as the first-line non-invasive screening modality owing to its safety and wide availability; however, its diagnostic accuracy is constrained by acoustic windows, especially for mid-to-distal coronary segments, stenotic lesions, and intraluminal thrombi [4, 5]. Magnetic resonance imaging (MRI) is radiation-free and permits integrated evaluation of myocardial inflammation, fibrosis, and intracoronary hemodynamics. Nevertheless, its relatively long acquisition time frequently requires sedation or patient cooperation in children, which may compromise image quality [6, 7]. Moreover, MRI exhibits lower spatial resolution compared with computed tomography coronary angiography (CTCA) or digital subtraction angiography (DSA), reducing its sensitivity for small aneurysms and distal lesions [8]. High equipment costs and limited availability also restrict its routine use in many centers. CTCA offers a non-invasive alternative that eliminates arterial puncture, thereby minimizing procedural trauma and complication risks [8]. Contemporary clinical practice recognizes CTCA as the preferred non-invasive modality for comprehensive coronary artery assessment in KD following initial echocardiography [9]. Recent reviews and large cohort studies have robustly demonstrated its diagnostic accuracy and clinical value, particularly in delineating the entire coronary tree [10, 11]. While CTCA provides clear visualization of distal coronary segments, its image quality can be degraded by patient motion or heart rate variability [12]. In contrast, DSA is still regarded as the gold standard for diagnosing vascular pathologies, including coronary aneurysms, due to its superior spatial resolution and diagnostic accuracy [13, 14]. DSA also allows real-time hemodynamic assessment and delivers more definitive evaluation of complex features such as intraluminal thrombi and collateral networks [15, 16]. Nevertheless, DSA necessitates arterial access and entails risks of vascular injury, bleeding, or contrast-induced nephropathy—concerns that are especially relevant in the pediatric population [17, 18]. Current international guidelines from the American Heart Association (AHA), the Japanese Circulation Society (JCS), and Chinese clinical recommendations advocate for CAG in children with giant coronary artery aneurysms (CAA) or multiple aneurysms during the early recovery phase [2, 19, 20]. This study analyzes the clinical data and CAG findings of 15 children with KD-CAL at our center, aiming to summarize the angiographic characteristics and reinforce the procedural value in pediatric patients.

Materials and methods

Baseline characteristics

The clinical data of 15 children with KD-CAL who underwent CAG at the Department of Pediatrics, Hainan Women and Children’s Medical Center from June 2020 to June 2024 were collected. This sample represents a consecutive series of eligible patients during the study period. Due to the retrospective nature of this study and the relatively low incidence of KD-CAL requiring CAG at our institution, the sample size is limited. In these children, there were 12 males and 3 females. The age ranged from 7 months to 9 years, with a median age of 1.5 years. The body weight ranged from 9 kg to 27 kg, with a median weight of 12 kg. All children underwent CAG in the early recovery phase (3–6 months after disease onset).

Imaging selection and indications for coronary angiography

This is a retrospective study of a cohort from 2020 to 2024. During this period at our institution, CTCA was not yet established as the routine non-invasive modality for comprehensive coronary evaluation in KD. The decision to proceed with invasive CAG was strictly guided by established guidelines [19, 20]. Indications for CAG were specifically for children with giant coronary artery aneurysms (Z-score ≥ 10 or absolute diameter ≥ 8 mm), multiple aneurysms, or those with clinical/echocardiographic evidence suggestive of myocardial ischemia, aligning with AHA and JCS recommendations [2, 9]. The specific indications for each patient are detailed in Supplementary Table 1.

Preparation for coronary angiography

Aspirin and clopidogrel were withheld for over seven days and warfarin for over three days prior to the procedure. The decision to discontinue antithrombotic therapy was made after multidisciplinary discussion (involving pediatric cardiologists and interventionalists), weighing the procedural bleeding risk against the thrombotic risk posed by the coronary aneurysms. No bridging anticoagulation therapy was used, as the interruption period was considered short and the perceived bleeding risk during arterial access was significant [21–23]. All patients completed preoperative investigations, which confirmed no contraindications to cardiac catheterization. These included a full blood count, coagulation profile, comprehensive metabolic panel, blood typing, chest X-ray, and electrocardiogram. Specific exclusions comprised active infection, severe arrhythmias, heart failure, significant hepatic or renal impairment, contrast allergy, hypokalemia, or severe anemia.

Echocardiographic examination

Transthoracic echocardiography was performed by experienced pediatric cardiologists using a Philips EPIQ 7 C ultrasound system with S8-3 or S12-4 transducers. Standard parasternal short-axis and modified high parasternal views were used to visualize the coronary arteries. Measurements of coronary artery dimensions (inlet, widest, and outlet diameters, and length of aneurysms) were performed offline by two independent cardiologists blinded to the CAG results, and the average values were used for analysis. Z-scores based on body surface area (BSA) [24] were calculated for classification according to Table 1. Absolute diameters (mm) were also recorded for direct comparison with CAG measurements.

Table 1.

Risk classification criteria for coronary artery lesions (CAL) in children with Kawasaki disease (KD) [20]

Grades	Criteria
Grade Ⅰ	No coronary artery involvement at any time (Z-score < 2)
Grade Ⅱ	Mild coronary artery dilation during the acute phase, with normalization within 30 days of illness onset.
Grade Ⅲ	Presence of a small to medium-sized coronary artery aneurysm persisting beyond 30 days of illness onset.
Grade Ⅲa	Small coronary artery aneurysm (Z-score 2.5 to 5)
Grade Ⅲb	Medium-sized coronary artery aneurysm (Z-score 5 to 10, with absolute diameter < 8 mm)
Grade Ⅳ	Giant coronary artery aneurysm (Z-score ≥ 10, or absolute diameter ≥ 8 mm), or multiple aneurysms within a single coronary artery, but not meeting criteria for GradeⅤ.
Grade Ⅴ	Coronary artery aneurysm with concomitant coronary artery stenosis
GradeⅤa	Without accompanying myocardial ischemia
GradeⅤb	With accompanying myocardial ischemia

Coronary angiography

Angiography was performed on a Philips DSA system using iopromide. Via right femoral access (Seldinger technique; 5 F sheath), heparin (50–100 U/kg) was administered. Imaging included: (1) non-selective aortography (LAO 45°; 5 F Pigtail catheter; 1–1.5.5 mL/kg contrast via power injector); and (2) selective coronary angiography (JL 3.5/JR 3.5 catheters; manual injection) in multiple projections (e.g., LAO45°+CRAN20°, RAO30°+CRAN20°) for CAL assessment. Measurements were made manually using the calibrated catheter as reference. Aneurysm dimensions (inlet, widest, outlet diameters, length) were measured in optimal projections. Throughout the procedure, the patient’s ECG, blood pressure, and oxygen saturation were continuously monitored. Intravenous nitroglycerin (2.5–5 µg/kg) was to be administered in case of ST-segment elevation or depression. For intraoperative bradycardia, intravenous atropine (0.01 mg/kg) was the designated intervention. Upon successful and uneventful completion of the angiography, the catheter and sheath were withdrawn, and hemostasis was achieved by manual compression. Procedural data, including fluoroscopy time, radiation dose (dose-area product, DAP), and total contrast volume (mL/kg), were recorded.

Statistical methods

All analyses used SPSS 26.0. Non-normally distributed continuous data are presented as median (25th-75th percentiles) [M(P25, P75)] and compared with Mann-Whitney U or Wilcoxon signed-rank tests. Categorical data are shown as n (%) and compared with chi-square or Fisher’s exact test. Aneurysm dimensions were compared per lesion; patient-level medians were also analyzed to address clustered lesions. P < 0.05 (two-tailed) was considered significant.

Results

Coronary angiography findings

Coronary angiography was successfully performed in all 15 children with KD-CAL. The coronary arteries were divided into four main branches: left main stem, left anterior descending artery, left circumflex artery, and right coronary artery. Among these patients, 9 had CALs in a single artery, 2 had CALs in two arteries, 2 had CALs in three arteries, and 2 had normal coronary arteries. After angiography, the CAL risk classification results showed that gradeⅡwas seen in 2, grade Ⅲ in 10, grade Ⅳ in 2, and grade Ⅴ in 1 child patients. A total of 21 CALs were identified, including 8 in the left main stem (38.1%), 8 in the left anterior descending branch (38.1%), 1 in the left circumflex artery (4.8%), 1 in the proximal part of the right coronary artery (4.8%), and 1 in the middle part of the right coronary artery (4.8%) (Table 2). The proportions of small aneurysms or dilatations, medium aneurysms, and giant aneurysms were 47.4% (9/19), 31.6% (6/19), and 21% (4/19), respectively. CAG revealed critical findings in two patients with giant aneurysms: one case of stenosis at the aneurysm entrance with collateral vessel formation (Fig. 1), and one case of an old thrombus within the aneurysm (Fig. 2).

Table 2.

Coronary angiography findings in children with KD complicated by CAL (n)

Grades of CAL risk classification	Left main artery	Left anterior descending branch			Left circumflex artery		Right coronary artery			Total
		proximal part	middle part	Distal part	proximal part	Distal part	proximal part	middle part	Distal part
Small aneurysm or dilatation	5	3	0	0	1	0	0	0	0	9
Medium aneurysm	1	4	0	0	0	0	1	0	0	6
Giant aneurysm	2	1	0	0	0	0	0	0	0	3
Giant aneurysm with stenosis	0	0	0	0	0	0	0	1	0	1
collateral vessels formation	0	0	0	0	0	0	1	0	0	1
Thrombus	0	0	0	1	0	0	0	0	0	1
Total	8	8	0	1	1	0	2	1	0	21

Fig. 1.

A: Beaded changes in the right coronary artery with a giant aneurysm (red arrow), stenosis at the entrance (white arrow), and collateral vessel formation (blue arrow); B and C：The giant aneurysm shown in B and C has dimensions of 1.46 mm (inlet), 2.88 mm (outlet), 8.27 mm (widest), and 17.01 mm (length)

Fig. 2.

A: A giant aneurysm in the proximal left coronary artery (red arrow) with an old thrombus (white arrow) at its distal end; B and C: The giant aneurysm shown inB and C has dimensions of 4.62 mm (inlet), 3.28 mm (outlet), 16.99 mm (widest), and 22.06 mm (length)

Electrocardiogram (ECG) findings

ECG examinations revealed sinus rhythm in all 15 patients, with no significant ST-T wave changes or pathological Q-waves.

Echocardiography vs. Coronary angiography

Preoperative echocardiography identified all patients as having Grade III or higher CALs (11 small, 6 medium, 4 giant aneurysms based on Z-scores/absolute diameters) but failed to detect any stenosis or thrombosis. Comparative analysis showed no statistically significant differences in the measured absolute dimensions (inlet, widest, and outlet diameters, length) of small, medium, or giant aneurysms between the two modalities (P > 0.05, Table 3). When comparing Z-scores derived from ECHO and CAG measurements (using BSA and the same reference equations), the results remained concordant regarding risk classification, and no significant differences in Z-scores were found (P > 0.05, Table 4). However, CAG correctly reclassified two patients, initially suspected of having CALs on echocardiography, as having normal coronary arteries.

Table 3.

Comparisons between echocardiography and coronary angiography findings in children with Kawasaki disease complicated by coronary artery lesions

Measurements	Echocardiography	Angiography	Z/X2	P
Small aneurysm/dilatation
Inlet diameter [M(P25, P75)](mm)	2.59(2.30,2.70)	2.30(2.25,2.99)	−0.573	0.566
Widest diameter [M(P25, P75)](mm)	2.80(2.60,3.20)	2.60(2.45,3.35)	−0.649	0.516
Outlet diameter [M(P25, P75)](mm)	2.30(2.20,2.57)	2.30(2.20,2.45))	−0.619	0.536
Length [M(P25, P75)](mm)	3.10(2.70,3.40)	3.20(2.80,3.40)	−0.345	0.730
Medium aneurysm
Inlet diameter [M(P25, P75)](mm)	2.70(2.23,3.48)	2.65(2.17,3.30)	−0.241	0.810
Widest diameter [M(P25, P75)](mm)	4.25(4.10,4.60)	4.25(3.68,4.53)	−0.403	0.687
Outlet diameter [M(P25, P75)](mm)	2.50(2.25,2.70)	2.60(2.38,3.05)	−1.052	0.293
Length [M(P25, P75)](mm)	4.55(4.13,4.85)	4.80(4.00,5.10)	−0.803	0.422
Giant aneurysm
Inlet diameter [M(P25, P75)](mm)	4.30(3.33,5.28)	3.70(1.87,4.54)	−1.155	0.248
Widest diameter [M(P25, P75)](mm)	8.50(7.20,10.40)	8.64(7.39,14.99)	−0.577	0.564
Outlet diameter [M(P25, P75)](mm)	2.75(2.15,5.08)	2.54(0.98,3.18)	−0.577	0.564
Length [M(P25, P75)](mm)	10.25(6.93,19.58)	12.71(7.20,20.80)	−0.577	0.564
Median Values of All Aneurysm Types (Pooled)
Inlet diameter [M(P25, P75)](mm)	2.50(2.30,3.10)	2.87(2.30,3.30)	−0.814	0.416
Widest diameter [M(P25, P75)](mm)	3.30(2.65,4.70)	3.60(2.60,4.50)	−0.027	0.978
Outlet diameter [M(P25, P75)](mm)	2.40(2.20,2.58)	2.40(2.20,2.60)	−0.082	0.935
Length [M(P25, P75)](mm)	3.90(2.95,5.10)	4.10(3.20,5.70)	−0.529	0.597
Stenosis [n(%)]	0(0)	1(6.67)		1.0a
Collateral vessels formation [n(%)]	0(0)	1(6.67)		1.0a
Thrombus [n(%)]	0(0)	1(6.67)		1.0a

a Fisher’s exact probability method

Table 4.

Comparison of Z-Scores for coronary artery aneurysm dimensions between echocardiography and coronary angiography in children with Kawasaki disease complicated by coronary artery lesions [M(P25, P75)]

Measurements	Echocardiography Z-score	Coronary Angiography Z-score	Z	P
Small Aneurysm/Dilatation
Inlet diameter	2.72(1.42,3.28)	2.27(1.89,4.04)	−0.190	0.849
Widest diameter	3.06(2.74,3.65)	3.67(2.56,4.50)	−0.760	0.447
Outlet diameter	1.79(1.25,2.64)	1.76(1.24,2.34))	−0.190	0.849
Medium aneurysm
Inlet diameter	3.46(1.84,4.46)	3.21(2.06,3.86)	−0.641	0.522
Widest diameter	6.08(5.18,7.61)	5.54(5.05,7.26)	−0.803	0.422
Outlet diameter	2.88(1.71,3.51)	2.74(2.32,4.11)	−0.561	0.575
Giant aneurysm
Inlet diameter	4.46(3.42,5.56)	3.54(−1.11,4.25)	−1.155	0.248
Widest diameter	10.04(9.01,11.50)	10.23(9.17,15.40)	−0.866	0.386
Outlet diameter	1.08(−0.20,4.60)	1.37(0.39,2.02)	−0.436	0.663
All Aneurysm Types (Pooled)
Inlet diameter	2.50(2.30,3.10)	2.87(2.30,3.30)	−0.230	0.818
Widest diameter	3.30(2.65,4.70)	3.60(2.60,4.50)	−0.488	0.626
Outlet diameter	2.40(2.20,2.58)	2.40(2.20,2.60)	−0.176	0.860

Procedural safety and Follow-up

All procedures were successfully completed. In this cohort, the median fluoroscopy time for diagnostic coronary angiography was 3.1 (range: 2.0–4.5 min) minutes, with a median radiation dose–area product of 42 Gy·cm² (range: 32–78 Gy·cm²), an estimated median effective radiation dose in this study was 1.6 mSv (range: 1.2–3.0.2.0 mSv), and a median contrast volume of 1.5 mL/kg (range: 1.0–3.0 mL/kg). No sedation-related complications were recorded. Furthermore, no immediate or post-procedural complications—including bleeding, pseudo-aneurysm formation, thrombosis, or malignant arrhythmias—were observed. The coronary angiography findings directly influenced clinical management in several cases. One 9.2-year-old male patient, diagnosed with coronary stenosis and collateral circulation, was referred to a tertiary center and underwent coronary artery bypass grafting. His postoperative recovery was uneventful, with no evidence of myocardial ischemia or cardiac dysfunction, and he was started on long-term oral warfarin anticoagulation. Another 8-year-old male patient, found to have an intra-aneurysmal thrombus, was managed with combined antiplatelet and anticoagulant therapy: maintenance-dose aspirin (3–5 mg/kg/day) plus warfarin, the latter titrated to 0.08–0.12 mg/kg/day (with monthly monitoring maintaining an international normalized ratio between 2.0 and 2.5). He also remained free of ischemic or cardiac dysfunction events. For the two patients whose angiograms were reclassified as normal, long-term antiplatelet therapy was discontinued and follow-up intensity was appropriately reduced. During a median follow-up of 33 months (available for all 15 patients), no coronary events were documented.

Discussion

This study explored the safety, feasibility, and clinical utility of coronary angiography for precise evaluation during the early recovery phase in children with Kawasaki disease complicated by coronary artery lesions. The prognosis of KD worsens with the increasing size, complexity, and distal extent of coronary artery lesions (CALs). Specifically, giant aneurysms carry the highest risk, as they are more susceptible to thrombosis, occlusion, and subsequent myocardial infarction [25, 26]. As such, precise characterization of CALs—including their size, shape, and location—is vital for classifying lesions and tailoring subsequent management. Our findings confirm that echocardiography remains reliable for measuring aneurysm dimensions, as evidenced by the lack of significant differences in inlet, widest, outlet diameters, length, and Z-scores compared to CAG (Tables 3 and 4). This is consistent with studies validating echocardiography for serial aneurysm monitoring [8]. The incremental value of invasive CAG in this high-risk cohort lay not in routine sizing, but in its superior ability to detect critical complications: one case of coronary stenosis with collateral vessel formation and one case of intra-aneurysmal thrombosis, both missed by preoperative echocardiography. This aligns with the recognized role of advanced imaging to identify stenosis, thrombus, and collaterals [11, 27]. Furthermore, CAG ruled out coronary artery aneurysms (Grade III) that had been suggested by preoperative echocardiography in two pediatric patients. Both of these cases exhibited left coronary artery dominance. We hypothesize that in dominant arteries, a diameter that appears enlarged on echocardiography may lead to potential overestimation. Thus, coronary angiography is indicated for children whose coronary dilation persists into early recovery. Beyond its diagnostic role, a further clinical benefit lies in its ability to delineate coronary dominance and confirm normal arteries in select cases. This precise assessment is crucial for mitigating the psychological impact of a chronic disease label and preventing overtreatment by avoiding unnecessary long-term medication.

It is important to acknowledge the established strengths of CT coronary angiography (CTCA) in the contemporary imaging algorithm for KD. CTCA is particularly valuable for visualizing distal coronary segments and assessing left circumflex artery involvement, areas often sub-optimally evaluated by echocardiography [11, 27]. The findings of our study, which highlight a predominance of proximal segment involvement (left main stem and proximal LAD), should be viewed as complementary to the extensive evidence base generated by CTCA studies [28, 29], rather than in competition with it.

In KD, necrotizing arteritis originates proximally and spreads distally [30, 31]. In this study, CALs in children with KD most frequently involved the proximal right coronary artery (RCA), proximal left anterior descending artery (LAD), and left main stem (LM). This pattern is consistent with the findings reported by He et al. [32]. In this study, coronary angiography identified one case of stenosis at the entrance of a giant aneurysm with collateral vessels and one case of intra-aneurysmal thrombosis, both of which were undetected by preoperative echocardiography. Consequently, for children with giant coronary aneurysms, we recommend performing coronary angiography early in the convalescent phase to screen for stenosis or thrombus formation.

The assessment of myocardial ischemia typically relies on indicators such as electrocardiographic ST-T wave changes and echocardiographic parameters—including cardiac dimensions, global function, and valvular regurgitation [33, 34]. Studies have shown a low rate of ECG abnormalities (approximately 5.3%) in children with Kawasaki disease, highlighting its limitations in sensitively detecting early myocardial ischemia [35]. In this study, some children exhibited transient ECG ST-T changes, elevated myocardial enzymes, and chest pain during the acute phase of the illness, raising suspicion of myocardial ischemia. However, prior to CAG evaluation during the recovery phase, follow-up ECG and echocardiographic examinations were conducted, and no significant abnormalities were found. A key finding of this study is the superior capability of CAG over echocardiography in identifying high-risk features such as coronary artery stenosis and intraluminal thrombus, as demonstrated in two patients with giant aneurysms. The absence of ischemic signs on ECG and echocardiography in the patient with collateral circulation further underscores that these non-invasive tools may not fully reflect underlying coronary compromise, thereby supporting the rationale for CAG in high-risk patients [36].

CAG in children necessitates specific technical considerations due to their smaller and shorter blood vessels compared to adults. In this study, the femoral artery approach was routinely employed for vascular access, using JL3.5 and JR3.5 catheters. Given the shorter ascending aorta in pediatric patients, the JL3.5 catheter required appropriate rotation and shortening to facilitate engagement of the left coronary artery. For cannulation of the right coronary artery, the JR3.5 catheter was rotated clockwise until a “jumping” motion was observed at the tip, at which point it was slightly withdrawn to avoid deep intubation. Contrast was then rapidly injected by hand, and the catheter was promptly withdrawn after satisfactory imaging was achieved. This standardized approach contributed to risk minimization, and all pediatric patients in this study successfully completed the procedure without complications such as bleeding, pseudo-aneurysm, thrombosis, or malignant arrhythmia. Thus, based on our operational experience, while coronary angiography in children presents certain technical challenges and risks, it appears to be generally safe and feasible. However, it is essential to weigh the procedural risks appropriately. Modern pediatric CTCA protocols can deliver low and well-tolerated radiation exposure, with recent study reporting a median dose of 0.83 mSv [37]. In comparison, the estimated median effective dose in our CAG cohort was higher, at 1.6 mSv. More importantly, although this small cohort demonstrated favorable safety outcomes, invasive CAG remains associated with inherent risks related to vascular access, contrast administration, and radiation. Therefore, patient selection must be careful and guided by clear, evidence-based indications [19].

Nevertheless, this study is subject to several limitations. First, the small sample size (n = 15) from a single institution restricts both statistical power and the broader applicability of the conclusions. The lack of procedural complications in this cohort cannot conclusively define the safety of CAG in pediatric KD-CAL patients, warranting further validation through larger, multi-center investigations. Second, the retrospective nature of the study introduces potential selection bias, as children referred for CAG were likely to present with more severe or complex coronary involvement. Third, according to current clinical guidelines, echocardiography remains the first-line modality for CAL assessment in KD, whereas CAG, CTA, or MRI should be reserved for cases with specific indications. Given the limited cohort size, the findings presented here should be regarded as exploratory. Future studies would benefit from prospective designs, expanded patient cohorts, and the integration of additional advanced imaging techniques for comprehensive comparison. Specifically, prospective studies directly comparing the diagnostic yield, clinical impact, and safety profiles of CTCA and invasive angiography in selected high-risk KD patients are warranted to refine imaging pathways [9, 11].

In conclusion, within the contemporary imaging algorithm for KD: (1) Echocardiography remains the indispensable first-line modality for initial detection and serial monitoring of coronary artery aneurysms; (2) CT coronary angiography (CTCA) is the preferred non-invasive modality for comprehensive anatomical assessment when detailed coronary evaluation beyond echocardiography is required; and (3) Invasive coronary angiography should be reserved for selected high-risk or complex cases, such as those with giant aneurysms or suspected complications, where it provides decisive anatomical and functional information to guide critical management decisions, as demonstrated in this cohort.

Authors’ contributions

Z.D.-f. and C.L. conceived the study and designed the methodology; C.L. performed data collection; C.L. and F.T.-t. conducted data analysis; C.L. wrote the ffrst draft. All authors reviewed and approved the final manuscript.

Funding

This research was supported by Scientific Research Project of Hainan Provincial Health Industry, China, No. 20A200081; and Clinical Medical Center Project of Hainan Province, China, No. QWYH202175.

Data availability

No datasets were generated or analyzed during the current study.

Declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Affiliated Hainan Women and Children’s Medical Center of Hainan Medical University (2025 − 121). Informed consent forms for angiography have been signed by all parents or guardians of the children participants. This study adhered to the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.