| American Heart Association guideline [15] | 1. No involvement: Always Z score < 22. Dilation only: 2 to < 2.5; or if initially < 2, a decrease in Z score during follow-up ≥ 13. Small aneurysm: ≥ 2.5 to < 54. Medium aneurysm: ≥ 5 to < 10, and absolute dimension < 8 mm5. Large or giant aneurysm: ≥ 10, or absolute dimension ≥ 8 mm |
| Japanese Circulation Society guideline [19] | Acute phase (< 30 days) | 1. Small aneurysm: Z score ≥ 2.5 to < 52. Medium aneurysm: ≥ 5 to < 103. Giant aneurysm: ≥ 10** Note(1) If it is difficult to evaluate by Z-score, evaluating by absolute value of inner diameter may be used in patients under 5 years old• Small aneurysm: 3 mm ≤ inner diameter < 4 mm• Medium aneurysm: 4 mm ≤ inner diameter < 8 mm• Giant aneurysm: 8 mm ≤ inner diameter Evaluation by Z-score is strongly recommended for age 5 years and older (It is overestimated if defined by absolute value).• The absolute value of a giant aneurysm is defined as an inner diameter ≥ 8 mm even at age 5 or older.(2) Even if the definition of an aneurysm is satisfied during the course, if it does not fulfil the definition of an aneurysm at the onset of 1 month, it will be defined as ‘transient dilation’ |
| Severity classification after 1 month | 1. No dilation change: no change in the dilation of coronary arteries including the acute phase.2. Transient dilation (in the acute phase): mild transient dilation that normalizes by 1 month after onset.3. Regression: complicated with coronary artery lesion beyond 1 month from onset, and bilateral coronary artery findings completely normalize during follow-up, and did not fall into group 5.4. Remaining coronary aneurysms: coronary aneurysms on one or both sides on coronary angiography but do not fall into group 5.5. Coronary artery stenotic lesion: coronary angiography shows a stenotic lesion in the coronary artery.(1) Without ischemic findings in various tests(2) With ischemic findings in various tests |