The “Supramitral Ring”—A Misleading Term for a Complex Congenital Mitral Valve Anomaly

Background: Congenital mitral stenosis is a rare but complicated disease due to its high recurrence rate despite successful surgical intervention. The stenosis can occur as a circumferential ridge directly on the atrial-facing side of the mitral valve (MV), which is often simplified and summarized as a supramitral ring (SMR). However, the present terminology to describe this lesion is highly heterogenous and often misleading, and detailed reports assessing its anatomic nature are lacking, although recognition is crucial for diagnosis and surgical planning. Thus, we sought to systematically determine the anatomic substrate of this lesion and based on our findings, establish a standardized clinical classification and terminology.

Methods: A retrospective, single-center cohort study of pediatric patients who underwent primary resection of an SMR at Boston Children’s Hospital between January 2013 and December 2023 was conducted. The anatomical assessment was based on the degree of extension of the lesion within the MV apparatus, according to the surgeon’s operative note.

Results: In total, 50 patients, 24 (48%) males and 26 (52%) females, underwent 63 SMR resections (50 primary and 13 reresections) from January 2013 to December 2023. The anatomical characteristics of the resections are shown in [Table 1] below. In none of the cases, the lesion was solely located above the MV annulus. However, in 6/63 (9.5%) cases, the SMR extended into the left atrium.

Table 1 Surgical Procedures

Anatomical localization	All resections (n = 63)	Primary resections (n = 50)	Re-resections (n = 13)
MV annulus	13/63 (20.6%)	11/50 (22%)	2/13 (15.4%)
MV annulus + leaflet(s)	23/63 (36.5%)	20/50 (40%)	3/13 (23.1%)
One or both MV leaflets	27/63 (42.9%)	19/50 (38%)	8/13 (61.5%)

Abbreviation: MV, mitral valve.

Conclusion: Our findings highlight the anatomic heterogeneity of this lesion. Based on the involvement of different levels of the MV apparatus, we identified three distinct anatomic types: the annular, annulo-leaflet, and leaflet subtype. The lesion often involved the MV annulus at primary resection, whereas leaflet involvement was more pronounced in disease recurrence. In contrast to its common term, in none of the cases, the SMR was located truly supramitrally; all SMRs were associated with the MV apparatus, and therefore, this lesion can be regarded as a valvar anomaly. Our data support the conclusion that the general term “annulo-leaflet mitral ring” plus the name of its distinct subtype is better suitable to describe this lesion, which can aid the clinician’s anatomical understanding and clarify clinical communication.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
11 February 2025