OBJECTIVE

To develop the classification of subaortic anatomical variants of interventricular septum (IVS) and substantiate its practical significance.

MATERIAL AND METHODS

A retrospective study included 244 patients with obstructive hypertrophic cardiomyopathy (HCM) (men 40.6%, mean age 56.8±11.6 years) who underwent septal myectomy between 2011 and 2022. The inclusion criterion was dynamic LVOT obstruction with systolic pressure gradient >50 mm Hg both at rest and during stress tests. Patients with valvular, fixed subvalvular and middle ventricular obstruction (terminology according to the AHA/ACC 2020 guidelines) were excluded. IVS anatomy in subaortic zone before septal myectomy was analyzed in each patient according to cardiac MRI. All patients were divided into groups depending on anatomical variants of IVS. We analyzed the incidence of each anatomical variant. The results of septal myectomy were evaluated in patients with various anatomical variants of IVS.

RESULTS

There were 8 anatomical variants of IVS in subaortic zone. The incidence of each form in our sample was as follows: variant «0» — 0.4%; variant «A» — 7.8%; variant «M» — 2%; variant «P» — 0%; variant «AM» — 27.5%; variant «AR» — 5.3%; variant «MR» — 0.8%; variant «AMR» — 56.2%. Among 244 patients, we found 5 (2%) cases of insufficient correction with systolic anterior motion of the mitral valve after surgery. All these cases were noted among patients with anatomical variant «AMR».

CONCLUSION

We first proposed a surgical classification of IVS variants in subaortic zone demonstrating the diversity of its structure. This classification is valuable to determine localization of myocardial thickening in a particular patient and evaluate anatomical results of surgery.