Resection of subaortic membrane for discrete subaortic stenosis

The prognostic significance of early troponin levels in patients undergoing aortic ridge surgery

Subaortic stenosis is a CHD that can lead to left ventricular hypertrophy, heart failure, and aortic valve damage if left untreated. The gold standard treatment for subaortic stenosis is septal myectomy. However, there is no clear consensus on the surgical margins required for adequate muscle resection. In this retrospective study, we reviewed the records of 83 patients who underwent subaortic stenosis surgery between 2012 and 2020 to investigate the effect of early troponin levels on prognosis. We excluded patients with additional cardiac pathologies, hypertrophic obstructive cardiomyopathy, and valvular aortic stenosis.Troponin levels were recorded in the early post-operative period, and patients were monitored for complications such as ventricular arrhythmia, left ventricular systolic dysfunction, infective endocarditis, and pacemaker implantation. The troponin levels were significantly higher in the patients who had septal myectomy. The degree of myectomy affected the risk of complications in the early post-operative period and recurrence in the later period. However, when the gradient was substantially or completely removed by myectomy, patients experienced significant symptom improvement in the early post-operative period, and their late survival was equivalent to that of healthy individuals of the same age.Our findings suggest that monitoring troponin levels in patients undergoing septal myectomy may be beneficial in predicting the risk of complications. However, further studies are needed to establish the optimal surgical technique and extent of muscle resection required for subaortic stenosis treatment. Our study adds to the existing knowledge of the benefits and risks associated with septal myectomy as a treatment option for subaortic stenosis.

Long-Term Aortic Valve Function in Patients With or Without Surgical Treatment for Discrete Subaortic Stenosis

The purpose of this study was to evaluate the long-term function of the aortic valve in patients with discrete subaortic stenosis (DSS), and its prognostic implications. 34 patients with the diagnosis of isolated DSS were treated at our pediatric heart center between 1992 and 2019. Demographic, echocardiographic and surgical data were analyzed. 26 patients had surgery to remove the subaortic membrane. The primary endpoint of this study was a change in the aortic valve function, secondary outcomes included functional class, aortic valve replacement, and reoperation due to recurrence of DSS. The mean post-operative follow-up time was 7.07 years (1-22.5). At the time of the most recent follow up, in the surgical group 11 patients (46%) had echocardiographic evidence of deterioration in their aortic valve insufficiency (AI) (p < 0.002). The deterioration was associated with a pre-operative left ventricular outflow tract (LVOT) gradient greater than 49 mmHg (p < 0.022). 8 patients with DSS were followed for a mean of 12.9 years (6.8-21.3), without meeting the criteria for surgical intervention, none showed any change in the aortic valve function during follow-up time. DSS resection may not prevent worsening of aortic valve insufficiency over time. Patients with stable AI and low LVOT gradient may not require surgery. Given these findings, it may be appropriate to carefully follow patients with new onset AI and low LVOT gradient, delaying surgical intervention.

Discrete Subaortic Stenosis: Perspective Roadmap to a Complex Disease

Discrete subaortic stenosis (DSS) is a congenital heart disease that results in the formation of a fibro-membranous tissue, causing an increased pressure gradient in the left ventricular outflow tract (LVOT). While surgical resection of the membrane has shown some success in eliminating the obstruction, it poses significant risks associated with anesthesia, sternotomy, and heart bypass, and it remains associated with a high rate of recurrence. Although a genetic etiology had been initially proposed, the association between DSS and left ventricle (LV) geometrical abnormalities has provided more support to a hemodynamic etiology by which congenital or post-surgical LVOT geometric derangements could generate abnormal shear forces on the septal wall, triggering in turn a fibrotic response. Validating this hypothetical etiology and understanding the mechanobiological processes by which altered shear forces induce fibrosis in the LVOT are major knowledge gaps. This perspective paper describes the current state of knowledge of DSS, articulates the research needs to yield mechanistic insights into a significant pathologic process that is poorly understood, and proposes several strategies aimed at elucidating the potential mechanobiological synergies responsible for DSS pathogenesis. The proposed roadmap has the potential to improve DSS management by identifying early targets for prevention of the fibrotic lesion, and may also prove beneficial in other fibrotic cardiovascular diseases associated with altered flow.