Highlight
1. Combined septal myectomy and secondary mitral valve chordal cutting yield a low surgical mortality (0.6%) in obstructive hypertrophic cardiomyopathy (HCM).
2. Long-term (median 5.6 years) survival parallels that of age- and sex-matched general population.
3. Majority of patients achieve NYHA functional class I with near-complete relief of outflow tract obstruction and mitral regurgitation.
4. This surgical strategy may expand referral and treatment options for severely symptomatic patients refractory to medical therapy including myosin inhibitors.
Study Background
Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder characterized by asymmetric hypertrophy of the left ventricle, often resulting in left ventricular outflow tract (LVOT) obstruction. This obstruction contributes to symptoms such as dyspnea, angina, syncope, and increases the risk of adverse outcomes. While pharmacological treatments—including newly introduced cardiac myosin inhibitors—have advanced medical management of obstructive HCM, a subset of patients remain severely symptomatic and refractory to medical therapy. These patients typically require invasive interventions to alleviate LVOT obstruction and improve functional status.
Septal myectomy, a surgical removal of hypertrophied septal myocardium, has long been the gold standard for relieving LVOT obstruction. However, mitral valve abnormalities such as anterior mitral leaflet (AML) motion and secondary chordal tethering also contribute to obstruction and mitral regurgitation in obstructive HCM. To address this, cutting thickened or retracted secondary chordae of the AML concomitant with myectomy has been proposed and shows promising short-term results. The lack of comprehensive long-term outcome data has limited widespread adoption.
Study Design
This was a single-center, prospective cohort study enrolling 350 consecutive patients with obstructive hypertrophic cardiomyopathy who underwent combined septal myectomy and secondary mitral valve chordal cutting at a tertiary referral center over a 5-year period. Median follow-up was 5.6 years (interquartile range 4.2–6.3 years). The primary endpoints included overall survival compared with the matched general Italian population, symptomatic status assessed by New York Heart Association (NYHA) functional class, and echocardiographic parameters including residual LVOT gradient, mitral regurgitation severity, and left ventricular systolic function. Surgical mortality and cause-specific mortality were also recorded. Follow-up evaluations included clinical visits and transthoracic echocardiography.
Key Findings
Surgical mortality was exceptionally low at 0.6% (2 in-hospital deaths among 350 patients). Long-term overall survival at 6 years was 96% and was statistically indistinguishable from the expected survival in the general Italian population matched by age and sex (P = 0.331), indicating normalization of survival with this surgical approach.
Follow-up clinical data were available for 344 patients (99%). At the most recent evaluation, 79% were symptom-free with NYHA class I status, 19% had mild symptoms (NYHA II), and only 2% had moderate symptoms (NYHA III), demonstrating robust and durable symptomatic relief.
During follow-up, there were 14 deaths reported, 6 of which were unrelated to hypertrophic cardiomyopathy, suggesting that surgical treatment effectively addresses HCM-related mortality risks.
Echocardiograms showed that more than 95% of patients exhibited no residual LVOT obstruction, clinically significant mitral regurgitation, or left ventricular systolic dysfunction at last assessment. These findings highlight sustained hemodynamic improvement.
These results affirm that cutting thickened and/or retracted secondary chordae of the anterior mitral leaflet combined with septal myectomy effectively addresses both LVOT obstruction and the mitral valve abnormalities contributing to symptomatic disease.
Expert Commentary
The introduction of cardiac myosin inhibitors has altered the treatment landscape in obstructive HCM by providing a potent medical alternative to surgery for many patients. However, this study reinforces that a significant subgroup with advanced, symptomatic disease continues to benefit from surgical intervention.
The combined surgical approach optimizes outcomes by targeting multiple pathophysiological contributors—septal hypertrophy and mitral valve apparatus abnormalities—that frequently coexist in obstructive HCM. This holistic approach may reduce the need for reintervention for residual gradients or mitral regurgitation following isolated myectomy.
Limitations include single-center experience and lack of randomized comparison to isolated myectomy or medical therapy; nonetheless, the large cohort and extended follow-up provide strong evidence supporting this technique’s long-term efficacy and safety.
With rising adoption, careful patient selection, surgeon expertise, and multidisciplinary evaluation remain paramount to reproduce these outcomes broadly.
Conclusion
Septal myectomy combined with secondary mitral valve chordal cutting demonstrates excellent long-term clinical and hemodynamic outcomes in patients with obstructive hypertrophic cardiomyopathy unresponsive to medical therapy. This surgical strategy yields survival comparable to that of the general population and durable symptom relief with minimal residual obstruction or mitral regurgitation.
These findings may encourage wider referral to centers proficient in this combined surgical technique and expand treatment options for severely symptomatic HCM patients, complementing emerging pharmacotherapies.
Funding and ClinicalTrials.gov
No specific funding source or clinical trial registration information is provided in the original publication.
References
Ferrazzi P, Spirito P, Binaco I, et al. Long-Term Outcome of Myectomy Associated With Secondary Mitral Valve Chordal Cutting in Obstructive Hypertrophic Cardiomyopathy. J Am Coll Cardiol. 2026 Jun 17; PMID: 42307496.
Marian AJ, Braunwald E. Hypertrophic Cardiomyopathy: Genetics, Pathogenesis, Clinical Manifestations, Diagnosis, and Therapy. Circ Res. 2017;121(7):749-770.
Olivotto I, Cecchi F, Poggesi C, Yacoub MH. Patterns of disease progression in hypertrophic cardiomyopathy: An individualized approach to treatment. Circulation. 2012;126(13):1835-1843.
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