Why Septal Thickness Does Not Tell the Whole Story: A Surgeon’s Reappraisal of Dynamic Outflow Obstruction in Hypertrophic Cardiomyopathy
Yong Cui, Zhenzhen Wang, Meijuan YanBackground
For more than half a century, left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM) has been understood primarily as a consequence of septal hypertrophy. However, the correlation between septal thickness and obstruction severity is inconsistent, and cardiac myosin inhibitors can markedly reduce, and in many patients eliminate, LVOTO without septal resection.
Aim
To reappraise the pathophysiology of dynamic LVOTO and its implications for surgical strategy.
Methods
We performed a narrative review of PubMed, MEDLINE, and Scopus (1990–2026), informed by our institutional experience with minimally invasive septal myectomy in over 1000 HCM patients (unpublished institutional data).
Results
Obstruction is best understood as a dynamic phenomenon arising from the interaction of four factors: ventricular geometry, the mitral and subvalvular apparatus, septal morphology, and contractile state. Septal thickness is one contributor among several rather than the dominant driver. Myosin inhibitors target the contractile component; surgery modifies geometry and mitral–septal relationships. A subset of patients requires adjunctive mitral–subvalvular procedures beyond isolated septal resection.
Conclusions
Septal myectomy is being redefined as a geometric intervention rather than a debulking procedure. Understanding the relative contribution of each mechanistic component can guide patient‐specific matching of surgical and medical therapies.