Reverse septal curvature in hypertrophic cardiomyopathy: Implications for function, structure and arrhythmic risk

Background: In patients with hypertrophic cardiomyopathy (HCM) reverse septal curvature (RSC) is a marker of higher clinical burden; however, its mechanical and structural implications remain underexplored. Methods and results: A total of 107 patients with HCM underwent comprehensive 2D echocardiography, 3D echocardiography, and cardiac magnetic resonance (CMR). In both imaging modalities, reverse septal curvature (RSC) was defined as left ventricular (LV) mid-septal convexity toward the LV cavity extending over more than one-third of the distance from the base to the apex. LV systolic behavior, including cavity and mid-cavity obliteration, was assessed. Forty-nine patients (46 %) were classified as having RSC. LV apical aneurysms were observed exclusively in patients with RSC (20 %). Subsequent analyses excluded patients with LV aneurysms. Compared with those without RSC, patients with RSC had higher rates of sarcomeric mutations (57 % vs. 33 %), non-sustained ventricular tachycardia (NSVT) (61 % vs. 21 %), greater wall thickness (23 ± 5 vs. 19 ± 4 mm), impaired GLS (−10 ± 3 % vs. −13 ± 3 %), and more frequent late gadolinium enhancement (100 % vs. 69 %) (all p < 0.05). In this subgroup, multivariate analysis identified RSC as an independent predictor of NSVT (OR = 5.571, 95 % CI 1.446–21.566, p = 0.013). Mid-cavity obliteration was observed in nine patients, all with RSC. Apical ejection fraction (EF) was significantly reduced in this group, with a marked apical–basal EF gradient (β = −30, p < 0.001). Conclusions: Our data demonstrated that RSC is not merely an anatomical variant, but it identifies a distinct HCM phenotype characterized by exclusive association with apical aneurysms, mid-cavity obliteration, impaired apical function, and worse arrhythmic profile independently of LV aneurysm.