Geometric predictors of left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy: a 3D computed tomography analysis.

Aims: To establish geometric predictors of left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM) patients by use of cardiac computed tomography (CT).

Methods and results: A total of 141 consecutive patients with HCM who underwent cardiac CT comprised the analytic sample. The degree, pattern, and extent of left ventricular (LV) hypertrophy were evaluated using 3D CT. Abnormality of papillary muscle (PM), mitral valve, and aorto-mitral angle were evaluated quantitatively. Multivariable logistic regression analysis and sensitivity analysis were performed to reliably identify predictors of LVOTO. LVOTO was present among 40 (28.4%) patients. Those with LVOTO displayed a higher prevalence for having a spiral pattern of LV hypertrophy (e.g. 51 vs. 16%, P < 0.001), a longer anterior mitral leaflet (AML) length (e.g. 18.0 vs. 15.6 mm, P = 0.007), and a longer distance from lateral PM base to LV apex (e.g. 26.4 vs. 22.0 mm, P < 0.001), as compared with the non-LVOTO group. Multivariable logistic regression revealed all three variables [i.e. spiral pattern (95% confidence interval (CI), 3.75, 1.59-8.84); AML length (95% CI, 1.20, 1.03-1.40); the distance between lateral PM base and LV apex (95% CI, 1.09, 1.01-1.19)] retained significance after adjustment for numerous covariates.

Conclusion: Spiral pattern of LV hypertrophy, the length of AML, and the distance between lateral PM base and LV apex were independent predictors of LVOTO in patients with HCM.