BACKGROUND Accurate left ventricular outflow tract obstruction (LVOTO) assessment is crucial for hypertrophic cardiomyopathy (HCM) management and prognosis. Traditional methods, requiring multiple views, Doppler, and provocation, is often infeasible, especially where resources are limited. This study aimed to develop and validate a deep learning (DL) model capable of predicting severe LVOTO in HCM patients using only the parasternal long-axis (PLAX) view from transthoracic echocardiography (TTE).

METHODS A DL model was trained on PLAX videos extracted from TTE examinations (developmental dataset, n = 1,007) to capture both morphological and dynamic motion features, generating a DL index for LVOTO (DLi-LVOTO; range 0-100). Performance was evaluated in an internal test dataset (ITDS; n = 87) and externally validated in the distinct hospital dataset (DHDS; n = 1,334) and the LVOTO reduction treatment dataset (n = 156).

RESULTS The model achieved high accuracy in detecting severe LVOTO (pressure gradient 50 mm Hg), with area under the receiver operating characteristics curve of 0.97 (95% CI, 0.92-1.00) in ITDS and 0.93 (0.92-0.95) in DHDS. At a DLi-LVOTO threshold of 70, the model demonstrated a specificity of 97.3% and negative predictive value of 96.1% in ITDS. In DHDS, a cutoff of 60 yielded a specificity of 94.6% and negative predictive value of 95.5%. The DLi-LVOTO also decreased significantly after surgical myectomy or Mavacamten treatment, correlating with reductions in peak pressure gradient (P < .001 for all).

CONCLUSIONS Our DL-based approach predicts severe LVOTO using only the PLAX view from TTE, serving as a complementary tool when Doppler assessment is unavailable and for monitoring treatment response.