LAUSR

A 69‐year‐old female with a history of hypertrophic obstructive cardiomyopathy, coronary heart disease and atrial fibrillation was admitted to our hospital due to dyspnea on exertion in 2 months despite the optimal medical therapy. The preoperative transthoracic echocardiography (TTE) revealed asymmetrical septal hypertrophy and severe subaortic left ventricular outflow tract (LVOT) obstruction (resting transaortic peak pressure gradient = 115 mmHg). Anomalous insertion of an anterior papillary muscle (APM) into the body of the anterior mitral leaflet was unexpectedly observed via computed tomography (CT) and patient‐specific three‐ dimensional printing model based on CT images (Figure 1A,B). The anomalous insertion was also confirmed by intraoperative transesophageal echocardiography and intraoperative findings (Figure 1C,D). Transmitral septal myectomy, mitral valve replacement, and closure of left atrial appendage were then performed via thoracoscopy (Figure 1E). Anomalous papillary muscle directly into the mitral leaflet is rare in patients with hypertrophic obstructive myocardiopathy, which contributes to dynamic LVOT obstruction. However, preoperative identification of anomalous insertion of APM remains a great challenge due to the low sensitivity in the detection of TTE and cardiac magnetic resonance imaging. In an analysis of 10 patients with anomalous insertion of APM, only one patient was recognized in preoperativeTTE. Similarly in a recent report by Lentz Carvalho et al., preoperative TTE identified this anomaly in only 11% of patients. In our case, it suggested that CT and three‐dimensional printing models can help in the