Objective To investigate the changes and characteristics of electrocardiogram and echocardiography in patients with hypertrophic obstructive cardiomyopathy at 1 year after left ventricular outflow tract dredging.Methods To investigate patients diagnosed with hypertrophic obstructive cardiomyopathy who underwent left ventricular outflow tract dredging surgery in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from January 1 to December 31 in 2018. A total of 38 cases were enrolled, the clinical features, electrocardiogram and echocardiography data before, 1 year after surgery were collected for comparative analysis and summarizations.Results There were significant statistical differences in the proportion of left ventricular hypertrophy (LVH) and complete left bundle branch block (CLBBB) on electrocardiogram (52.6% vs 12.9%, P<0.01) and (2.6% vs 58.1%, P<0.01), respectively. Echocardiography showed a significant reduction in left ventricular ejection fraction (LVEF) (68.50%±4.11% vs 63.87%±4.00%, P<0.01). In post-surgery patients with CLBBB (67.46%±2.96% vs 64.83%±4.20%, P=0.082), there was a significant reduction in LVEF (69.39%±5.29% vs 63.40%±4.15%, P<0.01), while there was no statistical difference in patients without CLBBB.Conclusions Left ventricular outflow tract dredging surgery could effectively reduce the proportion of LVH in patients with hypertrophic obstructive cardiomyopathy and alleviate outflow tract obstruction. However, patients who developed CLBBB after surgery showed a tendency of reduced LVEF.