Propensity score-matched analysis comparing modified Konno procedure and transaortic septal myectomy in children with left ventricular outflow tract obstruction

BACKGROUND The comparative clinical outcomes of the modified Konno procedure (MKP) and transaortic septal myectomy (TSM) for severe left ventricular outflow tract (LVOT) obstruction in children remain unclear. METHODS A total of 177 consecutive patients (age <14 years old) underwent surgical treatments, categorized by MKP or TSM technique (MKP n=45, TSM n=132). After propensity-score matching, 45 MKP patients were matched 1:1 with TSM patients. RESULTS At discharge, the MKP group demonstrated a significantly lower LVOT peak gradient compared to TSM group (median, 3.2 vs. 11.6 mmHg, P =.011), which persisted at follow-up (median, 4.8 vs. 11.6 mmHg, P =.01) in matched data. Although postoperative atrioventricular block was more frequent in MKP group, no significant difference was observed in permanent pacemaker implantation rate between groups (P =.108). During follow-up (median, 1.08 years, 0.25-2.5), the incidence of recurrent LVOT obstruction was higher in the TSM group (17.8% vs. 0%). Recurrent LVOT obstruction was associated with aortic annulus size (hazard ratio [HR]= 0.811; 95% confidence interval [CI], 0.675-0.974; P =.025) and preoperative LVOT peak gradient (HR = 1.030, 95% CI: 1.010-1.050, P =.003). The smaller aortic annulus size (<12.5mm) or severe LVOT obstruction (>82.5mmHg) significantly decreased risk of survival free from recurrent LVOT obstruction (P=.01, P<.001). CONCLUSIONS The MKP can provide better relief of LVOT obstruction than TSM in young children, particularly with a small aortic annulus or severe obstruction. MKP may not increase the risk of permanent pacemaker implantation and mortality.