Critical left ventricular outflow tract obstruction: The disproportionate impact of biventricular repair in borderline cases

Algorithm indicating the profile of neonates with critical LVOT obstruction enrolled with the CHSS between 1994 and 2001. The present study analyzed the 362 neonates who underwent an index procedure (within age 30 days) indicating intended univentricular or biventricular repair. HTX, Heart transplantation; UVR, univentricular repair; BVR, biventricular repair; LVOT, left ventricular outflow tract; CHSS, Congenital Heart Surgeons’ Society.

Subsequent procedures and mortality for patients who had an initial procedure indicating an intended univentricular management strategy. Bold entries represent “crossovers” (n = 7) to an alternative management strategy (BVR or transplantation) during the follow-up period. UVR, Univentricular repair; CPC, cavopulmonary connection; HTX, heart transplantation.

Subsequent procedures and mortality for neonates (n = 105) whose initial procedure was a balloon aortic valvotomy (BAV). Italicized entries represent “crossovers” (n = 7) to an alternative management strategy (UVR or transplantation) during the follow-up period. AVR, Aortic valve replacement; SAV, surgical aortic valvuloplasty; HTX, heart transplantation; CPC, cavopulmonary connection; SVALV, open surgical valvotomy; BVALV, balloon aortic valvotomy.

Subsequent procedures and mortality for patients who had an initial open surgical procedure indicating an intended BVR strategy. Bold entries represent “crossovers” (n = 5) to the opposite management strategy (BVR) during the follow-up period. BAV, Balloon aortic valvotomy; AVR, aortic valve replacement (Ross–Konno procedure); SAV, surgical aortic valvuloplasty; SVALV, open surgical valvotomy.

Unadjusted time-related survival plots for the study population stratified by intended management strategy. Solid line represents BVR (n = 139, 39 deaths). Dashed line represents UVR (n = 223, 84 deaths). Circles represent actuarial Kaplan–Meier estimates at events (deaths). Lines represent parametric continuous point estimates. The hazard domain for both BVR and UVR survival was only early, with no appreciable constant or late phases. Eighty-four percent of deaths had occurred within 1 year and 94% within 3 years. The difference in unadjusted survival between UVR and BVR did not reach statistical significance (P = .07). Error bars enclose 70% confidence intervals. BVR, Biventricular repair; UVR, univentricular repair.

Risk-adjusted percentage survival after UVR (n = 223) stratified by (a) the presence of moderate or severe tricuspid regurgitation, (b) the presence of a large ventricular septal defect (VSD), (c) smaller mitral valve annular z-score, or (d) smaller indexed length of the dominant ventricle. For each stratified plot the remaining 3 variables are set at their mean value, and for the indexed length of the dominant ventricle stratifications are shown for values based on mean heights and weights. Lines represent the parametric determination of continuous point estimates of survival. UVR, Univentricular repair.

Risk-adjusted percentage survival after BVR (n = 139) stratified by (a) smallest indexed minimum diameter of the left ventricular outflow tract, (b) the presence of left ventricular dysfunction, (c) grade of endocardial fibroelastosis, or (d) indexed diameter of the transverse aortic arch immediately proximal to the left subclavian artery. For each stratified plot the remaining 3 variables are set at their mean value, and for indexed left ventricular outflow tract and arch diameters, stratifications are shown for values based on mean heights and weights. Lines represent the parametric determination of continuous point estimates of survival. BVR, Biventricular repair.

Exploration into the association between age and BVR management. A, The logistic probability of death after intended BVR follows an inverse relationship to the age at index intervention. Discordantly managed patients (solid line) carry a higher risk of mortality at all ages, but especially so at young ages. Mortality for concordantly managed patients (broken line) is only associated with extremely young ages (<days). B, The probability of receiving a BVR discordant management is strongly associated with young age at intervention. C, The aortic valve z-score is the strongest predictor of age at intervention, but only in the BVR discordant group (r = 0.45). For concordant BVR management there is no relationship between aortic valve z-score and age at intervention (r = 0.06). Collectively, these findings imply that very early BVR intervention (BAV in 83% younger than 3 days) driven by small aortic valve z-scores is frequently a discordant decision with a high incidence of death. The UVR-SA tool will identify patients in whom UVR would offer better survival in tight valvular aortic stenosis. BVR, Biventricular repair; BAV, balloon aortic valvotomy; UVR-SA, univentricular repair survival advantage.

Distribution histogram of UVR-SA values for the BVR (solid line) and UVR (dashed line) cohorts. The median value was +29 for the UVR group (dashed arrow) and +4 for the BVR group (solid arrow). All of those 176 UVR children (79%) with a UVR-SA value > 0 had better predicted survival with UVR and therefore their management was “concordant” with the UVR-SA predictions. The 47 UVR children (21%) with a UVR-SA value < 0 had better predicted survival with BVR and therefore their management was “discordant.” All of the 63 BVR children (45%) with a UVR-SA value < 0 had better predicted survival with BVR, and therefore their management was “concordant” with the UVR-SA predictions. Those 76 UVR children (55%) with a UVR-SA value > 0 had better predicted survival with UVR, and therefore their management was “discordant.” See Figure 1 for definitions of abbreviations.

Actuarial Kaplan–Meier survival of UVR infants managed discordantly (circles), compared with parametric predicted survival for the same patients if they had instead received BVR as the UVR-SA decision tool advised. Error bars and dashed lines enclose 70% confidence intervals. Survival differences are significant (P = .02). UVR, Univentricular repair; BVR, biventricular repair; UVR-SA, univentricular repair survival advantage.

Actuarial time-related survival of biventricular patients managed discordantly (circles), compared with parametric continuous point estimates of survival for the same patients if they had instead received UVR in accordance with UVR-SA tool predictions. Error bars and dashed lines enclose 70% confidence intervals. Survival differences are significant (P < .001). UVR-SA, univentricular repair survival advantage.

Parametric continuous point estimates of predicted 5-year survival for (a) BVR or (b) UVR across the spectrum of UVR-SA values. The 95th centiles for UVR-SA values in the CHSS critical LVOT obstruction cohort range from −24 to +66. Fine dashed lines enclose 70% confidence intervals. Survival for BVR is far more sensitive to changes in UVR-SA values. The steep slope of the BVR curve (a) corresponds to a sharp fall in survival. See Figure 1 for definitions of abbreviations.