1. Hypertrophic Cardiomyopathy in Childhood: Disease Natural History, Impact of Obstruction, and Its Influence on Survival 
Edward J. Hickey, MD, Brian W. McCrindle, MD, Signe-Holm Larsen, BS, Lee Benson, MD, Cedric Manlhiot, BS, Christopher A. Caldarone, MD, Glen S. Van Arsdell, MD, Brett M. McCrindle, BS, William G. Williams, MD 
The Annals of Thoracic Surgery 
Volume 93, Issue 3, Pages (March 2012)
DOI: /j.athoracsur
Copyright © 2012 The Society of Thoracic Surgeons Terms and Conditions

2. Fig 1
Time-related development of peak instantaneous left ventricular outflow tract (LVOT) gradient greater than 30 mm Hg (“obstruction”) in all 120 children, according to patient age. The proportion transitioning to each of the mutually exclusive competing end states is shown: (1) developing obstruction >30 mm Hg (blue lines); (2) death without obstruction, or otherwise (red lines); and (3) alive without obstruction (black lines). Distinct early and late hazard phases for developing obstruction existed. Within 3 years of age, a large early hazard for obstruction was present, after which the hazard was low in early childhood. Beyond 5 to 10 years of age, a late hazard phase gradually became prominent and extended into adulthood. At age 20 years, 48% ± 5% had been obstructive at some stage, 48% ± 8% were alive with no obstruction, and 5% ± 3% had died without obstructive features. Numbers at risk: 73, 41, 23, and 6 at 5, 10, 15, and 20 years, respectively. Lines represent parametric models of survival.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2012 The Society of Thoracic Surgeons Terms and Conditions

3. Fig 2
(A) Progression of peak left ventricular outflow tract gradient in children with obstructive hypertrophic cardiomyopathy stratified according to whether myectomy (n = 23, 91 echocardiograms) was undertaken or not. The groups were distinguishable at the time of diagnosis by a gradient approximately 34 mm Hg higher (95% confidence interval 15.5 to 52.7, p < 0.01), which also increased with time (p < 0.01) in those who underwent myectomy. By contrast, the peak gradient regressed (p < 0.001) in children in whom myectomy was not undertaken. (B) Progression of peak gradient in the 29 children with obstructive gradients who did not undergo myectomy stratified according to the following: (1) septal hypertrophy was predominantly in the outflow tract causing systolic anterior motion of the mitral valve; or (2) predominantly midventricular septum or apex, causing midcavity obstruction. Those with midcavity obstruction showed a significant progressive decline in peak gradient (p < 0.001). Those with outflow tract hypertrophy instead displayed a lesser and nonsignificant decline (p = 0.62). For each plot, time transformations were explored to optimize log likelihood model fit (nonmyectomy plots are all square transformations). Lines represent parametric regression equations (“best-fit” curves) adjusted for repeated measures.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2012 The Society of Thoracic Surgeons Terms and Conditions

4. Fig 3
(A) Outcomes of surgical myectomy on progression of peak instantaneous left ventricular outflow tract gradient over time. Regression equations (adjusted for repeated measures) have been solved for the following groups of children: (1) nonobstructive hypertrophic cardiomyopathy (HCM); (2) preoperative in those who underwent myectomy; or (3) postoperative in those who underwent myectomy. Children with nonobstructive HCM showed a progressive fall in peak gradients over time (p = 0.04). In contrast, those who underwent myectomy had significantly higher peak gradients (p < 0.001) and exhibited a time-related increase in these gradients (p = 0.04) preoperatively. Surgical myectomy was effective in both significantly reducing the peak gradient (mean, 57 mm Hg reduction; 95% CI, 25.3 to 87.8; p < 0.01) and the gradient continued to reduce thereafter at a rate comparable with nonsurgically managed children. For each plot, time transformations were explored to optimize log likelihood model fit (“no surgery” = square transformation and “preoperative” = log transformation). (B) Outcomes of surgical myectomy on maximal interventricular septum zscore thickness. Regression equations (adjusted for repeated measures) have been solved for the following groups of children: (1) nonsurgically managed; (2) preoperative in those who underwent myectomy; or (3) postoperative in those who underwent myectomy. Children who do not undergo myectomy did not show a significant change in septal z score over time (p = 0.76). In contrast, those who underwent myectomy had higher septal z scores at the time of diagnosis (p = 0.04) and exhibited a time-related increase in septal hypertrophy (p < 0.001) preoperatively. Surgical myectomy then reduced the septal thickness to values comparable with nonsurgically managed children and septal z scores did not significantly alter thereafter. For each plot, time transformations were explored to optimize log likelihood model fit (“preoperative” = square transformation). Lines represent parametric regression equations (“best-fit” curves) adjusted for repeated measures.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2012 The Society of Thoracic Surgeons Terms and Conditions

5. Fig 4
Percent frequencies of grade of mitral regurgitation (“None” = none or trivial). Children who underwent myectomy immediately before (black boxes) and immediately after (crossed boxes) surgery. At the time of myectomy, the incidence of moderate regurgitation was significantly reduced (p = 0.01). At latest follow-up, only 1 child in the entire cohort had moderately severe mitral regurgitation, indicating that mitral regurgitation did not recur after surgical myectomy. (HCM = hypertrophic cardiomyopathy.)
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2012 The Society of Thoracic Surgeons Terms and Conditions

6. Fig 5
(A) Survival for all children (n = 120) diagnosed with hypertrophic cardiomyopathy (HCM) stratified by whether baseline peak instantaneous left ventricular outflow tract gradient greater than 30 mm Hg (obstructive) or less than 30 mm Hg (nonobstructive) at the time of diagnosis. Obstructive HCM at the time of diagnosis did not significantly influence either the early (p = 0.18) or late (p = 0.96) hazard phase for death. (B) Survival for all children (n = 120) diagnosed with HCM stratified by whether surgical myectomy was undertaken during the course of follow-up. Whether or not surgical myectomy was undertaken did not significantly influence either the early hazard phase (p = 0.50) or late hazard phase (p = 0.32) for death. Lines represent parametric models of survival.
The Annals of Thoracic Surgery  , DOI: ( /j.athoracsur )
Copyright © 2012 The Society of Thoracic Surgeons Terms and Conditions