Common deletion variants causing protocadherin-α deficiency contribute to the complex genetics of BAV and left-sided congenital heart disease

Bicuspid aortic valve (BAV) with ~1%-2% prevalence is the most common congenital heart defect (CHD). It frequently results in valve disease and aorta dilation and is a major cause of adult cardiac surgery. BAV is genetically linked to rare left-heart obstructions (left ventricular outflow tract obstructions [LVOTOs]), including hypoplastic left heart syndrome (HLHS) and coarctation of the aorta (CoA). Mouse and human studies indicate LVOTO is genetically heterogeneous with a complex genetic etiology. Homozygous mutation in the Pcdha protocadherin gene cluster in mice can cause BAV, and also HLHS and other LVOTO phenotypes when accompanied by a second mutation. Here we show two common deletion copy number variants (delCNVs) within the PCDHA gene cluster are associated with LVOTO. Analysis of 1,218 white individuals with LVOTO versus 463 disease-free local control individuals yielded odds ratios (ORs) at 1.47 (95% confidence interval [CI], 1.13-1.92; p = 4.2 × 10-3) for LVOTO, 1.47 (95% CI, 1.10-1.97; p = 0.01) for BAV, 6.13 (95% CI, 2.75-13.7; p = 9.7 × 10-6) for CoA, and 1.49 (95% CI, 1.07-2.08; p = 0.019) for HLHS. Increased OR was observed for all LVOTO phenotypes in homozygous or compound heterozygous PCDHA delCNV genotype comparison versus wild type. Analysis of an independent white cohort (381 affected individuals, 1,352 control individuals) replicated the PCDHA delCNV association with LVOTO. Generalizability of these findings is suggested by similar observations in Black and Chinese individuals with LVOTO. Analysis of Pcdha mutant mice showed reduced PCDHA expression at regions of cell-cell contact in aortic smooth muscle and cushion mesenchyme, suggesting potential mechanisms for BAV pathogenesis and aortopathy. Together, these findings indicate common variants causing PCDHA deficiency play a significant role in the genetic etiology of common and rare LVOTO-CHD.

Pediatric heart transplantation across a positive crossmatch: First year results from the CTOTC-04 multi-institutional study

Sensitization is common in pediatric heart transplant candidates and waitlist mortality is high. Transplantation across a positive crossmatch may reduce wait time, but is considered high risk. We prospectively recruited consecutive candidates at eight North American centers. At transplantation, subjects were categorized as nonsensitized or sensitized (presence of ≥1 HLA antibody with MFI ≥1000 using single antigen beads). Sensitized subjects were further classified as complement-dependent cytotoxicity crossmatch (CDC-crossmatch) positive or negative and as donor-specific antibodies (DSA) positive or negative. Immunosuppression was standardized. CDC-crossmatch-positive subjects also received perioperative antibody removal, maintenance corticosteroids, and intravenous immunoglobulin. The primary endpoint was the 1 year incidence rate of a composite of death, retransplantation, or rejection with hemodynamic compromise. 317 subjects were screened, 290 enrolled and 240 transplanted (51 with pretransplant DSA, 11 with positive CDC-crossmatch). The incidence rates of the primary endpoint did not differ statistically between groups; nonsensitized 6.7% (CI: 2.7%, 13.3%), sensitized crossmatch positive 18.2% (CI: 2.3%, 51.8%), sensitized crossmatch negative 10.7% (CI: 5.7%, 18.0%), P = .2354. The primary endpoint also did not differ by DSA status. Freedom from antibody-mediated and cellular rejection was lower in the crossmatch positive group and/or in the presence of DSA. Follow-up will determine if acceptable outcomes can be achieved long-term.

Myocardial Infarction in Adults With Congenital Heart Disease

We compared the incidence and 30-day mortality of myocardial infarction (MI) in adults with congenital heart disease (CHD) relative to the general population. This cohort study used nationwide population-based medical databases to identify individuals born before 1982 and diagnosed with CHD in Denmark between 1963 and 2012. Patients were followed for first-time MI using data from the Danish National Registry of Patients. For each subject with CHD, we identified 10 controls from the general population, matched by sex and birth year. A unique personal identifier enabled follow-up for migration, death, or MI. We computed cumulative incidences and hazard ratios (HR) adjusted for birth year and sex for MI and 30-day mortality after MI. We identified 10,501 CHD adults alive at 30 years. By 70 years of age, the cumulative incidence of MI was 10% versus 6.5% for controls. The overall HR of MI in subjects with CHD compared with controls was 2.0 (95% CI 1.7 to 2.3). The 30-day mortality was 18% for the 296 subjects with CHD experiencing an MI during follow-up. The overall HR comparing 30-day mortality after MI between subjects with CHD and controls was 1.4 (95% CI 1.0 to 1.8). The greatest mortality was observed in adults with severe CHD (HR 2.7 [95% CI 1.5 to 5.0]). In conclusion, the incidence of MI and the 30-day mortality after MI for severe CHD were increased in adults with CHD compared with the general population. Underlying mechanisms need to be clarified.

Outcomes and risk factors for heart transplantation in children with end-stage cardiomyopathy†

OBJECTIVES

Heart transplantation (HT) is the treatment of choice in children with end-stage cardiomyopathy. Several clinical, morphological, demographic, donor and recipient transplant factors have been demonstrated to affect survival in those patients following listing for HT and following HT. We aim to report our single institution results of HT in children with cardiomyopathy, and explore variables affecting survival and the need for heart retransplantation (RHT).

METHODS

Between 1988 and 2013, 125 children with cardiomyopathy underwent HT. Competing risks analysis modelled events after HT (RHT, death without RHT). Multivariable regression analysis examined risk factors affecting outcomes and parametric models were used to compare survival between diverse groups of patients.

RESULTS

There were 62 males (50%). Cardiomyopathy types were dilated (n = 104, 83%), restrictive (n = 10, 8%), chemotherapy-induced (n = 7, 6%), and other (n = 4, 3%). Median age at listing was 6.9 years and median age at HT was 7.0 years with median waiting list duration of 29 days. Thirty-four patients were infants <1 year. At time of HT, 106 patients (85%) were at United Network for Organ Sharing status-1, 25 (20%) were ventilated and 17 (14%) had mechanical circulatory support. There was 1 operative death. Competing risks analysis showed that at 10 years following HT, 10% of patients have undergone RHT, 32% have died without RHT and 58% of patients were alive without RHT. On multivariable analysis, risk factors for death following HT were panel-reactive antibodies >10% {hazard ratio [HR]: 4.1 [95% confidence interval (CI): 1.7-9.9], P = 0.002}, age group >10 years [HR: 3.2 (95% CI: 1.4-8.1), P = 0.009] and pre-HT mechanical circulatory support [HR: 2.9 (95% CI: 1.1-7.7), P = 0.033]. Additionally, earlier era <2000 was a significant risk factor for early phase mortality [HR: 8.7 (95% CI: 1.8-42.5), P = 0.017] but not for constant or late phase mortality [HR: 0.8 (95% CI 0.3-1.8), P = 0.6]. Following RHT, 6/11 (55%) expired yielding overall parametric survival estimates of 92, 77 and 57% at 1, 5 and 15 years, respectively.

CONCLUSIONS

Despite remarkable improvement in operative mortality and 1-year survival of children undergoing HT for cardiomyopathy in the current era, that advantage is reduced at the later follow-up, especially in teenagers indicating ongoing compliance and chronic management challenges. In children requiring pre-HT mechanical support, mid-term attrition is higher despite low operative mortality.

Association of race and socioeconomic position with outcomes in pediatric heart transplant recipients

We assessed the association of socioeconomic (SE) position with graft loss in a multicenter cohort of pediatric heart transplant (HT) recipients. We extracted six SE variables from the US Census 2000 database for the neighborhood of residence of 490 children who underwent their primary HT at participating transplant centers. A composite SE score was derived for each child and four groups (quartiles) compared for graft loss (death or retransplant). Graft loss occurred in 152 children (122 deaths, 30 retransplant). In adjusted analysis, graft loss during the first posttransplant year had a borderline association with the highest SE quartile (HR 1.94, p = 0.05) but not with race. Among 1-year survivors, both black race (HR 1.81, p = 0.02) and the lowest SE quartile (HR 1.77, p = 0.01) predicted subsequent graft loss in adjusted analysis. Among subgroups, the lowest SE quartile was associated with graft loss in white but not in black children. Thus, we found a complex relationship between SE position and graft loss in pediatric HT recipients. The finding of increased risk in the highest SE quartile children during the first year requires further confirmation. Black children and low SE position white children are at increased risk of graft loss after the first year.

Tissue Doppler imaging detects severely abnormal myocardial velocities that identify children with pre-terminal cardiac graft failure after heart transplantation

BACKGROUND

Children with orthotopic heart transplants (OHT) may die or require retransplantation due to chronic graft failure usually due to severe coronary allograft vasculopathy (CAV). Non-invasive detection of chronic transplant failure has been problematic due to lack of specific echocardiographic findings. Tissue Doppler Imaging (TDI) is a non-invasive ultrasound methodology, which measures myocardial contraction and relaxation velocities. The purposes of this study were to: 1. Determine quantitative changes of longitudinal TDI velocities characteristic to "pre-terminal" patients who subsequently either died or were listed for re-transplantation due to graft failure; 2. to define the time course of these changes, and 3. to show whether RV and LV velocities were equally effected.

METHODS

53 heart transplantation recipients were evaluated. Of these, 45 were "well" patients. They ranged in age at enrollment from 0.5 to 20.1 (mean 10.21) years, age at transplantation from 0.2 to 18 (mean 5.7) years. The time from transplantation to enrollment was 1 day to 14.9 (mean 4.5) years. There were 8 "pre-terminal" (test group) patients who died or were listed for re-transplantation within 9 months after TDI echo. These ranged in age from 2.6 to 17 (mean 11.6) years, age at transplant from 1 month to 15.9 (mean 8.1) years, and time from transplant to enrollment was 0.7 to 9.8 (mean 3.6) years. TDI was performed in the apical four-chamber view. Systolic (S, cm/s) and diastolic early (E, cm/s) and late (A, cm/s) velocity. Mitral and tricuspid annular TDI velocities were measured. Tricuspid regurgitation and LV ejection fraction were also compared.

RESULTS

Pre-terminal patient's Left Ventricular Ejection Fraction began diverging from controls at 3 to 6 months prior to endpoint (p < 0.001). Tricuspid TDI S velocities of pre-terminal patients diverged by 2.0 cm/sec from controls (p < 0.002) 6 months prior to, and reduced further by 2.9 cm/sec 3 months prior to endpoint (p < 0.001). Tricuspid TDI E velocities diverged 3 to 6 months before endpoint, by 1.9 cm/sec (p < 0.02) and by 3.7 cm/sec 0-3 months prior to endpoint, (p < 0.001). Mitral S velocities diverged from controls by 1.5 cm/sec at 0 to 3 months before terminal endpoints (p = 0.002). Mitral E velocities were statistically similar at all time intervals (p > or = 0.15). Septal S velocities equaled controls 6 months (p = 0.92) and between 3 to 6 months (p = 0.83) but diverged by 1.6 cm/sec 0 to 3 months before terminal endpoints (p = 0.01). Septal E velocities equaled controls. Mortality Prediction: LVEF, tricuspid annulus systolic and diastolic velocities, and tricuspid regurgitation severity were significant in predicting mortality. Coronary angiography was performed in 26 patients, 5 had severe coronary artery disease and all were pre-terminal.

DISCUSSION

The TDI data reported here show 3 to 6 months before the terminal graft failure, tricuspid, but not mitral, S and E TDI velocities, deteriorated to uniquely low levels not seen in other clinically well pediatric transplant recipients. Further RV deterioration occurred during the final 3 months before death and severely reduced left ventricular velocities then occurred. Small decreases in LVEF and progressive increases in the severity of tricuspid regurgitation were also detectable and predicted an increased likelihood of mortality. Seven of the 8 preterminal patients had angiograms 5 of which showed severe CAV. These data suggest that there is a critical "pre-terminal" window of time in which children demonstrate uniquely reduced right and subsequently left sided myocardial velocities at approximately 6 months prior to graft failure. The practice of annual catheterization and coronary angiography may not allow caregivers an opportunity to intervene early in the process of graft dysfunction. Therefore, a strategy of tissue Doppler echocardiography 2 or 3 times each year might be an appropriate regimen to survey for graft impairment.

Pre- and Postoperative Quantitation of Right Ventricular Tissue Doppler Velocities in Infants with Hypoplastic Left Heart Syndrome

BACKGROUND

The purpose of this study was to use tissue Doppler imaging (TDI) to serially quantitate initial and preoperative right ventricular (RV) TDI velocities and compare them to postoperative RV TDI velocities as measures of RV function in newborns with hypoplastic left heart syndrome (HLHS).

METHODS

Twelve consecutive patients were prospectively studied with diagnosis of HLHS. Systolic (Sw) and early diastolic (Ew) velocities were recorded at the tricuspid annulus and the ventricular septum at (1) admission, (2) immediately preoperative, and (3) during recovery. All patients were treated preoperatively with prostaglandins (PGE). Velocities were compared using repeated measure analysis of variance.

RESULTS

Mean age at diagnosis was 1 day (0-4 days). Time from diagnosis to surgery was 4 days (1-9 days), age at surgery 5.3 days (2-10 days), and time from surgery to postoperative echo 12.3 days (5-19 days). Tricuspid annular and septal systolic velocities increased from admission to preoperative. Both tricuspid Sw and Ew and septal Sw velocities decreased postoperatively. No significant changes occurred in the ventricular septal diastolic (Ew) velocities from admission to preoperative.

CONCLUSION

These data indicate that following the institution of PGE and initial medical and ventilatory management, there is an increase in RV annular and septal systolic velocities from the initial to the preoperative period and that these indices as well as RV annular diastolic velocities decline significantly postoperatively. Initial septal diastolic velocities were severely abnormal and did not significantly change pre- and postoperatively. These data may have significance for both postoperative and subsequent long-term RV function.