Search

ObjectivesThis study sought to determine the relationship between long QT syndrome (LQTS) subtype (LTQ1, LTQ2, LTQ3) and postnatal cardiac events (CEs).BackgroundLQTS presenting with 2:1 atrioventricular block or torsades de pointes in the fetus and/or neonate has been associated with risk for major CEs, but overall outcomes and predictors remain unknown.MethodsA retrospective study involving 25 international centers evaluated the course of fetuses/newborns diagnosed with congenital LQTS and either 2:1 atrioventricular block or torsades de pointes. The primary outcomes were age at first CE after dismissal from the newborn hospitalization and death and/or cardiac transplantation during follow-up. CE was defined as aborted cardiac arrest, appropriate shock from implantable cardioverter-defibrillator, or sudden cardiac death.ResultsA total of 84 fetuses and/or neonates were identified with LQTS (12 as LQT1, 35 as LQT2, 37 as LQT3). Median gestational age at delivery was 37 weeks (interquartile range: 35 to 39 weeks) and age at hospital discharge was 3 weeks (interquartile range: 2 to 5 weeks). Fetal demise occurred in 2 and pre-discharge death in 1. Over a median of 5.2 years, there were 1 LQT1, 3 LQT2, and 23 LQT3 CEs (13 aborted cardiac arrests, 5 sudden cardiac deaths, and 9 appropriate shocks). One patient with LQT1 and 11 patients with LQT3 died or received cardiac transplant during follow-up. The only multivariate predictor of post-discharge CEs was LQT3 status (LQT3 vs. LQT2: hazard ratio: 8.4; 95% confidence interval: 2.6 to 38.9; p < 0.001), and LQT3, relative to LQT2, genotype predicted death and/or cardiac transplant (p < 0.001).ConclusionsIn this large multicenter study, fetuses and/or neonates with LQT3 but not those with LQT1 or LQT2 presenting with severe arrhythmias were at high risk of not only frequent, but lethal CEs.

Background The objective of this international multicenter study was to investigate both early and late outcomes of cardiac resynchronization therapy (CRT) in patients with a systemic right ventricle (SRV) and to identify predictors for congestive heart failure readmissions and mortality. Methods and Results This retrospective international multicenter study included 13 centers. The study population comprised 80 adult patients with SRV (48.9% women) with a mean age of 45±14 (range, 18-77) years at initiation of CRT. Median follow-up time was 4.1 (25th-75th percentile, 1.3-8.3) years. Underlying congenital heart disease consisted of congenitally corrected transposition of the great arteries and dextro-transposition of the great arteries in 63 (78.8%) and 17 (21.3%) patients, respectively. CRT resulted in significant improvement in functional class (before CRT: III, 25th-75th percentile, II-III; after CRT: II, 25th-75th percentile, II-III; P=0.005) and QRS duration (before CRT: 176±27; after CRT: 150±24 milliseconds; P=0.003) in patients with pre-CRT ventricular pacing who underwent an upgrade to a CRT device (n=49). These improvements persisted during long-term follow-up with a marginal but significant increase in SRV function (before CRT; 30%, 25th-75th percentile, 25-35; after CRT: 31%, 25th-75th percentile, 21-38; P=0.049). In contrast, no beneficial change in the above-mentioned variables was observed in patients who underwent de novo CRT (n=31). A quarter of all patients were readmitted for heart failure during follow-up, and mortality at latest follow-up was 21.3%. Conclusions This international experience with CRT in patients with an SRV demonstrated that CRT in selected patients with SRV dysfunction and pacing-induced dyssynchrony yielded consistent improvement in QRS duration and New York Heart Association functional status, with a marginal increase in SRV function.

BACKGROUND: The objective of this international multicenter study was to investigate both early and late outcomes of cardiac resynchronization therapy (CRT) in patients with a systemic right ventricle (SRV) and to identify predictors for congestive heart failure readmissions and mortality. METHODS AND RESULTS: This retrospective international multicenter study included 13 centers. The study population comprised 80 adult patients with SRV (48.9% women) with a mean age of 45±14 (range, 18–77) years at initiation of CRT. Median follow-up time was 4.1 (25th–75th percentile, 1.3– 8.3) years. Underlying congenital heart disease consisted of congenitally corrected transposition of the great arteries and dextro-transposition of the great arteries in 63 (78.8%) and 17 (21.3%) patients, respectively. CRT resulted in significant improvement in functional class (before CRT: III, 25th–75th percentile, II– III; after CRT: II, 25th–75th percentile, II– III; P=0.005) and QRS duration (before CRT: 176±27; after CRT: 150±24 milliseconds; P=0.003) in patients with pre-CRT ventricular pacing who underwent an upgrade to a CRT device (n=49). These improvements persisted during long-term follow-up with a marginal but significant increase in SRV function (before CRT; 30%, 25th–75th percentile, 25– 35; after CRT: 31%, 25th–75th percentile, 21– 38; P=0.049). In contrast, no beneficial change in the above-mentioned vari-ables was observed in patients who underwent de novo CRT (n=31). A quarter of all patients were readmitted for heart failure during follow-up, and mortality at latest follow-up was 21.3%. CONCLUSIONS: This international experience with CRT in patients with an SRV demonstrated that CRT in selected patients with SRV dysfunction and pacing-induced dyssynchrony yielded consistent improvement in QRS duration and New York Heart Association functional status, with a marginal increase in SRV function.

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) >= 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean +/- SD, 12.5 +/- 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 +/- 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 +/- 4.1). The overall mean IVST was 20.5 +/- 9.6 mm and the overall mean PWT was 11.0 +/- 8.4 mm. The mean IVST in the obese patients was 21.6 +/- 10.0 mm and mean PWT was 13.3 +/- 14.7 mm. The mean IVST in the non-obese patients was 20.1 +/- 9.5 mm and mean PWT was 10.4 +/- 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

BACKGROUND Predictors of risk of lethal arrhythmic events (LAE) is poorly understood and may differ from adults in children with hypertrophic cardiomyopathy (HCM). OBJECTIVE The purpose of this study was to determine predictors of LAE in children with HCM. METHODS A retrospective data collection was performed on 446 children and teenagers 20 years and younger (290 [65%] male; mean age 10.1 +/- 5.7 years) with idiopathic HCM from 35 centers. Patients were classified as group 1 (HCM with LAE) if having a secondary prevention implantable cardioverter-defibrillator (ICD) or primary prevention ICD with appropriate interventions or group 2 (HCM without LAE) if having a primary prevention ICD without appropriate interventions. RESULTS There were 152 children (34%) in group 1 and 294 (66%) in group 2. Risk factors for group 1 by univariate analysis were septal thickness, posterior left ventricular (LV) wall thickness, lower LV outflow gradient, and Q wave > 3 mm in inferior electrocardiographic leads. Factors not associated with LAE were family history of SCD, abnormal blood pressure response to exercise, and ventricular tachycardia on ambulatory electrocardiographic monitoring. Risk factors for SCD by multivariate analysis were age at ICD placement (hazard ratio [HR] 0.9; P = .0025), LV posterior wall thickness z score (HR 1.02; P < .005), and LV outflow gradient < 30 mm Hg (HR 2.0; P < .006). LV posterior wall thickness z score >= 5 was associated with LAE. CONCLUSION Risk factors for LAE appear different in children compared to adults. Conventional adult risk factors were not significant in children. Further prospective studies are needed to improve risk stratification for LAE in children with HCM.

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) >= 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean +/- SD, 12.5 +/- 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 +/- 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 +/- 4.1). The overall mean IVST was 20.5 +/- 9.6 mm and the overall mean PWT was 11.0 +/- 8.4 mm. The mean IVST in the obese patients was 21.6 +/- 10.0 mm and mean PWT was 13.3 +/- 14.7 mm. The mean IVST in the non-obese patients was 20.1 +/- 9.5 mm and mean PWT was 10.4 +/- 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

BACKGROUND Predictors of risk of lethal arrhythmic events (LAE) is poorly understood and may differ from adults in children with hypertrophic cardiomyopathy (HCM). OBJECTIVE The purpose of this study was to determine predictors of LAE in children with HCM. METHODS A retrospective data collection was performed on 446 children and teenagers 20 years and younger (290 [65%] male; mean age 10.1 +/- 5.7 years) with idiopathic HCM from 35 centers. Patients were classified as group 1 (HCM with LAE) if having a secondary prevention implantable cardioverter-defibrillator (ICD) or primary prevention ICD with appropriate interventions or group 2 (HCM without LAE) if having a primary prevention ICD without appropriate interventions. RESULTS There were 152 children (34%) in group 1 and 294 (66%) in group 2. Risk factors for group 1 by univariate analysis were septal thickness, posterior left ventricular (LV) wall thickness, lower LV outflow gradient, and Q wave > 3 mm in inferior electrocardiographic leads. Factors not associated with LAE were family history of SCD, abnormal blood pressure response to exercise, and ventricular tachycardia on ambulatory electrocardiographic monitoring. Risk factors for SCD by multivariate analysis were age at ICD placement (hazard ratio [HR] 0.9; P = .0025), LV posterior wall thickness z score (HR 1.02; P < .005), and LV outflow gradient < 30 mm Hg (HR 2.0; P < .006). LV posterior wall thickness z score >= 5 was associated with LAE. CONCLUSION Risk factors for LAE appear different in children compared to adults. Conventional adult risk factors were not significant in children. Further prospective studies are needed to improve risk stratification for LAE in children with HCM.

BACKGROUND Subcutaneous implantable cardioverter-defibrillator (SICD) shows promise for select patients at risk of sudden cardiac death. However, patients need to pass an electrocardiographic (ECG) screening (ECG-S) test before they can receive an SICD. Predictors of ECG-S failure in children are unclear. OBJECTIVE The purpose of this study was to identify the incidence and predictive factors for failure of ECG-S in children. METHODS Patients 18 years and younger with a preexisting ICD underwent ECG-S for SICD. ECG and demographic data were analyzed for factors predictive of failure. RESULTS Seventy-three patients (mean age 14.2 +/- 3.3 years; range 5-18 years) with hypertrophic cardiomyopathy (n = 24, 33%), long QT syndrome (n =18, 25%), other inherited arrhythmia syndromes (n = 20, 27%), congenital heart disease (n = 9, 12%), and miscellaneous conditions (n = 2) with an existing transvenous ICD underwent prospective ECG-S. Nineteen (26%) failed ECG-S. Failed patients had a longer corrected QT (QTc) interval (457 ms vs 425 ms; P = .03), a longer QRS duration (120 ms vs 98 ms; P = .04), and a lower ratio of R-wave to T-wave amplitudes (R:T ratio) in lead aVF (4 vs 5; P = .001). Multivariable logistic regression identified QTc interval (odds ratio [OR] 4.31; P = .04), QRS duration (OR 4.93; P = .03), R:T ratio in lead aVF (OR 3.13; P = .08) as predictors of failure. A risk score with 1 point each for QTc interval >440 ms, QRS duration >120 ms, and R:T ratio <6.5 in lead aVF was associated with probability of failure of 15.4% (1 point), 47.4 0 /. (2 points), and 88.6% (3 points), respectively. CONCLUSION ECG-S failure for SICD occurred in 26% of children, which is higher than the reported incidence in adults. Factors predicting ECG-S failure included longer QTc interval, longer QRS duration, and lower R:T ratio in lead aVF.

BACKGROUND Subcutaneous implantable cardioverter-defibrillator (SICD) shows promise for select patients at risk of sudden cardiac death. However, patients need to pass an electrocardiographic (ECG) screening (ECG-S) test before they can receive an SICD. Predictors of ECG-S failure in children are unclear. OBJECTIVE The purpose of this study was to identify the incidence and predictive factors for failure of ECG-S in children. METHODS Patients 18 years and younger with a preexisting ICD underwent ECG-S for SICD. ECG and demographic data were analyzed for factors predictive of failure. RESULTS Seventy-three patients (mean age 14.2 +/- 3.3 years; range 5-18 years) with hypertrophic cardiomyopathy (n = 24, 33%), long QT syndrome (n =18, 25%), other inherited arrhythmia syndromes (n = 20, 27%), congenital heart disease (n = 9, 12%), and miscellaneous conditions (n = 2) with an existing transvenous ICD underwent prospective ECG-S. Nineteen (26%) failed ECG-S. Failed patients had a longer corrected QT (QTc) interval (457 ms vs 425 ms; P = .03), a longer QRS duration (120 ms vs 98 ms; P = .04), and a lower ratio of R-wave to T-wave amplitudes (R:T ratio) in lead aVF (4 vs 5; P = .001). Multivariable logistic regression identified QTc interval (odds ratio [OR] 4.31; P = .04), QRS duration (OR 4.93; P = .03), R:T ratio in lead aVF (OR 3.13; P = .08) as predictors of failure. A risk score with 1 point each for QTc interval >440 ms, QRS duration >120 ms, and R:T ratio <6.5 in lead aVF was associated with probability of failure of 15.4% (1 point), 47.4 0 /. (2 points), and 88.6% (3 points), respectively. CONCLUSION ECG-S failure for SICD occurred in 26% of children, which is higher than the reported incidence in adults. Factors predicting ECG-S failure included longer QTc interval, longer QRS duration, and lower R:T ratio in lead aVF.