MedicalResearch.com Interview with:
Thomas Hadberg Lynge MD
The Department of Cardiology
The Heart Centre, Copenhagen University Hospital
MedicalResearch.com: What is the background for this study?
Response: Congenital heart defects are common and affect ≈0.8% of all live births. Despite substantially improve survival over the past decades, morbidity and mortality remain significant, in particular among patients with complex congenital heart defects. This decreased life expectancy is in part explained by an increased risk of sudden cardiac death among people with congenital heart defects. However, the incidence of sudden cardiac death among people with congenital heart defects is largely unknown in an unselected and nationwide setting.
Sudden cardiac death can occur both at rest and during exercise and it is well-known that exercise is associated with an increased risk of sudden cardiac death during activity. Fear of sudden cardiac death has led to restrictions of physical activity among patients with congenital heart defects and these patients have lower levels of physical activity compared with healthy peers. Appropriate counseling of these patients requires estimates on risk of sudden cardiac death in relation to physical activity.
Nationwide fetal ultrasound screening was implemented in Denmark in 2005 and this together with improved surgical and medical treatment during the study period, is likely to have changed the epidemiology of sudden cardiac death in people with congenital heart defects. It was therefore also an important aim of the study to examine temporal changes in sudden cardiac death in people with congenital heart defects.
MedicalResearch.com: What are the main findings?
Response: In this nationwide and unselected study, we examined all 11,451 deaths among people aged 0-35 years in Denmark in 2000-2009. Our findings prove new insight into the epidemiology of sudden cardiac death in people with congenital heart defects.
In the study period, there were 809 people who suffered sudden cardiac death, of which 90 had congenital heart defects. The most common causes of sudden cardiac death were coarctation of aorta, transposition of the great arteries, and univentricular heart. Only 59% were diagnosed with their congenital heart defects prior to death, while the remaining patients were diagnosed post-mortem at autopsy. Incidence of sudden cardiac death was ≈10-fold higher among patients with congenital heart defects compared to people without congenital heart defects.
Annual incidence of physical activity-related sudden cardiac death in patients aged 2-35 years with congenital heart defects was low. In the 10-year study period, we found only 2 cases of physical activity-related sudden cardiac death in people with congenital heart defects first diagnosed at autopsy. Both of these deaths occurred in people with coronary anomalies.
Finally, we observed a ≈4-fold decrease in incidence of sudden cardiac death in infants with congenital heart defects after implementation of nationwide fetal ultrasound screening in 2005.
MedicalResearch.com: What should readers take away from your report?
Response: Sudden cardiac death is fortunately a rare event among young persons, also among most people with congenial heart defects. However, certain subtypes of congenital heart defects are associated with an increased risk of sudden cardiac death, and in this study, we observed a ≈10-fold higher risk of sudden cardiac death in patient with congenital heart defects compared with the general population.
We found a low rate of sudden cardiac death during physical activity among people with congenital hearts defects. Proportion of deaths that occurred during activity varied with subtype of congenital heart defect. In our study, coronary anomaly was the most common cause of physical activity-related death. Restriction of physical activity in persons with such high-risk phenotypes may be warranted. However, taken together, our findings indicate a low risk of sudden cardiac death during physical activity among people with congenital heart defects.
From 2000-2009, we observed a significant and marked decline in incidence of sudden cardiac death in infants with congenital heart defects. Although this decline coincides with the implementation of nationwide fetal ultrasound screening in 2005, our findings offer no causative link between the two due to the observational nature of our study. Other possible explanations for our findings include a decreased live birth prevalence of congenital heart defects unrelated to screening and improved medical and surgical treatment of these defects in general.
Prenatal screening for congenital heart defects can lead to a decreased incidence of sudden cardiac death in several ways:
- First, in some countries, detection of severe heart defects may lead to termination of pregnancy;
- Second, prenatal detection allows for delivery in a specialized tertiary center;
- Third, postnatal and neonatal management can be initiated early.In our study, we found a significant decrease in incidence of sudden cardiac death among infants with undiagnosed severe congenital heart defects born after implementation of screening. Taken together with previous literature on the subject, these findings support that screening could be causally associated with a decreased incidence of sudden cardiac death.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Most previous studies on the epidemiology of sudden cardiac death among people with congenital heart diseases have been focused either exclusively on autopsied decedents or patients diagnosed with congenital heart defects prior to death. In our nationwide and unselected study, 29% of cases were not autopsied and 41% were first diagnosed with a congenital heart defect at autopsy. This underlines the importance of not only including autopsied decedents or patients known with a congenital heart defect before death when examining the epidemiology of sudden cardiac death in people with congenital heart defects.
Surprisingly, we found that only 59% of people with congenital heart defects suffering sudden cardiac death were diagnosed with their congenital heart defect prior to death. As many types of congenital heart defects are curable or treatable, detection of undiagnosed people, could potentially lead to a marked decreased morbidity and mortality in this patient group. Research aiming at increasing early detection of congenital heart defects therefore has potential for high yield.
Nationwide Study of Sudden Cardiac Death in People With Congenital Heart Defects Aged 0 to 35 Years
Thomas Hadberg Lynge, Alexander Gade Jeppesen, Bo Gregers Winkel, Charlotte Glinge, Michael Rahbek Schmidt, Lars Søndergaard, Bjarke Risgaard, Jacob Tfelt-Hansen
Circulation: Arrhythmia and Electrophysiology. 2018;11:e005757
Originally published June 1, 2018
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