Sudden cardiac death (SCD) is the unexpected death that occurs as a result of a sudden cardiac arrest from which resuscitation is unsuccessful or is not performed. It is defined as natural death occurring within one hour of the onset of symptoms, or in an unwitnessed death, within 24 hours of the person last being seen alive and well. SCD accounts for a substantial proportion of all cardiovascular deaths worldwide.
The most common cause is coronary artery disease: plaque rupture or acute thrombosis triggers ventricular fibrillation in the context of acute myocardial infarction or previously scarred myocardium. In younger people and those without obvious coronary disease, inherited cardiac conditions including hypertrophic cardiomyopathy, ARVC, long QT syndrome, and Brugada syndrome are important causes. Where no structural cause is found even at post-mortem, the death is classified as sudden arrhythmic death syndrome (SADS).
With immediate bystander CPR and defibrillation, a proportion of cardiac arrests can be converted from potential sudden cardiac death into successful resuscitation. This is the rationale for public access defibrillator programmes and bystander CPR training, which are central to SCA UK’s mission.
For families of those who have died suddenly from cardiac causes, specialist bereavement support, molecular autopsy (genetic testing on post-mortem samples), and cascade screening of living family members are important aspects of care, provided through inherited cardiac conditions and bereavement services.
« Back to Glossary Index