Sudden Cardiac Death (SCD)
Disease Description
Sudden cardiac death (SCD) is a non-traumatic death caused by cardiac reasons that occurs within one hour from the onset of symptoms.
Causes of the Disease
Causes of sudden cardiac death include acute coronary syndromes, cardiomyopathies (hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy), myocarditis, aortic dissection, inherited channelopathies (Brugada syndrome, long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia), and congenital or acquired heart defects.
The most common immediate cause of cardiac arrest is the development of malignant ventricular arrhythmias — ventricular tachycardia and ventricular fibrillation. Less commonly, cardiac arrest may result from bradyarrhythmias or electromechanical dissociation.
Sudden cardiac death accounts for approximately 25% of all cardiovascular deaths.
Risk Assessment
Reliable prediction of sudden cardiac death risk remains one of the most challenging problems in modern electrophysiology. Nearly half of patients who survive cardiac arrest had no previously known heart disease.
Patients who survive cardiac arrest (after successful resuscitation) require a comprehensive diagnostic evaluation, including echocardiography, long-term ECG monitoring, coronary angiography, cardiac MRI, genetic testing, and screening of close relatives.
Treatment
To prevent recurrent episodes of cardiac arrest (secondary prevention of SCD), implantation of a cardioverter-defibrillator (ICD) is required.
A cardioverter-defibrillator is a device that combines all the functions of a conventional pacemaker with the ability to automatically detect life-threatening arrhythmias and terminate them using antitachycardia pacing or a life-saving electrical shock (defibrillation).
Radiofrequency catheter ablation may be used in selected patients with implanted devices to reduce the frequency of ventricular arrhythmias and prevent inappropriate or frequent ICD shocks.