Risk Assessment for Sudden Cardiac Death (SCD)

Risk Assessment for Sudden Cardiac Death (SCD)

More than 80% of sudden cardiac death (SCD) in the young (≤35 years) is thought to be related to structural and/or electrical cardiovascular abnormalities.1,2 These abnormalities include cardiomyopathies, arrhythmias, and aortopathies, which may lead to lethal events such as ventricular fibrillation or aortic dissection.1,3,4 In many cases, these conditions are inherited. Familial forms are common for hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), long QT syndrome (LQTS), Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia (CPVT), Marfan syndrome, and Loeys-Dietz syndrome.1-3

Diagnosis of structural and/or electrical cardiac abnormalities is typically based on echocardiographic findings, such as left ventricular thickening in HCM or aortic dilation in Marfan syndrome,5 or electrocardiographic observations, such as an epsilon wave in ARVD/C or a prolonged QT interval for LQTS.5 Once a diagnosis has been made, the presence of additional risk factors (see table) may help assess the risk of SCD. In high-risk patients, use of an implantable cardioverter defibrillator (ICD)2,6 or, in the case of aortopathy, prophylactic surgery has been shown to reduce fatal cardiac events.4

While SCD occurs in only a minority of patients, it is frequently the presenting symptom and is often brought on by avoidable triggers, such as strenuous physical exercise.2,4,5 The challenge is to diagnose cardiac abnormalities that predispose individuals to SCD as early as possible to help enable preventative lifestyle adjustments, prophylactic surgery, and regular screening tests for risk factors associated with SCD.

Genetic testing can identify at-risk family members of SCD patients before symptoms develop and may facilitate the early diagnosis of structural and/or electrical cardiac abnormalities.2,7 Familial cardiomyopathies, arrhythmias, and aortopathies are typically inherited in a dominant fashion;3,7 thus, a single mutation is usually responsible for disease in any given family. Once this familial mutation has been identified, testing presymptomatic family members for the presence of the familial mutation can identify carriers who are at increased risk for symptoms, including SCD. More frequent screening may be recommended for carriers.7 Please refer to the LabCorp Sudden Cardiac Death LABupdate for additional information about these and other inherited cardiac diseases, or call Correlagen Diagnostics at 866-647-0735.

 

Disease

Risk Factors for Sudden Cardiac Death*

*Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines. Europace. 2006; 8(9):746-837.

†Judge DP, Deitz HC. Therapy of Marfan syndrome. Ann Rev Med. 2008; 59:43-59.

HCM

Cardiac arrest

Atrial fibrillation

Spontaneous ventricular tachycardia (VT)

Myocardial infarction

Family history of premature (SCD)

Left ventricular (LV) outflow obstruction

Unexplained syncope

High-risk mutation

LV thickness ≥30 mm

Intense (competitive) physical exertion

Abnormal exercise BP

Nonsustained spontaneous VT

DCM

Patients with advanced disease:

Low ejection fraction

End-diastolic volume

Older age

Hyponatremia

Pulmonary capillary wedge pressure

Systemic hypotension

Atrial fibrillations

Patients with less advanced disease:

Unknown

ARVD/C

Right ventricular (RV) abnormalities including dilation

Precordial repolarization abnormalities

Left ventricular (LV) involvement

LQT syndrome

LQT1 and LQT2 with QTc >500 ms

LQT3 and male sex

Brugada syndrome

Spontaneous presence of ST-segment elevation in the right precordial leads

CPVT

VT induced during physical activity or acute emotion in the presence of normal ECG

Recurrence of sustained VT, hemodynamically nontolerated VT while receiving beta blockers

Marfan syndrome

Aortic diameter >5 cm

Rate of dilation >1 cm per year

Family history of premature aortic dissection†

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