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;^3,7thus, 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†

References

1. Berger S, Campbell RM. Sudden cardiac death in children and adolescents: Introduction and overview. Pacing Clin Electrophysiol. 2009 Jul; 32(Suppl 2):S2-S5.PubMed 19602158

2. Shephard R, Semsarian C. Advances in the prevention of sudden cardiac death in the young. Ther Adv Cardiovasc Dis. 2009; 3(2):145-155.PubMed 19144665

3. Deitz HC. Marfan syndrome. June 30, 2009. Available at: http://www.ncbi.nlm.nih.gov/books/NBK1335/. Accessed January 8, 2010.

4. Judge DP, Deitz HC. Therapy of Marfan syndrome. Ann Rev Med. 2008; 59:43-59.PubMed 17845137

5. 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.PubMed 16935866

6. Maron BJ, Spirito P, Shen WK, et al. Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy. JAMA. 2007; 298(4):405-412.PubMed 17652294

7. Hershberger RE, Lindenfeld J, Mestroni L, et al. Genetic evaluation of cardiomyopathy−A Heart Failure Society of America guideline. J Card Failure. 2009; 15(2):83-97.PubMed 19254666