Practice Update: Cardiology

MY APPROACH 29

My Approach to the Risk Stratification of Patients for Sudden Cardiac Death By Sana M Al-Khatib MD, MHS

Dr Al-Khatib is Professor of Medicine, Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina.

I n risk-stratifying patients for sudden car- diac death (SCD), my approach depends on the following factors: • Whether or not a patient has had cardiac arrest due to ventricular fibrillation or ventricular tachycardia (VT) and whether such an event occurred in the absence of reversible causes • The presence of symptoms suggestive of arrhythmias, such as syncope or near-syncope • The presence of systolic heart failure with a left ventricular ejection fraction (LVEF) ≤35% and New York Heart Asso- ciation (NYHA) class II or III heart failure symptoms despite guideline-directed medical therapy (GDMT) • The presence of other structural heart diseases such as hypertrophic cardiomy- opathy, arrhythmogenic right ventricular cardiomyopathy, or cardiac sarcoidosis • The presence of a cardiac channelo- pathy such as long QT syndrome or Brugada syndrome Cardiac arrest due to ventricular fibrilla- tion or VT portends a high risk of future recurrence of such events. Therefore, I recommend an ICD to such patients if the arrhythmia occurred in the absence of reversible causes and if I expect them to survive for more than 1 year (the expecta- tion of survival for more than 1 year applies to all the scenarios below in which I recom- mend an ICD). In patients who present with syncope or near-syncope, I focus my attention on the history. Features that increase the

likelihood of an arrhythmic etiology for syn- cope include the absence of a prodrome, the presence of structural heart disease, older age, and resultant injury. In patients with syncope likely due to a ventricular arrhythmia who do not meet other crite- ria for an ICD (such as an LVEF ≤35% and NYHA class II symptoms despite GDMT), I perform an electrophysiology study to look for sustained ventricular arrhythmia that replicates the patient’s symptoms. If present, then I recommend an ICD. The risk of SCD is high in many patients with an LVEF ≤35% due to ischemic car- diomyopathy and NYHA class I, II, or III symptoms despite GDMT. The risk of SCD is also high in many patients with an LVEF ≤35% due to non-ischemic cardiomyopathy and NYHA class II or III symptoms despite GDMT. In such patients, I recommend an ICD. Risk stratification of patients with hyper- trophic cardiomyopathy for SCD and no prior cardiac arrest or known sustained ventricular arrhythmias involves the fol- lowing factors: • Syncope presumed to be due to a ven- tricular arrhythmia • Family history of SCD • Left ventricular wall thickness ≥3 cm • Blunted blood pressure response to exercise • Non-sustained VT In addition to these factors, I take into account the presence of delayed hyper- enhancement on a cardiac MRI. If syncope, family history of SCD, or left ventricular wall

thickness ≥3 cm is present, then I recom- mend an ICD. If blunted blood pressure response to exercise or non-sustained VT is present, then I look for risk modifi- ers such as delayed hyperenhancement on cardiac MRI. If present, then I recom- mend an ICD. Risk stratification of patients with long QT syndrome and no prior cardiac arrest or known sustained ventricular arrhythmias involves the following factors: • Syncope presumed to be due to a ven- tricular arrhythmia • QTc ≥500 ms • Onset of symptoms at <10 years of age In patients with syncope and QTc ≥500 ms despite treatment with a beta blocker, I rec- ommend an ICD. Although covering risk stratification for other conditions is beyond the scope of this review, a thoughtful and systematic approach to the risk stratification of every patient is essential. Many other tests have been proposed for risk stratification of patients for SCD, such as T-wave alter- nans and measures of autonomic tone. However, none of these tests have enough positive and negative predictive value and data from randomized clinical trials sup- porting their clinical utility to justify their routine use in clinical practice. www.practiceupdate.com/c/54253 • Genotypes LQT2 and LQT3 • Females with genotype LQT2 • Age <40 years

VOL. 2 • NO. 2 • 2017