Saturday, March 26, 2016

Early repolarization pattern & Early repolarization syndrome

The early repolarization (ER) pattern (ERP), initially described as elevation of the ST segment of ≥1 leads on the 12-lead ECG, has long been considered a benign phenomenon. However, more recent studies have demonstrated positive, negative, and neutral associations between an ERP and various end points, including all-cause, cardiac, and arrhythmic mortality. However there is still substantial uncertainty prevails about the definition, evaluation and management of individuals showing EP pattern in ECG. A recent scientific statement from American Heart Association tries to address some of these areas of doubt. Published observational studies suggest that the prevalence of ERP ranges between 1% and 18% in the general population.
There is no universal definition of ER pattern. Previous studies have used various definitions covering differing morphologies. The new statement has defined ER pattern as: Any one of the following
1. ST-segment elevation in the absence of chest pain
2. Terminal QRS slur or
3. Terminal QRS notch.
Figure: Examples of ER patterns
Early repolarization syndrome: Defined as occurring in patients with ERP who have survived idiopathic VF with clinical evaluation unrevealing for other  explanations. 
Features That May Raise Suspicion for a Malignant and Heritable Form of ER:
1. Family history of sudden cardiac arrest or early unexplained death
2. Personal evaluation and workup suggestive of a channelopathy (eg, short-QT syndrome, Brugada syndrome).
3. Personal history of unheralded syncope suggestive of an arrhythmogenic pathogenesis (particularly when at rest or recumbent)
    (ER indicates early repolarization)
4. ECG features suggestive of high risk:
- Tall J waves with limited ST-segment elevation, mainly in the inferior leads
- Augmentation of J-wave amplitude immediately after sudden pauses. J-wave amplitude should be evaluated during Holter recordings because patients with idiopathic VF demonstrate significantly taller J waves during slow heart rate at night.
-The pattern of J waves followed by a horizontal or descending ST segment is associated with increased arrhythmic risk.
Class I:
-ICD implantation is recommended in patients with a diagnosis of ER syndrome who have survived a cardiac arrest.

Class IIa:
- Isoproterenol infusion can be useful in suppressing electrical storms in patients with a diagnosis of ER syndrome.
-Quinidine in addition to an ICD can be useful for secondary prevention of VF in patients with a diagnosis of ER syndrome.

Class IIb:
-ICD implantation may be considered in symptomatic family members of ER syndrome patients with a history of syncope in the presence of ST-segment elevation >1 mm in 2 or more inferior or lateral leads.
-ICD implantation may be considered in asymptomatic individuals who demonstrate a high-risk ER ECG pattern( high J-wave amplitude, horizontal/descending ST segment) in the presence of a strong family history of juvenile unexplained sudden death with or without a pathogenic mutation.
Class III:
- ICD implantation is not recommended in asymptomatic  patients with an isolated ER ECG pattern.
2. HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. 
(Heart Rhythm, Vol 10, No12, December 2013)