EARLY REPOLARIZATION:CONCEPT IN THE CURRENT ERA

Dr SYED RAZAConsultant Cardiologist

MD,MRCP(UK),Dip.Card(UK),CCT(UK),FCCP(USA)

IMPORTANCE OF CLINICAL CORRELATION

• Remember "Step 7" in the Six Step Method for 12-Lead ECG Interpretation

• Although clinically silent acute myocardial infarction is recognised.....

• STEMI Alert protocol requires that the patient be experiencing signs and symptoms consistent with ACS. It need not be chest pain, but it would have to be an anginal equivalent if chest pain were absent.

Classic findings

1. J-point “notching”

2. Concave-up ST segment (smiley face)

3. ST segment elevation from baseline in V2-V5, typically <3mm

4. Large, symmetrically concordant T-waves in leads with STE

Early Repolarization

• Early repolarization is a slurring or notching producing a hump-like feature called a J wave, typically found at the junction at the end of the QRS complex and the beginning of the ST segment.

• Ventricular repolarization is abrupt and starts earlier than expected.

• Deviation of the J-point from the isoelectric line leads to the presence of a J-deflection. This typically produces a concave upward curve towards the T wave, helping to differentiate it from the convex, ‘tomb-stone’ waves seen with infarct

What is it?

• The truth of the matter is…we aren’t too sure!– Experimental data shows pts with ER to have

heterogeneous repolarization physiology with myocytes containing a larger concentration of transient outward current, inducing a voltage gradient during the ST segment (Kusumoto, Cardiovascular Pathophysiology, 2006)

• What to tell your patient:– This is a normal, benign variation that we see in a

lot of patients that has no clinical significance

PREVALANCE

• As reported by Wellens, approximately 2-5% of the population demonstrates the early repolarization changes on electrocardiogram;

• this population mostly consists of• men, • young adults, • athletes, • and people of African American heritage.

What does it look like?

Red arrows: concave up ST-segment elevation anteriorly Blue arrows: hyperdynamic, symmetrical, concordant T-waves

Can we tease it out?• The degree of ST segment elevation is thought to

be indirectly proportional to the degree of sympathetic tone

• In other words, the more relaxed the patient, the more pronounced the ST segment elevation (and vice versa)

• If you truly want to test your patient, get their heart rate up and look at the ST segment

24yo M Routine ECG

HR: 64

1. Notched J-point2. Concave down

ST elevation in precordial leads

Same patient after exercise (2 minutes of Jumping Jack)

HR 84 (up 20bpm from previous)

HR 64 HR 84

The ST segment is NOT fixed in pts with ER and changes with the degree of sympathetic strain

On the right, note the complete resolution of the ST elevation but maintenance of the J-point notching in V4

(…but is it really benign?)

Benign early repolarization

ER not benign : Where is the evidence?

• Early repolarization has been considered as benign ECG change, till a couple of studies published in 2008 in leading journals caught the attention of the cardiovascular fraternity.

• Haissaguerre et al, [N Engl J Med 2008;358:2016 –23] reported that sudden cardiac arrest was associated with early repolarisation pattern on the electrocardiogram.

• In another study Rosso et al, [J Am Coll Cardiol 2008;52:1231– 8] noted J-point elevation in survivors of ventricular fibrillation.

Study by Haissaguerre et al.• Evaluated the clinical association between early repolarization in

the inferolateral leads and idiopathic ventricular arrhythmias leading to syncope and/or sudden cardiac death.

• Case–control study involving 206 case subjects with a prior history of idiopathic ventricular fibrillation (IVF).

.• In the study, early repolarization prevalence was compared

between case subjects who had previously experienced an episode of IVF prior to the study and control subjects with no known heart disease.

• Early repolarization occurred statistically more frequently in the case subjects with IVF than the control subjects (31% vs. 5%, P<0.001).

• Furthermore, in select subjects, the origin of ectopy that initiated ventricular arrhythmia was mapped to sites concordant with the localization of the early repolarization abnormality and showed accentuation of early repolarization prior to the actual arrhythmia.

• In the study, electrocardiography was performed during an arrhythmic period (including frequent premature ventricular contractions and episodes of IVF) in 18 case subjects.

• all subjects showed a consistent increase in the amplitude of early repolarization so that the J-point amplitude increased from 2.6±1 mm to 4.1±2 mm (P<0.001).

• In six subjects with early repolarization recorded only in inferior leads, all ectopy originated from the inferior ventricular wall.

Tikkanen et al, NEJM Dec. 2009(Finnish Pop. 10,000. FU 30 YRS)

• Investigated the long-term outcomes associated with early repolarization on the electrocardiogram. This evaluation was an extension of the data described by Haïssaguerre et al

• The Tikkanen study sought to emphasize the prognostic significance of the J point pattern in the inferolateral leads which were hypothesized to be more arrhythmogenic than the more commonly studied anterior precordial leads (leads v1 through v3).

Inferior vs Lateral leads

• In addition, J-point elevations of more than 0.2 mV in the inferior leads had a statistically significant risk of death from arrhythmia (adjusted relative risk, 2.92; 95% CI, 1.45 to 5.89; P = 0.01) when compared to that in the lateral leads where it was not statistically significant.

Does Amplitude matter?

• In addition to the location of the early-repolarization pattern, the amplitude of the J-point elevation had great prognostic value. There was a significantly higher risk of death from cardiac causes among subjects with a markedly elevated J point (>0.2 mV) than among those with a more moderate elevation (≥0.1 mV).

Mechanism

It is not clear is how the early repolarization

pattern localized to the inferior leads increase the risk of arrhythmia and sudden cardiac death .

HYPOTHESIS• J-point elevation is a marker of increased transmural

heterogeneity of ventricular repolarization.• In addition, the left ventricular base defined by the

inferolateral leads is an area known to have increased current density. As such, having an episode of early repolarization in an area with known increased current density is what can make the myocardium more vulnerable to ventricular tachyarrhythmias.

• This vulnerability may be amplified under certain conditions such as a cardiac ischemic event, the use of specific drugs, various levels of autonomic tone, electrolyte disturbances, channelopathies and/or structural cardiac abnormalities

One can postulate that J point elevations in the anterior precordial leads are less arrhythmogenic (i.e. more benign) than J point elevations in the inferior leads.

There should be close monitoring on telemetry and consideration of further tests and treatment options.

• Unfortunately, there are no studies as of yet looking at appropriate interventions in asymptomatic patients with incidental findings of inferior J point elevations (i.e. ICD implantation for primary prevention)

• Patient should be provided with a copy of their ECG to keep in their pocket in case of an emergency, suggesting referral to a cardiologist and taking a concise cardiac and family history to prepare for possible future events.

• Benign Early Repolarisation vs Pericarditis• BER can be difficult to differentiate from pericarditis as

both conditions are associated with concave ST elevation.

• One useful trick to distinguish between these two entities is to look at the ST segment / T wave ratio:

• The vertical height of the ST segment elevation (from the end of the PR segment to the J point) is measured and compared to the amplitude of the T wave in V6.

• A ratio of > 0.25 suggests pericarditis• A ratio of < 0.25 suggests BER

• ST segment height = 1 mm• T wave height = 6 mm• ST / T wave ratio = 0.16• The ST / T wave ratio < 0.25 is consistent with

BER

• ST segment height = 2 mm• T wave height = 4 mm• ST / T wave ratio = 0.5• The ST / T wave ratio > 0.25 is consistent with

pericarditis.

• ER should be a diagnosis of exclusion and should ALWAYS be placed in clinical context!!!

• The above was taken in a patient with difficulty breathing and chest pain…and is an AMI, NOT BER!!!• Note the hyperacute T-waves (disproportionately larger than the QRS

complex, developing q-waves, and lack of J-point notching)

SUMMARY

• Common in Fit Young people.• Generally disappears in middle age, rare in the elderly.• Elevated J Point, often with notching.• Predominantly in anterior chest leads, but can occur

elsewhere.• Elevated J Point in Inferior leads more arrhythmogenic.• Associated with large, symmetrical, concordant T waves.• Absence of reciprocal changes or pathological Q waves.• Possibly related to high sympathetic tone on heart – can

normalise with exercise or Beta-Blockade.• Recognised cause for fatal arrhythmia and SCD.