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Optimizing the initial 12-lead electrocardiographic diagnosis of acute myocardial infarction... Optimizing the initial 12-lead electrocardiographic diagnosis of acute myocardial infarc

Acute Myocardial Infarction

• ST segment elevation MI – persistent complete occlusion of an

artery supplying a significant area of myocardium without adequate collateral circulation

• UA/NSTEMI – result from non-occlusive thrombus, small risk area, brief occlusion, or an occlusion with adequate collaterals

I Chẩn đoán NMCT

ECG trong NMCT

• Chẩn đoán (+) NMCT cấp có ST chênh lên

• Chẩn đoán giai đoạn NMCT cấp

• Chẩn đoán vùng NMCT

• Chẩn đoán biến chứng RLNT

ECG changes in AMI

• In the early stages of AMI the ECG may be normal

• <50% of patients with AMI have clear diagnostic

changes on their first trace.

• About 10% of patients with a proved acute myocardial infarction fail to develop ST segment elevation or

depression

• In most cases, however, serial ECG’s show evolving

changes that tend to follow well recognised patterns.

Biến đổi ECG trong NMCT

• ST – T chênh lên

• Sóng Q bệnh lý

J point

ST segment

Last deflection of QRS

Sự tạo thành các biến đổi của sóng ECG trong NMCT

Tạo thành sóng Q

Tạo thành đạon ST chênh lên hay chênh xuống

Minnesota Code

• The Minnesota code 9-2 requires ≥1 mm ST elevation in one or more

of leads I, II, III, aVL, aVF, V5, V6, or ≥ 2 mm ST elevation in one or more of leads V1–V4

• Menown IB, Mackenzie G, Adgey AA Optimizing the initial 12-lead electrocardiographic

diagnosis of acute myocardial infarction Eur Heart J 2000; 21 (4):275-83.

• Đoạn ST chênh lên ở ít nhất 2 chuyển đạo kế tiếp nhau

ST Segment Elevation

Acute Myocardial Infarction

• Irrespective of which definition is used, ST elevation has poor

sensitivity for AMI where up to 50% of patients exhibit ‘atypical’

changes at presentation including isolated ST depression, T inversion

or even a normal ECG

• Menown IB, Mackenzie G, Adgey AA Optimizing the initial 12-lead electrocardiographic

diagnosis of acute myocardial infarction Eur Heart J 2000; 21 (4):275-83.

How To Differentiate STE due to AMI from Other Causes?

• Magnitude of the elevation

Morphology of the ST

Elevation

Variable Shapes Of ST Segment Elevations in AMI

Goldberger AL Goldberger: Clinical Electrocardiography: A Simplified Approach 7th ed: Mosby Elsevier; 2006.

Morphology of STE

• Concave shape STE – non AMI causes

• AMI causes – usually demonstrate convex/straight STE

J point

Apex of T wave

Concave STE Convex STE

Notching or slurring of J point

Concave STE

Benign Early Repolarization

Large amplitude T wave

Benign Early Repolarization

• ECG characteristics:

1 STE <2 mm

2 Concavity of initial portion of the ST segment

3 Notching or slurring of the terminal QRS complex

4 Symmetrical, concordant T wave of large

amplitude

5 Widespread or diffuse distribution of STE

o Does not demonstrate territorial distribution

1 Relative temporal stability

• Inferior MI – II, III, aVF

• Diffuse STE – non AMI causes, e.g pericarditis

Lateral Wall MI: I, aVL, V5, V6

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.

Inferior Wall MI II, III, aVF

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.

Septal MI: Leads V1 and V2

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.

Anterior Wall MI V3, V4

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.

Anatomic Groups

Posterior MI – Reciprocal Changes ST Depression V1, V2, V3

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.

Những trường hợp cần phân biệt với đoạn ST chênh lên trong

NMCT

• Bất thường điện giải (Electrolyte abnormalities)

Left bundle branch block

Phình thất (T) (Aneurysm of left ventricle)

Lớn thất (T) (Ventricular hypertrophy)

Osborne waves (hypothermia or hypocalcemia)

Pericarditis (Viêm màng ngoài tim)

Goldberger AL Goldberger: Clinical Electrocardiography: A Simplified Approach 7th ed: Mosby Elsevier; 2006.

Differentiating ECG Changes of AMI vs Pericarditis

1 STE in pericarditis – concave; AMI – obliquely flat or convex

2 STE in pericarditis – diffuse; AMI – territorial

3 PR Depression – pericarditis; Q in AMI

4 T inversion in pericarditis occurs only after ST normalized; T

inversion accompanies STE in AMI (co-exist)

Goldberger AL Goldberger: Clinical Electrocardiography: A Simplified Approach 7th ed: Mosby Elsevier; 2006.

Acute Pericarditis – Four

• lasts up to several months

• gradual resolution of T wave

changes

Chan TC, Brady WJ, Pollack M Electrocardiographic manifestations: acute myopericarditis J Emerg Med 1999; 17 (5):865-72.

Stage 1 Pericarditis

PR

Depression

Stage 2 Pericarditis

Lớn thất (T)

• Saddle shaped or coved shaped ST elevation

• First described in 1992 by Brugada and Brugada

• The syndrome has been linked to mutations in the cardiac sodium-channel gene

• Amal Mattu, Robert L Rogers, Hyung Kim, Andrew D Perron and William J Brady The Brugada Syndrome The American Journal of Emergency Medicine, Vol 21, No 2, March 2003

ST Elevation morphologies in

Brugada Syndrome

RBBB with RSR pattern rather than rSR pattern and there is associated STE

ST Elevation morphologies in

Brugada Syndrome

RBBB with RSR pattern rather than rSR pattern and there is associated STE

HC Brugada

Re infarction by ECG

ST elevation of ≥ 0.1 mV re-occurs in a

patient having a lesser degree of ST

elevation or new pathological

Q waves in at least two contiguous leads, particularly when associated with ischemic symptoms.

• Bất kỳ sóng Q nào từ V1 đến V3

• Q 0.03 s ở I, II, aVL, aVF, V4, V5, V6 ≥

Đánh giá giai đoạn

Evolution of AMI

A - pre-infarct (normal)

B - Tall T wave (first few minutes of infarct)

C - Tall T wave and ST elevation (injury)

D - Elevated ST (injury), inverted T wave (ischemia),

Q wave (tissue death)

E - Inverted T wave (ischemia), Q wave (tissue

death)

F - Q wave (permanent marking)

Hyperacute T waves

NMCT VÀ BBB

“The diagnosis of myocardial

infarction in the presence of left

bundle branch block is impossible.”

Dr Braunwald says:

“Some findings are highly specific and predictive (90-100%) for MI with left bundle branch block.”

leads

ST-T Wave Changes with

Changes are same with both right and left

“Secondary” means normal, expected

“Primary” means abnormal: ischemia or infarction

Secondary ST-T Wave

Changes

These are normal , expected

Last deflection of QRS complex is key

J point displaced away from the last portion of the QRS complex

T wave oriented away from

the last portion of the QRS

complex

Primary ST-T Wave

Changes

“Primary” = abnormal, not a result of BBB

ST segment displaced toward last portion of QRS complex

T wave points toward last portion

of QRS complex

Primary ST-T Wave

Changes

Must be in two contiguous leads

Inferior: II, III and aVF

Septal: V1 and V2

Anterior: V3 and V4

Lateral: V5, V6, I and aVL (high lateral)

Don’t call ischemia/infarction if only one lead in transition from positive to

negative QRS

Right BBB in V 1

“ up down ”

Right BBB in V 6

Secondary (normal, discordant)

“ down up ”

Left BBB in V 1

“down up”

Left BBB in V 6

“up down”

“Down up” pattern

“Up down” pattern

Right BBB in V 1

“up up”

Primary Infarction (concordant)

Right BBB in V 6

Primary Ischemic (concordant)

“down down”

Primary Ischemic (concordant)

Left BBB in V 1

Left BBB in V 6

Primary Infarction (concordant)

“up up”

Primary = Concordant = Bad

“Up up” pattern

“Down down” pattern

Sgarbossa Criteria

In the GUSTO-1 trial the ECG criterion with a high specificity and statistical significance for the diagnosis of an acute MI was:

• Excessively discordant ST segment elevation ≥5 mm (in leads with a negative QRS complex).

Two other criteria with acceptable specificity were:

• Concordant ST elevation ≥1 mm in leads with positive QRS

• Concordant ST depression ≥1 mm in leads V1, V2, or, V3

Am J Cardiol 2000 Jan 15;85(2):147-53.

Clinical trial (GUSTO-1 and INJECT) evidence of earlier death for men than women after acute myocardial infarction.

ECG of Evolving MI with

ECG of Evolving MI with

Identified three predictive criteria:

ST segment elevation > 1 mm concordant with QRS

ST segment depression >1 mm concordant with QRS

ST segment elevation > 5mm discordant with QRS

> 5 mm

“too far up” normal

Left BBB in V 1

2-3 mm

ECG of Evolving MI

How did these factors perform on the validation set?

ST elevation > 1 mm concordant (bad) with QRS Sensitivity: 73%

ECG of Evolving MI with

Decision tree incorporates all three factors

in order of predictive power

ECG of Evolving MI

Does the T wave go the wrong way up ? Does the T wave go the wrong way down ? Does the T wave/ST segment go the right way, but too far ?

Three “yes” answers = 100% MI

Three “no” answers = 16% MI

Probability of MI % 100 92 93 88 100 66 50 16

elevation

depression

Wrong way up?

Wrong way down?

Right way, but too far?

LBBB with Secondary ST-T Wave Changes

LBBB with Exaggerated ST

Elevation: Anteroseptal/

lateral Infarction

> 5 mm

LBBB with Lateral Infarction

Left BBB

RBBB with Anteroseptal Infarction

Đọc ECG

NMCT/RBBB

NMCT tối cấp thành dưới