Total occlusion of a coronary artery first results in ischemia of the related myocardial territory.

  If the
ischemia lasts longer than 20 minutes, necrosis (infarction) of the myocardial cells

      starts in that territory.

  Complete necrosis of myocardial cells in the relevant territory requires at least 6 hours of uninterrupted

      coronary artery occlusion.

  Successful revascularization within the first 6 hours of myocardial infarction will decrease

      the area of infarction.

  The benefit depends on how early the successful revascularization is.

  If successful revascularization is achieved
within the first 2 hours, the patient will benefit very much.

  Especially when successful revascularization is achieved
within the first hour ,

      the late ECG abnormalities may be very subtle or may even be absent.

  Below are examples of cases with successful early revascularization.





ECG 1a. The ECG above belongs to a middle-aged man who arrived to the emergency room at the 20th minute of his chest pain.
It shows
more than 1 mm ST segment elevation and tall T waves in leads III and aVF.
The
ST segment elevation in lead II is even less than 1 mm.
This ECG suggests early phase of the acute inferior wall myocardial infarction.

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Figure 1a. His coronary arteriogram was performed within 15 minutes which showed
a
non-critical stenosis of the Circumflex coronary artery .




Figure 1b. His right coronary artery was totally occluded proximally.




Figure 1c. Successful PTCA (balloon angioplasty) and stenting resulted in
full revascularization of the well-developed right coronary artery.
His pain subsided immediately.




ECG 1b. The ECG above was recorded 15 minutes after stenting of the right coronary artery.
Neither ST segment elevation nor tall T waves are seen in the inferior leads.

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ECG 1c. The ECG above was recorded 12 hours after stenting of the right coronary artery.
Neither ST segment elevation nor tall T waves are seen in the inferior leads. Even T wave negativity is not seen.
By looking at this ECG alone, it is impossible to guess that this patient had a recent acute myocardial infarction.

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ECG 1d. The ECG above was recorded 5 months after stenting of the right coronary artery. Even T wave negativity is not seen.
By looking at this ECG alone, it is impossible to guess that this patient experienced acute inferior wall myocardial infarction.

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ECG 2a. The ECG above belongs to a 57 years-old man with recent onset chest pain.
This ECG was recorded at the 15th minute of the onset of chest pain.
He was administered t-PA (thrombolytic therapy) immediately after recording of the above ECG.

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ECG 2b. At the end of thrombolytic therapy, the abnormal ST segment changes in limb leads normalized and
his chest pain disappeared.

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ECG 2c. His ECG next day showed T wave negativity only in lead III. No Q waves developed in the inferior leads.
By looking at this ECG only, it would be impossible to tell that he had recent acute inferior myocardial infarction.
This case clearly shows the importance of early treatment in acute myocardial infarction.

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ECG 3. The ECG above belongs to a 59 years-old man who had experienced acute anterior ST elevation myocardial infarction
5 days ago. He had early intervention with stenting of the LAD coronary artery. RCA and Cx coronary arteries were normal.
Early and successful recanalization of the LAD artery resulted in the development of only biphasic T waves in leads V2 and V3.

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ECG 4. The ECG above belongs to a 39 years-old man who had experienced acute anterior wall myocardial infarction
8 months ago.
Because of early intervention, no ST segment elevation, T wave negativity or q waves in anterior leads.
The only nonspecific abnormality is rR' in lead V3.

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ECG 5a. The ECG above belongs to a 52 years-old man with very recent onset chest pain.
Acute anterior wall myocardial infarction is present.
He underwent coronary angiography immediately after recording the above ECG (within 60 minutes after the onset of pain).
His LAD coronary artery was stented.

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ECG 5b. Above ECG belongs to the same patient. It was recorded 24 hours after the acute infarct.
ST elevation is decreasing and precordial T waves are biphasic now.

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ECG 5c. Above ECG belongs to the same patient. It was recorded 48 hours after the acute infarct.
ST elevation is not present and precordial T waves are negative now.
QT interval is also mildly prolonged (QTc is 487 msec).

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ECG 5d. Above ECG belongs to the same patient. It was recorded 3 weeks after the acute infarct.
ST elevation is not present and precordial T wave negativity is regressing.
QT interval is not prolonged any more (QTc is 398 msec).

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ECG 5e. Above ECG belongs to the same patient. It was recorded 3 months after the acute infarct.
It is completely normal.
This case shows that in patients with acute myocardial infarction, early intervention has a great influence on late ECG findings.

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