Compare the Old and New ECG

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«Step 7: ST morphology Step 7+2: Conclusion»

Author(s) J.S.S.G. de Jong, MD
Moderator J.S.S.G. de Jong, MD
some notes about authorship

An abnormal ECG does not prove acute cardiac disease. And a normal ECG does not exclude cardiac disease. It is necessary therefore to compare new ECG with ECG's made in the past.

Hallmarks are:

So, one has to check for changes in all 7 steps.

Change in rhythm

Example: new atrial fibrillation. Atrial fibrillation occurs in ten percent of elderly people (>70 year) without clinical symptoms. Therefore atrial fibrillation in acute dyspnoic patients does not prove atrial fibrillation induced cardiac decompensation. Also other causes (e.g. cardiac ischemia, pneumonia) should be considered. Previous ECG registrations could provide additional information.


Example: bradycardia. New sinusbradycardia of 50 beats per minute (bpm) may cause dizziness, however, long existing bradycardias are often without symptoms. Therefore it is important to know about someones normal frequency.

Conduction time

An increase in PQ time may be seen in elderly patients, but may also be caused by the use of medication or by ischemia. Broadening of the QRS complex may be caused by medication or ischemia. An increase in QTc time may be caused by medication, but may also be heridetary. Comparison of previous made ECG registration with new registration may provide the clue.

Heart axis

Ischemia may cause a change in the heart axis, however also heridetary differences in heart axis may occur. Again, a previous ECG differentiates between old and new changes.

Pathological Q's

Hallmark of the comparison between old and new ECG are pathological Q's. New pathologische Q's provide evidence for the occurence of a myocardial infarction in the mean time.

Increase R wave

Decrease of the R wave may a a sign of occured infarction. Tamponade, cardiomyopathy and increased bodysize also decrease the R wave.

Increase of the R wave indicates hypertrofia of the left ventricle (leads V5-V6), or a posterior infarction (V2-V3) or a loss of body weight.

the ST segment

New elevation of the ST segment indicates a acute myocardial infarction. Chronic elevation of the ST segment may be caused by cardiac aneurysmata and long existing (several weeks) of pericarditis.

T wave

T top inversion is caused by ischemie, disturbances in electrolytes and stress. Often no distinction can be made between these causes. T top inversion indicates that something is possible wrong, however further investigation is needed.