Notching of the ascending limb of the S wave in leads C3 or C4 is called Cabrera's sign.

  It is used to diagnose acute myocardial infarction in the presence of left bundle branch block (LBBB).

  In the presence of other clinical findings Cabrera's sign suggests the presence of acute myocardial infarction. However, its sensitivity is low (27%).

  It has been suggested that Cabrera's sign may be used to diagnose acute or chronic myocardial infarction in patients with right ventricular pacing.




References

  Cardiol Clin 1987;5:393-401.

  Pacing Clin Electrophysiol 2002;25(7):1061-1065.

  Herzschrittmacherther Elektrophysiol 2016;27(3):307-322.




ECG 1. Cabrera's sign and LBBB. The rhythm is atrial fibrillation.

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ECG 2. The ECG above was recorded immediately after implantation of a stent to the LAD coronary artery for acute anterior
myocardial infarction.
LBBB is accompanied by the Cabrera's sign.
Baseline drift artifact is also seen.

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ECG 3. The ECG above is from a middle-aged man experiencing acute myocardial infarction.
It was recorded just before stenting of the Circumflex (Cx) coronary artery.
LBBB is accompanied by the Cabrera's sign.

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ECG 4. The ECG above is from a 73 years-old man who had had acute anterior myocardial infarction 2 years ago.
Now he has a dilated left ventricle with a very depressed systolic function.
Cabrera's sign and a VPC is seen.

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