Page 179 - Clinical Pearls in Cardiology

Ischemic Heart Disease 167

19. What are the features of nonpathological ST segment
depression in a person with sinus tachycardia?
ST segment depression in a normal person with
sinus tachycardia is up-sloping and is related to the
exaggerated atrial repolarization that occurs during
tachycardia. This depresses both the PR segment and the
initial portion of the ST segment when compared with
the TP segment. It has no pathologic significance (Fig. 6).

Fig. 6: ST segment depression patterns

20. What is the use of Sgarbossa criteria?
If a patient with chest pain has LBBB (left bundle
branch block) pattern in the ECG and if his recent
previous ECGs do not show this LBBB pattern, then
the patient is presumed to have a new onset LBBB. The
current guidelines accept new onset LBBB as a finding
supportive of acute myocardial infarction. If a patient
with chest pain has LBBB pattern in his ECG, and if no
previous ECG tracing is available for comparison, or if
the patient has preexisting LBBB pattern in his previous
ECG tracings, then the diagnosis of acute myocardial
infarction becomes difficult. In such situations, some
electrocardiographic characteristics [referred to as the
Sgarbossa criteria (Fig. 7)] can be applied to reliably