Introduction. Acute myocardial infarction is a clinical manifestation of
coronary disease which occurs when a blood vessel is narrowed or occluded in
such a way that it leads to irreversible myocardial ischemia. ST segment
depression in leads V1?V3 on the electrocardiogram points to the anterior
wall ischemia, although it is actually ST elevation with posterior wall
myocardial infarction. In the absence of clear ST segment elevation, it may
be overlooked, leading to different therapeutic algorithms which could
significantly affect the outcome. Case report. A 77 year-old female patient
was admitted to the Coronary Care Unit due to prolonged chest pain followed
by nausea and horizontal ST segment depression on the electrocardiogram in
V1?V3 up to 3 mm. ST segment elevation myocardial infarction of the posterior
wall was diagnosed, associated with the development of initial cardiogenic
shock and ischemic mitral regurgitation. An emergency coronarography was
performed as well as primary percutaneous coronary intervention with stent
placement in the circumflex artery, the infarct-related artery. Due to a
multi-vessel disease, surgical myocardial revascularization was indicated.
Conclusion. Posterior wall transmural myocardial infarction is the most
common misdiagnosis in the 12 lead electrocardiogram reading. Routine use of
additional posterior (lateral) leads in all patients with chest pain has no
diagnostic or therapeutic benefits, but it is indicated when posterior or
lateral wall infarction is suspected. The use of posterior leads increases
the number of diagnosed ST segment elevation myocardial infarctions
contributing to better risk assessment, prognosis and survival due to
reperfusion therapy.