Management of Acute Myocardial Infarction in the Presence of Left Bundle Branch Block

The primary objective of this study is to propose new treatment algorithm (strategy) for patients with Acute Coronary Syndrome (ACS) and left bundle-branch block (LBBB).

Current recommendations on the treatment of acute coronary syndrome (ACS) dictate urgent reperfusion therapy in the case of evolving myocardial infarction with ST-segment elevation (STEMI). Optimal use of PCI (preferably) or thrombolysis in this situation requires a rapid and correct diagnosis.

According to the ESC'2008 and ACC/AHA'2009 focused update guidelines patients admitted to the hospital within 12 hours after the onset of chest pain with new (or presumably new) left bundle-branch block (LBBB) should be treated like patients having STEMI (class I, level A). However, it is well-known that in patients with concomitant LBBB, the ECG manifestations of acute myocardial injury may be masked.

ACS may occur in a patient with "true old" LBBB (when doctor has/has not an ability to compare the new ECG with the previous one) or (presumably) new LBBB.

There is a high risk of non receiving appropriate therapy or of receiving inappropriate therapy (thrombolysis instead of LMWH/UFH/fondaparinux).

Inclusion Criteria:

• Age 18 - 75 years
• Ischemic discomfort (ie, ischemic chest pain or equivalent) at rest ≥20 minutes within previous 24 hours.
• Any (new, presumably new, or old) LBBB on the prehospital (ambulance) or admission ECG.
• Urgent coronary angiography (followed, when indicated, by PCI), ideally within 90 minutes after admission

Exclusion Criteria:

• all-comers design