Our objective is to reappraise the effectiveness of beta blockers for secondary prevention after MI. Our protocol defined main outcome addressed was all cause mortality and the secondary outcome was non fatal reinfarction. The specific a priori defined aims are to examine: the effectiveness of beta blockers in the acute phase immediately post MI; their role in longer term secondary prevention post MI; the importance of early initiation after the onset of symptoms; the extent to which specific pharmacological features of different beta blockers may affect their performance; the magnitude of benefits achieved by beta blockers and their clinical importance.