A system and a method for automatically detecting a new left bundle branch block (LBBB) in an ECG series and then issuing an alert for the purpose of accelerating treatment for acute myocardial infarction. A serial comparison program is used to compare each current ECG with a previous ECG for the same patient. Diagnostic statements, measurements and waveforms are compared and based on the comparisons, the system is able to automatically determine that the patient has a new LBBB. The system then automatically determines whether the patient belongs to the category of patients having a high probability of acute myocardial infarction. If acute myocardial infarction is suspected, the system generates a diagnostic statement stating that the new left bundle branch block may be due to acute myocardial infarction. The current ECG exhibiting a new LBBB is then identified with a special tag and sent to a central database server. The special tag enables the central database server to perform special routing of that record, e.g., via facsimile or digital pager, to alert on-call medical personnel to the need for immediate treatment.