Medical history is filled with widely applied therapeutic habits that replicate longstanding practices based upon theories that have no true scientific background. Treatment of acute myocardial infarction has not escaped this general, though unfortunate, rule. Thus, in the past, lidocaine has been used systematically in patients with acute myocardial infarction because of its antiarrhythmic properties, until serious doubt was raised about a potentially toxic effect that might result in increased mortality.1 It is to the credit of Wijesinghe and colleagues that they have looked thoroughly at the evidence available for the clinical effects of oxygen therapy, a commonly used treatment at the acute stage of myocardial infarction (see page 198).2

The first cause of surprise in their report is their observation of the extraordinary discrepancy between the high incidence of myocardial infarction, affecting millions of people each year, and the paucity of scientific data on one of its most widely used methods of treatment. Indeed, only 207 patients were included in the only two randomised controlled trials devoted …