Thalassaemia trait and myocardial infarction: low infarction incidence in male subjects confirmed.

A total of 4401 subjects admitted to the Medical Division of St Camillo Hospital in Comacchio (Ferrara, Italy) over a period of 7 years were prospectively evaluated in order to determine whether the heterozygous beta-thalassaemic (HBT) could be considered as a protective factor against the occurrence of acute myocardial infarction (AMI). Of the total patient sample, 3954 subjects were non beta-thalasaemics (NBTs), and 447 subjects were heterozygous beta-thalassaemics (HBTs). AMI was diagnosed in 384 patients, of whom 17 individuals were HBTs and 367 subjects were NBTs. The prevalence of HBTs in this group was significantly lower than expected (4.43%, P less than 0.0001). Furthermore, an analysis by sex showed that this lower prevalence could be attributed to male patients. Moreover, only in male subjects was a significant negative correlation observed between AMI and HBT. The mean age at which AMI occurred in male HBTs was significantly higher than in male NBTs (72 +/- 2.69 vs. 63 +/- 0.7 years, P less than 0.05), while no differences were found in the mean age at which AMI occurred between HBT and NBT female subjects. This study demonstrates that the thalassaemic trait may afford some protection against the occurrence of AMI in men.