[Myocardial infarction in the young subject: a medium-term clinical and coronary angiographic study in 40 patients under 36 years of age. Comparison with coronary angiographic data of myocardial infarction in patients after 50 years of age].

A series of 40 myocardial infarctions, occurring in patients under 36 years of age was studied retrospectively (Group I: mean age 31.3 years). The medium term results of coronary angiography in this group were compared with those of 60 myocardial infarctions after 50 years of age (Group II: mean age 56.6 years). Group I had a clear male predominance (92.5%), a high incidence of smoking (69%), hypercholesterolaemia (69%); myocardial infarction was the first manifestation of their disease in 54% and it was often extensive (42%). A comparative angiographic study between the two groups showed: 1) Less widespread lesions in Group I, as assessed by the number of main arteries stenosed (p less than 0.001), the coronary index (p less than 0.01) and the mean coronary score using Friesinger's method (p less than 0.01). 2) A higher incidence of subnormal coronary angiogrammes in Group I (absence of 50% stenosis) (15%) and of single vessel disease (40%): compared with Group II in which multivessel disease was observed in 86.5% of cases. 3) Collateral circulation was less common in Group I (p less than 0.01). On the other hand, a comparative study of regional and global left ventricular function showed no difference between the two groups. Two subgroups were distinguished in Group I: in one subgroup, multiple lesions similar to those found in Group II, suggestive of premature coronary atherosclerosis (52.5%); the other group (47.5%) presented unilocular lesions i.e. focal mono-arterial lesions compatible with other causes of infarction (thrombosis and/or spasm). These patients were younger (p less than 0.05) and had significantly fewer cardiovascular risk factors (p less than 0.01). Despite the fact that the coronary lesions were limited, the myocardial damage was comparable with the other groups as the collateral circulation was much less developed (p less than 0.02). These appearances were only observed in 3.5% of patients in Group II. The study of the angiographic outcomes of these two types of lesions should show a difference and could contribute to the understanding of their mechanisms.