Introduction: While acute myocardial infarction  (AMI) mostly is a disease of the elderly it also affects younger individuals, often with serious consequenses. In 1980-1984 a study was carried out on the incidence, risk factors, infarct location and distribution of atherosclerosis among Icelanders forty years and younger with AMI. Here we present the results of a similar study carried out for the five year period 2005-2009.

Materials and methods: Medical and autopsy records of all individuals, forty years and younger, diagnosed with AMI (I21 in ICD-10) at Landspitali, National University Hospital 2005-2009, or suffering sudden cardiac death in Iceland during the same period were reviewed. Blood tests, electrocardiograms, echocardiograms, coronary angiograms and autopsy results were reviewed with respect to AMI-criteria. Statistical comparisons of ratios and means were carried out using Chi-square test and T-test, respectively.

Results: 38 individuals 40 years and younger, 32 males and 6 females, fulfilled the diagnostic criteria of AMI. Calculated incidence for the population at risk was 10/100.000/year  (14/100.000/year in 1980-1984) and the mean age ±S.D. was 36.7±3.9. Three (7.9%) died suddenly before reaching hospital but of the 35 hospitalised patients 30 day mortality was zero, compared to nine (23.7%) pre-hospital deaths and two (6.9%) hospital deaths in 1980-1984. Thus, combined pre-hospital and in-hospital (30 day) mortality was 28.9% and 7.9% in the previous and recent time periods, respectively (p=0.02). In 2005-2009, 77.1% had a smoking history and 31.4% were hypertensive compared to 97% and 6.9% in 1980-85 (p=0.026 and p=0.015, respectively). Body mass index (BMI) was higher in the later period, 28.6±4,8 kg/m2 compared to 26.1±3.6 (mean±S.D.; p=0.04) but s-cholesterol was lower, 5.1±1.4 mmol/L compared to 6.3±1.16 ( mean±S.D.; p<0.01). In both studies single coronary artery disease was the most common angiographic pattern and the left anterior descending artery most often involved.

Conclusion: Our results show that in two surveys 25 years apart AMI patients 40 years and younger are most often men. Smoking and family history were the most prominent risk factors during both periods but hypertension and high BMI were more common in 2005-2009 than  in 1980-1984. Prognosis, as indicated by combined pre-hospital and in-hospital (30 day) mortality has improved.

¹Faculty of Medicine University of Iceland, ²National University Hospital, Reykjavík, Iceland.

Key words: Myocardial infarction, forty and younger, incidence, risk factors, mortality, time trend

Correspondence: Guðmundur Þorgeirsson gudmth@landspitali.is

Figure I. Incidence of acute myocardial infarction per 1000 individuals per year in the population at risk. Age range 25-74 is red. Age range 25-40 is blue. P for trend <0.001

Figure II. Localization of angiographically significant coronary stenosis (>50% diameter stenosis) in 2005-2009 (blue) compared to 1980-1984 (red).