A 6-year follow-up based on an arterial morphology classification defined with an ultrasound assessment of carotid and femoral artery bifurcations was conducted on 2322 asymptomatic subjects. Four morphology classes were considered. When 2000 subjects (86% of total subjects; 1124 males, 876 females) completed a 6-year follow-up, the study was terminated. At 6 years, no cardiovascular events were observed in subjects who were in class I (80.05% of the population sample) at inclusion; there were 69 events in classes II, III and IV (19.95% of the population; incidence, 17.3%); 59 events,including the five deaths, occurred in classes III and IV (10.85% of the population), producing an event incidence of 27.2%. The increased event rate in classes II, III, and IV was significant (log-rank test; P<.05, P<.025, and P<.025, respectively). Thus, the arterial morphology classification identified 19.95% of the population (subjects in classes II, III, and IV in which all events occurred. There was a higher (P<.05) rate of progression of altered arterial morphology in 6 years in classes III (26.5% of subjects progressed) and IV (41.9% progressed) than in classes I and II. The total number of cigarette-years was higher (P<.05) in classes II, III, and IV than in class I. In conclusion, the ultrasound-based arterial classification was useful in selecting from the population sample 80.05% of subjects (class I) who remained event-free for 6 years. All events occurred in class II, III, and IV subjects (19.95%), and ail five deaths (0.25% of the population) occurred in classes III and IV (10.85% of the sample).
