ASYMPTOMATIC DISEASE OF CORONARY ARTERIES IN YOUNG MEN.

Abstract

Epidemiol?gica! and pathological studies of atherosclerosis have recently received impetus through the agency of the World Health Organization. This work, together with the majority of the previous literature, is largely concerned with overt disease and death from coronary heart disease ; there is a comparative dearth of information on the preva lence of occult affection of the coronary arteries, the study of which cannot be divorced from that of ischaemic heart disease (Strong and McGill, 1962). So as to eliminate any possible adverse effects of unrelated disease on the health of the coronary arteries, the basic extent of symptomless atheroma must be sought in supposedly healthy persons killed accidentally rather than in hospital populations ; most of the relevant reports have therefore emanated from military medicine. M?nckeberg (1915a, 1915b, 1916) appears to have been the first to explore this field. His three series include 167 combatant troops compared with 136 men exempt from war service, all of whom were killed either in action or accidentally ; atherosclerosis was discovered in 50.9% of the combatants and in 63.2% of the non-combatants, the potentiating effect of age being demonstrated in both groups?even so, 44.5% of soldiers under the age of 30 were found to be affected to some extent. This study must surely have been followed up, but the next apposite refer ence that 1 discovered is that Enos, Holmes, and Beyer (1953). These authors made a strictly comparable study of American soldiers killed in action in Korea. Narrowing of one or more coronary arteries resulting in more than 50% restriction was found in 12.3% of 300 cases, the average age of the men being 22.1 years. In civilian life, Spain and Bradess (1959) reported their findings in 166 white men aged 31-60 who were killed accidentally ; they confirmed the presence of widespread asymptomatic coron ary atheroma, although completely normal arteries were discovered even in a proportion of their oldest subjects. Strong and McGill (1962) also studied accidental death and concluded that it was impossible to divide American white males into those having and not having coronary athero sclerosis after the age of 20 years?the only distinction lay in the severity of disease. The activities of the Joint Committee on Aviation Pathology (Brody, 1957) have in recent years focused attention on the occurrence of pre-existing disease in air crew?possibly the most highly physically selected group available?who ' were killed while flying, and numerous articles have been published from the United States of America dealing in general terms with coronary arterial disease in the context of aircraft accident pathology (Town send, 1957; Berry and Stembridge, 1958; Silliphant and Stembridge, 1958; Townsend and Stembridge, 1958; Townsend and Davidson, 1961). Specific studies of occult coronary arterial disease in American aircrew have been reported from the Armed Forces Institute of Pathology (Glantz and Stembridge, 1959 ; Townsend and Glantz, 1959; Rigal, Lovell, and Townsend, 1960; Catherman, Davidson, and Townsend, 1962). Depending primarily on the age-group involved and secondarily on the method of examination, these various authors have assessed the incidence of restrictive disease as from 14% in the age group 20-24 to 32% marked sclerosis?that is, more than 75% restriction?in the age-group 40-49 years. Compar able British series of aircrew fatalities have been reported (Mason, 1959, 1962 ; Stevens, 1961, 1962), but the articles have been of a limited distribution. It is also noted that the problem has been considered by the Soviet Air Force (Koldovski, Novak, and Vorel, 1961); this article has been seen only in abstract form. It therefore seemed appropriate to collect and publish the British data in more readily available form so that valid comparisons of the occurrence of asymptomatic coronary arterial disease in physically fit young men on both sides of the Atlantic could be made. The significance in aviation of discovered arterial disease could be threefold. Firstly, it might be shown to be a disease state directly related to the stresses of professional aviation. Secondly, it might be shown to be a significant cause of unexplained aircraft accidents ; this possibility is not considered in detail in this paper. Thirdly, it could be no more than a marker of the incidence of atherosclerosis throughout the population.