killed while flying, with 24 percent classified as having more than 50 percent
Juminal restriction (4). In a later article, Mason discusses some inter-
actions between trauma and previous disease that may present difficulties in
interpretation with specific reference to coronary disease. Mason points out
that severe cardiac damage, a frequent feature of aircraft accidents, may have
resulted in conservative interpretation and underestimation of the importance
of coronary disease in fatal general aviation accidents (5).

Of the 710 autopsied airmen, 112 could not be classified as to presence or
absence of coronary atherosclerosis due to incineration or traumatic destruc~
tion of the heart. After removing these 112 “unknown” cases, no coronary
atherosclerosis was found in 30.9 percent of the remaining autopsied cases.
The prevalence of coronary atherosclerosis to any extent, regardless of how
minor, among those airmen who came to autopsy as a result of a fatal general
aviation aircraft accident during the years 1980-82 was 69.1 percent. This
finding is higher than for a similar group of pilots studied during the years
1975-77 (see Figures 1-3 and Tables I-III)(2).

Severe coronary atherosclerosis, implying at least a two-thirds luminal
narrowing, was found in 2.7 percent of the cases (or an average of five cases
per year). This is about half the rate observed in the previous study.
Obviously, these prevalence findings are of the greatest concern since they
represent those most likely to have been subject to sudden incapacitation.
However, positive statements regarding sudden incapacitation due to
cardiovascular disease were noted in only six instances, or about two per
year. The age-specific rates of severe coronary atherosclerosis at autopsy
found among the group of airmen studied yield results consistent with previous
findings, but different in some important respects. Prevalence of severe
coronary atherosclerosis increased with age from 5.8 per 1,000 for ages 39
years and under to 73.9 for ages 50 years and above, also reflecting lower
age-specific rates for severe coronary atherosclerosis than were found in the
previous study. Recent emphasis on autopsy format and attention to sudden
incapacitation is felt to have resulted in more accurate reporting for recent
years. The biggest increase between sequential age intervals is observed
between ages 40-49 and 50-59, where an approximate fourfold increase is seen.
This is different from the previous study, where the biggest increase was seen
to occur between ages 30-39 and 40-49, which would be more consistent with
known patterns of substantial increase in the incidence of cardiovascular
disease beginning at age 40.

CONCLUSIONS

While the findings of this study are indicative of a continued serious
public health problem with cardiovascular disease in the United States popula-
tion, it is noteworthy that prevalence of severe coronary atherosclerosis
observed in the FAA autopsied cases studied is less than what has been
observed in other aviation groups studied as well as a previous FAA study.
Continued vigilance is obviously called for in screening and in education of
airmen and aviation medical examiners. However, it seems unlikely that the
low prevalence of severe coronary atherosclerosis could be reduced signifi-
cantly by the addition of classical noninvasive diagnostic techniques, given
the recognized problems of these procedures with regard to sensitivity and
specificity.


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5.

REFERENCES

Berkheiser S. Cardiovascular disease in the young age group.
Aerosp. Med. 1970; 41:1307-8.

Booze CF, Pidkowicz J, Davis A, Bolding F. Postmortem coronary
atherosclerosis findings in general aviation accident pilot
fatalities: 1975-77. Aviat. Space Environ. Med. 1981; 52:24-7.

Dreifus LS, et al. Cardiovascular problems associated with
aviation safety. Am. J. Cardiol. 1975; 36:575-628.

Mason JK. Pre-existing disease and aircraft accidents. In:
Mason JK, Reals WJ, ed. Aerospace pathology. Chicago: College
of American Pathologists Foundation, Chapter 9, 1973.

Mason JK. Previous disease in aircrew killed in flying accidents.
Aviat. Space Environ. Med. 1977; 48:944-8.

Mohler SR, Booze CF. U.S. fatal general aviation accidents due
to cardiovascular incapacitation: 1974-75. Aviat. Space Environ.
Med. 1978; 49:1225-8.

Pettyjohn F, McMeekin RR. Joint Committee on Aviation Pathology:
XVL. Coronary artery disease and preventive cardiology in aviation
medicine. Aviat. Space Environ. Med..1975; 46:1299-1304.

Rayman R. Myocardial infarction: An in-flight problem? Aerosp.
Med. 1974; 45:86-9.

se U.S. Government Printing Office: 1985—61-816/20507


Technical Report Documentation Page

T. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
DOT /FAA~AM-85-6
4. Title and Subtitle 5. Report Date

A COMPARISON OF POSTMORTEM CORONARY ATHEROSCLEROSIS | August 1985
FINDINGS IN GENERAL AVIATION PILOT FATALITIES ~ Performing Organization Code

8. Performing Organization Report No.

7. Author’s)

Charles F. Booze, Jr., and Clara M. Staggs

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
FAA Civil Aeromedical Institute

P.O. Box 25082 11. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name and Address
Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, SW. 14. Sponsoring Agency Code
Washington, DC 20591

15. Supplementary Notes

16. Abstract
Recognition of medical risk factors is of paramount importance to the Federal Aviation|

Administration (FAA) with regard to the agency's primary mission of insuring air
safety.

The autopsy reports of 710 pilots involved in fatal general aviation accidents and
received by the FAA for the years 1980-82 were reviewed to appraise the age-specific
prevalence of coronary atherosclerosis among the autopsied group and compare findings
with those of an earlier study of a similar pilot group. All data were received by
the FAA in connection with its responsibilities for medical investigation of accidents

Sixty-nine percent of the autopsies on pilots killed in aircraft accidents indicated
some degree of coronary atherosclerosis ranging from minimal to severe. This finding
is higher than for a similar group of pilots studied during the years 1975-77.
However, only about 2.5 percent of the 1980-82 study group were found to have severe
coronary atherosclerosis, compared with 5 percent in the previous study. Prevalence
of severe coronary atherosclerosis increased with age from 5.8 per 1,000 for ages
less than 40 years to 73.9 for ages 50 years and above, also reflecting lower age-
specific rates for severe coronary atherosclerosis than were found in the previous
study.

Recent emphasis on autopsy format and attention to sudden incapacitation is felt to
have resulted in more accurate reporting for recent years. Prevalence of severe
coronary atherosclerosis among the recently studied pilot group was less than that
observed in an earlier study of a similar group

17, Key Words 18. Distribution Statement
Coronary Atherosclerosis Document is available to the public
Autopsy through the National Technical
Sudden Incapacitation Information Service, Springfield,
Virginia 22161.
19. Security Classif, (of this report) 20. Security Clossif, (of this page) Qi. No, of Pages | 22, Price
Unclassified Unclassified 9

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized



Table II
DISTRIBUTION OF CORONARY ATHEROSCLEROSIS
BY DEGREE OF INVOLVEMENT, 1980-82 FATAL
GENERAL AVIATION ACCIDENT VICTIMS

Degree of Involvement Frequency Percent
None 185 30.9
Minimal to Moderate
(Grades I & II) 397 66.4
Severe
(Grade III) 16 2.7
Total Cases With Findings 598 100.0
Table III

AGE-SPECIFIC RATES OF SEVERE CORONARY
ATHEROSCLEROSIS AMONG 1980-82 FATAL
GENERAL AVIATION ACCIDENT VICTIMS

Age Group (yr) Rate per 1,000
29 & under 0
30-39 5.8
40-49 14.9

50 & above 73.9



Such terms as “few atheromatous plaques,” “no significant atheroscle-
rosis,” and "minimal atherosclerosis" were placed into the Grade I category.
When a pathologist simply stated “moderate” or “severe” atherosclerosis with
no percentage figures, the cases were placed in Grade II and Grade III respec
tively. Whenever the pathologist used combinations such as “mimimum-
moderate,” "moderate-severe," or “moderately severe" atherosclerosis, the
lower category was recorded; e.g., Grade II was recorded for “moderate-severe"
atherosclerosis. Similar rationale was used for percentage figures; e.g.,
60-70 percent occlusion was recorded as Grade II. In all cases, the per-
centage figure took priority over the descriptive term; e.g., moderate athero-
sclerosis with 30 percent occlusion was recorded as Grade I. Recording the
lower category and giving priority to the percentage figure resulted in a more
conservative estimate of the prevalence of coronary atherosclerosis by grade.

BACKGROUND

Coronary atherosclerosis is an extremely common form of simple intimal
arteriosclerosis in which deposits of yellowish plaques containing choles-
terol, lipoid material, and lipophages are found within the intima and inner
media of large and medium-sized arteries. There appear to be four visual
gradings of coronary atherosclerosis: fatty streak, fibrous plaque, compli-
cated lesion, and calcification. The fatty streak is any intimal lesion that
is distinctly stained by a fat-soluble dye and does not show any other type of
cellular change. The fibrous plaque is a firm elevated intimal lesion that,
in the fresh state, is pale gray, glistening, and translucent. A complicated
atherosclerotic lesion is one in which there is ulceration, hemorrhage, or
thrombosis with or without calcium deposits. And finally, the calcified
lesion is an area where calcium deposition is detectable (visually or by
palpation) without overlying hemorrhage, ulceration, or thrombosis.

As in most chronic diseases, the etiology of coronary atherosclerosis is
complex and multifactorial; the three strongest risk factors for coronary
atherosclerosis appear to be hyperlipidemia, hypertension, and smoking. Diet
seems to play a major role in the disease process. Diets high in saturated
fats predispose to'hyperlipidemia; it has been noted that this disease corre-
lates well with the percent of fat intake in the total diet. Recently, the
levels of cholesterol in the blood have been definitely associated with an
increased risk to coronary atherosclerosis. Prolonged periods of excessive
external stress and the increased intake of alcohol are known to raise the
level of blood lipids.

Relatively little is known about the contribution of cardiovascular
disease to aviation accidents. While the potential for accident outcome has
been recognized for some time by the aviation medical community, attention ‘has
centered mostly on the commercial or air transport category pilot, and
research concerning the general aviation segment of the population has been
scarce. Some recent research efforts have, however, focused attention on the
signifi- cant potential for interaction between existing cardiovascular
disease and aircraft accidents (1-8). Pettyjohn and McMeekin found coronary
artery disease present to some extent at autopsy in about 87 percent of a 20-
to 34-year-old military pilot group with 17 percent classified as moderate and
severe (7). Mason's study of preexisting disease and aircraft accidents among
United Kingdom aviators found a prevalence of coronary artery disease
amounting to 62 percent for a group of British military and civilian pilots


A COMPARISON OF POSTMORTEM ‘CORONARY ATHEROSCLEROSIS FINDINGS
IN GENERAL AVIATION PILOT FATALITIES

INTRODUCTION

Cardiovascular disease is the leading cause of death and a significant
cause of sudden incapacitation in the United States today. Because sudden
incapacitation and sudden death are frequently the first and only manifes-
tations of coronary atherosclerosis, it is of utmost importance, not only to
the airman, but to the Federal Aviation Administration (FAA), that cardio—
vascular disease that could lead to sudden incapacitation be detected early.
To that end, FAA screening programs and airman and aviation medical examiner
educational programs emphasize the importance of early cardiovascular disease
detection. Cardiovascular disease represents the leading cause for denial of
medical certification to airman applicants, accounting for over a third of
denials for all causes.

Autopsies for 710 pilots involved in fatal general aviation accidents
during the years 1980 through 1982 were reviewed to appraise the age-specific
prevalence of coronary atherosclerosis among the autopsied group.

METHODS

Autopsy reports are received, maintained, and reviewed by the Medical
Statistical Section, Aeromedical Certification Branch, Civil Aeromedical
Institute, Federal Aviation Administration, Oklahoma City, Oklahoma.

For the 3 years studied, 710 pilot autopsy reports were received by the
Medical Statistical Section. The total number of fatal aviation accidents was
2,068 for the 3 years 1980-82, which yields an autopsy rate of 34 percent.

There is no reason to believe that the pilots autopsied were a select
group. While it is true that a few well-publicized accidents are likely to
receive intensive investigation due to air-to-ground communications, the
discovery of selected medications at the scene of the accident, and other
isolated factors suggestive of in-flight incapacitation, such instances are
rare and would have minimal effect on summary data. Some other factors deter-
mining whether an autopsy is performed are: the location and circumstances of
the accident; availability of a pathologist and facilities; cooperation of the
local coroner; and how actively the accident investigation program is pursued
in an FAA region.

The autopsies were performed by various medical examiners, hospital
pathologists, and forensic pathologists. Reports varied greatly with regard
to the length, completeness, detail, and description. These limitations were
necessarily considered in the accumulation and presentation of findings.

A three~category classification system based on degree of luminal occlu-
sion was formulated as follows:

1. Grade I : <¢ 33% luminal occlusion
2. Grade II : 33-66% luminal occlusion
3. Grade III: > 66% luminal occlusion


Acknowledgment

Appreciation is extended to Ms. Shirley Dark, Mrs. Leslie Downey,
and Mrs. Lisa Casey for their assistance in the review and preparation
of this study.