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cause subtle incapacitation. In the presence of normal coronary arteries, such symptoms carry a normal
prognosis.
Minor coronary artery disease
Coronary angiography has predictive power in terms of future cardiovascular events. It is noteworthy that
of 347 patients who presented with chest pain in one study, but who had normal coronary arteries, only
two (0.6 per cent) died from coronary artery disease over the following ten years. Those with obstruction
of <30 per cent had a two per cent ten-year mortality; in those with obstruction of > 30 per cent but < 50
per cent, the ten-year mortality was 16 per cent. The Coronary Artery Surgery Study (CASS)2 registry
1 Prinzmetal’s angina: an atypical form of angina, in which the attacks occur during rest and often in the early hours of the
morning. Focal spasm of an epicardial coronary artery causes transient, abrupt reduction of arterial diameter resulting in
myocardial ischaemia. After Myron Prinzmetal, American cardiologist ( 1908-1994)
2 CASS - Coronary Artery Surgery Study: a multicenter patient registry and a randomized controlled clinical trial,
designed to assess the effect of coronary artery bypass surgery on mortality and selected non-fatal end points. It was
carried out under the auspices of the National Heart, Lung, and Blood Institute, Bethesda, Maryland (USA), and
involved 24 959 patients, enrolled between 1974 and 1979.
ICAO Preliminary Unedited Version — October 2008 III-1-16
data gave a 96 per cent seven-year survival for the 3136 patients with normal coronary arteries or arteries
which were stenosed only minimally. The long-term study of the natural history of 1487 flyers with
“normal” vessels and vessels with “luminal irregularity” from the US Air Force demonstrated no events in
either group at five years. Between five and ten years, the event rate was 0.1 per cent per annum in the
first group and 0.56 per cent per annum in the second group. The event rate for “minimal or nonocclusive
coronary disease of <50 per cent” was 1.2 per cent per annum over the second five-year period.
In the absence of disqualifying symptoms or other contraindication, aircrew with chest pain and normal
coronary arteries or with only minor irregularities may be permitted unrestricted certification to fly,
subject to ongoing review. Stenosis > 30 per cent in any major vessel should predicate a restriction to
multi-crew operation, while stenosis > 50 per cent is disbarring. When the left main-stem or proximal left
anterior descending vessels are involved, pilots with lesions >30 per cent should be denied certification.
Moderate/severe coronary artery disease and sudden cardiac death (SCD)
It is conventional to describe the coronary circulation as consisting of three arteries — the right main
vessel and the two branches of the left main vessel, i.e. the anterior descending and circumflex branches.
There is, however, significant individual variation in the size, relative importance and physiological
balance of the vessels. The early Cleveland Clinic data demonstrated a five-year survival of 83 per cent in
patients with at least “moderate” single-vessel disease, falling to 62 per cent and 48 per cent at 10 and 15
years, respectively. Such a high event rate is not tolerable in the context of aviation. But much has
changed over the past 30 years: not only has there been a general decline in the prevalence of coronary
artery disease in many (predominantly Western) countries but there is also overwhelming evidence that
brisk intervention against vascular risk factors (hyperlipidaemia, hypertension, smoking, diabetes)
significantly improves outcome in terms of reduction of a major adverse cardiac event (MACE) and
stroke.
Two-thirds of sudden deaths are attributable to the cardiovascular system with a population incidence of
approximately one per 1000 persons per year. The majority of such events in middle years and later are
due to coronary artery disease. Increased left ventricular muscle mass is a powerful predictor, as are
hypertension, hyperlipidaemia, smoking, diabetes mellitus and a family history (male death < age 55
years, female death <age 60 years). In the Framingham study, electrocardiographic left ventricular
hypertrophy was associated with a five-year mortality of 33 per cent in males and 21 per cent in females.
Left ventricular hypertrophy bears a relative risk, independent of the presence or absence of hypertension,
similar to that of coronary artery disease.
Other causes of sudden cardiac death include hypertrophic cardiomyopathy, dilated cardiomyopathy
(including arrhythmogenic right ventricular cardiomyopathy), ischaemic left ventricular dysfunction, ion
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Manual of Civil Aviation Medicine 1(80)
