Stress and ectopic beats in ships' pilots

There has been much discussion about the significance and causes of ectopic beats. They may be found in the electrocardiograms of apparently healthy subjects, although ectopic beats with aberrant contour are commonly regarded as indicating an underlying cardiac pathology. There has been speculation that stress may play a part in precipitating them, but this does not necessarily imply that aberrant beats are a completely normal response. Ships' pilots were studied at work using long-term ambulatory ECG recordings which were analysed for aberrant beats both visually and by computer. A group of eight subjects whose recordings contained more than one or two isolated aberrant beats also tended to have more indications of abnormality in their clinical electrocardiograms (p less than 0.02), and to score higher on the Neuroticism scale of the Eysenck Personality inventory (p less than 0.05), than a Control Group of six other pilots. At work, the aberrant beats occurred most often when the pilots were involved in demanding activities, notably maneuvoring ships in hazardous situations; these periods were frequently marked by large increase in heart rate. Coronary risk factors, such as serum cholesterol and overweight, while being generally high, did not discriminate between those subjects who produced frequent aberrant beats and those who did not.