Exercise in an hypoxic environment as a screening test for ischaemic heart disease.

Submaximal and maximal exercise testing have been used to predict coronary events but these tests do not give reliable information regarding employability of subjects with abnormal electrocardiogram. In 30 subjects with stabilized ischaemic heart disease (Group A) and 70 subjects with abnormal resting electrocardiogram (Group B), resting electrocardiograms--at ground level and at a simulated height of 4592 m (15000 ft)--after 40-min exposures were recorded. The double Master's two-step exercise test (DM) was performed at ground level as well as at stimulated height (DMH). In the ischaemic group, exercise combined with hypoxia did not yield better results than exercise alone; but among the asymptomatic subjects, exercise in an hypoxic environment gave significantly better results than exercise alone (p less than 0.005) or hypoxia alone (p less than 0.01). Those with negative responses to the test have been employed on strenous duties, including employment at high altitude for the last 3 years. None of them have manifested any objective or subjective evidence of ischaemic heart disease. DM exercise testing in an hypoxic environment is a reliable method to assess subjects with abnormal electrocardiogram and evaluate their functional status.