Analysis of 1150 post-infarct and post-aorto-coronary bypass graft patients referred to the Toronto Rehabilitation Centre revealed that approximately 10% have not returned to work six months after the acute event. White-collar workers are more successful than blue-collar workers in resuming work, as are those medically treated as compared with the surgically treated. The reasons for prolonged unemployment were more frequently non-medical than medical. Detailed assessment is required where there is doubt about the patient's work capacity, or where legislation and/or trade practices demand it. The simplest procedure is an exercise test with energy cost matching. Telemetry during simulated work tasks or while on work stations in the Centre allows more flexibility, with actual observation and telemetry on the job site the only recourse in certain situations.
Bus drivers with ischemic heart disease have been denied normal employment, although they satisfy Canadian Cardiovascular Society (CCS) Guidelines. To show the safety of their reemployment, we compared their responses when driving buses with those seen during graded exercise testing.
Twenty-two male city bus drivers, aged 48.1 +/- 5.6 years (19 had a myocardial infarction, 2 had coronary artery bypass graft, 1 had documented ischemic heart disease) were referred for work evaluation. After a CCS cardiopulmonary exercise test, they were accompanied by a physician and a therapist/technician on a normal shift. Note was kept of symptoms, signs, electrocardiogram (telemetry), blood pressure (ambulatory recording unit), and Borg rating of effort throughout.
Average values for peak heart rate (101 +/- 12.5 versus 148.2 +/- 17.2 beats/min), peak systolic pressure (150.0 +/- 20.8 versus 198.9 +/- 25.7 mm Hg), peak rate-pressure product (15,259 +/- 3,369 versus 29,500 +/- 5,283 units), peak Borg RPE (9.9 +/- 1.4 versus 17.4 +/- 3.0 units), and peak ST-segmental depression (-0.03 +/- 0.07 versus -0.07 +/- 0.09 mV) during the shift were only about a half of average values reached during the graded stress test. Moreover, peak values were reached at the end of the shift, when carrying the loaded fare box, rather than when driving.
Cardiovascular strain during bus driving is much less than during the CCS stress test for drivers. Using CCS methodology, the risk that a sudden cardiovascular incident will cause injury or death of others in the first year after recovery from myocardial infarction is estimated at 1 in 50,000 driver-years. Thus, those satisfying CCS requirements can return to full driving duties promptly, with minimal risk to themselves, passengers, or other road users.