Cardiac risk of coronary patients after reintegration into occupations with heavy physical exertion

The job related reintegration of patients with coronary artery disease (CAD) is a central part of cardiac rehabilitation. However, specific occupational demands like jobs with heavy physical exertion (> 6 METs) could increase the cardiovascular risk because the relative risk for acute myocardial infarction (MI) and cardiac death is temporarily elevated after vigorous exertion ("hazard period"). Thus, in 2001 any male patient with proven CAD who performed a job with heavy exertion until the occurrence of an index event (MI/ACS, any interventional or surgical revascularization measure) received a questionnaire after an average of 20 months. Complete data were available in 108 from 119 included patients (90.8%), aged 51.8+/-7.8 years. Ejection fraction was 61.5+/-13.1% and the functional capacity at the time of hospital discharge averaged 130.1+/-31.2 W. 75% of the patients had a previous MI and 59.3% underwent bypass surgery. During follow-up the previous job with heavy exertion was performed over a cumulated time of 74 years. The aim of the study was to compare the observed and the expected incidence of MI and cardiac death with and without job performance. The expected ("basal") risk for MI and cardiac death without heavy physical exertion was determined from pooled study results and assumed to be 5.2% per year. The combined risk due to performing an occupation with strenuous exertion can be calculated from time periods with and without working hours and amounts to 11.9%. There could be expected 0.119 . 74=8.8 cardiac events related to the job. In contrast, 5 MIs (4 NSTEMI, 1 STEMI) were observed (6.8%). The relative risk for an expected event compared to the basal risk without heavy exertion was 2.3 (95% CI: 0.7-7.4). The relative risk for the observed cardiac events amounts to 1.3 (95% CI: 0.4-4.8). The lower observed risk is probably due to the high grade of physical fitness in this patient group. In spite of several limitations, our study showed no convincing evidence for increasing the cardiac risk of patients with CAD performing occupations with heavy physical exertion. Because of the importance of this prognostic finding, a representative and prospective study is strongly required.