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Published on: April 5, 2011
QTc interval and electrocardiographic changes by type of shift work
Michele Meloni1, Davide Setzu, Alberto Del Rio
1Department of Public Health, Clinical and Molecular Medicine, Occupational Health Section, University of Cagliari, Monserrato (Cagliari), Italy. melonim@medicina.unica.it
Background:
We conducted a cross sectional survey of electrocardiographic changes among shift-workers.
Methods:
We classified the electrocardiogram morphology, and measured the QTc interval in 91 male workers engaged in regular daily work-shifts, 32 in 24 hr work-shift (h24), and 93 in irregular 6 hr work-shift (h6).
Results:
With reference to daily workers, the QTc interval was prolonged among h6 workers (P < 0.001) and h24 workers (P < 0.005). The age- and obesity-adjusted standardized prevalence ratio (SPR) of a borderline/prolonged QTc was 2.2-fold among h6 workers (95% CI 1.2, 4.2); conduction disorders (SPR = 2.6; 95% CI 1.3, 5.2) and repolarization disorders (SPR = 1.9; 95% CI 1.0, 3.5) were also more frequently observed among h6 workers. Excluding 19 subjects with risk factors for prolonged QTc did not change the results.
Conclusions:
Our study reveals significant changes in the ECG morphology in relation to shift-work, especially in unpredictable and non-standard working hours.
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