Article Text
Abstract
Objective: To investigate whether a workload which an individual is able to perform at the heart rate (HR) of 100 beats/min (WL100) independently predicts mortality in middle-aged men with known or suspected coronary heart disease (CHD).
Design: Prospective population-based study based on 365 middle-aged men with known or suspected CHD at baseline.
Results: During an average follow-up of 11.1 years, there were 75 deaths (20.5%). In Cox multivariable models mortality increased by 72% (95% CI 32% to 122%, p<0.001) with 1 SD (34 Watts) decrement in WL100 after adjustment for age, examination year, alcohol consumption, body mass index, cigarette smoking, cardiac insufficiency, history of myocardial infarction, diabetes, myocardial ischaemia during exercise test, serum low-density lipoprotein and high-density lipoprotein cholesterol, systolic and diastolic blood pressure at rest, testing protocol, and use of HR-lowering medication. The risk of death was 2.4 (95% CI 1.5 to 4.0, p<0.001) times higher in 130 men with WL100 <55 W than in 235 men with WL100 ⩾55 W. In men using and not using HR-lowering medication the risk of death increased 72% (95% CI 14% to 163%, p = 0.01), and 54% (95% CI 14% to 108%, p = 0.005) with 1 SD decrement in WL100, respectively. WL100 improved the predictive power of the adjusted Cox models including other HR and exercise test variables.
Conclusions: WL100 predicts mortality in men with known or suspected CHD. The association of WL100 with mortality was not explained by other well-established HR and exercise test variables. WL100 is derived from a submaximal test which avoids the cardiovascular risks associated with a high-intensity exertion.
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Footnotes
Funding: This study was supported by grants from the Ministry of Education in Finland (74/722/2003), the Finnish Cultural Foundation of Northern Savo, the Foundation of Sports Institutes in Finland, the Maire Taponen Foundation, the Mehiläinen Research Foundation, and the Paulo Foundation.
Competing interests: None.
Contributors: TAL was a Research Fellow of the Academy of Finland. KPS: conception and design; analysis and interpretation of data; drafting of the manuscript; final approval of the manuscript submitted. TAL: conception and design; analysis and interpretation of data; drafting of the manuscript; final approval of the manuscript submitted. JAL: conception and design; analysis and interpretation of data; critically revising the manuscript for important intellectual content; final approval of the manuscript submitted. THR: conception and design; analysis and interpretation of data; critically revising the manuscript for important intellectual content; final approval of the manuscript submitted. JTS: conception and design; critically revising the manuscript for important intellectual content; final approval of the manuscript submitted. RR: conception and design; analysis and interpretation of data; drafting of the manuscript; final approval of the manuscript submitted. KPS is the guarantor.