Workload at the heart rate of 100 beats/min and mortality in middle-aged men with known or suspected coronary heart disease.

Abstract

To investigate whether a workload which an individual is able to perform at the heart rate (HR) of 100 beats/min (WL(100)) independently predicts mortality in middle-aged men with known or suspected coronary heart disease (CHD). Prospective population-based study based on 365 middle-aged men with known or suspected CHD at baseline. 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 WL(100) 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 WL(100) <55 W than in 235 men with WL(100) >or=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 WL(100), respectively. WL(100 )improved the predictive power of the adjusted Cox models including other HR and exercise test variables. WL(100) predicts mortality in men with known or suspected CHD. The association of WL(100) with mortality was not explained by other well-established HR and exercise test variables. WL(100) is derived from a submaximal test which avoids the cardiovascular risks associated with a high-intensity exertion.