Increased heart rate ‘not an independent CV risk factor’

20 November 2008

MedWire News: Increased heart rate (HR) is a marker for increased cardiovascular (CV) mortality rather than an independent CV risk factor, Norwegian researchers believe.

Their conclusion is based on a prospective study of 180,353 men and women who completed government health surveys between 1985 and 1999. All participants were aged 40–45 years and free of CV disease or diabetes at enrolment.

The average duration of follow-up was 13 years, during which time 8915 participants died, report Aage Tverdal (The Norwegian Institute of Public Health, Oslo) and coauthors in the European Heart Journal.

All the major CV risk factors – cholesterol, triglycerides, blood pressure, body mass index, family history of CV disease, smoking, and sedentary lifestyle – increased significantly across increasing quartiles of HR.

In unadjusted analyses, there were positive linear associations between HR and all-cause mortality, as well as between HR and deaths from CV disease, ischemic heart disease (IHD), and stroke.

After adjusting for major risk factors, however, these associations were markedly attenuated. The only result that remained significant was a link between high HR and increased CV and IHD mortality in men, with hazard ratios of 1.40 and 1.42, respectively, for each 10-bpm. increase.

Tverdal and co-workers note that high HR is associated with an unfavorable pattern of risk factors and may be a marker for sympathetic nervous system activity. In contrast to several recent studies, however, these data do not support HR as an independent risk factor for CV mortality.

“In this cohort of middle-aged men and women, a crude association between HR and death from CV disease was greatly weakened when we adjusted for the main risk factors of disease,” they write.

“This suggests that an increased HR in middle age may be a marker of high cardiovascular risk, but is not an independent risk factor.”

Eur Heart J 2008; 29: 2772–2781