Aim: To study the relationship between heart rate and (a) all deaths and (b) cardiovascular deaths in a large cohort of middle-aged Norwegian men and women.
Methods and results: A prospective study of participants in cardiovascular surveys that were carried out in 1985-1999 and covered men and women aged 40-45 years in all counties except the capital, Oslo. In total, 180,353 men and 199,490 women aged 40-45 years without cardiovascular history or diabetes accrued 4 775 683 years of follow-up. There was a positive and graded association between heart rate and mortality from all causes, as well as between heart rate and deaths from cardiovascular disease (CVD), ischaemic heart disease, and stroke. However, these associations were greatly reduced when we adjusted for the main risk factors of disease. The hazard ratios for any death were reduced from 3.14 to 1.82 for men (95% CI, 1.62-2.04) and from 2.14 to 1.37 for women (95% CI, 1.19-1.59), when we compared > or =95 b.p.m. with <65 b.p.m. The corresponding figures for CVD were a reduction from 4.79 to 1.51 for men (95% CI, 1.21-1.87) and from 2.68 to 0.78 for women (95% CI, 0.53-1.15).
Conclusion: In this cohort of middle-aged men and women, a crude association between heart rate and death from CVDs was greatly weakened when we adjusted for the main risk factors of disease. This suggests that an increased heart rate in middle age may be a marker of high cardiovascular risk, but is not an independent risk factor.