Association of resting heart rate and hypertension stages on all-cause and cardiovascular mortality among elderly Koreans: the Kangwha Cohort Study

BACKGROUND Elevated resting heart rate and hypertension independently increase the risk of mortality. However, their combined effect on mortality in stages of hypertension according to updated clinical guidelines among elderly population is unclear. METHODS We followed a cohort of 6100 residents (2600 males and 3500 females) of Kangwha County, Korea, ranging from 55 to 99 year-olds as of March 1985, for all-cause and cardiovascular mortality for 20.8 years until December 31, 2005. Mortality data were collected through telephone calls and visits (to 1991), and were confirmed by death record matching with the National Statistical Office (1992-2005). Hazard ratios were calculated for all-cause and cardiovascular mortality by resting heart rate and hypertension defined by Eighth Joint National Committee criteria using the Cox proportional hazard model after controlling for confounding factors. RESULTS The hazard ratios associated with resting heart rate > 80 beats/min were higher in hypertensive men compared with normotensives with heart rate of 61-79 beats/min, with hazard ratios values of 1.43 (95% CI: 1.00-1.92) on all-cause mortality for prehypertension, 3.01 (95% CI: 1.07-8.28) on cardiovascular mortality for prehypertension, and 8.34 (95% CI: 2.52-28.19) for stage 2 hypertension. Increased risk (HR: 3.54, 95% CI: 1.16-9.21) was observed among those with both a resting heart rate ≥ 80 beats/min and prehypertension on cardiovascular mortality in women. CONCLUSIONS Individuals with coexisting elevated resting heart rate and hypertension, even in prehypertension, have a greater risk for all-cause and cardiovascular mortality compared to those with elevated resting heart rate or hypertension alone. These findings suggest that elevated resting heart rate should not be regarded as a less serious risk factor in elderly hypertensive patients.