Abstract
Objective:
Elevated resting heart rate has been independently associated with cardiovascular and all-cause mortality, but association of it with cerebrovascular disease has been unexplored. The pathophysiological mechanisms by which this increased risk occurs are unclear. We hypothesized that elevated resting heart rate will be associated with increased development of atherosclerosis, as assessed by the incidence and progression of carotid artery stenosis and plaque morphology.
METHODS:
The Multi-Ethnic Study of Atherosclerosis is a prospective cohort study of participants free of clinical cardiovascular and cerebrovascular disease at entry. Healthy Subjects with baseline carotid stenosis by carotid duplex were stratified into five categories according to resting heart rate of: 36-55, 56 -60, 61-65, 66-71, >71bpm). Carotid stenosis incidence was assessed by relative risk regression after adjusting for comorbidities. Heart rate 36-55 was kept as a reference tier system.
RESULTS:
Of 6667 healthy individuals with an average age of 62, 3462 were men and 3511 were females. With successive increase in heart rate there was increased in associated comorbidities like hypertension, (40.3%,42%,43.2% with respective p value of 0.0001,0.0003,0.02 in tier 2,3 & 4), DM (9.7%,13.6%,20.2% with p=0.01,<0.0001 and 0.0001 respectively in tier 3, 4 & 5). Similar trend was noticed in baseline labs with increment in heart rate Total cholesterol 36.4%,36.1%,39.4% with p=0.0004,0.001,<0.0001 respectively in tier 3,4,5), CRP (4.5%,5.6%,6%,8.4% with p= ,0.0001, in each tier 2, 3,4,5). However, there did not seem to be any correlation between carotid stenosis and resting heart rate.
CONCLUSION:
Elevated resting heart rate, a well-described predictor of cardiovascular mortality with unclear mechanism, is associated with cerebrovascular risk factors, but not with the occurrence of asymptomatic extracranial carotid artery stenosis.