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Health See other Health Articles Title: High Heart Rate, Low Variability Associated with Functional Decline in Elderly Medscape... LEIDEN, NETHERLANDS — Markers of cardiac autonomic function may also be markers of both current and future functional status in older patients, "independent of cardiovascular disease," note researchers[1]. Data on more than 5000 participants from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) showed that those who had high baseline resting heart rates (between 71 and 117 beats/minute) had significantly higher risk than those with slower heart rates for decline in both basic activities of daily living (such as grooming, feeding, and urinary continence) and instrumental activities (such as housework, using technology, and taking medication as prescribed). In addition, those with the lowest heart-rate variability at baseline were more likely to develop both types of functional decline vs those with higher heart-rate variability. "This could be a tool used by clinicians and researchers to identify older subjects who are at risk of decline in subsequent years. And it may be a clue to work on them and do follow-up to prevent this decline," corresponding author Dr Behnam Sabayan (Leiden University Medical Center, the Netherlands) told heartwire from Medscape. Sabayan pointed out that more than half the study participants were female. "Yet there were no significant differences in terms of the associations between men and women. This is promising because the findings appear generalizable to both genders." The findings were published online August 31, 2015 in CMAJ. PROSPER and Decline For this analysis, the investigators evaluated data from 5042 PROSPER participants from Ireland, Scotland, and the Netherlands (52% women; mean age 75.3 years) who were followed for a mean of 3.2 years. All underwent 10-second, 12-lead ECG at baseline. This was used to determine heart rate (group mean, 65 beats/minute) and heart-rate variability, defined as standard deviation of normal-to-normal R-R intervals (SDNN; mean 18.6 ms). At baseline and at follow-up, the Barthel Index questionnaire was administered to measure basic activities, and the Lawton Instrumental Activities of Daily Living Scale (IADL) scale was used to measure more complex activities. In both minimally adjusted and fully adjusted models, higher heart rates at baseline were significantly associated with lower basic and instrumental functioning scores compared with slower heart rates (all comparisons, P for trend <0.05). However, lower SDNN rates were associated with low functioning in both types of activities only in the minimally adjusted model. In the fully adjusted model, SDNN was associated only with lower instrumental-activity scores (all P<0.05). Still, fully adjusted models showed that those classified as being in the lowest heart-rate–variability tertile, between 1.70 and 13.30 ms, had a significantly higher risk of future decline in both basic (odds ratio 1.21, 95% CI 1.0–1.5) and instrumental functioning (OR 1.25, 95% CI 1.1–1.5; both P<0.05) vs those in the high SDNN tertile of 26.6–422.6 ms. Those in the highest tertile of resting heart rate had significant ORs of 1.79 for developing a decline in basic skills (95% CI 1.5–2.2) and of 1.35 for a decline in instrumental skills (95% CI 1.1–1.6; both P<0.001). "Just the Beginning" "Participants with a higher resting heart rate were older and more likely to be female and current smokers and had a higher [body mass index] BMI and a higher prevalence of diabetes mellitus," report the researchers. Those with lower resting heart rates used beta-blockers more frequently and, interestingly, had a higher prevalence of MI. The lowest heart-rate–variability group had higher BMI, were not frequent users of beta-blockers, and had a high prevalence of diabetes. Sabayan said the investigators were pleasantly surprised to see these associations after the 10-second ECG, "because previous studies on heart-rate variability and heart rate were based on longer time-measurement indicators, such as 10 minutes or 24 hours." Results did not change significantly after researchers excluded participants receiving beta-blockers or those with incident stroke or coronary events during the follow-up period. In addition, sex, use of statins, and history of hypertension did not affect any of the associations found. "Because functional disability has a long preclinical phase, it is crucial to identify potential interventions to delay it," write the investigators. However, "further research is needed to establish whether heart rate and heart-rate variability are . . . potentially modifiable risk factors for functional decline," they write. "Pharmacologic and nonpharmacologic interventions . . . aimed at modulating cardiac autonomic function may be beneficial in preserving functional status." Sabayan added that "this is just the beginning" and opens the door for future studies. "One of the most important things we found is that the associations were independent of cardiovascular events. That means we need to explore the pathways and mechanisms for these associations," he said. Related Links Low Resting Heart Rate Linked to Violent Crime Higher Heart-Rate Variability With Mediterranean Diet Post Comment Private Reply Ignore Thread
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