Ambulatory Heart Rate Research Articles

Office and Ambulatory Heart Rate as Predictors of Age-Related Kidney Function Decline.

The decline in glomerular filtration rate (GFR) associated with aging is one of the most important predisposing causes of kidney failure in old age. Identifying persons at risk for accelerated GFR decline is an essential first step in the development of preventive measures to preserve kidney function in the elderly. Heart rate (HR) has not yet been studied as a risk factor for GFR decline in the general population. In the RENIS-T6 (Renal Iohexol-Clearance Survey in Tromsø 6), we measured baseline ambulatory HR and GFR as iohexol clearance in a representative, middle-aged cohort of 1627 persons without self-reported diabetes mellitus, cardiovascular disease, or kidney disease. In the RENIS-FU (RENIS Follow-Up Study), we repeated the GFR measurements and calculated the rate of GFR decline in 81% of the participants after a median follow-up of 5.6 years. The unadjusted mean rate of GFR decline was 0.96 mL/min per year. In multivariable-adjusted linear mixed models, 10 bpm higher ambulatory 24-hour and daytime HRs and office HR were associated with steeper GFR decline rates of 0.20 to 0.21 mL/min per year ( P≤0.01). The odds ratio for predicting a rate of GFR decline twice that of the population mean in a fully adjusted model was 1.24 ( P=0.01) for ambulatory 24-hour HR. Office HR was also an independent predictor of a steeper rate of GFR decline. HR may be a useful biomarker to identify persons at risk of accelerated GFR decline.

Cardiovascular benefits of short-term indoor air filtration intervention in elderly living in Beijing: An extended analysis of BIAPSY study

BackgroundAdverse cardiovascular effects associated with air pollution exposure have been widely demonstrated. However, inconsistent cardiovascular responses were observed from reducing indoor air pollution exposure. We aimed to assess whether short-term air filtration intervention could benefit cardiovascular health in elderly living in high pollution area. MethodsA randomized crossover intervention study of short-term indoor air filtration intervention on cardiovascular health was conducted among 35 non-smoking elderly participants living in Beijing in the winter of 2013, as part of Beijing Indoor Air Purifier StudY (BIAPSY). Portable air filtration units were randomly allocated to active filtration for 2 weeks and sham filtration for 2 weeks in the households. Twelve-hour daytime ambulatory heart rate variability (HRV) and blood pressure (ABP) were measured during active and sham filtration. Concurrently, real-time indoor and outdoor particulate matter with diameter less than 2.5 µm (PM2.5) and indoor black carbon (BC) concentrations were measured. We applied generalized additive mixed models to evaluate the associations of 1- to 10-h moving average (MA) exposures of indoor PM2.5 and BC with HRV and ABP indices, and to explore whether these associations could be modified by air filtration. ResultsWe observed decreases of 34.8% in indoor PM2.5 and 35.3% in indoor BC concentrations during active filtration. Indoor PM2.5 and BC exposures were significantly associated with reduced HRV and increased ABP indices, and greater changes were observed during sham filtration. In specific, each 10 μg/m3 increase in indoor PM2.5 at MA8-h was associated with a significant reduction of 1.34% (95% CI: −2.42, −0.26) in SDNN during sham filtration, compared with a non-significant reduction of 0.81% (95% CI: −6.00, 4.68) during active filtration (Pinter< 0.001). Each 1 μg/m3 increase in indoor BC at MA8-h was associated with a significant increase of 2.41% (95% CI: 0.38, 4.47) in SBP during sham filtration, compared with a non-significant increase of −1.09% (95% CI: −4.06, 1.96) during active filtration (Pinter = 0.135). Nonlinear inverse exposure-response relationships of indoor air pollution exposures with predicted HRV and ABP indices also confirmed some cardiovascular benefits of short-term air filtration intervention. ConclusionsOur results suggested that short-term indoor air filtration intervention can be of some cardiovascular benefits in elderly living with high pollution episodes.

Association between preoperative ambulatory heart rate and postoperative myocardial injury: a retrospective cohort study

BackgroundResting heart rate is well established as a predictor of morbidity and mortality in the general population. However, the relationship between preoperative heart rate and perioperative outcomes, specifically myocardial injury, is unclear. MethodsThis retrospective cohort study included patients undergoing elective major non-cardiac surgery from 2008 to 2014 at a multisite healthcare system. The exposure was ambulatory heart rate measured during the outpatient preoperative clinic visit, whereas the outcome of interest was myocardial injury (peak postoperative troponin I concentration >30 ng L−1). Covariates included patient characteristics, comorbidities, and preoperative medications. We constructed several multivariable regression models that each modelled heart rate in a different manner, including as a simple continuous variable, categories, and fractional polynomials. ResultsThe cohort included 41 140 patients, of whom 4857 (11.8%) experienced myocardial injury. Based on pre-specified heart categories thresholds, a heart rate ≥90 beats min−1 was associated with an elevated odds of myocardial injury compared with a heart rate <60 beats min−1 (adjusted odds ratio, 1.22; 95% confidence interval, 1.06–1.39; P=0.005). This result was consistent regardless of the method used for categorisation. When fractional polynomials were used to model heart rate, a ‘J-shaped’ relationship between heart rate and odds of myocardial injury was observed. ConclusionsThis cohort study found that both very high preoperative heart rates, and possibly also very low heart rates, are associated with increased risk of myocardial injury. Whether heart rate is a modifiable risk factor, or rather simply a marker of underlying cardiac pathology, needs to be determined in further research.

Heart rate variability as a marker of healthy ageing

BackgroundWith population ageing a significant concern, modifiable factors contributing to healthy ageing must be identified. Autonomic responding reflected by heart rate variability (HRV) has well-established links to general health and wellbeing in younger populations; but has yet to be explored in older individuals. MethodsForty-five healthy participants (49–82 years old) completed questionnaires about sleep and physical and psychological health. Autonomic activity was measured during rest and whilst completing a computerised battery of cognitive tasks. Participants then wore an ambulatory heart rate monitor overnight, and recorded their sleep and physical activity for one week. HRV parameters reflecting cardiac vagal tone were derived from electrocardiograph recordings. ResultsAge and resting HRV were not related; however a positive association was identified between higher HRV in the 2 h prior to sleep and older age. Higher resting HRV, older age, and better sleep quality significantly predicted psychological wellbeing; and fewer somatic and physical health symptoms and older age predicted better average sleep quality ratings. Older age and poorer general health were significant predictors of cognitive performance deficits. ConclusionThese findings suggest that an age-related decline in HRV is not inevitable. Longitudinal designs exploring within-individual changes in cardiac vagal tone are required to better understand the factors contributing to healthy ageing.

Diazepam as an oral hypnotic increases nocturnal blood pressure in the elderly.

No study has evaluated the cardiovascular effects of diazepam in elderly subjects that assume diazepam to induce sleep. The present study was carried out in order to evaluate the effects of chronic administration of diazepam as hypnotic drug on blood pressure (BP) and heart rate (HR) in healthy elderly subjects. Healthy, elderly subjects, aged 65-74years, were treated with diazepam 5mg or placebo-both administered once a day in the evening-for 4weeks in two cross-over periods, each separated by a 2-week placebo period, according to a randomized, double-blind, cross-over design. At the end of each study period, clinical as well as 24-h ambulatory BP and HR were evaluated. A total of 25 subjects were included in the analysis. At the end of a 4-week diazepam treatment, clinical as well 24-h BP and HR mean values were not significantly affected. Analysis of sub-periods showed that during night-time, systolic BP (SBP) values under diazepam were 7.6% higher than under placebo, with a mean difference of 7.9mmHg (p < 0.01), diastolic BP (DBP) values were 5.8% higher, with a mean difference of 3.7mmHg (p < 0.05 vs placebo) and HR values were 6.6% higher with a mean difference of 4.2b/min (p < 0.05). The HR increase observed with diazepam persisted during the morning hours, whereas during the afternoon and evening hours SBP, DBP and HR values were similar in the two treatment groups. In elderly subjects chronic assumption of diazepam as hypnotic agent produced an increase in BP, in particular SBP, during night-time and of HR during night-time and morning hours. These effects, which probably depend on a diazepam-mediated increase in sympathetic drive and decrease in vagal tone, might be of clinical relevance due to the role of increased BP and HR as independent predictors of cardiovascular morbidity and mortality.

SPYRAL HTN-OFF MED TRIAL

Objective: Heart rate (HR) is associated with cardiovascular outcomes in hypertensive high-risk vascular patients and heart failure. Recently, the randomized, sham-controlled SPYRAL HTN-OFF MED trial showed reduction of office and ambulatory blood pressure (BP) at 3 months post-renal denervation. The objective of the current analysis is to evaluate the effect of renal denervation on HR in an uncontrolled hypertensive population without medication. Design and method: The SPYRAL HTN-OFF MED trial enrolled uncontrolled hypertensive patients who were drug naïve or removed from their antihypertensive medications. Patients were randomized 1:1 to renal denervation or sham control procedure. BP and HR were measured at baseline and 3 months post-procedure using ambulatory BP monitoring and in the office. For office BP and HR, each data point was an average of 3 measurements. Post-hoc analyses compared changes at 3 months in BP and HR for patients with baseline office HR above and below the median. Results: At 3 months, average office, 24-hour, daytime and night-time HR were significantly reduced in the renal denervation group but not in the sham control group (Table 1). Also, the change in 24-hour HR at 3 months was significantly different between groups. Three-month changes in 24-hour systolic BP, diastolic BP and HR were significantly lower for renal denervation patients with higher baseline HR compared to those with lower baseline HR (Table 2). Similar trends were not seen in the sham control group.Conclusions: In the SPYRAL HTN-OFF MED trial, significant reductions in HR were seen at 3 months in the renal denervation group but not in the sham control group. Post-hoc analyses suggest patients with higher baseline HR could experience greater reductions in ambulatory HR and BP post-renal denervation.

Undergraduate training for medical students on breaking bad news in oncology: A continuation study exploring the patient perspective

Social interaction quality is related to cardiovascular functioning. Trait emotional reactivity may amplify cardiovascular responses to social interactions, but is often examined as a tendency to react to negative events. We took a broader approach by examining the joint effects of positive and negative emotional reactivity and social interaction quality on ambulatory blood pressure (ABP) and heart rate (HR) responses to daily social interactions.Participants were part of a larger study on BP and cardiovascular health (N = 805; MAge = 45.3; 40.1% male). Participants completed a measure of emotional reactivity (BIS/BAS) and 24-hour ABP monitoring accompanied by ecological momentary assessments (EMA) about just-experienced social interactions and their pleasantness. Multilevel models tested the associations of emotional reactivity, average pleasantness, and momentary pleasantness with BP and HR.Participants who reported more pleasant interactions on average had lower BP (systolic BP: B = −0.51 mmHg; diastolic BP: B = −0.46 mmHg). These effects did not depend on emotional reactivity. The effect of momentary pleasantness depended on BIS/BAS; in less reactive participants, greater pleasantness was associated with lower HR, B = −0.13 bpm; in more reactive participants, greater pleasantness was associated with increased HR, B = 0.16).Participants who had more pleasant social interactions throughout the day had lower mean ABP. The acute effect of a given social interaction on HR depended on emotional reactivity: HR increased for participants high in emotional reactivity during pleasant interactions. Thus, emotional reactivity may influence cardiovascular responses to social stimuli.

The joint influence of emotional reactivity and social interaction quality on cardiovascular responses to daily social interactions in working adults

ObjectiveSocial interaction quality is related to cardiovascular functioning. Trait emotional reactivity may amplify cardiovascular responses to social interactions, but is often examined as a tendency to react to negative events. We took a broader approach by examining the joint effects of positive and negative emotional reactivity and social interaction quality on ambulatory blood pressure (ABP) and heart rate (HR) responses to daily social interactions. MethodsParticipants were part of a larger study on BP and cardiovascular health (N = 805; MAge = 45.3; 40.1% male). Participants completed a measure of emotional reactivity (BIS/BAS) and 24-hour ABP monitoring accompanied by ecological momentary assessments (EMA) about just-experienced social interactions and their pleasantness. Multilevel models tested the associations of emotional reactivity, average pleasantness, and momentary pleasantness with BP and HR. ResultsParticipants who reported more pleasant interactions on average had lower BP (systolic BP: B = −0.51 mmHg; diastolic BP: B = −0.46 mmHg). These effects did not depend on emotional reactivity. The effect of momentary pleasantness depended on BIS/BAS; in less reactive participants, greater pleasantness was associated with lower HR, B = −0.13 bpm; in more reactive participants, greater pleasantness was associated with increased HR, B = 0.16). ConclusionsParticipants who had more pleasant social interactions throughout the day had lower mean ABP. The acute effect of a given social interaction on HR depended on emotional reactivity: HR increased for participants high in emotional reactivity during pleasant interactions. Thus, emotional reactivity may influence cardiovascular responses to social stimuli.

Association Between Heart Rate and Subclinical Cerebrovascular Disease in the Elderly.

Although increased heart rate (HR) is a predictor of cardiovascular events and mortality, its possible association with subclinical cerebrovascular disease, which is prevalent in the elderly, has not been evaluated. This study aimed to investigate the association of daytime, nighttime, 24-hour HR, and HR variability with subclinical cerebrovascular disease in an elderly cohort without history of stroke. The study cohort consisted of 680 participants (mean age, 73±7 years; 42% men) in sinus rhythm who underwent 24-hour ambulatory blood pressure and HR monitoring, 2-dimensional echocardiography, and brain magnetic resonance imaging as part of the CABL study (Cardiac Abnormalities and Brain Lesion). Subclinical cerebrovascular disease was defined as silent brain infarcts and white matter hyperintensity volume (WMHV). The relationship of HR measures with the presence of silent brain infarct and upper quartile of log WMHV (log WMHV4) was analyzed. Presence of silent brain infarct was detected in 93 participants (13.7%); mean log WMHV was -0.92±0.93 (median, -1.05; min, -5.88; max, 1.74). Multivariate analysis showed that only nighttime HR (adjusted odds ratio, 1.29 per 10 bpm; 95% confidence interval, 1.03-1.61; P=0.026) was significantly associated with log WMHV4, independent of traditional cardiovascular risk factors, ambulatory systolic blood pressure, and echocardiographic parameters. No similar association was observed for daytime HR and HR variability. There was no significant association between all HR measures and silent brain infarct. In a predominantly elderly cohort, elevated nighttime HR was associated with WMHV, suggesting an independent role of HR in subclinical cerebrovascular disease.

The "Neurocentric" Approach to Essential Hypertension: How Reliable is the Paradigm of Hyperkinetic Hypertension? A Focus on the Sympathetic Nervous System Dysregulation in Essential Hypertensive Patients with Elevated Resting Heart Rate.

Clinic resting heart rate (RHR), is one of the cardiovascular parameters more easily measurable. In the general population RHR has been associated with total and cardiovascular mortality and higher rate of vascular events. The case of essential hypertension is in some ways peculiar: in the past decades has often been attributed to hypertensive subjects higher values of RHR than healthy controls as a result of the effects of the different factors leading to the development of essential hypertension itself, first of all the presence of an increased tone of the sympathetic nervous system Methods: Several excellent articles debated the issue of autonomic dysfunction in essential hypertension; nevertheless of this, after various decades of debate, this issue is to-date unresolved. The aim of this review is to discuss the reliability of the hypothesis that elevated resting heart rate in hypertensive subjects is associated to high blood pressure and both to elevated sympathetic nervous system activity or rather if these three phenomena coexist in a limited portion of subjects being not necessarily linked each other with a causal relationship. The ascertainment of the exact proportion of the hypertensive subjects having sympathetic overdrive appears to be hard, not only due to the multiple interferences and the constant interplay between the various determinants of the sympathetic tone, but also because a significant uncertainty remains with regard to the validity of the methods used for assessing the sympathetic tone. To date, any threshold used to define tachycardia is arbitrary. The percentage of hypertensive patients with elevated RHR varies considerably between the various studies, first of all because the modality of assessment influences the results. The "white coat tachycardia" is a clinical entity that must be taken into account. Ambulatory heart rate represents a good diagnostic alternative, since nocturnal mean heart rate appears to be the parameter with the highest prognostic value, probably because is less conditioned by external factors, being more representative of the "real" heart rate of the subject.

Effect of Diazepam on 24-Hour Blood Pressure and Heart Rate in Healthy Young Volunteers

Aim: To assess the effects of evening chronic administration of diazepam on 24-h blood pressure (BP) and heart rate (HR) in healthy young adults. Methods: This randomized double blind, cross-over study evaluated the effects of diazepam 5 mg or placebo, both ingested in the evening, on 24-h ambulatory BP and HR in healthy subjects aged 21–30. Results: A total of 30 subjects were included in the analysis. At the end of 4-week diazepam intake, an increase in 24-h HR mean values was found (+5.2 beats/min, p < 0.05). Analysis of subperiods showed that diazepam produced a 10.1% increase in night-time HR (+6.1 beats/min, p < 0.01) without affecting BP. A significant HR rise (+4.9 beats/min, p < 0.05) and SBP reduction (–3.8 mm Hg, p < 0.05) were observed in the morning hours. The HR increase persisted in day-time hours (+4.6 beats/min, p < 0.05), while BP values resulted unaffected. Conclusions: In healthy subjects, diazepam taken as a hypnotic agent induces a significant HR increase, possibly mediated by a decrease in vagal tone. This effect might be of clinical relevance due to the role that HR plays as an independent cardiovascular risk factor.

Ambulatory blood pressure results and heart rate variability in patients with premature ventricular contractions

ABSTRACTBackground: The presence of premature ventricular contractions (PVCs) is a sign of arrhythmia and typically trigerred by over stimulation of the sympathetic nervous system. This study examined the relationships among PVCs, heart rate variability (HRV), and 24-hour ambulatory blood pressure (ABP) results. Methods: This observational clinical study evaluated a cohort of 100 consecutive patients (58 women and 42 men) with PVCs. The individuals were split into occasional (n = 50) and frequent (n = 50) PVCs groups. All Holter recordings were performed during a working day. Results: Daytime low-frequency power (LFP), daytime low frequency/high frequency (LF/HF), nighttime LFP, and nighttime LF/HF and 24-hour systolic blood pressure (SBP) were slightly higher in the frequent PVCs group (p = 0.046, p = 0.027, p = 0.038, p = 0.032, and p < 0.001, respectively). Hypertension, LF, LF/HF, 24-hour SBP were positively correlated with PVCs (r = 0.305, p = 0.002; r = 0.269, p = 0.007; r = 0.403, p < 0.001, respectively). Conclusion: Frequent PVCs reflect dominance of the sympathetic system according to the results of Holter recordings. This study showed that PVC had a significant association with high blood pressure values. Assessment of ABP and HRV in patients with PVCs is part of a comprehensive approach to the assessment of cardiovascular regulation.

BP.11.05] URIC ACID AND HYPERTENSION. ROLE OF RENIN ANGIOTENSIN AND SYMPATHETIC NERVOUS SYSTEMS ACTIVITY

Objective: A number of studies have documented an association of serum uric acid (SUA) with risk of hypertension. We did a prospective study to investigate whether SUA was an independent predictor of risk of hypertension in the young and whether plasma renin activity (PRA) and office and ambulatory heart rates differed according to SUA tertile. Design and method: The study was conducted in a cohort of 1156 young-to-middle-age subjects screened for stage 1 hypertension and followed for a median of 11.4 years. Mean age was 33.0 ± 8.6 years and mean office blood pressure at screening was 145.3 ± 10.6/93.4 ± 5.8 mmHg. PRA was measured in 799 participants. In multivariable Cox analyses, data were adjusted for age, gender, body mass index, parental hypertension, 24-hour systolic and diastolic BP, serum creatinine, and lifestyle factors. Results: At follow-up end, 63.3% of study participants developed hypertension needing treatment. SUA was an independent predictor of future hypertension (p = 0.005). Participants with SUA >5.60 mg/dL (top tertile) had a 31% (95%CI, 6%-60%) increase in risk compared to those of the bottom tertile (SUA <4.32 mg/dL). Office heart rate, average 24-hour heart rate, and night-time heart rate significantly increased across SUA tertiles (p = 0.008, p = 0.033, and p = 0.007, respectively, for ANCOVA after adjusting for age, sex, and lifestyle factors). PRA adjusted for age, sex, smoking, coffee and alcohol use increased on going from the first to the third SUA tertile (mean ± SEM, 3.1 ± 0.5, 3.8 ± 0.4, and 4.9 ± 0.5 ng/ml/h, respectively, p = 0.038). Inclusion of physical activity in the model slightly attenuated the relationship (p = 0.044). PRA was lower in active than in sedentary participants (3.2 ± 0.7 versus 4.8 ± 0.4 ng/ml/h, p = 0.050) as were office and ambulatory heart rates (both p < 0.001). No association between SUA and risk of hypertension was found among the active participants (p = 0.71). Conclusions: In keeping with our previous results, these data confirm that SUA is an independent predictor of hypertension in young-to-middle-age subjects. This may be due to the unfavourable effect of SUA on several factors including sympathetic tone and renin-angiotensin-system activity. Regular physical activity can counteract these pathophysiological mechanisms and prevent the development of hypertension in hyperuricemic subjects.

Regular physical activity prevents development of hypertension in young people with hyperuricemia.

The association of serum uric acid (SUA) with risk of hypertension is controversial and may be modulated by lifestyle factors. We did a prospective study to investigate whether SUA was an independent predictor of hypertension in the young and whether physical activity influences this association. The study was conducted in a cohort of 1156 young to middle-age participants screened for stage 1 hypertension and followed for a median of 11.4 years. In multivariable Cox analyses, participants were stratified by tertiles of uric acid and physical activity habits. At follow-up end, 63.3% of the study participants developed hypertension needing treatment. In the whole group, SUA was an independent predictor of future hypertension (P = 0.005). Participants with SUA more than 5.60 mg/dl (top tertile) had a 31% increase in risk compared with those of the bottom tertile. However, the risk of hypertension related to SUA was increased only among the sedentary participants with a hazard ratio of 1.44 (95% confidence interval, 1.11-1.88) for the participants of the top SUA tertile. In contrast, among the active participants no association was found between SUA and risk of hypertension. Alcohol intake was another modulator of the SUA-hypertension relationship (hazard ratio, 95% confidence interval: 1.38, 1.02-1.87). Plasma renin activity, office and ambulatory heart rates, and metabolic variables were proportional to SUA level and were lower in active than sedentary participants. These data confirm that SUA is a predictor of hypertension and suggest that exercise may counteract the pathophysiological mechanisms involved in the association between hyperuricemia and future hypertension.

Acute Effects of Heated Water Based Exercise on Ambulatory Blood Pressure and Heart Rate Variability in Long Term Treated Elderly Hypertensive Patients

PURPOSE: Although heated water-based exercise (HEx) training has shown to largely reduce blood pressure (BP) in patients with resistant hypertension, the effect of a single exercise bout on ambulatory BP (ABP) in elderly subjects is unknown. Our purpose was to evaluate the acute effect of HEx versus land-based exercise (LEx) on ABP and heart rate variability (HRV) in long-term treated elderly hypertensive patients. METHODS: Twelve sedentary elderly hypertensive patients (6 women) aged 60±10 yr, under drug therapy for 15±3 yr, underwent a 30 min of HEx (walking inside the pool), LEx (walking on a treadmill) and nonexercise control session (CON) in random order (2-5 days between interventions). HEx and LEx intensity was set at 11-13 in the 6-20 RPE scale. HRV was analyzed before and after each intervention, and twenty-four hour (24-h) ABP monitoring was performed after each intervention. RESULTS: There was a tendency toward (P = 0.06) increase in low-frequency (pre = 43±7.3 n.u.; post = 57.9±5.5 n.u.) and decrease in high-frequency (pre = 56.7±7.3 n.u.; post = 42±5.5 n.u.) HRV after LEx, but no changes were observed after HEx and CON. However, 24-h (-6 mmHg), daytime (-6 mmHg) and nighttime (-6 mmHg) systolic ABP were significant lower (P < 0.05) after HEx than after LEx and CON. Although daytime (-3 mmHg) and nighttime (-4 mmHg) diastolic ABP was lower after HEx than after LEx and CON, this reduction was not statistically significant. CONCLUSIONS: Although there was an improvement in HRV after LEx, 24-h, daytime and nighttime systolic ABP reduced only after HEx. This result suggest that HEx may be superior than LEx to manage BP hypertension in long-term treated elderly hypertensive patients.

Cardioprotective Benefits Associated With Routine Physical Activity In Middle Aged Population

PURPOSE: It is well known that routine intensive physical activity (PA) will result in positive cardiovascular adaptations. Similarly, it is known that aging will cause decrements in similar common measures of cardiovascular health. However, there is only limited data on the cardiovascular performance of an older, presumably healthy, physically active population who have remained active for decades. METHODS: Thirteen masters level swimmers (MS) and eight controls (IC) (54.3 ± 12.7yrs and 57.5 ± 7.9yrs; respectively) were asked to wear an ambulatory heart rate monitor (Actiheart) for seven consecutive days. Subjects were partitioned based upon self-reported long-term physical activity and asked to maintain their normal daily activities for the entirety of the data collection period. Heart rate was collected during waking hours (14.8 ± 3.2 hrs). All HR data was verified via accelerometer. To measure HRpeak and estimate cardiovascular fitness level, subjects completed a 1-mile timed walk. Independent two-sample t-tests were used for all comparisons, significance set at p<0.05. RESULTS: Mean daily HRmin and HRavg was lower in MS than IC (54 ± 5 vs 67 ± 8bpm, 72 ± 8bpm vs. 83 ± 9bpm; p<0.05, respectively) while mean daily HRmax was higher in MS (139 ± 18bpm vs. 131 ± 19bpm; p<0.05). Mean daily HRmax was higher than HRpeak during the 1-mile test for MS (139 ± 19 vs. 123 ± 20bpm; p<0.05) but not for IC (131 ± 18 vs. 135 ± 18; p = 0.69). CONCLUSIONS: Persistent participation in routine physical activity at any age appears to result in training induced changes consistent with improved cardiovascular health. Results from the present study, however, suggest that a 1 mile walk may not be an appropriate test for the physically active as it tends to underestimate maximum values for heart rate.

Stress among Parents of Children with and without Autism Spectrum Disorder: A Comparison Involving Physiological Indicators and Parent Self-Reports

Parents of children with Autism Spectrum Disorder (ASD) have been reported as experiencing higher levels of stress and poorer physical health than parents of typically developing children. However, most of the relevant literature has been based on parental self-reports of stress and health. While research on physiological outcomes has grown in recent years, gaps still exist in our understanding of the physiological effects, if any, of stress related to parenting a child with ASD. The present study compared parent-reported stress, anxiety, and depression, as well as selected physiological measures of stress (i.e., cortisol, alpha-amylase, and ambulatory blood pressure and heart rate) between matched groups of parents of children with (N = 38) and without (N = 38) ASD. Participants completed questionnaires, collected saliva samples for the purpose of measuring cortisol and alpha-amylase, and wore an ambulatory blood pressure monitor for 24 h. Parents of children with ASD reported significantly higher levels of parental distress, anxiety, and depression than parents of typically developing children. Parent-reported distress, anxiety, depression, and health were not correlated with physiological measures. With the exception that parents of children with ASD had significantly lower cortisol levels 30 min after waking, no other significant group differences were found for physiological measures. Parents of children with ASD reported significantly higher use of a number of adaptive coping strategies (e.g., emotional support) in comparison to parents of typically developing children. Results are discussed in the context of implications for future research directions, stress research, and practical implications for parental support.

(315) Ambulatory heart rate variability identifies differences in sleep between people with fibromyalgia and matched controls

(315) Ambulatory heart rate variability identifies differences in sleep between people with fibromyalgia and matched controls

Masked tachycardia. A predictor of adverse outcome in hypertension.

The relative role of office heart rate (HR) and ambulatory HR for predicting major adverse cardiovascular events (MACEs) and mortality is not well known. Aim of this study was to investigate the association of white-coat tachycardia and masked tachycardia with MACE and mortality in hypertensive patients. We performed 24-h ambulatory blood pressure and HR monitoring in 7602 hypertensive patients (4165 men) aged 52 ± 16 years enrolled in six prospective studies in Italy, Japan, and Australia. Participants were divided into four groups: normal office and normal night-time HRs (N = 5238), white-coat tachycardia (N = 998), masked tachycardia (N = 796), and sustained tachycardia (N = 570). Median follow-up was 5.0 years. In age-and-sex-adjusted Cox model, using the normal HRs group as a reference, white-coat tachycardia was not a significant predictor of excess MACEs or all-cause death. In contrast, both masked tachycardia [hazard ratio, 95% confidence interval (CI); 1.40, 1.11-1.77] and sustained tachycardia (1.86, 1.44-2.40) were associated with risk of excess MACE. In addition, masked tachycardia (hazard ratio, 95% CI; 1.62, 1.14-2.29) but not sustained tachycardia (1.35, 0.83-2.19) was a significant predictor of excess mortality. These relationships held true in multivariable parsimonious Cox models including major risk factors. In these models, masked tachycardia remained an independent predictor of excess MACE (hazard ratio, 95% CI; 1.34, 1.06-1.71) and all-cause mortality (1.68, 1.18-2.41). The current study confirms that measurement of HR adds to the risk stratification for MACE and mortality and shows that an elevated night-time HR confers an increased mortality risk to hypertensive patients who have normal office HR.

Perceived social support predicts lower cardiovascular reactivity to stress in older adults

The benefits of perceived social support for physical and psychological health are well-established. However, little research has explored associations between perceived social support and cardiovascular reactivity in older adults. This exploratory study recruited a sample of older adults (Mage=69years, SD=5.62) and examined quality and quantity of perceived social support as predictors of cardiovascular reactivity to laboratory-based stress (N=39 participants) and ambulatory cardiovascular activity in everyday life (n=28). The results suggest that quality, but not quantity, of perceived social support predicts reduced blood pressure reactivity to stress in the laboratory. Although quality of support was not associated with ambulatory blood pressure, results suggest that quantity of daily social support may be associated with higher ambulatory heart rate, but not with social contact during measurement. This preliminary study extends prior work on social support and cardiovascular function to a group of older adults in both laboratory and field settings. Challenges for much-needed future research in this area are discussed.