Dataset Information

Acute Changes in Ambient Temperature Are Associated With Adverse Changes in Cardiac Rhythm.

ABSTRACT: BACKGROUND:Both increases and decreases in ambient temperature have been associated with increased cardiovascular mortality and morbidity. However, the mechanism(s) remain unclear. OBJECTIVES:We examined associations between biomarkers of pathways thought to, in part, explain these associations and changes in ambient temperature in a panel of predominantly post-myocardial infarction or post-stent patients. METHODS:We studied 76 subjects who had a recent coronary event and were participating in a cardiac rehabilitation program. In these patients, we measured heart rate variability, repolarization, and baroreflex sensitivity parameters using Holter ECG recordings before and during supervised, graded, twice weekly, exercise sessions. Hourly temperature measurements were made at a monitoring site near the rehabilitation center. RESULTS:Using linear mixed models, we observed decreases in rMSSD (square root of the mean of the sum of the squared differences between adjacent NN intervals) and deceleration capacity, associated with increases in ambient temperature in the previous four days. Additionally, decreased rMSSD was associated with both increasing temperature (mean in previous 6 hours) in the summer and decreasing temperature (mean in the previous 3 weeks) in the winter. CONCLUSIONS:In a panel of cardiac rehabilitation patients, changes in ambient temperature were associated with decreases in markers of heart rate variability and baroreflex sensitivity, which may lead to increased risk of arrhythmic events and sudden death in post-infarction patients.

SUBMITTER: Wasserman EB

PROVIDER: S-EPMC4215641 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Acute Changes in Ambient Temperature Are Associated With Adverse Changes in Cardiac Rhythm.

Wasserman Erin B EB Zareba Wojciech W Utell Mark J MJ Oakes David D Hopke Philip K PK Frampton Mark M Chalupa David D Beckett William W Rich David Q DQ

Air quality, atmosphere, & health 20140901 3

<h4>Background</h4>Both increases and decreases in ambient temperature have been associated with increased cardiovascular mortality and morbidity. However, the mechanism(s) remain unclear.<h4>Objectives</h4>We examined associations between biomarkers of pathways thought to, in part, explain these associations and changes in ambient temperature in a panel of predominantly post-myocardial infarction or post-stent patients.<h4>Methods</h4>We studied 76 subjects who had a recent coronary event and w ...[more]

PMID: 25368681

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Project description:BackgroundPrevious studies suggest that pathways reducing oxidative stress may have a protective effect against adverse cardiac responses associated with ambient PM. However, few studies have directly assessed total antioxidant capacity (TAC) as a potential effect modifier of cardiac responses to increased ambient PM.ObjectivesWe examined if TAC modifies the association between ambient PM and markers of heart rate variability (HRV), repolarization, systemic inflammation, and systolic blood pressure (SBP) in post-infarction patients.MethodsWe recruited 76 patients with a recent coronary event (myocardial infarction or unstable angina) who participated in a cardiac rehabilitation program from June 2006 to November 2009 in Rochester, New York. Ambient fine particle (PM2.5,≤2.5µm in aerodynamic diameter), accumulation mode particle (AMP, 100-500nm) and ultrafine particle (UFP, 10-100nm) concentrations were measured continuously by fixed-site monitors. Markers of HRV and repolarization were measured by continuous Holter electrocardiogram (ECG) recordings before and during exercise sessions of the rehabilitation program. Blood pressure was measured and venous blood samples were collected before exercise to measure TAC and inflammation markers. We applied linear mixed models to assess changes in markers of HRV, repolarization, systemic inflammation, and SBP associated with increased PM concentrations in the low, medium and high TAC tertile groups, after adjusting for covariates including temperature, calendar time since the beginning of the study, visit number, month of year, and hour of day.ResultsBased on subject-visits with available TAC, we observed increases in SBP, C-reactive protein, and fibrinogen, and decreases in rMSSD (square root of the mean of the sum of the squared differences between adjacent normal to normal intervals) and SDNN (standard deviation of normal to normal beat intervals) associated with increased PM2.5, AMP and UFP in the previous 6-120h (e.g. change in SBP associated with each interquartile range (IQR) increase in PM2.5 lagged 0-5h was 1.27mmHg [95%CI: 0.09, 2.46mmHg]). However, we did not observe a consistent pattern of effect measure modification by TAC for any combination of pollutant and outcome (e.g. changes in SBP associated with each IQR increase in PM2.5 lagged 0-5h for the low, medium and high TAC tertile groups were 1.93mmHg [95%CI: 0.23, 3.63 mmHg], -0.31 mmHg [95%CI: -2.62, 2.01 mmHg], and 1.29mmHg [95%CI: -0.64, 3.21 mmHg], respectively. P for interaction=0.28).ConclusionsIn a post-infarction population, total antioxidant capacity does not appear to modify the association between biomarkers of heart rate variability, repolarization, systemic inflammation, and systolic blood pressure and ambient PM concentrations in the previous 6-120h.

Project description:BackgroundClimate change is increasing global average temperatures, as well as the frequency of extreme weather events. Both low and high ambient temperatures have been associated with elevated mortality; however, little is known about the cardiovascular impacts of hourly temperature.MethodsWe assessed the association between hourly ambient temperature and risk of myocardial infarction (MI) across adult residents of New York State (NYS). We identified cases across NYS hospitals from 2000 to 2015 in the New York Department of Health Statewide Planning and Research Cooperative System dataset, using ICD codes. Hourly ambient temperature was assessed at each patient's residential ZIP code, up to 48 hours prior to MI. We employed a time-stratified case-crossover study design matching case to control periods on hour of day, day of week, month and year.ResultsOf the 791,695 primary MI hospital admissions, 45% were female, the mean (standard deviation; SD) age was 70 (15) years, and 49% of cases occurred among New York City residents. The observed temperature range was -29 °C to 39 °C, with a mean of 10.8 °C (10.5 °C). Temperature in the 6 h preceding the MI was positively associated with risk of MI, across the range of observed temperatures, with null or nearly null associations for earlier hours. We estimated a cumulative percent increase in hourly myocardial infarction rate of 7.9% (95% confidence interval [CI]: 5.2%, 10.6%) for an 11 °C (median) to 27 °C (95th percentile) temperature increase for lag hours 0-5. Men, Medicare-ineligible individuals (age < 65), and those experiencing their first MI were most sensitive.ConclusionOur study provides evidence that increases in hourly ambient temperature can trigger myocardial infarction. Health-based definitions of extreme heat events may better capture the deleterious effects of heat by accounting for hourly temperature. Our findings can inform the design of more effective preparedness strategies for the increasingly frequent extreme heat events.

Project description:Background and objectiveExposure to fine airborne particles (PM2.5) has been shown to be responsible for cardiovascular and hematological effects, especially in older people with cardiovascular disease. Some epidemiological studies suggest that individuals with diabetes may be a particularly susceptible population. This study examined effects of short-term exposures to ambient PM2.5 on markers of systemic inflammation, coagulation, autonomic control of heart rate, and repolarization in 22 adults (mean age: 61 years) with type 2 diabetes.MethodsEach individual was studied for four consecutive days with daily assessments of plasma levels of blood markers. Cardiac rhythm and electrocardiographic parameters were examined at rest and with 24-hour ambulatory ECG monitors. PM2.5 and meteorological data were measured daily on the rooftop of the patient exam site. Data were analyzed with models adjusting for season, weekday, meteorology, and a random intercept. To identify susceptible subgroups, effect modification was analyzed by clinical characteristics associated with insulin resistance as well as with oxidative stress and by medication intake.ResultsInterleukin (IL)-6 and tumor necrosis factor alpha showed a significant increase with a lag of two days (percent change of mean level: 20.2% with 95%-confidence interval [6.4; 34.1] and 13.1% [1.9; 24.4], respectively) in association with an increase of 10 mug/m3 in PM2.5. Obese participants as well as individuals with elevated glycosylated hemoglobin, lower adiponectin, higher ferritin or with glutathione S-transferase M1 null genotype showed higher IL-6 effects. Changes in repolarization were found immediately as well as up to four days after exposure in individuals without treatment with a beta-adrenergic receptor blocker.ConclusionsExposure to elevated levels of PM2.5 alters ventricular repolarization and thus may increase myocardial vulnerability to arrhythmias. Exposure to PM2.5 also increases systemic inflammation. Characteristics associated with insulin resistance or with oxidative stress were shown to enhance the association.

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Acute Changes in Ambient Temperature Are Associated With Adverse Changes in Cardiac Rhythm.

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Acute Changes in Ambient Temperature Are Associated With Adverse Changes in Cardiac Rhythm.

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