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ObjectiveEvidence points to a decreased breast cancer risk in systemic lupus erythematosus (SLE). We analyzed data from a large multisite SLE cohort, linked to cancer registries.MethodsInformation on age, SLE duration, cancer date, and histology was available. We analyzed information on histological type and performed multivariate logistic regression analyses of histological types according to age, SLE duration, and calendar year.ResultsWe studied 180 breast cancers in the SLE cohort. Of the 155 cases with histology information, 11 were referred to simply as 'carcinoma not otherwise specified'. In the remaining 144 breast cancers, the most common histological type was ductal carcinoma (n = 95; 66%) followed by lobular adenocarcinoma (n = 11; 8%), 15 cancers were of mixed histology, and the remaining ones were special types. In our regression analyses, the independent risk factors for lobular versus ductal carcinoma was age [odds ratio (OR) 1.07, 95% confidence interval (CI) 1.01-1.14] and for the 'special' subtypes it was age (OR 1.06, 95% CI 1.01-1.10) and SLE duration (OR 1.05, 95% CI 1.00-1.11).ConclusionsGenerally, up to 80% of breast cancers are ductal carcinomas. Though our results are not definitive, in the breast cancers that occur in SLE, there may be a slight decrease in the ductal histological type. In our analyses, age and SLE duration were independent predictors of histological status.

We postulated that the commonly observed constant linear relationship between VO2 and work rate during cycle ergometry to exhaustion is fortuitous and not due to an unchanging cost of external work. Therefore we measured VO2 continuously in 10 healthy men during such exercise while varying the rate of work incrementation and analyzed by linear regression techniques the relationship between VO2 and work rate (delta VO2/delta wr). After excluding the first and last portions of each test we found the mean +/- SD of the delta VO2/delta wr in ml.min-1.W-1 to be 11.2 +/- 0.15, 10.2 +/- 0.16, and 8.8 +/- 0.15 for the 15, 30, and 60 W.min-1 tests, respectively, expressed as ml.J-1 the values were 0.187 +/- 0.0025, 0.170 +/- 0.0027 and 0.147 +/- 0.0025. The slopes of the lower halves of the 15 and 30 W.min-1 tests were 9.9 +/- 0.2 ml.min-1.W-1 similar to the values for aerobic work reported by others. However the upper halves of the 15, 30, and 60 W.min-1 tests demonstrated significant differences: 12.4 +/- 0.36 vs 10.5 +/- 0.31 vs 8.7 +/- 0.23 ml.min-1.W-1 respectively. We postulate that these systematic differences are due to two opposing influences: 1) the fraction of energy from anaerobic sources is larger in the brief 60 W.min-1 tests and 2) the increased energy requirement per W of heavy work is evident especially in the long 15 W.min-1 tests.

Cigarette smoking is the primary cause of world-wide premature death. Therefore, thoracic physicians should try to inform patients of the harm smoking causes to airways and blood vessels. Unfortunately, in pursuing the goal of reducing the impact of chronic obstructive pulmonary disease, simple 'global' guidelines were established to identify airway obstruction, but only when the ratio of the one-second to forced vital capacity (FEV1/FVC) was less than 70%. The FEV1/FVC is the key identifier of airway obstruction and normally declines with age, approximately 1% every 4 years. At age 30, the mean FEV1/FVC for non-smokers is about 84%, minimally dependent on ethnicity, gender, or height. When a smoker's FEV1/FVC is a few percentage points below the mean predicted for their age, airway obstruction is likely. At age 30, FEV1/FVC values of 75% (9% below mean predicted) are statistically abnormal. Calling such a smoker 'normal' could be considered deceptive. I recommend that we: 1) identify airway obstruction early, especially in younger smokers; 2) counsel smokers and non-smokers regarding the damage smoking causes to airways and blood vessels; and 3) help our smokers with pharmacologic tools and single or group counseling to help them overcome their addiction. These practices should help reduce premature deaths. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mismatching of ventilation to perfusion is found in patients with COPD, left ventricular failure (LVF), and pulmonary vascular diseases. Such mismatching may be due to ventilation or perfusion defects or both. Our primary hypothesis was that pressures of mixed-expired CO2 pressure (Peco(2)), end-tidal Pco(2) pressure (Petco(2)), and their ratios would differ between groups during exercise testing, depending on whether the ventilation/perfusion (V/Q) abnormality was dominantly caused by airways or perfusion defects. METHODS: We administered incremental cycle ergometry tests to 25 normal subjects and three groups of 25 patients, each group with uncomplicated COPD, LVF, or primary pulmonary arterial hypertension (PAH). We compared Peco(2), Petco(2), and their ratios at rest, unloaded pedaling, anaerobic threshold, and peak exercise. RESULTS: Although each patient group had mean peak O(2) uptake of approximately 50% of predicted normal, the levels and patterns of change for each group for Peco(2), Petco(2), and their ratios were surprisingly distinctive. As hypothesized, the COPD group always had markedly lower Peco(2)/Petco(2) ratios than all other groups (p < 0.001). In addition, patients with LVF had slightly lower Peco(2)/Petco(2) ratios at heavy exercise than normal subjects (p < 0.05). At all times, except for COPD group Petco(2) at peak exercise, each group had significantly lower Petco(2) and Peco(2) than normal subjects (p < 0.001). In patients with PAH, the Petco(2) decline with exercise was distinctive. CONCLUSIONS: The levels and changes in Peco(2), Petco(2), and their ratios during cardiopulmonary exercise testing are distinctive and explained by the differing pathophysiologies of V/Q mismatching in these disorders. [ABSTRACT FROM AUTHOR]

BACKGROUND: Current authoritative spirometry guidelines use conflicting percentage of FEV(1)/FVC ratios (FEV(1)/FVC%) to define airway obstruction. The American Thoracic Society/European Respiratory Society Task Force characterizes obstruction as a FEV(1)/FVC% below the statistically defined fifth percentile of normal. However, many recent publications continue to use the Global Initiative for Chronic Obstructive Lung Disease (GOLD) primary criterion that defines obstruction as a FEV(1)/FVC% < 70%. Data from the Third National Health and Nutrition Examination Survey (NHANES-III) should identify and quantify differences, help resolve this conflict, and reduce inappropriate medical and public health decisions resulting from misidentification. METHODS: Using these two guidelines, individual values of FEV(1)/FVC% were compared by decades in 5,906 healthy never-smoking adults and 3,497 current-smokers of black (African American), Hispanic (Latin), or white ethnicities aged 20.0 to 79.9 years. RESULTS: In the never-smoking population, the lower limits of normal used in other reference equations fit reasonably well the NHANES-III statistically defined fifth percentile guidelines. But nearly one half of young adults with FEV(1)/FVC% below the NHANES-III fifth percentile of normal were misidentified as normal because their FEV(1)/FVC% was > 70% (abnormals misidentified as normal). Approximately one fifth of older adults with observed FEV(1)/FVC% above the NHANES-III fifth percentile had FEV(1)/FVC% ratios < 70% (normals misidentified as abnormal). CONCLUSIONS: The GOLD guidelines misidentify nearly one half of abnormal younger adults as normal and misidentify approximately one fifth of normal older adults as abnormal. [ABSTRACT FROM AUTHOR]

RATIONALE: Spirometric detection of airway obstruction in adults requires separate predictive formulae for each ethnicity and sex for percentage of FEV(1)/FVC (%FEV(1)/FVC) and percentage of FEV(3)/FVC (%FEV(3)/FVC), the major measurements for defining airway obstruction. OBJECTIVES: To eliminate the need for multiple formulae for black, Latin, and white men and women by developing single formulae with less variance than current formulae for %FEV(1)/FVC and %FEV(3)/FVC. METHODS: Data from nearly 6,000 healthy never-smokers 20.0-79.9 yr of age in the Third National Health and Nutrition Examination Survey were reevaluated mathematically and graphically based on the preliminary hypothesis that predictive normal FEV(1)/FVC and FEV(3)/FVC ratios could be calculated from the age and FVC alone, without considering ethnicity, sex, or height. Current and new formulae were evaluated, first considering the population as consisting of 36 equally weighted subgroups (6 decades x 3 ethnicities x 2 sexes) and then weighting each individual equally. MEASUREMENTS AND RESULTS: For each year of age, the slope of %FEV(1)/FVC versus FVC approximated -1.8%/l/yr; the slope of %FEV(3)/FVC versus FVC approximated -0.8%/l/yr. After trial and error iterations, the optimal formulae were %FEV(1)/FVC = 98.8 - 0.25 x years - 1.79 x FVC and %FEV(3)/FVC = 105.4 - 0.20 x years - 0.75 x FVC. CONCLUSIONS: These two new predicting formulae for %FEV(1)/FVC and %FEV(3)/FVC, which require only age and FVC as variables, approximate actual values closer than previously published separate formulae for each ethnicity and sex. With 95% confidence limits, they should allow better discrimination between normality and airway obstruction in adults of at least these three ethnicities. [ABSTRACT FROM AUTHOR]

Objectives: To develop mean and 95% confidence limits for the lower limit of normal (LLN) values for forced expiratory volume in 3 s (FEV3)/FVC ratio for Latin, black, and white adults; to ascertain comparative variability of the FEV1/FVC ratio, the FEV3/FVC ratio, and forced expiratory flow, midexpiratory phase (FEF(25-75)) in never-smoking adults; to evaluate their utility in measuring the effect of smoking on airflow limitation; and to develop and use the fraction of the FVC that had not been expired during the first 3 s of the FVC (1 - FEV3/FVC) to identify the growing fraction of long-time-constant lung units.Design: Analysis of the Third National Health and Nutrition Examination Survey (NHANES III) database of never-smokers and current smokers.Participants: A total of 5,938 adult never-smokers and 3,570 current smokers from NHANES III with spirometric data meeting American Thoracic Society standards.Measurements and Results: After establishing new databases for never-smokers and current smokers, we quantified the mean and LLN values of FEV3/FVC in never-smokers, and identified spirometric abnormalities in current smokers. When associated with older age, FEV3/FVC decreases and 1 - FEV3/FVC increases as FEV1/FVC decreases. On average, using these measurements, the condition of current smokers worsened about 20 years faster than that of never-smokers by middle age. If < 80% of the mean predicted FEF(25-75) was used to identify abnormality, over one quarter of all never-smokers would have been falsely identified as being abnormal. Using 95% confidence limits, 42% of 683 smokers with reduced FEV1/FVC and/or FEV3/FVC would have been judged as normal by FEF(25-75).Conclusions: FEV1/FVC, FEV3/FVC, and 1 - FEV3/FVC characterize expiratory obstruction well. In contrast, FEF(25-75) measurements can be misleading and can cause an unacceptably large number of probable false-negative results and probable false-positive results. [ABSTRACT FROM AUTHOR]

Objectives: Primary pulmonary hypertension (PPH) is a pulmonary vasculopathy resulting in exercise intolerance, usually due to dyspnea. We hypothesized that ventilation is increased during exercise in PPH relative to normal because the ventilated lung is underperfused, cardiac output increase is restricted, and arterial hypoxemia may develop. Our aim was to determine the size of the reduction in end-tidal PCO2 (PETCO2) as a reflection of the abnormality in ventilatory efficiency and ventilatory drive in PPH patients.Methods: We performed cardiopulmonary exercise testing (CPET) in 52 PPH patients. All had hemodynamic measurements to confirm the diagnosis of PPH. A subgroup of 29 patients who underwent right-heart catheterization within 50 days of CPET were studied to compare their CPET responses to resting hemodynamics. Nine healthy volunteers matched for age and gender served as CPET control subjects.Results: In PPH patients, the percentage of predicted peak oxygen uptake (O2) correlated significantly with mean pulmonary artery pressure (mPAP) [r = - 0.59, p = 0.0007, n = 29]. PETCO2 values at rest, anaerobic threshold (AT), and peak O2 were proportionately reduced as percentage of predicted peak O2 decreased (r = 0.66 to 0.72, p < 0.0001, n = 52). PETCO2 values at rest, AT, and peak O2 were also reduced as mPAP increased (r = - 0.51 to - 0.53, p < 0.005, n = 29). In contrast to normal subjects in whom PETCO2 increased from rest to AT, PETCO2 decreased in PPH patients, except for two patients with mild PPH in whom there was no change. Also, PETCO2 increased rather than decreased further at the start of recovery, in contrast to normal. Although usually normal at rest, oxyhemoglobin saturation decreased during exercise in most PPH patients.Conclusions: In patients with PPH, PETCO2 at rest and exercise is significantly reduced in proportion to physiologic disease severity. The range of values is unusually low. Furthermore, the directional changes of PETCO2 during exercise and early recovery are in the opposite direction of normal. [ABSTRACT FROM AUTHOR]

Background and Study Objective: Theoretically, cardiac output (CO) calculated by the Fick principle should be the same using O(2) (CO[O2]) or CO2 (CO[CO2]) as the test gas. However, agreement depends on the accuracy of gas exchange and blood gas measurements and the validity of the equations to convert measured variables into blood gas contents. Considering the widespread use of indirect estimates of pulmonary artery blood PCO2 and CO2 content to measure Fick principle CO during exercise, we wished to determine whether CO[O2] and CO[CO2] were equal during exercise and whether CO[CO2] could be accurately and precisely determined using direct measures of pulmonary artery blood. PREPARATION AND METHODS: Five healthy young nonsmoking volunteer men performed incremental exercise from rest to peak exercise on two separate occasions with intervening rest. Catheters were placed in brachial and pulmonary arteries to allow repeated blood sampling every minute during concurrent breath-by-breath gas exchange measurements from rest to peak exercise. CO[O2] was compared with CO[CO2] at multiple levels of exercise. Using standard equations, arterial and mixed venous O2 contents were calculated from hemoglobin concentration (Hb), oxyhemoglobin saturation (SO2), and PO2, whereas CO2 contents were calculated from PCO2, pH, Hb, and SO2. Blood gas analyzers were used for measurement of pH, PCO2, and PO2, and a co-oximeter was used for measurement of Hb and SO2. Initial calculations suggested that exercise CO[CO2] was 14% higher than CO[O2] and helped disclose small systematic measurement errors in PCO(2) for values > 45 mm Hg detected by proficiency testing surveys and documented with blood tonometry in the blood gas analyzer.Results: After correcting PCO2 for the small systematic measurement error found, the measures and equations used to calculate arterial and mixed venous O2 and CO2 contents were adequate to provide mean CO values that are reasonably similar. However CO[CO2] values were more than twice as variable as CO[O2].Conclusions: The increased variability of Fick principle CO[CO2] compared with CO[O2] is attributable to the much lower extraction ratio for CO2 and the greater complexity in calculation of blood CO2 than O2 contents. These results raise concerns about the accuracy and precision of estimating CO and stroke volume using CO2 as a test gas, even with direct measurement of blood CO2 contents in normal subjects. [ABSTRACT FROM AUTHOR]

Protein binding of disopyramide, binding capacities, affinity constants and serum concentrations of alpha 1-acid glycoprotein (AAG) were studied in five groups of patients. A: young healthy volunteers (n = 8); B: elderly patients with minor symptoms of ischaemic heart disease (n = 9); C: patients with cirrhosis of the liver and normal values of coagulation factors (II, VII and X), albumin and immunoglobulin G (n = 8); D: patients with cirrhosis and at least two abnormal of the previously mentioned values (n = 9) and E: eleven patients with severely impaired renal function. Subfractions of AAG (Fr1, Fr2 and Fr3) were determined by affinoimmunoelectrophoresis. AAG concentration was significantly (P less than 0.005) elevated in group E patients and decreased (P less than 0.025) in group D patients. Fr2 is probably associated with the high affinity, first binding site of disopyramide to AAG. Earlier observations of a reduced qualitative binding of disopyramide in patients with cirrhosis can be explained by a significant decrease in Fr2 (P less than 0.001) in group D patients. The protein binding of disopyramide in patients with uraemia was significantly increased due to a significant (P less than 0.005) increase in AAG concentration in spite of a smaller (P less than 0.025) affinity constant. Suggestions for therapeutic drug monitoring based on total serum concentrations are given. [ABSTRACT FROM AUTHOR]

Clearance of phenytoin after i.v. injection of 100 mg was studied in six patients before and after 2 weeks daily treatment with 450 mg rifampicin, and in 14 patients with tuberculosis receiving standard treatment with 450 mg rifampicin, 300 mg isoniazid, and 1200 mg ethambutol daily. Acetylator status was measured by urinary acetylated sulphadimidine. Clearance of phenytoin in patients receiving only rifampicin increased from 46.7 ml min-1 +/- 20.6 ml min-1 to 97.8 ml min-1 +/- 33.4 ml min-1 (P less than 0.01), while clearance in patients on three drugs increased from 47.1 +/- 23.4 ml min-1 to 81.3 ml min-1 +/- 41.6 ml min-1 (P less than 0.01). No significant differences were observed between the six fast acetylators and the eight slow acetylators. Phenytoin kinetics were unchanged after further 3 months of combined treatment. Rifampicin is a strong inducer of the elimination of phenytoin. Combined treatment with isoniazid has no counter-acting effect in either fast or slow acetylators. [ABSTRACT FROM AUTHOR]

Serum protein binding of propylthiouracil (PTU) was measured by ultrafiltration in healthy and hyperthyroid patients. The serum protein binding in 12 euthyroid subjects was 76.2 +/- 1.2% (mean +/- s.d.), not significantly different from the values in 10 hyperthyroid patients: 76.6 +/- 1.3% Binding was unaffected by incubation time and temperatures between 25 and 37 degrees C, but increased from 76.5 to 79.1% when pH changed from 7.4 to 7.9. PTU is predominantly bound to albumin with two classes of binding groups with different number of binding sites and affinity. Displacement experiments showed interaction with acetylsalicylic acid, warfarin and phenylbutazone, but not with antipyrine and nortriptyline or other basic drugs. [ABSTRACT FROM AUTHOR]

Abstract Background MicroRNAs (miRNAs) are post-transcriptional regulators involved in numerous biological processes including the pathogenesis of Alzheimer’s disease (AD). A key gene of AD, ADAM10, controls the proteolytic processing of APP and the formation of the amyloid plaques and is known to be regulated by miRNA in hepatic cancer cell lines. To predict miRNAs regulating ADAM10 expression concerning AD, we developed a computational approach. Methods MiRNA binding sites in the human ADAM10 3' untranslated region were predicted using the RNA22, RNAhybrid and miRanda programs and ranked by specific selection criteria with respect to AD such as differential regulation in AD patients and tissue-specific expression. Furthermore, target genes of miR-103, miR-107 and miR-1306 were derived from six publicly available miRNA target site prediction databases. Only target genes predicted in at least four out of six databases in the case of miR-103 and miR-107 were compared to genes listed in the AlzGene database including genes possibly involved in AD. In addition, the target genes were used for Gene Ontology analysis and literature mining. Finally, we used a luciferase assay to verify the potential effect of these three miRNAs on ADAM10 3'UTR in SH-SY5Y cells. Results Eleven miRNAs were selected, which have evolutionary conserved binding sites. Three of them (miR-103, miR-107, miR-1306) were further analysed as they are linked to AD and most strictly conserved between different species. Predicted target genes of miR-103 (p-value = 0.0065) and miR-107 (p-value = 0.0009) showed significant overlap with the AlzGene database except for miR-1306. Interactions between miR-103 and miR-107 to genes were revealed playing a role in processes leading to AD. ADAM10 expression in the reporter assay was reduced by miR-1306 (28%), miR-103 (45%) and miR-107 (52%). Conclusions Our approach shows the requirement of incorporating specific, disease-associated selection criteria into the prediction process to reduce the amount of false positive predictions. In summary, our method identified three miRNAs strongly suggested to be involved in AD, which possibly regulate ADAM10 expression and hence offer possibilities for the development of therapeutic treatments of AD.

Abstract Background Neutrophil gelatinase associated lipocalin (NGAL) is a biomarker of kidney injury. We examined plasma levels of NGAL in a cohort of 57 kidney allograft recipients (Tx group, 39 ± 13 years), a uraemic group of 40 patients remaining on the waiting list (47 ± 11 years) and a control group of 14 healthy subjects matched for age, sex and body mass index (BMI). The kidney graft recipients were studied at baseline before transplantation and 3 and 12 months after transplantation and the uraemic group at baseline and after 12 months. Methods NGAL was measured using a validated in-house Time-Resolved Immuno-flourometric assay (TRIFMA). Repeated measurements differed by < 10% and mean values were used for statistical analyses. Spearman rank order correlation analysis and the Kruskal-Wallis non-parametric test were used to evaluate the association of NGAL concentrations with clinical parameters. Results Plasma NGAL levels before transplantation in the Tx and uraemic groups were significantly higher than in the healthy controls (1,251 μg/L, 1,478 μg/L vs. 163 μg/L, p < 0.0001). In the Tx group NGAL concentrations were associated with serum creatinine (R = 0.51, p < 0.0001), duration of end-stage renal failure (R = 0.41, p = 0.002) and leukocyte count (R = 0.29, p < 0.026). At 3 and 12 months plasma NGAL concentrations declined to 223 μg/L and 243 μg/L, respectively and were associated with homocysteine (R = 0.39, p = 0.0051 and R = 0.47, p = 0.0007). Conclusions Plasma NGAL is a novel marker of kidney function, which correlates to duration of end-stage renal failure (ESRD) and serum creatinine in uraemic patients awaiting kidney transplantation. Plasma NGAL is associated with homocysteine in transplanted patients. The prognostic value of these findings requires further studies.

Objectives: As a part of the chain of survival, the emergency medical communication centre (EMCC) and the emergency medical dispatcher (EMD) has an important role in early identification of out-of-hospital cardiac arrests (OHCA). The EMD may provide instructions to the caller and thereby initiate cardiopulmonary resuscitation in a substantial number of subjects and thus contribute to increased survival. The EMCC provides a response with first responders, ambulances, physician manned units and potentially other health care providers. EMCC in many cases initiates the communication with experts in the referral hospital and provide added value to the post resuscitation care by providing advanced transport, logistics and follow up. In research there is a growing focus on the EMCC/EMDs impact on survival in OHCA. The lack of standards in reporting results from medical dispatching is an obstacle for thorough evaluation of results in this area and comparison of data. The objective for this paper is to introduce a framework for uniform reporting of the dispatching process for quality improvement, collecting and reporting data and exchanging information regarding OHCA. [ABSTRACT FROM AUTHOR]

Purpose: Recent diagnostic advantages enable detection of cerebral palsy (CP) in infants before five months of age. Parents of children with CP often face mental health problems, but specific knowledge for infancy is needed. In this study, depressive symptoms in mothers of 16-week-old infants and associations with infant development were investigated., Materials and Methods: This cross-sectional study involves 56 families, 22 high-risk and 34 infants without risk of CP. High-risk-CP was identified following international clinical guidelines. We assessed infant cognitive and language development using the Bayley-III and motor development using the Alberta Infant Motor Scale. Maternal depressive symptoms were self-reported using the Edinburgh Postnatal Depression Scale., Results: Mothers of CP high-risk infants were 15.6 times more likely to experience risk of postnatal depression compared to mothers of infants without risk. Additionally, linear regression analyses showed that having an infant at high-risk of CP ( β = .359, p = .006) and delayed language development ( β = -0.510, p < .001) were associated with increased maternal depressive symptoms., Conclusions: We recommend systematic screening of postnatal depressive symptoms following detection of high-risk-CP in infants. Early interventions could include a mother-infant interactional component to support caregivers in interpreting and responding to infant communicative cues.

Background: Emerging evidence suggests that routine physical activity may improve exercise capacity, long-term outcomes, and quality of life in individuals with Fontan circulation. Despite this, it is unclear how active these individuals are and what guidance they receive from medical providers regarding physical activity. The aim of this study was to survey Fontan patients on personal physical activity behaviours and their cardiologist-directed physical activity recommendations to set a baseline for future targeted efforts to improve this., Methods: An electronic survey assessing physical activity habits and cardiologist-directed guidance was developed in concert with content experts and patients/parents and shared via a social media campaign with Fontan patients and their families., Results: A total of 168 individuals completed the survey. The median age of respondents was 10 years, 51% identifying as male. Overall, 21% of respondents spend > 5 hours per week engaged in low-exertion activity and only 7% spend > 5 hours per week engaged in high-exertion activity. In all domains questioned, pre-adolescents reported higher participation rates than adolescents. Nearly half (43%) of respondents reported that they do not discuss activity recommendations with their cardiologist., Conclusions: Despite increasing evidence over the last two decades demonstrating the benefit of exercise for individuals living with Fontan circulation, only a minority of patients report engaging in significant amounts of physical activity or discussing activity goals with their cardiologist. Specific, individualized, and actionable education needs to be provided to patients, families, and providers to promote and support regular physical activity in this patient population.

Purpose: Physical activity and a healthy lifestyle play an essential role in optimizing long-term health in patients with Fontan physiology. Wrist-worn activity trackers may be useful in medically directed exercise programs for patients with Fontan physiology. The objective of this study was to measure the validity of Garmin and Fitbit activity tracker heart rate detection in patients with Fontan circulation when compared to electrocardiogram (ECG) during cardiopulmonary exercise testing (CPET)., Methods: 47 Fontan patients undergoing CPET for clinical indications were included and wore activity trackers during CPET. Heart rate via the activity tracker was collected at baseline, maximal exercise, and recovery. Patient heart rates, peak VO2, and peak respiratory exchange ratio (RER) were collected using standard CPET protocols and equipment. Heart rate at each time point was compared between the activity trackers and CPET ECG., Results: Median age of participants was 17.1 years, 15.1 years since Fontan completion. Mean percent of predicted peak VO2 was 56.8%, z-score -3.2 with 61.7% of participants completing a maximal CPET (RER ≥ 1.09). Baseline oxygen saturation mean was 92.9%, 90.0% at maximal exercise. Activity trackers demonstrated mean absolute percentage error < 10% at most time points, comparable with other studies. Demographics, Fontan-associated comorbidities, and echocardiogram findings did not impact the accuracy., Conclusions: Consumer-oriented wrist-worn activity trackers show promising accuracy for heart rate monitoring in medically directed exercise programs for adolescents and young adults with Fontan physiology. Further validation across different exercise modalities is needed., Competing Interests: Conflict of Interest and Funding Source: The authors have no funding source for the present study. The authors disclose no relevant conflicts of interest in the present study., (Copyright © 2024 by the American College of Sports Medicine.)