Obstructive sleep apnea is associated with increased high-sensitivity cardiac troponin T levels

Obstructive sleep apnea, myocardial perfusion and myocardial blood flow: A study of older male twins

BACKGROUND

Obstructive sleep apnea (OSA) has been associated with incidence of cardiovascular disease and with nocturnal angina, but evidence of a link with coronary atherosclerosis and myocardial ischemia is limited and previous studies may have been affected by selection bias or unmeasured confounding factors.

METHODS

We performed overnight polysomnography in 178 older male twins. The Apnea/Hypopnea Index (AHI) was calculated to assess OSA from the overnight sleep evaluation. AHI ≥15 was used as indicator of moderate/severe OSA. The following day, twins underwent myocardial perfusion imaging with [82Rb]-chloride positron emission tomography. Quantitative and semiquantitative measures of myocardial perfusion and absolute myocardial blood flow were obtained.

RESULTS

The mean age was 68 years and 40% of the sample had an AHI≥15, which indicates moderate to severe OSA. Abnormal myocardial perfusion, both with stress and at rest, was more common in twins with elevated AHI. After adjusting for clinical, lifestyle and behavioral factors, and previous history of cardiovascular disease, twins with AHI ≥15 had 3.6 higher odds (95% CI, 1.5-8.9) of an abnormal total severity score, defined as a score ≥100, and for each 5-point increment in AHI, the odds of abnormality increased by 20% (95% CI, 7%-34%). Twin pairs where both twins had OSA exhibited the greatest risk. There were no differences in measures of ischemia and absolute myocardial blood flow and flow reserve by AHI status.

CONCLUSIONS

OSA is associated with myocardial perfusion abnormalities that suggest prior subclinical myocardial scarring or infarction. Early environmental factors that affect both twins equally may play a role and should be further explored.

Novel oxygen desaturation parameters are associated with cardiac troponin I: Data from the Akershus Sleep Apnea Project

Novel diagnostic markers for obstructive sleep apnea beyond the apnea-hypopnea index (AHI) have been introduced. There are no studies on their association with markers of subclinical myocardial injury. We assessed the association between novel desaturation parameters and elevated cardiac troponin I and T. Participants with polysomnography (498) from the Akershus Sleep Apnea study were divided into normal and elevated biomarker groups based on sex-specific concentration thresholds (cardiac troponin I: ≥4 ng/L for women, ≥6 ng/L for men; and cardiac troponin T: ≥7 ng/L for women, ≥8 ng/L for men). Severity of obstructive sleep apnea was evaluated with the AHI, oxygen desaturation index, total sleep time with oxygen saturation below 90% (T90), lowest oxygen saturation (Min SpO₂ %), and novel oxygen desaturation parameters: desaturation duration and desaturation severity. How the AHI and novel desaturation parameters predicted elevated cardiac troponin I and cardiac troponin T levels was assessed by the area under the curve (AUC). Based on multivariable-adjusted linear regression, the AHI (β = 0.004, p = 0.012), desaturation duration (β = 0.007, p = 0.004), and desaturation severity (β = 0.147, p = 0.002) were associated with cardiac troponin I levels but not cardiac troponin T. T90 was associated with cardiac troponin I (β = 0.006, p = 0.009) and cardiac troponin T (β = 0.005, p = 0.007). The AUC for the AHI 0.592 (standard error 0.043) was not significantly different from the AUC of T90 (SD 0.640, p = 0.08), desaturation duration 0.609 (SD 0.044, p = 0.42) or desaturation severity 0.616 (SD 0.043, p = 0.26) in predicting myocardial injury as assessed by cardiac troponin I. Oxygen desaturation parameters and the AHI were associated with cardiac troponin I levels but not cardiac troponin T levels. Novel oxygen desaturation parameters did not improve the prediction of subclinical myocardial injury compared to the AHI.

Effects of curtailed sleep on cardiac stress biomarkers following high-intensity exercise

Objective

Physical exercise—especially at high intensity—is known to impose cardiac stress, as mirrored by, e.g., increased blood levels of cardiac stress biomarkers such as cardiac Troponin T (cTnT) and NT-proBNP. We examined healthy young participants to determine whether a few nights of short sleep duration alter the effects of acute exercise on these blood biomarkers.

Methods

Sixteen men participated in a randomized order in a crossover design, comprising three consecutive nights of a) normal sleep duration (NS, 8.5 h of sleep/night) and b) sleep restriction (SR, 4.25 h of sleep/night). Blood was repeatedly sampled for determination of NT-proBNP and cTnT serum levels before and after a high-intensity exercise protocol (i.e., 75% VO₂^maxReserve cycling on an ergometer).

Results

Under pre-exercise sedentary conditions, blood levels of cTnT and NT-proBNP did not significantly differ between the sleep conditions (P > 0.10). However, in response to exercise, the surge of circulating cTnT was significantly greater following SR than NS (+37–38% at 120–240 min post-exercise, P ≤ 0.05). While blood levels of NT-proBNP rose significantly in response to exercise, they did not differ between the sleep conditions.

Conclusion

Recurrent sleep restriction may increase the cardiac stress response to acute high-intensity exercise in healthy young individuals. However, our findings must be further confirmed in women, older subjects and in patients with a history of heart disease.

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Chronic sleep curtailment increases the risk of cardiovascular disease.

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Here, we examined whether exercise-induced cardiac strain in healthy young adults is altered by sleep curtailment.

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Blood levels of the cardiac stress marker troponin were higher after exercise under conditions of recurrent sleep restriction.

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Sleep restriction may increase exercise-induced cardiac strain in adults.

Cardiopulmonary coupling and serum cardiac biomarkers in obesity hypoventilation syndrome and obstructive sleep apnea with morbid obesity

STUDY OBJECTIVES

The main cause of death in patients with obesity hypoventilation syndrome (OHS) is cardiac rather than respiratory failure. Here, we investigated autonomic-respiratory coupling and serum cardiac biomarkers in patients with OHS and obstructive sleep apnea (OSA) with comparable body mass index (BMI) and apnea-hypopnea index (AHI).

METHODS

Cardiopulmonary coupling (CPC) and cyclic variation of heart rate (CVHR) analysis was performed on the electrocardiogram signal from the overnight polysomnogram. Cardiac serum biomarkers were obtained in patients with OHS and OSA with a BMI > 40kg/m². Samples were obtained at baseline and after 3 months of positive airway pressure (PAP) therapy in both groups.

RESULTS

Patients with OHS (n=15) and OSA (n=36) were recruited. No group differences in CPC, CVHR and serum biomarkers were observed at baseline and after 3 months of PAP therapy. An improvement in several CPC metrics, including the sleep apnea index, unstable sleep (low frequency coupling and elevated low frequency coupling narrow band [e-LFC_NB]) and CVHR were observed in both groups with PAP use. However, distinct differences in response characteristics were noted. e-LFC_NB coupling correlated with highly sensitive troponin (hs-troponin-T, p<0.05) in the combined cohort. Baseline hs-troponin-T inversely correlated with awake oxygen saturation in the OHS group (p<0.05).

CONCLUSIONS

PAP therapy can significantly improve CPC stability in obese patients with OSA or OHS, with key differences. e-LFC_NB may function as a surrogate biomarker for early subclinical cardiac disease. Low awake oxygen saturation could also increase this biomarker in OHS.

CLINICAL TRIAL REGISTRATION

Registry: Australian New Zealand Clinical Trials Registry; Name: Obesity Hypoventilation Syndrome and Neurocognitive Dysfunction; URL: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367492; Identifier: ACTRN12615000122550.

The impact of cardiac troponin in elderly patients in the absence of acute coronary syndrome: A systematic review

Comorbidities are common risk factors for rising cardiac troponin in non-acute coronary syndromes conditions. Furthermore, the risk for all-cause mortality appears to be correlated to the troponin levels. Consequently, measurement of cardiac troponin in hospital admission may contribute to predict the mortality risk in elderly patients. Among geriatric patients without acute coronary syndrome, with concomitant diseases, the correct interpretation of elevated cardiac troponin, particularly in emergency conditions poses a diagnostic dilemma. Although in several studies it is suggested that at the presence of comorbidity, there is an increase in cardiac troponin values, the elderly patients have not been included conclusively. In order to assess the diagnostic and prognostic role of cardiac troponin elevation in geriatric patients suffering from chronic diseases, a systematic review was performed. The study included the elderly patients free of acute coronary syndrome admitted to the hospital with concomitant disease, with a report of at least one cardiac troponin measurement. We found that elevated cardiac troponin is an independent prognostic factor, predicting all-cause morbidity and mortality burden in geriatric patients without acute coronary syndromes.

Evaluation of right ventricular performance and impact of continuous positive airway pressure therapy in patients with obstructive sleep apnea living at high altitude

Obstructive sleep apnea syndrome (OSAS) can lead to alterations in right ventricular (RV) performance and pulmonary vascular haemodynamics. Additionally, altitude-related hypoxia is associated with pulmonary vasoconstriction, and the effect of high-altitude on the pulmonary circulation in OSAS patients can be further altered. We sought to assess alterations in RV morphology and function in OSAS patients living at high altitude by way of 2-dimensional speckle tracking echocardiography (2D-STE), real-time 3- dimensional echocardiography (RT-3DE) and cardiac biomarkers. We also evaluate the impact of continuous positive airway pressure (CPAP) treatment on RV performance. Seventy-one patients with newly diagnosed OSAS and thirty-one controls were included in this study. All individuals were assessed for cardiac biomarkers as well as underwent 2D-STE and RT-3DE. Forty-five OSAS patients underwent CPAP therapy for at least 24 weeks and were studied before and after CPAP treatment. RT-3DE was used to measure RV volume, and calculate RV 3D ejection fraction (3D RVEF). Peak systolic strain was determined. Cardiac biomarkers, including C-reactive protein (CRP), N-terminal pro-B-type natriuretic peptide, and cardiac troponin T were also measured. Right atrium volume index, RV volume, RV volume index, systolic pulmonary artery pressure (sPAP), pulmonary vascular resistance (PVR) and level of serum CRP were significantly higher in OSAS group, while OSAS patients showed lower 3D RVEF and RV longitudinal strains. Compared to the patients with sPAP < 40 mmHg, RV longitudinal strains in patients with sPAP ≥ 40 mmHg were lower. Both RV global longitudinal strain and sPAP were associated with apnea–hypopnea index. Patients treated with 6 months of CPAP therapy had significant improvement in RV geometry and performance. RV structural abnormalities and RV function impairments were observed in OSAS patients living at moderate high altitude compared to control highlanders. The reversibility of these changes after application of CPAP were further confirmed.

Interactions among Obstructive Sleep Apnea Syndrome Severity, Sex, and Obesity on Circulatory Inflammatory Biomarkers in Patients with Suspected Obstructive Sleep Apnea Syndrome: A Retrospective, Cross-Sectional Study

The interaction among obstructive sleep apnea syndrome (OSAS) severity, sex, and obesity on cardiovascular risk as determined by serum levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) remains unclear. Therefore, this study aimed to analyze individual associations between these three OSAS characteristics and three cardiovascular biomarkers and to determine whether the relationship was affected by other features in patients with suspected OSAS. For all participants (n = 100), OSAS severity and sex had an interaction effect on IL-6 level (p = 0.030). Specifically, the male patients (p = 0.005) with severe OSAS had higher IL-6 levels than those with normal to moderate OSAS, but this relationship was not significant in the female patients (p = 0.438). Moreover, in patients with normal to moderate OSAS (p = 0.004), but not in those with severe OSAS (p = 0.824), the female patients had higher IL-6 levels than the male patients. Both CRP (p = 0.001) and IL-6 (p = 0.000) levels were higher in the obese group than in the non-obese group independently of OSAS severity and sex. The three features had no effects on TNF-α level individually and interactively. Our findings suggest that circulatory inflammatory markers should be comprehensively evaluated in this population and that treatment and preventive therapies should be modified accordingly.

Sleep apnea and galectin-3: possible sex-specific relationship

PURPOSE

Sleep apnea is associated with increased risk of cardiovascular disease. Elevated plasma galectin-3 levels, a biomarker associated with myocardial fibrosis, are also associated with adverse cardiovascular events, including heart failure. Our objective was to determine the relationship between severity of sleep apnea and plasma levels of galectin-3 and to determine whether this relationship was modified by sex.

METHODS

We performed a cross-sectional study of 471 Mexican Americans from Starr County, TX who underwent an overnight, in-home sleep evaluation, and plasma measurement of galectin-3. Severity of sleep apnea was based on apnea hypopnea index (AHI). Multivariable linear regression modeling was used to determine the association between categories of sleep apnea and galectin-3. We also tested for interactions by sex.

RESULTS

The mean age was 53 years, and 74% of the cohort was female. The prevalence of moderate to severe sleep apnea (AHI > 15 apnea-hypopnea events per hour) was 36.7%. Moderate to severe sleep apnea was associated with increased levels of galectin-3 in the entire population, but we identified a statistically significant interaction between galectin-3 levels and category of sleep apnea by sex (p for interaction = 0.02). Plasma galectin levels were significantly higher in women with moderate or severe sleep apnea than women with no/mild sleep apnea (multivariable adjusted p < 0.001), but not in men (p = 0.5).

CONCLUSIONS

Sleep apnea is associated elevated galectin-3 levels in women but not men. Our findings highlight a possible sex-specific relationship between sleep apnea and galectin-3, a biomarker of potential myocardial fibrosis that has been associated with increased cardiovascular risk.

Untreated Obstructive Sleep Apnea Is Associated With Myocardial Injury Independent of Blood Pressure Control in Hypertension

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) and hypertension are independent risk factors of cardiovascular morbidities. This study aims to investigate the relationship between OSA, blood pressure (BP) control, and myocardial injury in patients with difficult-to-control hypertension.

METHODS

Patients with hypertension who required three or more medications were prospectively recruited at a tertiary referral center. In-laboratory polysomnography, followed by blood tests for fasting glucose, glycated hemoglobin, lipids, high-sensitivity troponin I (hsTnI), B-type natriuretic peptide (BNP), C-reactive protein, and advanced oxidation protein products were performed. After polysomnography, 24-hour ambulatory BP monitoring was arranged.

RESULTS

A total of 98 participants were analyzed, with mean age 51 ± 9 years and body mass index 30 ± 5 kg/m². Previously undiagnosed severe OSA (apneahypopnea index [AHI] ≥ 30 events/h) was present in 51 patients (52%). hsTnI was negatively correlated with nocturnal dip in systolic BP (r = -.205, P = .048). After controlling for confounders, including BP control, AHI and oxygen desaturation index (ODI) were positively correlated with hsTnI (r = .282, P = .009 and r = .279, P = .010, respectively) and C-reactive protein (r = .302, P = .005 and r = .285, P = .008, respectively), but not with BNP or advanced oxidation protein products. Age, ODI, and loss of nocturnal systolic BP dip were significant determinants of hsTnI level (β = .225, P = .022; β = .293, P = .003; and β = -.215, P = .029; R² = .151). Age, female sex, 24-hour mean diastolic BP, and metabolic syndrome, but not indices of apnea severity, were predictors of BNP level.

CONCLUSIONS

Unrecognized severe OSA was common in patients with difficult-to-control hypertension, and OSA severity was associated with myocardial injury, independent of BP control with medications.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov, Title: A Cross-sectional Study of the Occurrence and Effect of Obstructive Sleep Apnea in Subjects With Resistant Hypertension, Identifier: NCT00843583, URL: https://clinicaltrials.gov/ct2/show/NCT00843583.

High-sensitivity cardiac troponin T in obstructive sleep apnea patients without cardiovascular diseases: Efficacy of CPAP treatment

The aims of this article were to determine the levels of serum high-sensitivity cardiac troponin T (hs-cTnT) in obstructive sleep apnea (OSA) patients without cardiovascular disease (CVD) and to assess the efficacy of continuous positive airway pressure (CPAP). Snorers referred for polysomnography (PSG) for the investigation of OSA were eligible and hs-cTnT levels measured in our pilot study. Hs-cTnT was measured again after 3 months of CPAP treatment in participants with severe OSA. A total of 93 participants recruited after PSG. When compared with simple snoring group, severe OSA group had comparable higher hs-cTnT (7.5 ± 3.0 vs. 5.0 ± 2.1; p < 0.05). Hs-cTnT was positively correlated with apnea hypopnea index, and oxygen desaturation index (r = 0.283, 0.282; p = 0.006, 0.006, respectively). Hs-cTnT levels were not significantly altered in 28 individuals who received 3 months of CPAP treatment (8.4 ± 2.4 vs.7.6 ± 2.1; p = 0.064). Elevated hs-cTnT levels were observed in severe OSA patients without CVD, and CPAP treatment had no influence on this levels.

Repercusiones cardiovasculares del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

En la población de sujetos con síndrome de apnea-hipopnea obstructiva del sueño se describen entidades clínicas cardiovasculares asociadas con esta entidad y que afectan su curso y pronóstico. Dentro de estas se encuentran hipertensión arterial, arritmias, enfermedad coronaria, insuficiencia cardíaca, hipertensión pulmonar y tromboembolismo venoso. Del mismo modo, se describen los mecanismos fisiopatológicos de estas asociaciones, su prevalencia e impacto. Dado que afectan el curso de la enfermedad y, por tanto, la severidad de la misma, estas entidades juegan un papel muy importante en la toma de decisiones al momento de ofrecer el mejor manejo en cada caso, el cual debe ser abordado de forma multidisciplinaria.

Biomarkers in Sleep Apnea and Heart Failure

PURPOSE OF REVIEW

Sleep-disordered breathing (SDB) is highly prevalent in heart failure (HF) and may confer significant stress to the cardiovascular system and increases the risk for future cardiovascular events. The present review will provide updates on the current understanding of the relationship of SDB and common HF biomarkers and the effect of positive airway pressure therapy on these biomarkers, with particular emphasis in patients with coexisting SDB and HF.

RECENT FINDINGS

Prior studies have examined the relationship between HF biomarkers and SDB, and the effect of SDB treatment on these biomarkers, with less data available in the context of coexisting SDB and HF. Overall, however, the association of SDB and circulating biomarkers has been inconsistent. Further research is needed to elucidate the relationship between biomarkers and SDB in HF, to evaluate the clinical utility of biomarkers over standard methods in large, prospective studies and also to assess the impact of treatment of SDB on these biomarkers in HF via interventional studies.

Predictors of obstructive sleep apnoea in patients admitted for acute coronary syndrome

Identifying undiagnosed obstructive sleep apnoea (OSA) patients in cardiovascular clinics could improve their management. Aiming to build an OSA predictive model, a broad analysis of clinical variables was performed in a cohort of acute coronary syndrome (ACS) patients.

Sociodemographic, anthropometric, life-style and pharmacological variables were recorded. Clinical measures included blood pressure, electrocardiography, echocardiography, blood count, troponin levels and a metabolic panel. OSA was diagnosed using respiratory polygraphy. Logistic regression models and classification and regression trees were used to create predictive models.

A total of 978 patients were included (298 subjects with apnoea–hypopnoea index (AHI) <15 events·h−1and 680 with AHI ≥15 events·h−1). Age, BMI, Epworth sleepiness scale, peak troponin levels and use of calcium antagonists were the main determinants of AHI ≥15 events·h−1(C statistic 0.71; sensitivity 94%; specificity 24%). Age, BMI, blood triglycerides, peak troponin levels and Killip class ≥II were determinants of AHI ≥30 events·h−1(C statistic of 0.67; sensitivity 31%; specificity 86%).

Although a set of variables associated with OSA was identified, no model could successfully predict OSA in patients admitted for ACS. Given the high prevalence of OSA, the authors propose respiratory polygraphy as a to-be-explored strategy to identify OSA in ACS patients.

Sleep apnea in total joint arthroplasty patients and the role for cardiac biomarkers for risk stratification: an exploration of feasibility

Obstructive sleep apnea (OSA) is highly prevalent in patients undergoing total joint arthroplasty (TJA) and is a major risk factor for postoperative cardiovascular complications and death. Recognizing this, the American Society of Anesthesiologists urges clinicians to implement special considerations in the perioperative care of OSA patients. However, as the volume of patients presenting for TJA increases, resources to implement these recommendations are limited. This necessitates mechanisms to efficiently risk stratify patients having OSA who may be susceptible to post-TJA cardiovascular complications. We explore the role of perioperative measurement of cardiac troponins (cTns) and brain natriuretic peptides (BNPs) in helping determine which OSA patients are at increased risk for post-TJA cardiovascular-related morbidity.

Natriuretic Peptide and High-Sensitive Troponin T Concentrations Correlate with Effectiveness of Short-Term CPAP in Patients with Obstructive Sleep Apnea and Coronary Artery Disease

The risk of cardiovascular complications is increased in patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) is the most effective way to treat clinically significant OSA. We hypothesized that the concentrations of the cardiac risk markers N-terminal brain natriuretic peptide (NT-proBNP) and high-sensitive troponin T (hs-TropT) correlate with the effectiveness of CPAP therapy in patients with OSA and coexisting coronary artery disease (CAD). Twenty-one patients with severe OSA and coexisting CAD (group 1) and 20 control patients with severe OSA alone (group 2) were treated with CPAP and monitored by laboratory-based polysomnography. NT-proBNP and hs-TropT levels were measured before and after CPAP. Apnea-hypopnea index (AHI) and oxygen desaturation were similar in both groups. In group 1, hs-TropT levels correlated with AHI and oxygen desaturation upon CPAP. Elevated NT-proBNP levels in group 1 were significantly reduced by CPAP. NT-proBNP levels correlated with AHI and showed negative correlation with ST-segment depression. No such correlations were found in group 2. CPAP has the potential to normalize elevated NT-proBNP serum levels in patients with severe OSA and coexisting CAD. Levels of NT-proBNP and hs-TropT correlated with AHI and oxygen desaturation.

A clinical approach to obstructive sleep apnea as a risk factor for cardiovascular disease

Obstructive sleep apnea (OSA) is associated with cardiovascular risk factors, cardiovascular diseases, and increased mortality. Epidemiological studies have established these associations, and there are now numerous experimental and clinical studies which have provided information on the possible underlying mechanisms. Mechanistic proof-of-concept studies with surrogate endpoints have been performed to demonstrate that treatment of OSA by continuous positive airway pressure (CPAP) has the potential to reverse or at least to attenuate not only OSA but also the adverse cardiovascular effects associated with OSA. However, no randomized studies have been performed to demonstrate that treatment of OSA by CPAP improves clinical outcomes in patients with cardiovascular risk factors and/or established cardiovascular disease and concomitant OSA. In the present review, we summarize the current knowledge on the role of OSA as a potential cardiovascular risk factor, the impact of OSA on cardiac function, the role of OSA as a modifier of the course of cardiovascular diseases such as coronary artery disease, atrial fibrillation, and heart failure, and the insights from studies evaluating the impact of CPAP therapy on the cardiovascular features associated with OSA.

Markers of Myocardial Ischemia in Patients With Coronary Artery Disease and Obstructive Sleep Apnea: Effect of Continuous Positive Airway Pressure Therapy

BACKGROUND

Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular complications. OSA and coronary artery disease (CAD) share the same risk factors and coexist in many patients. In previous studies, repeated nocturnal cardiac ischemic events in OSA patients with CAD have been reported.

HYPOTHESIS

We hypothesized that OSA may precipitate myocardial ischemia, evidenced by ST-segment depression and elevated N-terminal brain natriuretic peptide (NT-proBNP) and high-sensitivity troponin T (hs-TropT) levels in patients with severe OSA and concomitant CAD. We also aimed to evaluate if the effects could be reversed by continuous positive airway pressure (CPAP) therapy.

METHODS

Twenty-one patients with severe OSA (apnea-hypopnea index >15/h, nadir oxygen desaturation ≤ 80%), and coexisting CAD underwent in-hospital polysomnography at baseline and under CPAP. Blood samples for hs-TropT and NT-proBNP measurements were drawn prior and immediately after sleep. ST-segment depression was measured at the time of maximum oxygen desaturation during sleep.

RESULTS

CPAP significantly decreased elevated NT-proBNP levels from 475 ± 654 pg/mL before sleep to 353 ± 573 pg/mL after sleep and attenuated ST-segment depression during sleep. hs-TropT was not elevated and did not differ after nocturnal oxygen desaturation at baseline and after CPAP.

CONCLUSIONS

CPAP significantly reduced NT-proBNP in patients suffering from severe OSA and coexisting CAD. Repeated nocturnal myocardial ischemia did not cause myocyte necrosis evidenced by elevated hs-TropT or ST-segment depression.

Markers of Myocardial Ischemia in Patients with Obstructive Sleep Apnea and Coronary Artery Disease

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia during sleep. We tested the hypothesis that nocturnal myocardial ischemia is detectable by ST segment depression and elevation of high sensitive troponin T (hsTrop T) and B-type natriuretic peptide (NT-proBNP) in patients with OSA and coexisting coronary artery disease (CAD). Twenty-one patients with OSA and CAD and 20 patients with OSA alone underwent in-hospital polysomnography. Blood samples for hsTrop T and NT-proBNP measurements were drawn before and after sleep. ST segment depression was measured at the time of maximum oxygen desaturation during sleep. The apnea-hypopnea-index (AHI), oxygen saturation nadir, and time in bed with oxygen saturation of ≤80% were similar in both groups. Levels of hsTrop T and NT-proBNP did not differ significantly before and after sleep but NT-proBNP levels were significantly higher in patients suffering from OSA and CAD compared to patients with OSA alone. No significant ST depression was found at the time of oxygen saturation nadir in either group. Despite the fact that patients with untreated OSA and coexisting CAD experienced severe nocturnal hypoxemia, we were unable to detect myocardial ischemia or myocyte necrosis based on significant ST segment depression or elevation of hsTrop T and NT-proBNP, respectively.

The correlation of serum growth differentiation factor-15 level in patients with obstructive sleep apnea

PURPOSE

Growth differentiation factor-(GDF-) is a prognostic biomarker in cardiovascular disorders (CVD). GDF-15 level was not studied in patients with obstructive sleep apnea syndrome (OSAS) before. In this study, we investigated serum GDF-15 levels in OSAS patients and compared them with healthy controls.

MATERIAL AND METHODS

Polysomnographically, confirmed forty consecutive OSAS patients (20 men and 20 women) and forty consecutive healthy controls (23 men and 17 women) were enrolled in the study. The samples in each group had similar demographic characteristics and body mass index (BMI) values.

RESULTS

In the study, no significant correlation was found about GDF-15 levels of OSAS group and healthy controls. However, there was a significant statistical correlation between age and GDF-15 level. In correlation analysis, there was not any significant correlation between age and BMI.

CONCLUSION

Although various developing biomarkers have been studied in cardiovascular disorders, GDF-15 levels have attracted a widespread interest as predictors of cardiovascular risk. GDF-15 level has not been evaluated previously in patients with OSAS. A significant statistical correlation was found between age and GDF-15 level. To reveal close relation between OSAS and GDF-15, further studies are needed with combination of GDF-15 and other biomarkers in OSAS.

Relationship between serum cardiac troponin T level and cardiopulmonary function in stable chronic obstructive pulmonary disease

Background

High-sensitivity cardiac troponin T (hs-cTnT) in serum is a useful marker of acute myocardial injury, yet information is limited in patients with chronic obstructive pulmonary disease. We aimed to explore the association between hs-cTnT levels and cardiac and pulmonary dysfunction in patients with stable chronic obstructive pulmonary disease and at-risk individuals.

Methods

We examined community-dwelling adults with/without chronic obstructive pulmonary disease, with a life-long smoking history, current symptoms of dyspnea during exertion, prolonged coughing, and/or sputum. Serum hs-cTnT concentrations were measured, and subjects underwent pulmonary function tests, high-resolution computed tomography of the chest, an echocardiogram, and a 6-minute walking test.

Results

Eighty-six stable patients were identified (mean age 65.5 years; predicted forced expiratory volume in 1 second [FEV₁% predicted] 75.0%). Their overall mean hs-cTnT level was 0.008 ng/mL. Logarithmically transformed hs-cTnT levels significantly and positively correlated with age, smoking index, serum high-sensitivity C-reactive protein levels, right ventricle systolic pressure, low attenuation area percentage, and brain natriuretic peptide levels (range r=0.231–0.534, P=0.000 to P=0.042). Further, logarithmically transformed hs-cTnT values significantly and negatively correlated with forced vital capacity, FEV₁% predicted, diffusion capacity, arterial oxygen tension, and 6-minute walking distance (range r= −0.482 to −0.377, P=0.000 to P=0.002). Multivariate analyses showed that hs-cTnT values varied independently according to the following three parameters: high-sensitivity C-reactive protein levels (B=0.157, β=0.450, t=3.571, P=0.001), age (B=0.008, β=0.352, t=2.789, P=0.009), and right ventricular systolic pressure (B=0.008, β=0.280, t=2.202, P=0.035).

Conclusion

Even in patients with stable chronic obstructive pulmonary disease, the serum troponin T concentration was controlled by at least three major factors, ie, systemic inflammation, advancing age, and right cardiac overload.

Comprehensive biomarker profiling in patients with obstructive sleep apnea

OBJECTIVES

The pathophysiological links between obstructive sleep apnea syndrome (OSAS) and cardiovascular mortality are incompletely understood. We aimed to contribute to a better characterization by using comprehensive biomarker profiling quantifying hemodynamic cardiac stress, cardiomyocyte injury, inflammation, endothelial function, matrix turnover and metabolism.

DESIGN AND METHODS

In 65 patients with moderate or severe OSAS [apnea-hypopnea index (AHI) 39±20/h] and 33 patients with no or mild OSAS (AHI 8+4/h), B-type natriuretic peptide (BNP), N-terminal-pro-BNP (NT-proBNP), high-sensitivity cardiac troponin I (hs-cTnI), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), and insulin were measured before and after sleep. In a subgroup measurements were repeated in a second night with continuous positive airway pressure (CPAP).

RESULTS

Patients with moderate/severe OSAS had higher insulin before sleep [median (interquartile range), 36.4 (21.9-52.1) vs. 20.8 (10.6-32.8)mU/mL; p=0.006], higher IL-6 after sleep [1.00 (0.73-1.58) vs. 0.72 (0.48-0.94)pg/mL; p=0.005], and larger relative overnight reduction in BNP [-9 (-35-0) vs. -3 (-21-13)%; p=0.04] than those with mild/no OSAS. Insulin before sleep was the only independent predictor of moderate/severe OSAS. Insulin before and IL-6 after sleep were independent predictors of severe OSAS, and when combined provided high diagnostic accuracy for severe OSAS (area under the receiver operator characteristic curve 0.80; 95%-confidence interval 0.69-0.91). In contrast, there were no significant differences in NT-proBNP, hs-cTnI, VEGF, and MMP-9 between moderate/severe and mild/no OSAS. Short-term CPAP had no impact on biomarker concentrations before and after sleep.

CONCLUSIONS

Significant OSAS is characterized by a distinct biomarker profile including high insulin before and high IL-6 after sleep.

Severity of obstructive sleep apnea is associated with cardiac troponin I concentrations in a community-based sample: data from the Akershus Sleep Apnea Project

OBJECTIVES

Previous community-based studies have failed to demonstrate an independent association between OSA and circulating cardiac troponin concentrations, a marker of myocardial injury. However, these studies have used troponin assays with modest analytic sensitivity to detect low-level, chronic increments in troponin levels. Using a highly sensitive troponin I (hs-TnI) assay, we tested the hypothesis that the severity of OSA is associated with myocardial injury independently of comorbidities.

DESIGN

Cross-sectional study.

SETTING

Community-based.

PARTICIPANTS

514 subjects (54% men, age 48 ± 11 y [mean ± SD]).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

hs-TnI concentrations were measured in fasting morning blood samples and 318 participants (62%) had hs-TnI concentration above the limit of detection ([LoD] 1.2 ng/L). The severity of OSA, expressed as the apnea-hypopnea index (AHI) and nocturnal hypoxemia, was assessed by in-hospital polysomnography. After adjustment for age, gender, estimated creatinine clearance, history of coronary artery disease and hypertension, smoking, diabetes mellitus, systolic blood pressure, heart rate, body mass index, left ventricular hypertrophy, and cholesterol ratio in multivariate linear regression models, higher AHI (standardized β = 0.12, P = 0.006), lower mean SpO2 (β = -0.13, P = 0.012) and higher percentage of total sleep time with SpO2 < 90% (β = 0.12, P = 0.011) were all associated with higher hs-TnI levels in separate models. Additional analyses with hs-TnI categorized in tertiles or using a different strategy for persons with hs-TnI levels below the LoD did not change the results.

CONCLUSION

Increased obstructive sleep apnea (OSA) severity is independently associated with higher concentrations of hs-TnI, suggesting that frequent apneas or hypoxemia in OSA may cause low-grade myocardial injury.

Effect of CPAP treatment on plasma high sensitivity troponin levels in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with an increased prevalence of cardiovascular diseases. New generations of highly sensitive assays for cardiac troponin (hs-cTnT) have been introduced recently, and a number of clinical observations have challenged the notion that troponins are only increased in blood following irreversible necrosis.

OBJECTIVE

The aims of this study were to compare the levels of hs-cTnT between a group of healthy controls and a group of patients with OSA without co-existent coronary artery disease, and to assess the possible influence of the treatment with Continuous positive airway pressure (CPAP) on these levels.

METHODS

The study population included 200 male participants. The case (n = 133) or control (n = 67) status was defined by an apnea-hypopnea index of 10 or greater. The hs-cTnT assay was validated as reported previously, with a limit of detection of 3 ng/L and an upper reference limit (99th percentile) of 14 ng/L.

RESULTS

The proportion of subjects with detectable plasma hs-cTnT was higher in patients with OSA than in controls (61 vs 75%, p = 0.04). In patients, a significant increase in hs-cTnT levels was observed after an effective treatment with CPAP (7.3 ± 3.4 vs 10.1 ± 4.9 ng/L; p < 0.01).

CONCLUSION

This study shows that the percentage of subjects with detectable hs-cTnT is associated with the presence of OSA. It also evidences that treatment with CPAP is followed by a rise in hs-cTnT concentrations. It is reasonable to suggest that CPAP therapy might induce a potential degree of cardiac stress, resulting in deleterious consequences for the heart.

Sleep apnea is associated with subclinical myocardial injury in the community. The ARIC-SHHS study

RATIONALE

Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality, although the underlying mechanisms are not well understood.

OBJECTIVES

We aimed to determine whether more severe OSA, measured by the Respiratory Disturbance Index (RDI), is associated with subclinical myocardial injury and increased myocardial wall stress.

METHODS

A total of 1,645 participants (62.5 ± 5.5 yr and 54% women) free of coronary heart disease and heart failure and participating in both the Atherosclerosis Risk in the Communities and the Sleep Heart Health Studies underwent overnight polysomnography and measurement of high-sensitivity troponin T (hs-TnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP).

MEASUREMENTS AND MAIN RESULTS

OSA severity was defined using conventional clinical categories: none (RDI ≤ 5), mild (RDI 5-15), moderate (RDI 15-30), and severe (RDI > 30). Hs-TnT, but not NT-proBNP, was associated with OSA after adjusting for 17 potential confounders (P = 0.02). Over a median of 12.4 (interquartile range, 11.6-13.1) years follow-up, hs-TnT was related to risk of death or incident heart failure in all OSA categories (P ≤ 0.05 in each category).

CONCLUSIONS

In middle-aged to older individuals, OSA severity is independently associated with higher levels of hs-TnT, suggesting that subclinical myocardial injury may play a role in the association between OSA and risk of heart failure. OSA was not associated with NT-proBNP levels after adjusting for multiple possible confounders.

Impact of sleep-disordered breathing on myocardial damage and metabolism in patients with chronic heart failure

Sleep-disordered breathing (SDB) has a critical association with mortality and morbidity of patients with chronic heart failure (CHF). Troponin T is a marker of ongoing myocardial damage and predicts adverse clinical outcomes in patients with CHF. Carnitine plays an important role in the utilization of fatty acids in the myocardium. It has been reported that myocardial carnitine levels decrease in the failing heart. We hypothesized that plasma troponin T and carnitine are increased due to the leakage from damaged cardiomyocytes or the alteration of myocardial metabolism in CHF patients with SDB. We examined the relation of plasma troponin T and carnitine levels with severity of SDB in CHF. We used portable sleep monitor and measured the apnea-hypopnea index (AHI), plasma levels of high-sensitive troponin T and carnitine in 131 CHF patients. These patients were divided into three groups based on AHI: group A (None-mild SDB AHI < 15/h, n = 45), group B (Moderate SDB 15 ≤ AHI < 30/h, n = 32) and group C (Severe SDB AHI ≥ 30/h, n = 54). Levels of high-sensitive troponin T and plasm total carnitine were significantly higher in group C than in groups A and B [high-sensitive troponin T; group A 0.009 (0.005-0.016), group B 0.012 (0.006-0.021), group C 0.021 (0.011-0.039) ng/ml, total carnitine; group A 61.0 ± 15.1, group B 65.0 ± 13.5, group C 73.3 ± 17.5 μmol/l, P < 0.01 vs. group A and P < 0.05 vs. group B, respectively]. Furthermore, in the multiple regression analysis, the independent factors to determine plasma levels of log (high-sensitive troponin T) were high-sensitive C-reactive protein and AHI, and the independent factors to determine plasma levels of carnitine were glomerular filtration rate and AHI. The present study suggests that SDB is associated with latent myocardial damage and alteration of myocardial carnitine metabolism in patients with CHF, presented by higher circulating troponin T and carnitine levels.

Obstructive sleep apnea: no independent association to troponins

BACKGROUND

Cardiac troponins (cTn) are to date the most sensitive and specific biochemical markers of myocardial injury. Abnormal breathing patterns in patients with obstructive sleep apnea (OSA) may cause myocardial cell stress detectable by novel cTn assays. The objectives of this study were to investigate whether a new single-molecule cTnI (S-cTnI) assay and a commercially available high-sensitivity cTnT (hs-cTnT) assay would detect myocyte injury in individuals evaluated for possible OSA, and to explore their relation to variables of disordered breathing during sleep.

METHODS

Consecutive individuals referred to Lovisenberg Diakonale Hospital's sleep laboratory between 1 October 2009 and 1 March 2010 were included. We measured cTn in specimens collected the morning after sleep and studied these in relation to variables recorded during polygraphy or polysomnography.

RESULTS

All 222 (100 %) individuals had measurable cTn levels using either assay. Stratified into categories according to the apnea-hypopnea index (AHI), patients with OSA (AHI ≥5) had a different distribution of S-cTnI (P = 0.036) and hs-cTnT (P = 0.002) compared to those without (AHI <5). The median (quartiles 1-3) were 3.0 (1.9-6.0) versus 2.3 (1.6-3.8) ng/l for S-cTnI, and 7.0 (5.5-8.7) versus 6.2 (4.9-7.2) ng/l for hs-cTnT. However, in multiple median regression analyses adjusted for conventional predictors, neither S-cTnI (P = 0.57) nor hs-cTnT (P = 0.80) were significantly associated with AHI.

CONCLUSIONS

This study reveals no association independent of conventional predictors between OSA and myocardial cell injury measured by S-cTnI and hs-cTnT assays. Our findings support a search for novel biomarkers for prognostication of OSA.

Obstructive sleep apnea and coronary artery disease: from pathophysiology to clinical implications

Coronary artery disease (CAD) and obstructive sleep apnea (OSA) are both complex and significant clinical problems. The pathophysiological mechanisms that link OSA with CAD are complex and can influence the broad spectrum of conditions caused by CAD, from subclinical atherosclerosis to myocardial infarction. OSA remains a significant clinical problem among patients with CAD, and evidence suggesting its role as a risk factor for CAD is growing. Furthermore, increasing data support that CAD prognosis may be influenced by OSA and its treatment by continuous positive airway pressure (CPAP) therapy. However, stronger evidence is needed to definitely answer these questions. This paper focuses on the relationship between OSA and CAD from the pathophysiological effects of OSA in CAD, to the clinical implications of OSA and its treatment in CAD patients.

Latest advances in sleep medicine: obstructive sleep apnea

This article is a review of the pertinent scientific data regarding obstructive sleep apnea (OSA) as presented in the medical literature. Attention regarding the diagnosis of OSA focused on the debate regarding home testing as compared with in-laboratory polysomnography (PSG), with a surprising result of possibly more cost benefit from PSG. New advances abound in the treatment of OSA, including those directed at preventing pharyngeal collapsibility. Multiple studies reviewed the comparative effects of oral appliances in conjunction with CPAP, with little difference between the two noted, especially for mild OSA. Finally, a number of studies evaluated both risks of OSA and outcomes from the use of CPAP, including functional outcomes, direct cardiac benefits, and overall cardiac mortality.