Sleep-Disordered Breathing in Patients With Idiopathic Cardiomyopathy

Phenotypic Disease Network-Based Multimorbidity Analysis in Idiopathic Cardiomyopathy Patients with Hospital Discharge Records

BACKGROUND

Idiopathic cardiomyopathy (ICM) is a rare disease affecting numerous physiological and biomolecular systems with multimorbidity. However, due to the small sample size of uncommon diseases, the whole spectrum of chronic disease co-occurrence, especially in developing nations, has not yet been investigated. To grasp the multimorbidity pattern, we aimed to present a multidimensional model for ICM and differences among age groups.

METHODS

Hospital discharge records were collected from a rare disease centre of ICM inpatients (n = 1036) over 10 years (2012 to 2021) for this retrospective analysis. One-to-one matched controls were also included. First, by looking at the first three digits of the ICD-10 code, we concentrated on chronic illnesses with a prevalence of more than 1%. The ICM and control inpatients had a total of 71 and 69 chronic illnesses, respectively. Second, to evaluate the multimorbidity pattern in both groups, we built age-specific cosine-index-based multimorbidity networks. Third, the associated rule mining (ARM) assessed the comorbidities with heart failure for ICM, specifically.

RESULTS

The comorbidity burden of ICM was 78% larger than that of the controls. All ages were affected by the burden, although those over 50 years old had more intense interactions. Moreover, in terms of disease connectivity, central, hub, and authority diseases were concentrated in the metabolic, musculoskeletal and connective tissue, genitourinary, eye and adnexa, respiratory, and digestive systems. According to the age-specific connection, the impaired coagulation function was required for raising attention (e.g., autoimmune-attacked digestive and musculoskeletal system disorders) in young adult groups (ICM patients aged 20-49 years). For the middle-aged (50-60 years) and older (≥70 years) groups, malignant neoplasm and circulatory issues were the main confrontable problems. Finally, according to the result of ARM, the comorbidities and comorbidity patterns of heart failure include diabetes mellitus and metabolic disorder, sleeping disorder, renal failure, liver, and circulatory diseases.

CONCLUSIONS

The main cause of the comorbid load is aging. The ICM comorbidities were concentrated in the circulatory, metabolic, musculoskeletal and connective tissue, genitourinary, eye and adnexa, respiratory, and digestive systems. The network-based approach optimizes the integrated care of patients with ICM and advances our understanding of multimorbidity associated with the disease.

Sleep-disordered breathing in heart failure patients with different etiologies

Background

The prevalence of sleep‐disordered breathing (SDB) is closely related to the severity of heart failure (HF), and the severity of HF is different in patients with HF of different etiologies.

Hypothesis: This study aimed to explore the prevalence of SDB in patients with HFof different etiologies.

Methods

Hospitalized HF patients were consecutively enrolled. All patients underwent portable overnight cardiorespiratory polygraphy. Patients were divided into five groups according to the etiology of HF: ischemic, hypertensive, myocardial, valvular, and arrhythmic. The prevalence of SDB and clinical data was compared among the five groups.

Results

In total, 248 patients were enrolled in this study. The prevalence of SDB in HF was 70.6%, with the prevalence of obstructive sleep apnea (OSA) at 47.6% and central sleep apnea (CSA) at 23.0%. Patients were divided into five groups: ischemic, hypertensive, myocardial, valvular, and arrhythmic. The prevalence of SDB among the five groups was 75.3%, 81.4%, 77.8%, 51.9%, and 58.5% (p = .014), respectively. The prevalence of OSA among the five groups was 42.7%, 72.1%, 36.1%, 37.0%, and 49.1% (p = .009), whereas the CSA was 32.6%, 9.3%, 41.7%, 14.8%, and 9.4% (p < .001), respectively.

Conclusions

SDB is common in HF patients. The prevalence and types of SDB varied in HF with different etiologies, which may be related to the different severities of HF. SDB was highly prevalent in patients with ischemic, hypertensive, and myocardial HF. Hypertensive HF patients were mainly complicated with OSA, while myocardial HF patients were mainly complicated with CSA. Both conditions were highly prevalent in ischemic HF patients. The prevalence of SDB was relatively low in valvular and arrhythmic HF patients, and OSA was the main type.

Obstructive Sleep Apnea Impacts Cardiac Function in Dilated Cardiomyopathy Patients Through Circulating Exosomes

Background

Obstructive sleep apnea (OSA) is common and independently associated with heart failure. This study aimed to investigate the impact of OSA on heart function in patients with dilated cardiomyopathy (DCM) as well as the possible mechanism related to exosomes regulated autophagy.

Methods and Results

A total of 126 patients with DCM who underwent sleep evaluations were analyzed retrospectively. Cardiomyocytes were treated with exosomes isolated from untreated OSA patients and healthy controls. Fibrotic and hypertrophic markers were evaluated, and Akt/mTOR pathway-mediated autophagy was investigated. DCM patients with severe OSA had larger right ventricular end-diastolic diameter (RVEDd) and right atrial diameter (RAD) and increased N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels than DCM patients without OSA. Moreover, NT-proBNP and diabetes mellitus were independently correlated with the apnea-hypopnea index in multiple linear regression analysis. Treatment with OSA-derived exosomes significantly increased Col1A1, ANP, and BNP protein expression and decreased the expression of the autophagy markers LC3B II/I and beclin1. Rapamycin treatment significantly increased the decreased autophagy markers and attenuated the increased expression of Col1A1, ANP and BNP induced by OSA-derived exosomes.

Conclusion

The severity of OSA is significantly associated with cardiac injury and remodeling. The underlying mechanism may be related to changed autophagy levels, which are regulated by circulating exosomes via the Akt/mTOR signaling pathway. This study may provide a new clue for the treatment of heart failure with OSA.

Interactions Between Body Mass Index and Glomerular Filtration Rate Increase the Identification Ability of Obstructive Sleep Apnea in Patients with Hypertrophic Cardiomyopathy

PURPOSE

Obstructive sleep apnea (OSA) is common in hypertrophic cardiomyopathy (HCM) patients and is related to worse adverse prognosis in HCM patients. However, there are no acknowledged warning characteristics to help to identify OSA in HCM patients.

METHODS

Seventy-one HCM patients and forty-nine hypertensive (HTN) patients as control group underwent polysomnography (PSG) examination at the Second Affiliated Hospital of Nanchang University from January 2015 to December 2019 patients were consecutively enrolled. The characteristics were analyzed and compared between HCM patients with OSA and without OSA.

RESULTS

A total of 37 (52%) HCM patients and 25 (51%) HTN patients were diagnosed with OSA. High body mass index (BMI) (OR = 1.228, 95% CI: 1.032,1.461, P = 0.020) and low estimated glomerular filtration rate (eGFR) (OR = 0.959, 95% CI: 0.931,0.989, P = 0.007) independently correlated with the occurrence of OSA in HCM patients, respectively. Multiplicative interaction was shown between high BMI and low eGFR on the risk of OSA in HCM patients (OR: 6.050, 95% CI: 1.598, 22.905, P = 0.008). The additive interaction analysis further suggested that 70.1% of HCM patients developed OSA due to the additive interaction between BMI and eGFR. The identification ability of OSA in HCM patients was significantly enhanced by using both BMI and eGFR (area under receiver-operating characteristic analysis curve 0.785; P = 0.000038) as compared with BMI (area under curve 0.683, P = 0.008) or eGFR (area under curve 0.700, P = 0.004), respectively.

CONCLUSION

High BMI or low eGFR independently related to the occurrence of OSA in HCM patients, and the multiplicative and additive interactions between BMI and eGFR increased the identification ability of OSA in HCM patients.

Diffuse Alveolar Hemorrhage Associated with Dilated Cardiomyopathy and Sleep Apnea Syndrome

We herein report a case of diffuse alveolar hemorrhage (DAH) associated with dilated cardiomyopathy (DCM) and sleep apnea syndrome (SAS) in a 47-year-old man. The patient exhibited recurring dyspnea and bloody sputum. Chest radiography showed bilateral diffuse infiltrative opacities without pleural effusion. A bronchoscopic analysis of bronchoalveolar lavage fluid revealed hemosiderin-laden macrophages. Based on these findings, he was diagnosed with DAH. Laboratory and pathological findings ruled out the possibility of collagen diseases and vasculitis. Overnight polysomnography revealed concomitant severe obstructive SAS. Treatment with continuous positive-pressure ventilation and pharmacological therapy for DCM prevented recurrence of DAH.

Implication of Apnea-Hypopnea Index, a Measure of Obstructive Sleep Apnea Severity, for Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy

Background

Obstructive sleep apnea (OSA) is common and independently associated with atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM). This study aimed to investigate the relationship between apnea‐hypopnea index (AHI), a measure of OSA severity, and prevalence of AF in a large series of patients with HCM.

Methods and Results

A total of 555 patients with HCM who underwent sleep evaluations were retrospectively included. Data from polysomnography studies, echocardiography, and baseline clinical characteristics were collected. OSA was present in 327 patients (58.9%). Patients with OSA or higher AHI quartiles were older, more often male, had a higher body mass index, and more clinical comorbidities. The prevalence of AF increased in patients with OSA (23.9% versus 13.6%, P=0.003) or across AHI quartiles (9.4%, 17.3%, 26.6%, and 25.2%, respectively; P for trend <0.001). After adjustment for age, sex, body mass index, New York Heart Association class, left atrial diameter, hypertension, oxygen desaturation index, and obstructive HCM, highest AHI quartile (odds ratio, 4.42; 95% CI, 1.35–14.52 [P=0.014]) or moderate to severe OSA (odds ratio, 3.03; 95% CI, 1.28–7.20 [P=0.012]) but not presence of OSA (odds ratio, 1.58; 95% CI, 0.84–2.97 [P=0.153]) were significantly associated with AF. Higher AHI levels were also factors associated with persistent or permanent AF (highest AHI quartile with odds ratio, 10.96; 95% CI, 1.07–111.85).

Conclusions

Severity of AHI level is independently associated with AF in patients with HCM. Clinical trials are required to determine the benefits of OSA treatment on AF in patients with HCM.

Sleep Disordered Breathing in Hypertrophic Cardiomyopathy-Current State and Future Directions

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy and sleep disordered breathing (SDB) is a treatable risk factor that has been seen to occur concurrently, and is known to propagate mortality and morbidity in a number of cardiovascular disease states including heart failure, and indeed hypertrophic cardiomyopathy. In this review, we summarize past studies that explored the simultaneous occurrence of HCM and SDB, and the pathophysiology of SDB in relation to heart failure, arrhythmias, cardiac ischemia and pulmonary hypertension in HCM. The current therapeutic modalities, with the effect of obstructive sleep apnea (OSA) treatment on HCM, are then discussed along with potential future directions.

Dilated Cardiomyopathy in Pregnancy: Outcomes From an Australian Tertiary Centre for Maternal Medicine and Review of the Current Literature

BACKGROUND

Peripartum cardiomyopathy is associated with significant risks of decline in left ventricular function and adverse maternal and fetal outcome in subsequent pregnancy. The risks of pregnancy in women with dilated cardiomyopathy are unclear. We aimed to assess the outcome of pregnancy in women with dilated cardiomyopathy seen at our institution and to review the literature on this subject.

METHODS

A retrospective audit of the outcomes of 14 pregnancies to 12 women with dilated cardiomyopathy.

RESULTS

There were no cardiac events and no woman had a decline in left ventricular function during pregnancy. There was a high rate of prematurity and adverse fetal outcome related to this, including four neonatal deaths.

CONCLUSION

Maternal outcomes in this small series were satisfactory though only three women had moderate-severe left ventricular dysfunction at baseline. There was a high rate of premature delivery and adverse neonatal outcome.

Risk of glomerular filtration rate decline in patients with hypertrophic cardiomyopathy and obstructive sleep apnoea

Sleep apnoea is associated with chronic kidney diseases. A high obstructive sleep apnoea (OSA) prevalence is shown in patients with hypertrophic cardiomyopathy (HCM). Whether the presence of OSA would affect the renal function of patients with HCM is unknown. Forty-five consecutive patients with HCM were divided into the HCM OSA− and OSA+ groups. Forty-three patients with OSA without HCM were recruited as controls. Clinical indices, including estimated glomerular filtration rate (eGFR) and urine 8-hydroxy-2-deoxyguanosine (8-OHdG), were measured. The eGFR was significantly lower in the HCM OSA+ group than in the HCM OSA− (P < 0.05) and OSA (P < 0.001) groups. Multivariate linear regression analysis identified that the apnoea-hypopnoea index was independently associated with eGFR in all patients with HCM (β = −1.329, 95% confidence interval: −1.942, −0.717, P < 0.001). The urine 8-OHdG level, an oxidative stress marker, was significantly higher in the HCM OSA+ group than in the HCM OSA− (P < 0.001) and OSA (P < 0.001) groups and significantly correlated with the AHI (r = 0.467, P = 0.003) and eGFR (r = −0.457, P = 0.004) in all patients with HCM. Our study suggests a risk of eGFR decline in patients with HCM and OSA.

Association between polymorphisms of the HSPB7 gene and Cheyne-Stokes respiration with central sleep apnea in patients with dilated cardiomyopathy and congestive heart failure

BACKGROUND

CSR-CSA is frequent in patients with CHF. Dilated cardiomyopathy (DCM) is a structural heart disease with strong genetic background, yet one of the leading etiological causes of CHF. Studies have showed that the HSPB7 gene is associated with DCM.

OBJECTIVES

We aimed to explore the prevalence of polymorphisms of the HSPB7 gene in the Chinese Han population with CSR-CSA and CHF caused by DCM.

METHODS

A total of 503 unrelated subjects of the Chinese Han population, including 283 CHF patients caused by DCM and 220 healthy controls, were involved in the study. The CHF patients were classified as the CSA-CHF group and the non-CSA-CHF group according to the PSG parameters. The rs1739843 polymorphisms of the HSPB7 gene were identified by real-time quantitative polymerase chain reaction.

RESULTS

In the present study, 35.8% of CHF patients caused by DCM had CSR-CSA. Comparison demonstrated that the CSA-CHF group had significantly higher TT genotype and T allele frequencies in the rs1739843 single nucleotide polymorphism (SNP) of the HSPB7 gene. There were no significant differences among the CC genotype distribution of the CSA-CHF group and the non-CSA-CHF group or the control group.

CONCLUSIONS

The rs1739843 polymorphism of the HSPB7 gene might be involved in the pathogenesis of CSR-CSA and CHF subjects caused by DCM in the Chinese Han population. This finding was from a genetic search for the role of the HSPB7 gene in CSR-CSA of CHF patients caused by DCM.

Prevalence, Severity, and Prognostic Value of Sleep Apnea Syndromes in Cardiac Amyloidosis

STUDY OBJECTIVES

To assess prevalence, severity, and prognostic value of sleep-disordered breathing (SDB), in the three main cardiac amyloidosis (CA) types, i.e., light-chain (AL), transthyretin-related familial (m-TTR), or senile (WT-TTR).

METHODS

Patients consecutively referred for CA diagnosis work-up underwent cardiac assessment and nocturnal polygraphy. SDB was defined as apnea-hypopnea index (AHI) ≥ 5/h. Multivariate analysis was used to identify predictors of a major adverse cardiac event (MACE) defined as death, heart transplantation and acute heart failure.

RESULTS

Seventy CA patients were included (31 AL, 22 m-TTR, 17 WT-TTR). The mean ± standard deviation age and left ventricular ejection fraction were 71 ± 12 years and 49% ± 13% and median (interquartile range) N terminal pro brain natriuretic peptide (NT-proBNP) was 3,932 (1,607; 7,028) pg/mL. The prevalence of SDB was 90% without difference between amyloidosis types. SDB was central in 27% and obstructive in 73%. AL had less frequent severe SDB compared to m-TTR and WT-TTR (P = 0.015) but longer time with peripheral capillary oxygen saturation (SpO2) < 90% (P = 0.037). After a median follow-up of 7.5 (2.8; 14.9) months, 49% patients experienced MACE. Time with nocturnal SpO2 < 90% was the only independent predictor of MACE. The best-identified threshold was 30 min. Values > 30 min were associated with bad prognosis (Log-rank χ(2): 8.01, P value = 0.005). Using binomial logistic regression, determinants of time with nocturnal SpO2 < 90% were New York Heart Association class (P = 0.011), and log-NT-proBNP (P = 0.04) but not AHI.

CONCLUSIONS

In CA population, prevalence of SDB is high (90%) and dominated by the obstructive pattern. Bad prognosis in this population was driven by nocturnal desaturation, reflecting heart failure severity and respiratory involvement.

Hypertrophic cardiomyopathy associated with sleep apnea: serious implications and cogent management strategy

Obstructive sleep apnea (OSA) affects an estimated 20 million adult Americans and is present in a large proportion of patients with hypertension and in those with other cardiovascular disorders, including hypertrophic cardiomyopathy (HCM). This review seeks to highlight concepts and evidence important to understanding the interactions between OSA and HCM, with particular attention to more recent advances in patient-oriented research. Studies of patients with HCM have found the prevalence of sleep-disordered breathing to range from 40 to 80%. Increased sympathetic activity, impaired vagal activity, increased afterload, insulin resistance and endothelial dysfunction have been proposed as potential mechanisms for the association. Specific questions include whether OSA is important in unmasking symptoms in hitherto undiagnosed patients with HCM, whether OSA in patients with established HCM accelerates disease progression and whether treatment of OSA results in clinical improvement, fewer cardiovascular events and reduced mortality. Because obesity, cardiovascular disease, metabolic syndrome, and diabetes are often present in patients with OSA, it can be difficult to attribute abnormalities evident in the sleep apnea patient with HCM to the effects of OSA, the effects of HCM or synergies between these conditions. Although further research is needed to answer these specific questions, recent investigations have clearly shown the coexistence of OSA and HCM, as well as elucidated the contribution of heightened sympathetic nerve activity in OSA to drug-refractory symptoms and worsening left ventricular outflow tract obstruction. This review aims to highlight the current literature available on the association of OSA and HCM, provide directions for future research and summarize the key features related to this association based on the authors' best understanding and experience.

Lack of reliable clinical predictors to identify obstructive sleep apnea in patients with hypertrophic cardiomyopathy

OBJECTIVE

Obstructive sleep apnea is common among patients with hypertrophic cardiomyopathy and may contribute to poor cardiovascular outcomes. However, obstructive sleep apnea is largely unrecognized in this population. We sought to identify the clinical predictors of obstructive sleep apnea among patients with hypertrophic cardiomyopathy.

METHODS

Consecutive patients with hypertrophic cardiomyopathy were recruited from a tertiary University Hospital and were evaluated using validated sleep questionnaires (Berlin and Epworth) and overnight portable monitoring. Ninety patients (males, 51%; age, 46±15 years; body mass index, 26.6±4.9 kg/m2) were included, and obstructive sleep apnea (respiratory disturbance index ≥15 events/h) was present in 37 patients (41%).

RESULTS

Compared with the patients without obstructive sleep apnea, patients with obstructive sleep apnea were older and had higher body mass index, larger waist circumference, larger neck circumference, and higher prevalence of atrial fibrillation. Excessive daytime sleepiness (Epworth scale) was low and similar in the patients with and without obstructive sleep apnea, respectively. The only predictors of obstructive sleep apnea (using a logistic regression analysis) were age ≥45 years (odds ratio [OR], 4.46; 95% confidence interval [CI 95%], 1.47-13.54; p = 0.008) and the presence of atrial fibrillation [OR, 5.37; CI 95%, 1.43-20.12; p = 0.013].

CONCLUSION

Consistent clinical predictors of obstructive sleep apnea are lacking for patients with hypertrophic cardiomyopathy, which suggests that objective sleep evaluations should be considered in this population, particularly among elderly patients with atrial fibrillation.

Obstructive sleep apnea and hypertrophic cardiomyopathy: a common and potential harmful combination

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac disease and is characterized by large and asymmetric septal and left ventricle hypertrophy. HCM is a cause of disability, including heart failure, atrial fibrillation, and sudden death, with an annual mortality varying from 1% to 6%. Obstructive sleep apnea (OSA) is extremely common among patients with established cardiovascular disease, including hypertension and atrial fibrillation and when present may contribute to worse cardiovascular outcome. Although patients with HCM do not necessarily have typical characteristics of patients with OSA, such as obesity and increasing age, there is recent evidence that OSA is extremely common among patients with HCM, with a prevalence ranging from 32% to 71%. The presence of OSA among patients with HCM is independently associated with worse structural and functional impairment of the heart, including atrial and aorta enlargement, worse New York Heart Association functional class, and worse quality of life. The prevalence of atria fibrillation, an independent marker of mortality among patients with HCM, is significantly higher (∼four times) in the presence of OSA. Therefore, the recognition of OSA is a new area of research that may impact the management of patients with HCM.

Psychometric testing of the MDASI-HF: a symptom assessment instrument for patients with cancer and concurrent heart failure

BACKGROUND

The debilitating symptoms of cancer and heart failure (HF) can adversely affect the patient's quality of life. This study evaluated the psychometric properties of the MD Anderson Symptom Inventory--Heart Failure (MDASI-HF), a 27-item self-report assessment instrument for patients with cancer and concurrent HF.

METHODS AND RESULTS

Psychometric testing used data from 156 patients (age 63.3 +/- 13.2 years, 56% male) with a diagnosis of cancer and HF receiving care in a major cancer center. Reliability of the MDASI-HF for the 13 symptoms (alpha = 0.89), 8 HF-specific items (alpha = 0.83), and interference items (alpha = 0.92) was high. Criterion-related validity with the Eastern Cooperative Oncology Group performance scale (r = 0.63) and the New York Heart Association classification (r = 0.65) were statistically significant, P = .01. Construct validity supported two constructs for the additional HF specific items: covert HF factor and overt HF factor.

CONCLUSION

The MDASI-HF is a valid and reliable instrument for symptom assessment in patients with cancer and HF. This instrument can be used to identify symptom occurrence and enhance the provider's understanding of the prevalence and severity of symptoms from the patient's perspective.

Daytime Cheyne-Stokes Respiration in Ambulatory Patients With Severe Congestive Heart Failure Is Associated With Increased Mortality

BACKGROUND

Cheyne-Stokes respiration (CSR) frequently occurs in patients with severe heart failure during sleep and may increase mortality. Daytime CSR supposedly poses an even greater risk, but its prevalence and prognostic importance remain elusive. Therefore, we investigated the circadian prevalence of CSR and its influence on survival in patients with heart failure.

METHODS

In 60 consecutive ambulatory patients (mean age+/-SE, 58.0+/-1.5 years; 6 women) with stable severe heart failure (left ventricular ejection fraction, 26+/-1%; New York Heart Association [NYHA] class, 2.6+/-0.1), the breathing pattern was unobtrusively monitored during 24 h of usual activities with a portable respiratory inductive plethysmograph.

RESULTS

During nights, 62% of patients had >or=15 periodic breathing cycles per hour; during days, the corresponding prevalence was 16%. CSR prevailed in 32+/-3% of the night and in 10+/-2% of the day, with peaks at 4:00 am, 2:00 pm, and 6:00 pm. Eighteen patients with CSR during >or=10% of the daytime lived shorter without heart transplantation than 42 patients with <10% of daytime CSR (p<0.05) during 836+/-27 days of follow-up. CSR during >or=10% of the daytime was an independent predictor of mortality (hazard ratio, 3.8; 95% confidence interval, 1.1 to 12.7; p<0.05) when controlling for age, sex, brain natriuretic peptide, left ventricular ejection fraction, and NYHA class.

CONCLUSIONS

CSR occurs in 62% of patients with severe heart failure at night and in 16% during the day. Since daytime CSR is associated with reduced survival, solely performing sleep studies may not allow to adequately assess prognosis and tailor treatment in patients with severe heart failure.

Sleep apnea: clinical investigations in humans

Sleep apnea syndrome (SAS), a common disorder, is characterized by repetitive episodes of cessation of breathing during sleep, resulting in hypoxemia and sleep disruption. The consequences of the abnormal breathing during sleep include daytime sleepiness, neurocognitive dysfunction, development of cardiovascular disorders, metabolic dysfunction, and impaired quality of life. There are two types of SAS: obstructive sleep apnea syndrome (OSAS) and central sleep apnea syndrome (CSAS). OSAS is a prevalent disorder in which there is snoring, repetitive apneic episodes, and daytime sleepiness. Anatomical conditions causing upper airway obstruction (obesity or craniofacial abnormalities such as retrognathia or micrognathia) can cause OSAS. CSAS, much less common than OSAS, is a disorder characterized by cessation of breathing which is caused by reduced respiratory drive from the central nervous system to the muscles of respiration. The latter condition is common in patients with heart failure and cerebral neurologic diseases. The diagnosis of SAS requires assessment of subjective symptoms and apneic episodes during sleep documented by polysomnography. Treatments of OSAS include continuous positive airway pressure (CPAP), oral appliances, and surgery; patients with CSAS are treated with oxygen, adaptive servo-ventilation, or CPAP. With assessment and treatment of the SAS, patients usually have resolution of their disabling symptoms, subsequently resulting in improved quality of life.

Normal coronary arteries in patients with systolic heart failure who have higher body mass index

BACKGROUND

Previous research has shown an association between higher body mass index (BMI) and lower mortality in patients with heart failure (HF).

METHODS

We compared the prevalence of angiographic coronary artery disease (CAD) and risk factors in obese versus non-obese patients with HF. Eighty-four consecutive patients with systolic HF who underwent coronary angiography in a single institution were categorized by BMI into non-obese (BMI < 30, n = 42) and obese (BMI >or= 30, n = 42) subjects.

RESULTS

Chi-square analysis demonstrated a greater prevalence of normal coronary arteries and a lesser prevalence of CAD in the obese patients compared with the non-obese patients (64% [27/42] of obese patients vs 43% [18/42] non-obese patients had normal coronary arteries, P < .05). Among the obese patients, the subgroup with normal coronary arteries had a higher BMI (39 vs 32, P < .001) and was younger (51 vs 63 years, P < .005) compared with those with CAD. Although the prevalence of significant CAD (>50% diameter stenosis) was similar between obese and non-obese patients, the obese subgroup had a lower high-density lipoprotein (39 vs 49 mg/dL, P < .05).

CONCLUSIONS

Angiographically normal coronary arteries were more prevalent in patients with systolic HF who have a higher BMI.

Assessment of central chemosensitivity and cardiac sympathetic nerve activity using I-123 MIBG imaging in central sleep apnea syndrome in patients with dilated cardiomyopathy

OBJECTIVE

Iodine-123 MIBG imaging has been used to study cardiac sympathetic function in various cardiac diseases. Central sleep apnea syndrome (CSAS) occurs frequently in patients with chronic heart failure (CHF) and is reported to be associated with a poor prognosis. One of the mechanisms of its poor prognosis may be related to impaired cardiac sympathetic activity. However, the relationship between chemosensitivity to carbon dioxide, which is reported to correlate with the severity of CSAS, and cardiac sympathetic activity has not been investigated. Therefore, this study was undertaken to assess cardiac sympathetic function and chemosensitivity to carbon dioxide in CHF patients.

METHODS

The oxygen desaturation index (ODI) was evaluated in 21 patients with dilated cardiomyopathy (male/female: 19/2, LVEF < 45%, 65 +/- 12 yr). Patients with an ODI > 5 times/h underwent polysomnography. Patients with an apnea hypopnea index > 15/h but without evidence of obstructive apnea were defined as having CSAS. Early (15 min) and delayed (4 hr) planar MIBG images were obtained from these patients. The mean counts in the whole heart and the mediastinum were obtained. The heart-to-mediastinum count ratio of the delayed image (H/M) and the corrected myocardial washout rate (WR) were also calculated. The central chemoreflex was assessed with the rebreathing method using a hypercapnic gas mixture (7% CO2 and 93% O2).

RESULTS

Ten of the 21 patients had CSAS. The H/M ratio was similar in patients both with and without CSAS (1.57 +/- 0.18 vs. 1.59 +/- 0.14, p = 0.82). However, the WR was higher in patients with CSAS than in patients without CSAS (40 +/- 8% vs. 30 +/- 12%, p < 0.05). ODI significantly correlated with central chemosensitivity to carbon dioxide. Moreover, there was a highly significant correlation between WR and central chemosensitivity (r = 0.65, p < 0.05). However, there was no correlation between ODI and the WR (r = 0.36, p = 0.11).

CONCLUSIONS

Cardiac sympathetic nerve activity in patients with CHF and CSAS is impaired. However, central sleep apnea might not directly increase cardiac sympathetic nerve activity. We suggest that central chemosensitivity, which is considered to be one of the mechanisms of CSAS, is correlated with cardiac sympathetic nerve activity.

Serum homocysteine levels and cardiovascular morbidity in obstructive sleep apnea syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular morbidity and mortality. Elevated levels of serum homocysteine are also associated with cardiovascular morbidity and mortality. We aimed to investigate serum homocysteine levels and conventional cardiovascular risk factors (cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides) in OSAS patients with and without cardiovascular diseases (CVD).

METHODS AND RESULTS

Levels of homocysteine, cholesterol, LDL, HDL and triglycerides were measured in 114 obese, male participants after overnight fasting. The presence of OSAS was determined by standard overnight polysomnography. The cases included OSAS patients (apnea-hypopnea index: AHI5) with CVD (OSAS+CVD group) (n:25) and without CVD (OSAS-CVD group) (n:47). Control group was patients without OSAS (AHI<5) with CVD (CVD group) (n:42). The serum homocysteine levels were significant.

Oxygen Therapy Prevents Ventricular Arrhythmias in Patients With Congestive Heart Failure and Sleep Apnea

BACKGROUND

Although ventricular arrhythmia is critical for the prognosis of patients with severe congestive heart failure (CHF), it is difficult to control the arrhythmia using conservative therapies. However, many CHF patients also have sleep apnea syndrome (SAS) and oxygen supply improves their prognosis. The beneficial effects of oxygen treatment for ventricular arrhythmia have not yet been clarified, so the present study was designed to evaluate the effects of oxygen treatment for premature ventricular contraction (PVC).

METHODS AND RESULTS

Patients with CHF and SAS were divided into 3 groups: (1) the "PVC declined" group that included patients who had frequent PVCs and oxygen treatment that suppressed the number of PVC; (2) the "PVC not affected" group that included patients who had frequent PVCs and oxygen treatment did not affect the number of PVC; and (3) the "few PVC" group that included patients who had no or few PVCs. The group 1 patients showed higher apnea-hypopnea index, standard deviation of all R-R intervals, left ventricular ejection fraction, and brain natriuretic peptide levels than the patients in group 2. Oxygen treatment in group 3 did not affect the PVC frequency.

CONCLUSIONS

Oxygen treatment may be useful for preventing ventricular arrhythmia in selected patients with CHF and SAS.

Effect of Obstructive Sleep Apnea on Aortic Elastic Parameters

BACKGROUND

Obstructive sleep apnea (OSA) syndrome has a critical association with cardiovascular mortality and morbidity. Aortic elastic parameters are important markers for left ventricular (LV) function and are deteriorated in cardiovascular disease.

METHODS AND RESULTS

Aortic elastic parameters and LV functions and mass were investigated in 40 patients with OSA (apnea - hypopnea index (AHI) >or=5) (mean age 51.3 +/-9 years, 32 males) and 24 controls (AHI <5) (mean age 51.9+/-5.2 years, 19 males). All subjects underwent polysomnographic examination and recordings were obtained during sleep. They also underwent a complete echocardiographic examination and systolic and diastolic aortic measurements were noted from M-mode traces of the aortic root. There were no significant differences in the demographic data of the patients with OSA and the controls. Subjects with OSA demonstrated higher values of aortic stiffness (7.1+/-1.88 vs 6.42+/-1.56, p=0.0001), but lower distensibility (9.47+/-1.33 vs 11.8+/-3.36, p=0.0001) than the controls. LV ejection fraction was significantly lower in patients with OSA when compared with the control group (61.3+/-5.2% vs 65.9+/-8.4%, p=0.0001). LV diastolic parameters were also compared and were worse in the subjects with OSA than in the control subjects (mitral E/A: 0.91 +/-0.42 vs 1.35+/-0.66, p=0.001; Em/Am: 0.86+/-0.54 vs 1.23+/-0.59, p=0.021). Respiratory disturbance index had a positive correlation with aortic stiffness (r=0.63, p=0.0001 and negative correlation with distensibility (r=-0.41, p=0.001).

CONCLUSION

Aortic elastic parameters are deteriorated in OSA, which has an extremely high association with cardiovascular disease. Increased aortic stiffness might be responsible for the LV systolic and diastolic deterioration in OSA syndrome.

Cutoff and Target Values for Intra-Abdominal Fat Area for Prevention of Metabolic Disorders in Pre- and Post-Menopausal Obese Women Before and After Weight Reduction

BACKGROUND

The Japan Society for the Study of Obesity originally proposed a cutoff value of >100 cm(2) for the intra-abdominal fat area (IFA) as a definition for "visceral fat obesity" in Japanese adults. There are no studies on the cutoff or target values after weight reduction in pre- and post-menopausal women.

METHODS AND RESULTS

In the present study 149 pre-menopausal obese women (PreM, 43.3 years, 27.3 kg/m(2)) and 58 post-menopausal women (PostM, 53.9 years, 27.7 kg/m(2)) participated in a 14-week weight reduction program. The IFA was measured by computed tomography. The program induced significant reductions in body weight (8.6 kg in PreM and 7.8 kg in PostM). The IFA decreased significantly from 80.4 +/- 41.3 to 50.7 +/- 23.8 (PreM) and from 115.4 +/- 38.0 to 75.7 +/- 30.5 (PostM).

CONCLUSIONS

The receiver-operating characteristic curve analyses revealed that the appropriate cutoff values were 80 cm(2) (PreM) and 110 cm(2) (PostM) before the program, and after the program the appropriate target values were determined as 60 and 70 cm(2), respectively.

Efficacy of nasal bi-level positive airway pressure in congestive heart failure patients with cheyne-stokes respiration and central sleep apnea

BACKGROUND

Cheyne - Stokes respiration with central sleep apnea (CSR-CSA) contributes to the poor prognosis in patients with congestive heart failure (CHF). Bi-level positive airway pressure (bi-level PAP) may be an effective alternative for treating CSR-CSA and CHF.

METHODS AND RESULTS

Fourteen patients with CSR-CSA were divided into 2 groups, a control group that included 7 patients who decided to receive only conventional medications and a group of 7 patients that received bi-level PAP. Left ventricular ejection fraction (LVEF), mitral regurgitation (MR) area, plasma brain natriuretic peptide (BNP) concentration and the New York Heart Association (NYHA) functional class were evaluated initially (baseline) and 3 months later. In the control group, there were no significant changes in cardiac function during the study period. In contrast, in the group that received bi-level PAP, there were significant improvements in LVEF (from 36.3+/-2.9% to 46.0+/-4.0%, p = 0.02), MR area (from 30.4+/-7.6% to 20.0+/-5.1%, p = 0.02), BNP (from 993.6+/-332.0 pg/ml to 474.0+/-257.6 pg/ml, p = 0.02) and NYHA functional class (from 3.1+/-0.1 to 2.1+/-0.1, p = 0.03).

CONCLUSION

Treatment with bi-level PAP improved cardiac functions in CHF patients with CSR-CSA.

Sleep disordered breathing and its treatment in congestive heart failure

Sleep disordered breathing (SDB) is a common problem with adverse cardiorespiratory, endocrinological, and endothelial effects. Recent studies demonstrate an even higher prevalence of SDB in congestive heart failure (CHF) than in a randomly selected population, with up to 40% and 11% having Cheyne Stokes respiration-central sleep apnoea and obstructive sleep apnoea-hypopnoea syndromes, respectively. Randomised controlled trials of nocturnal respiratory support for SDB associated with CHF for up to three months demonstrate significant benefits in terms of improvements in left ventricular ejection fraction, markers of sympathetic system activity, and quality of life. Further randomised controlled trials of larger scale and longer duration are required to establish the role and benefit of this intervention for the treatment of this debilitating condition. The evidence for the higher prevalence of SDB in CHF, its pathogenesis, its pathophysiological consequences, and the emerging benefits of respiratory support are reviewed.

Exercise tolerance, exercise hyperpnea and central chemosensitivity to carbon dioxide in sleep apnea syndrome in heart failure patients

BACKGROUND

Sleep apnea syndrome (SAS) and exercise hyperpnea are common in patients with chronic heart failure (CHF), and although it is not known whether they are both regulated by the same mechanisms, the hypothesis of the present study was that they are related to augmented central chemosensitivity.

METHODS AND RESULTS

The oxygen desaturation index (ODI) was evaluated in 29 patients and those with ODI > 5 times/h underwent polysomnography. Patients with an apnea-hypopnea index (AHI) > 15 /h without evidence of obstructive apnea were defined as central SAS (CSAS). Cardiopulmonary exercise testing was performed to determine peak oxygen uptake and the VE-VCO2 slope. A hypercapnic gas mixture (7% CO2/93% O2) was used to activate the central chemoreflex. Nine patients had central SAS (CHF-CSAS) and 20 did not have apnea (CHF-nonSAS). Patients with CHF-CSAS had a lower peak oxygen uptake than the CHF-nonSAS group (13.0+/-2.4 vs 16.9+/-4.3 ml x kg(-1) x min(-1), p < 0.05). There was a significant correlation between central chemosensitivity and the AHI (r = 0.63, p < 0.05), between central chemosensitivity and the VE - VCO2 slope (r = 0.50, p < 0.01), whereas the VE-VCO2 slope showed an insignificant tendency to correlate with AHI (r = 0.44, p = 0.07). Conclusion CHF-CSAS is associated with impaired exercise tolerance and elevated central chemosensitivity is the responsible mechanism for CSAS and exercise hyperpnea.

Amelioration of vascular endothelial dysfunction in obstructive sleep apnea syndrome by nasal continuous positive airway pressure--possible involvement of nitric oxide and asymmetric NG, NG-dimethylarginine

BACKGROUND

Asymmetric NG,NG-dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide (NO) synthase and its plasma concentration is elevated in patients with cardiovascular risk factors, including hyperlipidemia, hypertension, diabetes, and hyperhomocysteinemia. Obstructive sleep apnea syndrome (OSAS) has been attracting attention as a risk factor for cardiovascular disorders because it often accompanies hypertension, obesity, glucose impairment, and dyslipidemia, all of which are factors in metabolic syndrome and risk factors for cardiovascular disease.

METHODS AND RESULTS

In the present study, flow-mediated vasodilatation (FMD) of the brachial artery and plasma concentrations of ADMA were measured before and after nasal continuous positive airway pressure (nCPAP) therapy, which abrogates apnea, in 10 male patients aged 36-69 years old, who were given a diagnosis of OSAS by polysomnography. The percent FMD (%FMD) improved significantly from 3.3+/-0.3% to 5.8+/-0.4% (p<0.01) and 6.6+/-0.3% (p<0.01), before, 1 week, and 4 weeks after nCPAP, respectively. At the same time, the plasma NOx concentrations, metabolites of NO, tended to increase, but the plasma ADMA concentration decreased inversely to %FMD and NOx. A negative correlation between %FMD and plasma ADMA concentration, and a positive correlation between %FMD and plasma NOx concentrations were observed.

CONCLUSION

Nasal CPAP improves endothelial function, in part by the decreasing ADMA concentration, thereby potentiating NO production.

The role of high-frequency jet ventilation in the treatment of Cheyne-Stokes respiration in patients with chronic heart failure

BACKGROUND

Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) is common in patients with severe cardiac failure. Various modes of positive airway pressure have been suggested as treatments. The authors hypothesized that high frequency jet ventilation (HFJV) can improve central sleep apnea in patients with chronic heart failure.

METHODS

Eleven subjects with stable, optimally treated chronic heart failure and Cheyne-Stokes respiration were tested untreated and on four treatment nights in random order: nasal oxygen (4 L/min), continuous positive airway pressure (CPAP) (mean 9.3 cm H(2)O), bilevel positive airway pressure (BiPAP)(mean 12.0/5.3 cm H(2)O), or HFJV(60 approximately 80 breaths per minute) during polysomnography (EMBLA, Flaga, Reykjavik, Iceland).

RESULTS

The apnea-hypopnea index (AHI) declined from 30.9 +/- 8.3/h in untreated night to 23.6 +/- 6.6/h oxygen night and 18.5 +/- 5.0/h CPAP, 14.3 +/- 3.9/h BiPAP, and 20.1 +/- 4.1/h HFJV (all P < 0.001 versus control). There was no significant difference between the AHI of HFJV and that of CPAP (P = 0.541). Arousal index decreased from 31.4+/-13.2/h untreated to 25.0 +/- 7.1/h oxygen and 13.6 +/- 4.7/h CPAP, to 13.7 +/- 4.9/h BiPAP and 14.4 +/- 4.7/h HFJV. HFJV had the similar effect to the other therapeutic groups in arousal index (P > 0.05). There were large increases in slow-wave and rapid eye movement (REM) sleep with HFJV. All subjects preferred HFJV to CPAP.

CONCLUSIONS

One night of therapy with HFJV improved nocturnal breathing pattern and sleep quality in patients with Cheyne-Stokes respiration in chronic heart failure. HFJV therapy for sleep and breathing were the same as those during a nasal CPAP night. A long-term study of the effect of HFJV on cardiovascular function is needed.

Central Sympathetic Inhibition Augments Sleep-Related Ultradian Rhythm of Parasympathetic Tone in Patients With Chronic Heart Failure

BACKGROUND

Abnormal sleep dynamics in patients with heart failure is one of the mechanisms for the relative predominance of central sympathetic outflow over parasympathetic tone. This study was designed to examine whether central sympathoinhibition could improve the sympathovagal imbalance related to rapid-eye-movement (REM)/non-REM ultradian sleep rhythm in these patients.

METHODS AND RESULTS

Beat-by-beat RR intervals of overnight electrocardiogram were serially subject to power spectral analysis in 14 patients with chronic heart failure and 13 age-matched subjects with normal cardiac function. To assess autonomic sleep dynamics, the ultradian rhythm was extracted from all-night consecutive high-frequency (HF) components of heart rate variability (HRV) before and after administration of an (alpha2)-adrenergic agonist, guanfacine. Night-time HRV in heart failure was characterized by an attenuated ultradian rhythm of HF-components with a concomitant reduction in averaged HF power. Guanfacine reduced blood pressure, heart rate, and plasma norepinephrine concentrations by 7%, 8%, and 34% (p < 0.01), respectively. After guanfacine, HF power rose by 154% (p < 0.01) with a prominent augmentation of the all-night ultradian rhythm (+361%, p < 0.01).

CONCLUSIONS

Central sympathoinhibition augments a sleep-related ultradian rhythm of parasympathetic tone, suggesting a potential benefit to autonomic balancing and sleep quality in patients with chronic heart failure.

Nocturnal Oxygen Desaturation as a Predictive Risk Factor for Coronary Restenosis After Coronary Intervention Serial Quantitative Coronary Angiography Study

BACKGROUND

Sleep-disordered breathing may affect coronary artery disease, so patients treated by percutaneous transluminal coronary angioplasty were studied to investigate the relationship between nocturnal oxygen desaturation (NOD) and the loss index.

METHODS AND RESULTS

The nocturnal oxygen desaturation index (ODI) was determined by means of a pulse oximeter in 35 patients with coronary artery disease treated by stent placement. The patients were divided into 3 groups according to ODI: <5 events/h (group N, n=6), between 5 and 14 events/h (group A, n=19), and >or=15 events/h (group B, n=10). The relationship between the ODI and loss index was examined in each group. The loss index, 0.27+/-0.23 in group N, 0.30+/-0.27 in group A, and 0.70+/-0.32 in group B, differed significantly between groups N and B (p=0.007). In all patients, the loss index showed a significant positive correlation with the ODI (R=0.585, p=0.002).

CONCLUSIONS

These findings suggest that NOD may be an important contributor to coronary restenosis in patients treated with stent placement.