Predictors of Mortality, Rehospitalization for Syncope and Cardiovascular Events in Patients With Cardiovascular Syncope.

BACKGROUND: Predictors of poor outcomes remain unknown for cardiovascular syncope patients after discharge.Methods and Results:We reviewed the medical records of consecutive patients admitted to hospital with cardiovascular syncope. We then performed Cox stepwise logistic regression analysis to identify significant independent factors for death, rehospitalization for syncope, and cardiovascular events. The study group was 206 patients with cardiovascular syncope. Of them, bradycardia was diagnosed in 50%, tachycardia in 27%, and structural disease in 23%. During a 1-year follow-up period, 18 (8%) and 45 (23%) patients, respectively, were rehospitalized for syncope or a cardiovascular event, and 10 (4%) died. Independent predictors of cardiovascular events were systolic blood pressure <100 mmHg (odds ratio [OR] 3.25; 95%confidence interval [CI] 1.41-7.51, P=0.006) and implantation of a pacemaker (OR 0.19; 95% CI 0.05-0.51, P=0.0005) (inverse association). Drug-induced syncope (OR 4.57; 95% CI 1.54-12.8, P=0.007) was an independent risk factor for rehospitalization. Finally, a history of congestive heart failure (OR 11.0; 95% CI 2.78-54.7, P=0.0006) and systolic blood pressure <100 mmHg (OR 5.40; 95% CI 1.30-22.7, P=0.02) were identified as significant independent prognostic factors for death. CONCLUSIONS: Drug-induced syncope, hypotension, no indication for a pacemaker, and a history of congestive heart failure are risk factors post-discharge for patients with cardiovascular syncope and careful follow-up of these patients for at least 1 year is recommended.

Effects of Aging on the Coagulation Fibrinolytic System in Outpatients of the Cardiovascular Department.

BACKGROUND: Although clinical trials demonstrate that the elderly with atrial fibrillation have risks of thrombosis and bleeding, the relationship between aging and coagulation fibrinolytic system in "real-world" cardiology outpatients is uncertain. METHODS AND RESULTS: We retrospectively evaluated 773 patients (mean age: 58 years; 52% men; Asian ethnicity). To thoroughly investigate markers of coagulation and fibrinolysis, we simultaneously measured levels of D-dimer, prothrombin-fragment1+2 (F1+2), plasmin-α2 plasmin inhibitor complex (PIC), and thrombomodulin (TM). There were correlations between aging and levels of F1+2, D-dimer, PIC, and TM (R=0.61, 0.57, 0.49, and 0.30, respectively). We compared 3 age groups, which were defined as the Y group (<64 years), M group (65-74 years), and the O group (>75 years). Levels of markers were higher in older individuals (D-dimer: 1.0±0.8 vs. 0.8±0.8 vs. 0.6±0.4 µg/ml, F1+2: 281.8±151.3 vs. 224.6±107.1 vs. 155.5±90.0 pmol/L, PIC: 0.9±0.3 vs. 0.8±0.3 vs. 0.6±0.5 µg/ml, and TM: 2.9±0.8 vs. 2.7±0.7 vs. 2.5±0.7FU/ml). We performed logistic regression analysis to determine F1+2 and PIC levels. Multivariate analysis revealed that aging was the most important determinant of high F1+2 and PIC levels. CONCLUSIONS: Hypercoagulable states develop with advancing age in "real-world" cardiology outpatients. (Circ J 2016; 80: 2133-2140).

J-Wave in Patients With Syncope.

BACKGROUND: Syncope is a common occurrence. The presence of J-wave, also known as early repolarization, on electrocardiogram is often seen in the general population, but the relationship between syncope and J-wave is unclear. METHODS AND RESULTS: After excluding 67 patients with structural heart disease from 326 with syncope, we classified 259 patients according to the presence or absence of J-wave (≥1 mm) in at least 2 inferior or lateral leads. Head-up tilt test (HUT) was performed for 30 min. If no syncope or presyncope occurred, HUT was repeated after drug loading. Before tilt, 97/259 (37%) had J-wave (57 male, 47.6±22.5 years) and 162 patients had no remarkable change (89 male, 51.1±21.2 years). HUT-positive rate was higher in patients with J-wave, compared with patients without (P<0.0001). The combination of J-wave and descending/horizontal ST segment in the inferior leads was more strongly associated with positive HUT than J-wave with ascending ST segment (odds ratio, 3.23). CONCLUSIONS: Prevalence of J-wave in the inferior or lateral leads was high in patients with syncope and was associated with HUT-induced neurally mediated reflex syncope (NMRS). Furthermore, the combination of J-wave and descending/horizontal ST segment in the inferior leads could be associated with a much higher risk of NMRS.

Daily Dysfunction of Autonomic Regulation Based on Ambulatory Blood Pressure Monitoring in Patients with Neurally Mediated Reflex Syncope.

BACKGROUND: The onset of neurally mediated reflex syncope (NMRS) is associated with dysfunction of the autonomic regulatory system. Yet relatively little is known about the daily conditions of the autonomic regulation system in patients with NMRS. This study elucidated characteristics of daily autonomic function using ambulatory blood pressure monitoring (ABPM) and evaluated the utility of ABPM for NMRS diagnosis. METHODS: Patients with syncope underwent the head-up tilt test (HUT) (80°, 30 minutes). If no syncope occurred, the HUT was repeated with drug loading. ABPM was performed on a different day. RESULTS: The enrolled subjects were 152 consecutive patients with syncope and 12 controls. Sixty-four patients with other diseases related to autonomic dysfunction were excluded. HUT with/without drug loading was positive in 40 patients (Group P) and negative in 48 patients (Group N). The average systolic blood pressure (SBP) in daytime was lower in Groups P and N than in the control group (Group C) (P < 0.05). The average diastolic blood pressure in daytime was also lower in Group P than in Group C (P < 0.05). The average standard deviation-SBP at nighttime was higher in Groups P and N than in Group C (P < 0.05). In heart rate variability analysis, Group P had higher high frequency normalized unit in daytime than Groups C and N (P < 0.05, P < 0.1). Low frequency/high frequency was lower in Group P than in Group N in both daytime and nighttime (P < 0.1, P < 0.05). CONCLUSION: This study suggests that patients with NMRS present with daily vagal hyperactivity and sympathetic dysfunction. ABPM may support the diagnosis of NMRS.

Atelocollagen-mediated systemic administration of myostatin-targeting siRNA improves muscular atrophy in caveolin-3-deficient mice.

Small interfering RNA (siRNA)-mediated silencing of gene expression is rapidly becoming a powerful tool for molecular therapy. However, the rapid degradation of siRNAs and their limited duration of activity require efficient delivery methods. Atelocollagen (ATCOL)-mediated administration of siRNAs is a promising approach to disease treatment, including muscular atrophy. Herein, we report that ATCOL-mediated systemic administration of a myostatin-targeting siRNA into a caveolin-3-deficient mouse model of limb-girdle muscular dystrophy 1C (LGMD1C) induced a marked increase in muscle mass and a significant recovery of contractile force. These results provide evidence that ATCOL-mediated systemic administration of siRNAs may be a powerful therapeutic tool for disease treatment, including muscular atrophy.

Delivery of small interfering RNA with a synthetic collagen poly(Pro-Hyp-Gly) for gene silencing in vitro and in vivo.

Silencing gene expression by small interfering RNAs (siRNAs) has become a powerful tool for the genetic analysis of many animals. However, the rapid degradation of siRNA and the limited duration of its action in vivo have called for an efficient delivery technology. Here, we describe that siRNA complexed with a synthetic collagen poly(Pro-Hyp-Gly) (SYCOL) is resistant to nucleases and is efficiently transferred into cells in vitro and in vivo, thereby allowing long-term gene silencing in vivo. We found that the SYCOL-mediated local application of siRNA targeting myostatin, coding a negative regulator of skeletal muscle growth, in mouse skeletal muscles, caused a marked increase in the muscle mass within a few weeks after application. Furthermore, in vivo administration of an anti-luciferase siRNA/SYCOL complex partially reduced luciferase expression in xenografted tumors in vivo. These results indicate a SYCOL-based non-viral delivery method could be a reliable simple approach to knockdown gene expression by RNAi in vivo as well as in vitro.

Obstructive sleep apnea and aldosterone.

BACKGROUND: Obstructive sleep apnea (OSA) is a major risk factor for hypertension and has been associated with increased risk for cardiovascular morbidity. A dysregulated renin-angiotensin-aldosterone system may contribute to excess sodium retention and hypertension and may be activated in OSA. We tested the hypothesis that serum levels of aldosterone and plasma renin activity (PRA) are increased by apneic sleep in subjects without cardiovascular disease, compared to healthy control subjects. METHODS AND RESULTS: Plasma aldosterone level was measured in 21 subjects with moderate to severe OSA and was compared to 19 closely matched healthy subjects. Plasma renin activity (PRA) was measured in 19 OSA patients and in 20 healthy controls. Aldosterone and PRA were measured before sleep (9 pm), after 5 hrs of untreated OSA ( 2am) and in the morning after awakening (6 am). There were no baseline (9pm) differences in serum aldosterone levels and PRA between the healthy controls and OSA patients (aldosterone: 55.2 +/- 9 vs 56.0 +/- 9 pg/mL; PRA: 0.99 +/- 0.15 vs. 1.15 +/- 0.15 ng/mL/hr). Neither several hours of untreated severe OSA nor CPAP treatment affected aldosterone levels and PRA in OSA patients. Diurnal variation of both aldosterone and PRA was observed in both groups, in that morning renin and aldosterone levels were higher than those measured at night before sleep. CONCLUSIONS: Our study shows that patients with moderate to severe OSA without co-existing cardiovascular disease have plasma aldosterone and renin levels similar to healthy subjects. Neither untreated OSA nor CPAP treatment acutely affect plasma aldosterone or renin levels.

Mechanism of HMGB1 release inhibition from RAW264.7 cells by oleanolic acid in Prunus mume Sieb. et Zucc.

High mobility group box-1 protein (HMGB1), primarily from the nucleus, is released into the extracellular milieu either passively from necrotic cells or actively through secretion by monocytes/macrophages. Extracellular HMGB1 acts as a potent inflammatory agent by promoting the release of cytokines such as tumor necrosis factor (TNF)-alpha, has procoagulant activity, and is involved in death due to sepsis. Accordingly, HMGB1 is an appropriate therapeutic target. In this study, we found that an extract of Prunus mume Sieb. et Zucc. (Ume) fruit (Ume extract), an abundant source of triterpenoids, strongly inhibited HMGB1 release from lipopolysaccharide (LPS)-stimulated macrophage-like RAW264.7 cells. The inhibitory effect on HMGB1 release was enhanced by authentic oleanolic acid (OA), a naturally occurring triterpenoid. Similarly, the HMGB1 release inhibitor in Ume extract was found to be OA. Regarding the mechanisms of the inhibition of HMGB1 release, the OA or Ume extract was found to activate the transcription factor Nrf2, which binds to the antioxidative responsive element, and subsequently the heme oxygenase (HO)-1 protein was induced, indicating that the inhibition of HMGB1 release from LPS-stimulated RAW264.7 cells was mediated via the Nrf2/HO-1 system; an essentially antioxidant effect. These results suggested that natural sources of triterpenoids warrant further evaluation as 'rescue' therapeutics for sepsis and other potentially fatal systemic inflammatory disorders.

Obstructive sleep apnea and cardiovascular disease.

Over the past few decades, sleep apnea has emerged as an important potential etiologic factor in a broad range of cardiac and vascular diseases. These disease conditions include hypertension, coronary artery disease, myocardial infarction, heart failure, and stroke. Recognition of the role of sleep apnea in clinical cardiology is also increasing in Japan. Although sleep apnea has been strongly linked to obesity in Western populations, in Japanese and other Asian populations there is evidence to indicate that sleep apnea may be prevalent even at lower levels of obesity. In this review we address the epidemiology of sleep apnea. Since sleep apnea includes the combined stresses of hypoxemia, apnea, and disrupted sleep, we also review briefly the potential disease mechanisms that may be activated as a consequence of sleep apnea. We further examine the role of sleep apnea in the pathophysiology and management of specific cardiovascular conditions. Overall, while the evidence of sleep apnea as a causal mechanism in cardiovascular disease is strong and increasing, definitive evidence of the etiologic role of sleep apnea has yet to be obtained. The evidence is most clear in patients with hypertension. Also remaining to be established is whether the treatment of sleep apnea prevents cardiac and vascular events. With regard to this question, although the available data strongly suggest that continuous positive airway pressure treatment is beneficial, randomized control trials are needed in order to confirm this.

Obstructive sleep apnea and heart failure.

Obstructive sleep apnea (OSA) exerts several effects that may be particularly deleterious in patients with heart failure (HF). OSA should be considered especially in HF patients who are obese or have the metabolic syndrome, systemic hypertension, or pulmonary hypertension. HF patients in whom OSA is suspected should undergo a full evaluation by a sleep specialist, including a polysomnogram, to diagnose OSA and differentiate this disease from central sleep apnea. Those found to have OSA should then receive continuous positive airway pressure and/or other interventions, and standard disease management strategies should be used to maximize compliance. Those who cannot tolerate continuous positive airway pressure may be candidates for mandibular advancement devices or surgical therapies including tracheostomy. Standard HF medications should be used to treat HF, and optimization of fluid balance may help minimize OSA severity. However, it is still unknown whether treatment of OSA in HF patients will reduce hospitalizations or mortality.

Immediate discontinuation of ablation during pulmonary vein isolation remarkably decreases the incidence of esophageal thermal lesions even when using steerable sheaths.

BACKGROUND: Left atrial-esophageal fistulas (LAEFs) are serious complications with high mortality after atrial fibrillation radiofrequency ablation (AFRA). Decreasing the incidence of esophageal thermal lesions (EsoTLs) that may lead to LAEFs is important. The aim of this study was to suppress EsoTL development and determine the appropriate alarm setting for a temperature-monitoring probe by using steerable sheath (STS) methods. METHODS: We enrolled 82 consecutive patients (mean, 61.9±11.7 years; 75.6% men) who underwent AFRA, including pulmonary vein isolation for symptomatic, drug-refractory atrial fibrillation with esophageal temperature monitoring by using STS between January 2011 and April 2014. All patients underwent upper gastrointestinal endoscopy (UGE) 1-3 days after AFRA. The timing of ablation discontinuation in the first 17 patients was determined by each physician during AFRA (only monitoring group, OM). In the next 65 patients, physicians were to immediately discontinue ablation when an alarm set at 39 °C went off (instruction group, INS). We compared two groups with respect to the incidence of EsoTLs. RESULTS: Among the 82 patients, 5 (6.1%) had EsoTLs after AFRA. EsoTLs occurred in 3 of 17 patients (17.6%) and 2 of 65 patients (3.1%) in the OM and INS groups, respectively. The incidence of EsoTLs in the INS group was significantly lower than that in the OM group (p=0.0254). EsoTL did not occur at maximal temperature less than 39 °C, measured by using esophageal temperature-monitoring probe. CONCLUSIONS: Immediate discontinuation of ablation during pulmonary vein isolation remarkably decreased the incidence of EsoTLs, even when using STS.

Recurrence of atrial fibrillation within three months after pulmonary vein isolation for patients with paroxysmal atrial fibrillation: Analysis using external loop recorder with auto-trigger function.

BACKGROUND: Pulmonary vein isolation (PVI) via catheter ablation has been shown to be a highly effective treatment option for patients with symptomatic paroxysmal atrial fibrillation (AF). The recurrence of AF within 3 months after PVI is not considered to be the result of ablation procedure failure, because early recurrence of AF is not always associated with late recurrence. We examined the usefulness of an external loop recorder with an auto-trigger function (ELR-AUTO) for the detection of atrial fibrillation following PVI to characterize early recurrence and to determine the implications of AF occurrence within 3 months after PVI. METHODS: Fifty-three consecutive symptomatic patients with paroxysmal AF (age 61.6±12.6 years, 77% male) who underwent PVI and were fitted with ELR-AUTO for 7±2.0 days within 3 months after PVI were enrolled in this study. RESULTS: Of the 33 (62.2%) patients who did not have AF recurrence within 3 months after PVI, only 1 patient experienced AF recurrence at 12 months. Seven (35%) of the 20 patients who experienced AF within 3 months of PVI experienced symptomatic AF recurrence at 12 months. The sensitivity, specificity, positive predictive value, and negative predictive value of early AF recurrence for late recurrence were 87.5%, 71.1%, 35.0%, and 96.9%, respectively. CONCLUSIONS: AF recurrence measured by ELR-AUTO within 3 months after PVI can predict the late recurrence of AF. Freedom from AF in the first 3 months following ablation significantly predicts long-term AF freedom. ELR-AUTO is useful for the detection of symptomatic and asymptomatic AF.

Single center experience in Japanese patients with syncope.

BACKGROUND AND PURPOSE: The present diagnostic method and features of syncope in Japan are unclear. Implantable loop recorder (ILR) and head-up tilt tests have recently become available for diagnosing syncope. The examination method and rates of diagnosing syncope may vary. This study aimed to clarify the present diagnostic method and features of syncope in a single Japanese medical center. METHODS AND RESULTS: We retrospectively reviewed the medical records of consecutive patients who were seen at our hospital from January 1, 2009, to December 31, 2012. A total of 547 patients (328 men, 60.4±21.5 years) with syncope were seen at our hospital. Reflex syncope was diagnosed in 29.1% of the cases, orthostatic hypotension in 11.7%, cardiac syncope in 34.0%, and unexplained syncope in 23.9% by initial and early evaluations. The number of patients with situational syncope and orthostatic hypotension that could be diagnosed in the initial evaluation of the first examination was significantly greater than that in subsequent evaluations. Forty-three percent of the unexplained syncope patients received an ILR. The consent rate for ILR implantations in the unexplained syncope patients with a suspected arrhythmia nature was 53.1%. The cumulative ILR diagnostic rates were 47% and 65% at 1 and 2 years after the ILR implantation, respectively. The estimated ILR diagnostic rates were significantly greater than that for conventional test without using an ILR. When patients with unexplained syncope could be diagnosed, the recurrent symptoms were greatly reduced. CONCLUSIONS: Syncope is induced by various causes in Japan. It is important that we understand the characteristics of each syncope cause. The consent rate for implanting an ILR in appropriate unexplained syncope patients is low. We need to educate these patients about the importance of making a diagnosis of syncope.

Expression of Fibroblast growth factor 19 (Fgf19) during chicken embryogenesis and eye development, compared with Fgf15 expression in the mouse.

The normal development of eyes relies on proper signaling through Fibroblast growth factor (FGF) receptors, but the source and identity of cognate ligands have remained largely unknown. We have found that Fgf19 is expressed in the developing chicken retina. In situ hybridization discloses dynamic expression patterns for Fgf19 in the optic vesicle, lens primordia and retinal horizontal cells. Overall expression pattern of Fgf19 during chicken embryogenesis was also examined: Fgf19 is expressed in the regions associated with cranial placodes induction, boundary regions of rhombomeres, somites, specific groups of neural cells in midbrain, hindbrain, and those derived from epibranchial placodes, and the apical ectodermal ridge of limb buds. Expression pattern of the Fgf19-orthologous gene Fgf15 was further examined in the mouse developing eye. Fgf15 is expressed in the optic vesicle, a subset of progenitor cells of neural retina, and emerging ganglion and amacrine cells during retinogenesis.

Adacolumn, an adsorptive carrier based granulocyte and monocyte apheresis device for the treatment of inflammatory and refractory diseases associated with leukocytes.

Apheresis has been recognized both economically and therapeutically as a novel approach for the treatment of inflammatory diseases, and certain others, which respond poorly to drug therapy. This report is about Adacolumn, an adsorptive carrier based granulocyte and monocyte apheresis device with a volume of 335 mL, filled with about 220 g of cellulose acetate beads of 2 mm diameter as the column adsorptive carriers. Pre- and post-column leukocyte counts have shown that the carriers adsorb about 65% of granulocytes, 55% of monocytes and 2% of lymphocytes from the blood in the column. Additionally, after apheresis, there is a marked decrease in inflammatory cytokines (TNF-alpha, IL-1beta, IL-6 and IL-8) produced by blood leukocytes, together with down-modulation of L-selectin and the chemokine receptor CXCR3. Adacolumn has been used to treat patients with rheumatoid arthritis, ulcerative colitis and HIV infection. Typical apheresis sessions have been 4-10, at a frequency of one or two sessions per week. Treatment of patients with Adacolumn has been associated with very promising efficacy and safety data. Accordingly, in Japan, Adacolumn has been approved by the Ministry of Health for the treatment of ulcerative colitia. Furthermore, Adacolumn met the required quality and safety standards for medical devices and received an EC certification (CE-mark) from TUV in 1999. However, although Adacolumn carriers are very efficient in depleting excess and activated granulocytes and monocytes/macrophages, the clinical efficacy associated with Adacolumn apheresis cannot be fully explained on the basis of reducing granulocytes and monocytes per se. Hence, a long lasting effect on inflammatory cytokine generation, chemokine activities or immunomodulation is likely, but the precise mechanisms involved are not fully understood yet.

Experimental sleep restriction causes endothelial dysfunction in healthy humans.

BACKGROUND: Epidemiologic evidence suggests a link between short sleep duration and cardiovascular risk, although the nature of any relationship and mechanisms remain unclear. Short sleep duration has also been linked to an increase in cardiovascular events. Endothelial dysfunction has itself been implicated as a mediator of heightened cardiovascular risk. We sought to determine the effect of 8 days/8 nights of partial sleep restriction on endothelial function in healthy humans. METHODS AND RESULTS: Sixteen healthy volunteers underwent a randomized study of usual sleep versus sleep restriction of two-thirds normal sleep time for 8 days/8 nights in a hospital-based clinical research unit. The main outcome was endothelial function measured by flow-mediated brachial artery vasodilatation (FMD). Those randomized to sleep restriction slept 5.1 hours/night during the experimental period compared with 6.9 hours/night in the control group. Sleep restriction was associated with significant impairment in FMD (8.6±4.6% during the initial pre-randomization acclimation phase versus 5.2±3.4% during the randomized experimental phase, P=0.01) whereas no change was seen in the control group (5.0±3.0 during the acclimation phase versus 6.73±2.9% during the experimental phase, P=0.10) for a between-groups difference of -4.40% (95% CI -7.00 to -1.81%, P=0.003). No change was seen in non-flow mediated vasodilatation (NFMD) in either group. CONCLUSION: In healthy individuals, moderate sleep restriction causes endothelial dysfunction. CLINICAL TRIAL REGISTRATION URL: ClinicalTrials.gov. Unique identifier: NCT01334788.

Effects of experimental sleep restriction on caloric intake and activity energy expenditure.

BACKGROUND: Epidemiologic studies link short sleep duration to obesity and weight gain. Insufficient sleep appears to alter circulating levels of the hormones leptin and ghrelin, which may promote appetite, although the effects of sleep restriction on caloric intake and energy expenditure are unclear. We sought to determine the effect of 8 days/8 nights of sleep restriction on caloric intake, activity energy expenditure, and circulating levels of leptin and ghrelin. METHODS: We conducted a randomized study of usual sleep vs a sleep restriction of two-thirds of normal sleep time for 8 days/8 nights in a hospital-based clinical research unit. The main outcomes were caloric intake, activity energy expenditure, and circulating levels of leptin and ghrelin. RESULTS: Caloric intake in the sleep-restricted group increased by +559 kcal/d (SD, 706 kcal/d, P=.006) and decreased in the control group by -118 kcal/d (SD, 386 kcal/d, P=.51) for a net change of +677 kcal/d (95% CI, 148-1,206 kcal/d; P=.014). Sleep restriction was not associated with changes in activity energy expenditure (P=.62). No change was seen in levels of leptin (P=.27) or ghrelin (P=.21). CONCLUSIONS: Sleep restriction was associated with an increase in caloric consumption with no change in activity energy expenditure or leptin and ghrelin concentrations. Increased caloric intake without any accompanying increase in energy expenditure may contribute to obesity in people who are exposed to long-term sleep restriction. TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT01334788; URL: www.clinicaltrials.gov.

Sleep-disordered breathing in patients with the Brugada syndrome.

We investigated breathing patterns and the occurrence of arrhythmias and ST-segment changes during sleep in patients with Brugada syndrome. Patients with Brugada syndrome are more likely to die from ventricular arrhythmias during sleep. ST-segment changes have been correlated with risk of sudden cardiac death. Whether sleep disturbances may contribute to arrhythmogenesis is unknown. Patients with Brugada syndrome underwent overnight polysomnography with simultaneous 12-lead electrocardiographic recording. A control group matched by age, gender, and body mass index (BMI) also underwent polysomnography. Twenty patients were included (50 ± 15 years old, 75% men). Despite their normal BMI (24.7 ± 2.7 kg/m(2)), 45% had sleep-disordered breathing (SDB), with a mean apnea-hypopnea index of 17.2 ± 14 events/hour. In patients with a high risk of arrhythmias, 5 (63%) had SDB. In the control group, 27% had SDB. Atrial or ventricular arrhythmias were not observed. Spontaneous ST-segment changes occurred in 2 patients over 45 different time points. Most ST-segment changes were observed during rapid eye movement sleep (31%) or within 1 minute of arousals (44%). Regarding respiratory events, 25 (56%) of ST-segment changes were related to occurrence of apnea or hypopnea. In conclusion, patients with Brugada syndrome have a high prevalence of SDB even in the setting of normal BMI. The higher incidence of nocturnal death in patients with Brugada syndrome may be conceivably related to co-morbid SDB. Moreover, autonomic instability encountered in rapid eye movement sleep and arousals could potentiate the risk of arrhythmias.

Effect of weight gain on cardiac autonomic control during wakefulness and sleep.

Obesity has been associated with increased cardiac sympathetic activation during wakefulness, but the effect on sleep-related sympathetic modulation is not known. The aim of this study was to investigate the effect of fat gain on cardiac autonomic control during wakefulness and sleep in humans. We performed a randomized, controlled study to assess the effects of fat gain on heart rate variability. We recruited 36 healthy volunteers, who were randomized to either a standardized diet to gain ≈4 kg over 8 weeks followed by an 8-week weight loss period (n=20) or to serve as a weight-maintainer control (n=16). An overnight polysomnogram with power spectral analysis of heart rate variability was performed at baseline, after weight gain, and after weight loss to determine the ratio of low-frequency to high-frequency power and to examine the relationship between changes in heart rate variability and changes in insulin, leptin, and adiponectin levels. Mean weight gain was 3.9 kg in the fat gain group versus 0.1 kg in the maintainer group. Low frequency/high frequency increased both during wakefulness and sleep after fat gain and returned to baseline after fat loss in the fat gain group and did not change in the control group. Insulin, leptin, and adiponectin also increased after fat gain and fell after fat loss, but no clear pattern of changes was seen that correlated consistently with changes in heart rate variability. Short-term fat gain in healthy subjects is associated with increased cardiac sympathetic activation during wakefulness and sleep, but the mechanisms remain unclear.