New definition of hypotension in patients with reflex syncope using 24-hour ambulatory blood pressure monitoring (SynABPM Study)

Background

Diagnostic criteria for ambulatory blood pressure monitoring (ABPM) in patients with suspected reflex syncope are lacking.

Purpose

We hypothesized that patients with reflex syncope have a higher prevalence of systolic blood pressure (SBP) drops on ABPM than control subjects and we aimed to define the SBP cut-off values that allow identification of patients with hypotensive susceptibility.

Methods

We compared ABPM data from reflex syncope patients and controls, matched by average 24-hour SBP, age, sex and hypertension. Patients with constitutional hypotension, orthostatic hypotension, predominant cardioinhibition or competing causes of syncope were excluded. Daytime and night-time SBP drops (<110, 100, 90, 80 mmHg) were assessed. Findings were validated in an independent sample.

Results

In the Derivation cohort, daytime SBP drops were significantly more common in 158 syncope patients than 329 controls. One or more daytime drop <90 mmHg provided the best diagnostic yield (91% specificity, 32% sensitivity, Odds Ratio [OR]=4.6, p=0.001). Two or more-daytime drops <100 mmHg achieved 84% specificity and 40% sensitivity (OR=3.5, p=0.001). Results were confirmed in the Validation cohort: one or more daytime SBP drop <90 mmHg provided 94% specificity and 29% sensitivity (OR=6.2, p<0.001), while two or more daytime SBP drops <100 mmHg achieved 83% specificity and 35% sensitivity (OR=2.6, p<0.001) (Figure 1).

Conclusion

SBP drops during ABPM are more common in reflex syncope patients than in controls. Cut-off values that may be applied in clinical practice are defined. This study expands the current indications for ABPM to patients with reflex syncope.

Funding Acknowledgement

Type of funding sources: None.

Lifelong and mature-onset syncope in older adults may have different mechanisms

Background

Syncope is a common clinical problem with a sharp rise in the incidence after 70 years. In older patients, syncope is often a diagnostic challenge. It is unclear whether the age at which patients experience syncope for the first time impacts the results of syncope investigation.

Purpose

To study the influence of early-onset vs. mature-onset syncope on clinical characteristics and final head-up tilt (HUT) diagnosis in a large sample of unexplained syncope patients.

Methods

Consecutive patients (n=1928) with unexplained syncope after initial evaluation examined with a standard HUT protocol in a syncope unit were stratified into age groups below and above 60 years. Clinical characteristics and the final HUT diagnosis were analysed in relation to self-reported age at first syncope and age at investigation. The distribution of age at first syncope was bimodal with peaks at 15 and 70 years (Figure 1). In the present analysis, patients aged >60 years (n=836) with early-onset (<30 years) and mature-onset (>60 years) syncope were compared.

Results

Vasovagal syncope (VVS) was more common in early-onset syncope, 39% vs 19% (p<0.001), (Figure 2). Orthostatic hypotension (OH) was more common in mature-onset syncope, 23% vs 7% (p<0.001), as was hypertension, 59% vs 40% (p=0.001). The frequency of carotid sinus syndrome (CSS) was not affected by age at first syncope in patients aged >60 years.Complex syncope etiology (findings suggesting overlap between VVS, OH and/or CSS) was more common among patients with early-onset syncope, 37% vs 26% (p=0.023). No definite HUT-derived diagnosis was more common in mature-onset syncope, 23% vs 13% (p=0.023). Heart failure, 9% vs 2% (p=0.024) and atrial fibrillation, 20% vs 9% (p=0.013) were more common in mature-onset syncope. Prodromes were less common in mature-onset syncope, 26% vs 52% (p<0.001), however there was no significant difference in reported palpitations preceding syncope and dizziness on standing.

Conclusions

Mature-onset syncope was more often associated with absence of prodromes, orthostatic hypotension, inconclusive HUT findings and presence of heart failure and atrial fibrillation suggesting cardiac syncope to be the likely cause. Early-onset syncope was associated with presence of prodromes, vasovagal reflex mechanism and complex syncope diagnosis. Lifelong and mature-onset unexplained syncope may have different pathophysiological mechanisms in older patients and aetiologies other than vasovagal syncope should be carefully considered in patients with first-ever syncope in later life.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swedish heart and lung foundationCrafoord foundation

Cardiovascular morbidity and mortality related to non-alcoholic fatty liver disease: a systematic review and meta-analysis of prospective studies

Background

Whether non-alcoholic fatty liver disease (NAFLD) is a risk factor for cardiovascular (CV) events is still debated. Currently available evidence derives from non-homogeneous studies yielding conflicting results.

Purpose

We set out to assess the relationship between NAFLD and CV morbidity and mortality by pooling results of previous studies.

Methods

We performed a systematic review and meta-analysis of prospective observational studies published from 1966 through 2021 reporting summary-level outcome data in subjects with and without NAFLD. Adjusted risk ratios (RRs) and 95% confidence intervals (CIs) for all-cause mortality, CV mortality, myocardial infarction (MI), stroke, major adverse cerebrocardiovascular events (MACCE) and atrial fibrillation (AF) were pooled through inverse variance random-effect meta-analysis to compute the summary effect size. We performed post-hoc subgroup analysis stratified by geographical region and univariate mixed-effect model meta-regression analysis to address statistical heterogeneity.

Results

We identified a total of 29 studies pooling an overall population of 5,626,573 middle-aged individuals (mean age 56±8; male sex 53%; NAFLD 5.8%, n=326,389). Mean follow-up was 10±6 years. Compared with control population, presence of NAFLD was associated with similar risk of all-cause death (RR 1.17; 95% CI 0.89–1.52) and CV death (RR 0.84; 95% CI 0.64–1.10). When analysed by geographic location, pooled estimates of RR (95% CI) for all-cause death were 1.57 (1.00–2.48) for Western countries, and 0.81 (0.52–1.1.26) for Eastern countries (test for subgroup difference, P=0.04). Meta-regression analysis showed a stronger relationship between NAFLD and all-cause mortality proportional to increasing body mass index (P=0.048). NAFLD was associated with increased risk of myocardial infarction (RR 1.35; 95% CI 1.09–1.68), stroke (RR 1.20; 95% CI 1.06–1.35), MACCE (RR 2.09; 95% CI 1.57–2.78) and atrial fibrillation (RR 1.37; 95% CI 1.05–1.78).

Conclusion

NAFLD portends excess all-cause mortality but only in Western countries. CV mortality was similar in NAFLD and non-NAFLD groups. NAFLD is associated with increased risk of incident MI, stroke, MACCE and AF.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Association of incident fragility fractures in patients hospitalised due to unexplained syncope and orthostatic hypotension

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The study was funded by The Swedish Heart-Lung Foundation, The Greta and Johan Kock Foundation, and an Agreement for Medical Education and Research (ALF) grant by Swedish Research Council funding for clinical research in medicine.

Background

Fragility fractures are caused by low-energy insults such as falls from standing height or less and pose a growing health challenge as their incidence rises with increasing age. Impaired orthostatic blood pressure response and a number of cardiovascular biomarkers have been previously identified as risk factors for fractures. It is likely that severe episodes of syncope and orthostatic hypotension increase the risk of subsequent fragility fractures, however this relationship has not been thoroughly examined.

Purpose

To investigate the relationship of hospital admissions due to unexplained syncope and OH with incident fragility fractures in a middle-aged population.

Methods

We analysed a large population-based prospective cohort of 30,446 middle-aged individuals (age, 57.5 ± 7.6; men, 39.8%). We included patients hospitalised due to unexplained syncope and OH. Cox regression analysis adjusted for age, sex, prevalent fractures, body mass index (BMI) were applied to assess the impact of unexplained syncope/OH hospitalisations on subsequent incident fragility fractures. Prevalent fractures occurring before syncope/OH hospitalisation were excluded (n = 39) as well as cases with no follow-up time after the event of syncope/OH (n= 8).

Results

The mean follow-up from baseline to first incident fracture or end of follow-up was 17.8 + 6.5 years, and 8201 (27%) suffered incident fracture. The mean age of patients with unexplained syncope (n = 493) and OH patients (n = 406) at baseline was 61.5 ± 7.1 years (50.1%, male) and 62.6 ± 6.6 years (49.8% male), respectively. The mean time between baseline and first admission for syncope and OH was 12.3 ± 4.5 years, and the mean age at first hospitalisation was 74.4 ± 7.6 years. In the multivariable-adjusted Cox regression, the risk of subsequent incident fractures was increased among patients hospitalised due to unexplained syncope (HR: 1.20; 95% CI 1.03–1.40; p < 0.02) and OH (HR: 1.40; 95% CI 1.20–1.64; p < 0.001), respectively (Kaplan-Meier curves; Figure 1).

Conclusions

Patients hospitalised due to unexplained syncope and OH demonstrate increased risk of subsequent fragility fractures. We suggest that patients who are hospitalised for unexplained syncope and OH should be clinically assessed for true syncope aetiology, systematically treated against fall risk, and evaluated for additional risk factors for fragility fractures. Abstract Figure 1. Kaplan-Meier curves

Effect of aging on cerebral tissue oxygenation in relation to reflex syncope

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Swedish Heart and Lung Foundation, The Swedish Heart and Lung Association, ALF funds, Skåne University Hospital Funds, The Crafoord Foundation.

Background

There is an increased susceptibility to syncope with aging attributed to age-related physiological impairments. Cerebral oximetry non-invasively measures cerebral tissue oxygenation (SctO2) and has been shown to be valuable in syncope evaluation. SctO2 has been found to decrease with aging but it is unknown whether the decrease in SctO2 is related to increased susceptibility to syncope during orthostatic provocation. By measuring SctO2 during head up tilt test (HUT) we can study age-related differences in SctO2 and their impact on developing reflex syncope.

Purpose

To investigate the effect of age on the cerebral tissue oxygenation threshold for syncope and presyncope among patients with vasovagal syncope.

Methods

Non-invasive haemodynamic monitoring and near-infrared spectroscopy (NIRS) were applied during head-up tilt (HUT) in 139 vasovagal syncope patients (mean [SD] 45[17] years, 60% female), and 82 control patients with a normal response to HUT (45[18] years, 61% female). Group differences in SctO2 and systolic blood pressure (SBP) during HUT in supine position, after 3 and 10 min of HUT, 30 seconds prior to syncope ("presyncopal phase") and during syncope in different age groups (<30, 30-60 and  >60 years) were compared using one-way ANOVA and Tukey"s multiple comparison test. Associations between age and SctO2 were studied using linear regression models adjusted for sex and concurrent SBP.

Results

Lower SctO2 in supine position was associated with increasing age among controls (B=-0.085, p = 0.010) but not among VVS patients (B=-0.036, p = 0.114). No age-related differences in SctO2 were found after 3 and 10 minutes of HUT and during syncope.  Mean SctO2 (%) during the presyncopal phase decreased over the advancing age groups (<30: 66.9 ± 6.2, 30-60: 64.5 ± 6.1, >60: 62.2 ± 5.8; p = 0.009 for inter-group comparison). In contrast, mean SBP during the presyncopal phase did not differ by age groups (<30: 85.6 ± 21.8, 30-60: 77.6 ± 19.7, >60: 77.6 ± 20.8 mmHg, p = 0.133). Age was associated with lower SctO2 during the presyncopal phase after adjusting for sex and SBP (B = 0.096, p = 0.001).

Conclusion

Older VVS patients have lower cerebral tissue oxygenation in the presyncopal phase compared with younger patients independently of systolic blood pressure. These results suggest either that with imminent reflex syncope cerebral tissue oxygenation diminishes more with advancing age or that cerebral deoxygenation is better tolerated by older reflex syncope patients. Abstract Figure.

Prognostic significance of cardiac amyloidosis in patients with aortic stenosis: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

 Cardiac amyloidosis (CA) has been increasingly recognized in elderly patients with aortic stenosis (AS), but with uncertain prognostic significance.

Objectives

We performed a systematic review and meta-analysis to clarify whether concurrent CA portends excess mortality in patients with aortic stenosis AS.

Methods

Our systematic review of the literature published through June 2020, sought observational studies reporting summary-level outcome data of all-cause mortality in AS patients with or without concurrent CA. Pooled estimate of Mantel-Haenszel odds ratio (OR) and 95% confidence intervals (CIs) for all-cause death was assessed as the primary endpoint. We performed subgroup analysis stratified by severity of left ventricular hypertrophy (LVH) and study-level meta-regression analysis to explore the effect of covariates on summary effect size and to address statistical heterogeneity.

Results

We identified 4 studies including 609 AS patients (9% AS-CA; 69% men; age, 84 ± 5 years). The average follow-up was 20 ± 5 months. Compared with lone AS, AS-CA was associated with 2-fold increase in all-cause mortality (pooled OR: 2.30; 95% CI: 1.02-5.18; I2 = 62%). When analysed according to LVH severity, pooled ORs (95% CI) for all-cause mortality were 1.29 (0.65-2.22) for mild LVH (≤16 mm), and 4.81 (2.19-10.56) for moderate/severe LVH (>16 mm). Meta-regression analysis confirmed a stronger relationship proportional to the degree of LVH, regardless of age and aortic valve replacement, explaining between-study heterogeneity variance.

Conclusions

CA heralds significantly higher risk of all-cause death in elderly patients with AS. Severity of LVH appears to be a major prognostic determinant in patients with dual AS-CA pathology.

Abstract Figure.

Downregulation of growth hormone in postural orthostatic tachycardia syndrome: insights from the SYSTEMA cohort

Background

Postural orthostatic tachycardia syndrome (POTS) is a variant of cardiovascular autonomic disorder occurring predominantly in young women. POTS is characterized by an excessive heart rate increase when assuming upright posture accompanied by symptoms of orthostatic intolerance. The pathophysiology of POTS has not been fully established and is believed to be multifactorial.

Purpose

We aimed to investigate the alterations in circulating growth hormone level in POTS.

Methods

We conducted an age-matched case-control study enrolling 42 patients with POTS (age 31±9 years; 36 women) verified by positive head-up tilt testing and cardiovascular autonomic tests, and 46 controls (32±9 years; 35 women) with negative active standing test and no history of syncope, orthostatic intolerance and endocrine disease. We measured plasma levels of growth hormone using a high-sensitivity chemiluminescence immunoassay in relation to presence of POTS diagnosis. All study participants completed the validated Orthostatic Hypotension Questionnaire (OHQ), consisting of two components: the symptoms assessment scale (OHSA) and daily activity scale (OHDAS) to evaluate the burden of symptoms. We applied standard statistical tests for group differences. Growth hormone values were log-transformed and standardized before the group comparison.

Results

POTS patients had significantly lower plasma levels of growth hormone (ng/mL) (median=0.53, IQR, 0.10–2.83 vs. median=2.33, IQR, 0.26–7.2, p=0.04) than controls. Levels of growth hormone were reversely related to OHDAS (p=0.049) among POTS patients. Supine heart rate was significantly higher in POTS patients (69.0±11.1 beats/min vs. 63.3±10.8 beats/min, p=0.02), as well as diastolic blood pressure (72.9±9.1 mmHg vs. 69.0±8.5 mmHg, p=0.04). We observed no significant difference in supine systolic blood pressure (116.6±13.3 mmHg vs. 115.2±10.0 mmHg, p=0.60). POTS patients had a significantly higher composite OHQ score than controls (60.0±18.6 vs. 4.2±7.5, p<0.001), as well as OHSA (36.2±10.0 vs. 3.6±6.4, p<0.001) and OHDAS (23.8±9.7 vs. 0.6±1.3, p<0.001).

Conclusion(s)

Our study shows that patients with POTS have significantly reduced plasma levels of circulating growth hormone. Lower growth hormone levels among POTS patients are associated with increased impairment of daily life activities. Further studies are necessary to confirm our findings in the independent populations and explain the mechanisms behind this alteration.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Crafoord Foundation, Swedish Heart and Lung Foundation

High circulating levels of midregional proenkephalin A predict vascular dementia: a population-based prospective study

Midregional Pro-enkephalin A (MR-PENK A) and N-terminal Protachykinin A (NT-PTA) have been associated with vascular dementia. However, the longitudinal relationship between these biomarkers and incident dementia has not been fully investigated. In the population-based Malmö Preventive Project, circulating levels of MR-PENK A and NT-PTA were determined in a random sample of 5,323 study participants (mean age: 69 ± 6 years) who were followed-up over a period of 4.6 ± 1.6 years. The study sample included 369 patients (7%) who were diagnosed in the same period with dementia. We analyzed relationship of MR-PENK A and NT-PTA with the risk of developing dementia by using multivariable-adjusted Cox regression models adjusted for traditional risk factors. Increased plasma levels of MR-PENK A were associated with higher risk of incident vascular dementia whereas no associations were found with all-cause or Alzheimer dementia. The risk of vascular dementia was mainly conferred by the highest quartile of MR-PENK as compared with lower quartiles. Elevated levels of NT-PTA yielded significant association with all-cause dementia or dementia subtypes. Elevated plasma concentration of MR-PENK A independently predicts vascular dementia in the general population. MR-PENK A may be used as an additional tool for identifying vascular subtype in ambiguous dementia cases.

P1588Beta-blocker therapy and risk of dementia: a population-based prospective study

Introduction

Cerebral side effects have long been recognized as complications to beta-blocker treatment. However, evidence of a longitudinal relationship between the use of beta-blockers and incident dementiais still controversial.

Objective

To evaluate the longitudinal relationship between use of beta-blockers, as a class, and incident risk of all-cause dementia, vascular dementia, Alzheimer and mixed dementia.

Methods

From the prospective, population-based, Malmö Preventive Project, 18,063 individuals (mean age 68.2, males 63.4%) were included at baseline and followed for 84,506 person-years. Patients with prevalent cerebrovascular disease and dementia were excluded. In order to weight the risk of incident dementia associated with beta-blocker consumption, we performed propensity score matching analysis, resulting in 3,720 matched pairs of beta-blocker users and non-users at baseline, and multivariable Cox proportional-hazardsregression.

Results

Overall, 122 study participants (1.6%) were diagnosed with dementia over the course of follow-up. Use of beta-blockers was independently associated with increased risk of developing vascular dementia, regardless of confounding factors (HR: 1.72, 95% CI 1.01–3.78; p=0.048). Conversely, treatment with BB was not associated with increased risk of all-cause, Alzheimer and mixed dementia (HR: 1.15; 95% CI 0.80–1.66; p=0.44; HR: 0.85; 95% CI 0.48–1.54; P=0.59 and HR: 1.35; 95% CI 0.56–3.27; p=0.50, respectively).

Conclusions and relevance

We observed that use of beta-blockers, as a class, is associated with increased longitudinal risk of vascular dementia in the general elderly population, regardless of cardiovascular risk factors, prevalent or incident history of atrial fibrillation, stroke, coronary events and heart failure. Further studies are needed to confirm our findings in the general population and to explore the mechanisms underlying the relationship between use of beta-blockers and increased risk of vascular dementia.

P6223Relationship between platelet indices and future cardiovascular events: results from a population-based cohort study

Background

Studies evaluating the relationship between platelet indices and cardiovascular outcome yielded conflicting results. In particular, the evidence from large, population-based, prospective studies with extended follow-up duration is scarce.

Purpose

We investigated the incidence of major adverse events in relation to baseline values of platelet count, mean platelet volume (MPV) and platelet distribution width (PDW) in the prospective cohort of the Malmö Diet and Cancer Study.

Methods

A total of 30,314 middle-aged individuals (mean age 57±8 years; 40% men) were overall included and followed up for a median of 16 years (in total, 468,490 person-years). The following outcome measures were considered: all-cause death, myocardial infarction (MI) and ischemic stroke.

Results

There was no relationship between increase in MPV or PDW values and adverse events during follow-up. In particular, the incidence of all-cause death, MI and stroke in patients in the 4thquartile of MPV was 19.8% (vs. 20.7% in the 1stquartile; p=0.08), 8.5% (vs. 8.2%; p=0.78) and 7.9% (vs. 7.1%; p=0.09), respectively. The rates of all-cause death, MI and stroke in patients in the 4thquartile of PDW were 20.1% (vs. 20.7% in the 1stquartile; p=0.16), 8.7% (vs. 8.1%; p=0.30) and 8.1% (vs. 7.2%; p=0.09), respectively. There was a significant rise in mortality by platelet count increase (log-rank p<0.001). In multivariable analysis, patients in the 4thquartile of platelet count (>264 x 109/L) showed a significantly higher incidence of all-cause death (HR 1.17, 95% CI 1.07–1.28; p=0.001), MI (HR 1.24, 95% CI 1.08–1.43; p=0.003) and stroke (HR 1.20, 95% CI 1.04–1.39; p=0.014) vs the 1stquartile. The higher mortality in the 4thquartile of platelet count was independent of the history of previous stroke, was significant in patients without prior MI (HR 1.18, 95% CI 1.08–1.29; p<0.001) and non-significant in those with prior MI (HR 0.86, 95% CI 0.56–1.33; p=0.51). The risk of MI in the 4thquartile of platelet count was higher regardless of the history of previous MI (p for interaction=0.11). The risk of stroke in the 4thquartile of platelet count was higher regardless of the history of previous stroke (p for interaction=0.15).

Conclusions

In this population-based, prospective, cohort study there was no difference in the incidence of adverse events across various strata of baseline platelet morphology. However, patients with highest platelet count at baseline showed a significantly higher risk of all-cause death, MI and stroke. Whether or not these individuals should be targeted by more aggressive primary prophylactic measures including antiplatelet treatment, remains to be proven.

P2555Efficacy and safety of oral anticoagulant versus antiplatelet therapy for secondary prevention of cardiovascular disease in patients without atrial fibrillation

Background

Anticoagulation is the mainstay of prevention of arterial thromboembolism in patients with atrial fibrillation, but it could be effective also in secondary prevention of patients who are in sinus rhythm.

Purpose

We performed this meta-analysis to determine relative efficacy and safety of oral anticoagulant therapy (OAC) as compared with antiplatelet therapy (APT) in patients with prevalent cerebro-cardiovascular disease without atrial fibrillation.

Methods

Our systematic review of the literature published through January 31st, 2019 sought all phase III randomized controlled trials which compare OAC with APT in patients with sinus rhythm and report at least one of the following outcomes: ischemic stroke, death, myocardial infarction, and major bleeding, assessed at the longest available follow-up. We used random-effects models to estimate summary relative risk reduction (RRR) and 95% confidence intervals (95% CI).

Results

We identified a total of 9 randomized controlled trials including a total of 34,912 patients (ASA, n=17,726; adjusted-dose warfarin, n=4,460; rivaroxaban, n=12726), with a mean follow-up of 2.2 years. When compared with antiplatelet therapy, OAC was associated with reduced risk of ischemic stroke (RRR 38%, 95% CI: 1; 47; P=0.04; I2=72%) and myocardial infarction (RRR 13%, 95% CI: 0,23; P=0.05, I2=0%), but increased risk of major bleeding (RRR −52%, 95% CI: −129; −1; P=0.04; I2=76%). Compared to antiplatelet treatment, OAC did not significantly affect the risk of all-cause death (RRR 1%, 95% CI: −9; 10; P=0.86; I2=12%).

Conclusions

In sinus rhythm patients with prevalent cardiovascular disease, OAC reduces risk of ischemic stroke and myocardial infarction, but significantly increases risk of major bleeding. The choice of antithrombotic treatment does not appear to influence all-cause mortality.

P4441Serum activity against specific G-protein coupled receptors is associated with the severity of orthostatic symptoms in patients with POTS

Background

Postural orthostatic tachycardia syndrome (POTS) is characterised by an excessive heart rate increase upon standing and orthostatic intolerance. Previous studies indicate autoimmune involvement mediated via G-protein coupled receptors (GPCRs) as a possible aetiology.

Purpose

To test if serum from POTS patients and controls activates selected GPCRs and if the activation associates with the severity of symptoms.

Methods

A total of 34 POTS patients (age 28.9 [9.9] years; 29 women) and a population-based control group of 25 healthy subjects (age 30.7 [8.6] years; 21 women) were included. The subjects performed an active standing test and completed the orthostatic hypotension questionnaire (OHQ) including ten items related to orthostatic intolerance. The OHQ composite score was calculated (range 0–10).

Sera were analysed by a FRET-based reporter system (Tango GeneBLAzer, Thermo Fischer) based on a beta-arrestin-linked transcription factor driving transgenic betalactamase transcription. HEK293M-cells over-expressing one of the GPCRs, adrenergic alpha-1 (ADRA1), adrenergic beta-2 (ADRB2), muscarinic type-2 (CHRM2) and opioid-receptor-like 1 (OPRL1) receptor were plated in 96-well optical plates and allowed to re-attach during 48 hrs. The cells were treated with 10% sera diluted in RPMI for 5 hours, followed by addition of the FRET-substrate, incubation for 60 min and quantification analysis in a CLARIOStar multi-purpose plate reader.

Quantification of the activation of the GPCRs was log-transformed and related to the OHQ composite and individual scores in age-adjusted linear regression models. OHQ scores were compared according to the median of sera activation, using independent samples t-test.

Results

Serum ADRA1 activation associated with the OHQ composite score (beta 0.77 OHQ points per SD of activity; p=0.009), whereas there were no significant associations among controls (p=0.953). The association between ADRA1 and total OHQ was significant also after adjusting for heart rate and systolic blood pressure at 3 min (p=0.024). The OHQ composite score was higher in with above median serum ADRA1 activation (Figure 1).

ADRA1 activation associated with a higher score for vision problems (p<0.001) and symptoms during prolonged standing (p=0.037) and walking for short (p=0.042) or long periods (p=0.001).

The activity of ARB2, CHRM2 and OPRL1 did not associate with OHQ composite score in neither POTS patients nor controls.

Figure 1. OHQ according to ADRA1 activation

Conclusions

Activating serum proteins for the adrenergic alpha-1 receptor are associated with the severity of orthostatic symptoms in POTS patients, partly independent of the orthostatic hemodynamic response. Serum activity against alpha1 receptors is related particularly to symptoms of disturbed vision and symptoms during walking or prolonged standing. Serum activity against the adrenergic alpha 1 receptor may be a one factor underlying the orthostatic symptoms in POTS.

Acknowledgement/Funding

The Swedish Heart-Lung Foundation, The Swedish Heart and Lung Association, Solidex, ALF funds, Crafoord Foundation, Ernhold Lundströms Foundation.

A practical guide to active stand testing and analysis using continuous beat-to-beat non-invasive blood pressure monitoring

PURPOSE

The average adult stands approximately 50-60 times per day. Cardiovascular responses evoked during the first 3 min of active standing provide a simple means to clinically assess short-term neural and cardiovascular function across the lifespan. Clinically, this response is used to identify the haemodynamic correlates of patient symptoms and attributable causes of (pre-)syncope, and to detect autonomic dysfunction, variants of orthostatic hypotension, postural orthostatic tachycardia syndrome and orthostatic hypertension.

METHODS

This paper provides a set of experience/expertise-based recommendations detailing current state-of-the-art measurement and analysis approaches for the active stand test, focusing on beat-to-beat BP technologies. This information is targeted at those interested in performing and interpreting the active stand test to current international standards.

RESULTS

This paper presents a practical step-by-step guide on (1) how to perform active stand measurements using beat-to-beat continuous blood pressure measurement technologies, (2) how to conduct an analysis of the active stand response and (3) how to identify the spectrum of abnormal blood pressure and heart rate responses which are of clinical interest.

CONCLUSION

Impairments in neurocardiovascular control are an attributable cause of falls and syncope across the lifespan. The simple active stand test provides the clinician with a powerful tool for assessing individuals at risk of such common disorders. However, its simplicity belies the complexity of its interpretation. Care must therefore be taken in administering and interpreting the test in order to maximise its clinical benefit and minimise its misinterpretation.

Monitoring of cerebral oximetry during head-up tilt test in adults with history of syncope and orthostatic intolerance

Aims

We applied near-infrared-spectroscopy (NIRS) to measure absolute frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients investigated for unexplained syncope.

Methods and results

Synchronized non-invasive beat-to-beat haemodynamic monitoring, ECG, SctO2 (NIRS; normal range: 60-80%), and peripheral oxygen saturation (left hand, SpO2) were applied during HUT in a random sample of patients with unexplained syncope. Tracings of 54 patients (mean-age: 55 ± 19 years, 39% male) with negative HUT, vasovagal syncope (VVS), or orthostatic hypotension (OH) were analysed. In 44 patients HUT was diagnostic, in 10 HUT was negative. Thirty-one experienced VVS. Of these, 6 had spontaneous and 25 nitroglycerin-induced syncope. Thirteen patients had orthostatic hypotension (OH). Although there was no significant change in mean-arterial pressure from baseline to 1 min before syncope or end of passive HUT phase (-1.4 ± 13.9 mmHg; P = 0.45), there was a significant fall in SctO2 during the same period (-3.2 ± 3.2%; P ≤ 0.001). Among patients who experienced syncope, a decrease in SctO2 from 71 ± 5% at baseline to 53 ± 9% (P < 0.001) at syncope was observed. During HUT, there was a significant difference in delta SctO2 between spontaneous VVS (-4.5 ± 3.0%) and negative HUT (-1.3 ± 1.9%; P  = 0.021), but not between spontaneous VVS and OH (-5.4 ± 4.2%; P = 0.65). In spontaneous VVS, progressive decrease of SctO2 was independent of mean arterial pressure decrease (P  = 0.22).

Conclusions

Progressive decrease in cerebral tissue oxygenation independent of mean-arterial pressure may precede spontaneous vasovagal reflex during tilt. Patients experience syncope when SctO2 falls below 60%. These data confirm clinical utility of absolute cerebral oximetry monitoring for syncope investigation. We applied NIRS to measure frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients with unexplained syncope. In 44 of 54 patients, HUT was diagnostic. In patients with syncope, a significant SctO2-decrease was observed. Different patterns of SctO2 can be detected.

Postural orthostatic tachycardia syndrome: clinical presentation, aetiology and management

Postural orthostatic tachycardia syndrome (POTS) is a variant of cardiovascular autonomic disorder characterized by an excessive heart rate increase on standing and orthostatic intolerance. POTS affects younger individuals 15-45 years old with a distinct female predominance (≈80%). The prevalence ranges between 0.2% and 1.0% in developed countries. The onset of POTS is typically precipitated by immunological stressors such as viral infection, vaccination, trauma, pregnancy, surgery or psychosocial stress. The most common complaints are dizziness, weakness, rapid heartbeat and palpitation on standing. Moreover, patients often report physical deconditioning and reduced exercise capacity as well as headache, 'brain fog', dyspnoea, gastrointestinal disorders and musculoskeletal pain. The aetiology of POTS is largely unknown and three main hypotheses include an autoimmune disorder, abnormally increased sympathetic activity and catecholamine excess, and sympathetic denervation leading to central hypovolaemia and reflex tachycardia. The golden standard for POTS diagnosis is head-up tilt test with a non-invasive beat-to-beat haemodynamic monitoring. Although long-term prognosis of POTS is poorly explored, around 50% of patients spontaneously recover within 1-3 years. After the diagnosis has been established, patient should be thoroughly educated about non-pharmacological measures alleviating the symptoms. Exercise training may be very effective and counteract deconditioning. In more symptomatic patients, different drugs directed at controlling heart rate, increasing peripheral vasoconstriction and intravascular volume can be tested. However, the overall effects of pharmacological therapy are modest and the most affected patients remain handicapped. Future efforts should focus on better understanding of POTS pathophysiology and designing randomized controlled trials for selection of more effective therapy.

Biomarkers of microvascular endothelial dysfunction predict incident dementia: a population-based prospective study

BACKGROUND

Cerebral endothelial dysfunction occurs in a spectrum of neurodegenerative diseases. Whether biomarkers of microvascular endothelial dysfunction can predict dementia is largely unknown. We explored the longitudinal association of midregional pro-atrial natriuretic peptide (MR-proANP), C-terminal endothelin-1 (CT-proET-1) and midregional proadrenomedullin (MR-proADM) with dementia and subtypes amongst community-dwelling older adults.

METHODS

A population-based cohort of 5347 individuals (men, 70%; age, 69 ± 6 years) without prevalent dementia provided plasma for determination of MR-proANP, CT-proET-1 and MR-proADM. Three-hundred-and-seventy-three patients (7%) were diagnosed with dementia (120 Alzheimer's disease, 83 vascular, 102 mixed, and 68 other aetiology) over a period of 4.6 ± 1.3 years. Relations between baseline biomarker plasma concentrations and incident dementia were assessed using multivariable Cox regression analysis.

RESULTS

Higher levels of MR-proANP were significantly associated with increased risk of all-cause and vascular dementia (hazard ratio [HR] per 1 SD: 1.20, 95% confidence interval [CI], 1.07-1.36; P = 0.002, and 1.52; 1.21-1.89; P < 0.001, respectively). Risk of all-cause dementia increased across the quartiles of MR-proANP (p for linear trend = 0.004; Q4, 145-1681 pmol L^-1 vs. Q1, 22-77 pmol L^-1 : HR: 1.83; 95%CI: 1.23-2.71) and was most pronounced for vascular type (p for linear trend = 0.005: HR: 2.71; 95%CI: 1.14-6.46). Moreover, the two highest quartiles of CT-proET-1 predicted vascular dementia with a cut-off value at 68 pmol L^-1 (Q3-Q4, 68-432 pmol L^-1 vs. Q1-Q2,4-68 pmol L^-1 ; HR: 1.94; 95%CI: 1.12-3.36). Elevated levels of MR-proADM indicated no increased risk of developing dementia after adjustment for traditional risk factors.

CONCLUSIONS

Elevated plasma concentration of MR-proANP is an independent predictor of all-cause and vascular dementia. Pronounced increase in CT-proET-1 indicates higher risk of vascular dementia.

Syndromes of orthostatic intolerance: a hidden danger

Orthostatic hypotension (OH) is a relatively common heterogenous and multifactorial disorder, traditionally classified as neurogenic (less common but often more severe) or nonneurogenic (more common, with no direct signs of autonomic nervous system disease). The different clinical variants of orthostatic intolerance include initial, classical and delayed OH as well as postural tachycardia syndrome. Orthostatic instability may induce syncopal attacks either alone or in combination with other mechanisms, and is often dismissed as a precipitating factor. Moreover, prevalent OH is an independent risk factor for all-cause mortality and cardiovascular morbidity, and the majority of patients with OH are asymptomatic or have few nonspecific symptoms. Management of symptomatic orthostatic intolerance includes both nonpharmacological and pharmacological methods, but it is not always successful and may lead to complications. Future studies of OH should focus on mechanisms that lead to neurogenic and nonneurogenic OH, novel diagnostic methods and more effective therapeutic modalities.

Novel cardiovascular biomarkers in unexplained syncopal attacks: the SYSTEMA cohort

OBJECTIVES

The aim of the study was to investigate the resting levels of novel cardiovascular biomarkers in common types of noncardiac syncope.

DESIGN AND SETTING

An observational study was conducted including 255 patients (mean age 60 years, range 15-93; 45% men) with unexplained syncopal attacks. Subjects underwent an expanded head-up tilt test including carotid sinus massage, and nitroglycerin provocation if indicated. Using logistic regression, we explored the associations between specific diagnoses of syncope and resting levels of circulating biomarkers: C-terminal pro-arginine vasopressin (CT-proAVP), C-terminal endothelin-1 precursor fragment (CT-proET-1), midregional fragments of pro-atrial natriuretic peptide (MR-proANP) and pro-adrenomedullin (MR-proADM).

RESULTS

A total of 142 (56%) patients were diagnosed with vasovagal syncope (VVS), 85 (33%) with orthostatic hypotension (OH) and 47 (18%) with carotid sinus hypersensitivity (CSH); in addition, 74 (29%) patients had more than one diagnosis. Thirty-five patients (14%) demonstrated a cardioinhibitory reflex. The probability of VVS was highest in the first quartile of MR-proANP [Q1 vs. Q4: odds ratio (OR) 5.57, 95% confidence interval (CI) 1.86-16.74; P < 0.001] and CT-proET-1 (OR 7.17, 95% CI 2.43-21.13; P < 0.001). By contrast, the probability of OH was highest in the fourth quartile of CT-proET-1 (Q4 vs. Q1: OR 8.66, 95% CI 2.49-30.17; P < 0.001). Furthermore, CSH was most frequently observed in the first quartile of MR-proANP (Q1 vs. Q4: OR 6.57, 95% CI 1.62-26.62; P = 0.008) among those over 60 years of age, whereas the cardioinhibitory reflex was strongly associated with low CT-proET-1 levels (Q1 vs. Q4: OR 69.7, 95% CI 6.97-696.6; P < 0.001). Moreover, in patients with VVS, a high concentration of CT-proET-1 was predictive of OH (OR per 1 SD 2.4, 95% CI 1.15-5.02; P = 0.02), whereas low CT-proET-1 suggested involvement of the cardioinhibitory reflex (OR per 1SD 0.42, 95% CI 0.25-0.70; P = 0.001).

CONCLUSIONS

The levels of MR-proANP and CT-proET-1 are markedly changed in common forms of syncope, suggesting the involvement of novel neurohormonal mechanisms in syncopal attacks.

Orthostatic hypotension and long-term incidence of atrial fibrillation: the Malmö Preventive Project

OBJECTIVES

Orthostatic hypotension (OH), a common manifestation of autonomic dysfunction, has been identified as an independent risk factor for all-cause mortality and incident cardiovascular disease. However, the role of OH in the development of atrial fibrillation has not been studied.

DESIGN

We investigated the incidence of atrial fibrillation in relation to baseline presence of OH according to international consensus criteria in the Swedish population-based prospective cohort of the Malmö Preventive Project. The study sample consisted of 33,346 individuals (67.3% men; mean age, 45.6 ± 7.4 years; range, 26-61 years). The association between OH and incidence of atrial fibrillation during follow-up was assessed using the Kaplan-Meier method and multivariable Cox proportional hazard models, taking into account conventional risk factors for atrial fibrillation.

RESULTS

At baseline, 1987 participants (6.1%) met the diagnostic criteria for OH. Over a follow-up period of approximately 24 years, 2312 individuals (3.0 events/1000 person-years) were diagnosed with new-onset atrial fibrillation. Of these, 196 had OH at baseline (4.6 events/1000 person-years amongst all OH-positive individuals). In a multivariable Cox regression analysis, OH predicted incidence of atrial fibrillation independently of other risk factors (hazard ratio [HR]: 1.30; 95% confidence interval [CI]: 1.05-1.61; P = 0.016), and this association was significant in hypertensive (HR: 1.44; 95%CI: 1.10-1.88; P = 0.008), but not in normotensive participants (HR: 1.10; 95%CI: 0.77-1.58; P = 0.60).

CONCLUSIONS

The presence of OH predicts the incidence of atrial fibrillation in middle-aged hypertensive individuals, independently of conventional risk factors. Further studies of the association of autonomic dysfunction and OH with atrial fibrillation are needed.

[Interdisciplinary interventional therapy for tracheobronchial stenosis with modern metal net stents]

STUDY OBJECTIVES

Assessment of the therapeutic potential of tracheobronchial stenting for obstructive tracheobronchial disease, in-vivo comparison of different stent types and development of helpful criteria for choosing the suitable stent type.

MATERIAL AND METHODS

Prospective case analysis. Between 1993 and 1999 53 stents were implanted into the tracheobronchial system of 39 consecutive patients with benign or malignant airway obstruction. Every single stent (26 Strecker Stents, 18 Wallstents, 6 Accuflex Nitinolstents, 1 Dumon-, 1 Rüsch- and 1 Palmazstent) was recorded in an unified database. Analysis comprised clinical effectiveness, lung function if possible, relevant complications and radiologic follow-up parameters. The probability of their remaining within the tracheobronchial system, of their remaining undislocated and uncompressed was calculated using Kaplan-Meier analysis for three stent types.

RESULTS

Stent placement proved itself to be an effective treatment in 86 % of the patients. Resistance could be normalized in 9/9 patients. Kaplan-Meier analysis clearly revealed a higher probability for the Wall- and Nitinolstent to remain within the tracheobronchial system and to remain uncompressed. Dislocation also occurred more rarely. Explantation of the Wallstent, however, if desired, was much more difficult compared to the Strecker stent. The Wallstent also occasionally led to the formation of granulation tissue especially at the proximal stent end and, as such, required reintervention.

CONCLUSION

Any of the 3 stent types proved to be an effective therapeutic option in the management of obstructive tracheobronchial disease. Choise of the stent type should be determined through definition of the therapeutic intention. It is useful to distinguish between (a) benign stenosis, (b) malignant stenosis but curative therapeutic situation and (c) malignant stenosis in a palliative therapeutic situation with limited life expectancy. In spite of its superior mechanical properties the Wallstent is rather suited for a palliative situation because explantation may be difficult. The Strecker Stent requires more reinterventions but removal is easy to perform. The Nitinolstent possibly represents a reasonable compromise.

[Basic fibroblast growth factor (b-FGF) in the perimatrix of cholesteatoma]

The growth of a cholesteatoma requires angioneogenesis in the connective tissue of the perimatrix. Angioneogenesis is also needed for wound healing as a host response to tissue injury. Normal wound repair is conducted through a wide number of growth factors. Basic fibroblast growth factor (b-FGF) plays a pivotal role in wound repair. This cytokine exerts its effects through stimulation of a wide range of target cells. B-FGF is chemotactic and mitogenic for fibroblasts, endothelial cells and keratinocytes. In addition, b-FGF can stimulate the production of collagenase and plasminogen activators to enhance fibroblast proliferation and angioneogenesis. Its necessity for normal wound repair has been confirmed by several workers.

METHOD

In order to demonstrate angioneogenesis in the cholesteatoma perimatrix the distribution of b-FGF as the pivotal cytokine of the process was investigated in the perimatrix of 18 cholesteatoma specimens.

RESULTS

B-FGF could be observed in 12 of 18 specimens (66%) in close approximation to histological signs of inflammation and wound healing. Areas with b-FGF also exhibited proliferation of the covering squamous epithelium. Cholesteatoma matrix tissue without inflammation or any sign of wound healing did not express b-FGF (6 of 18).

CONCLUSION

Histological changes and distribution pattern of b-FGF in the perimatrix of cholesteatoma in the present study indicate that the perimatrix cells and substances of the wound healing cascade may play an important role in cholesteatoma development, angiogenesis and growth.

[Biological effects of non-ionizing electromagnetic radiation]

Since the mid 1970's, when Adey discovered that extremely-low-frequency electromagnetic field (ELF EMF) may affect the calcium ions efflux from various cells, bioeffects of non-ionizing radiation (NIR) have become the subject of growing interest and numerous research projects. At present, the fact that NIR exerts both stimulatory and inhibitory effects on different physiological cellular parameters is rather unquestionable. At the same time, some epidemiological studies suggest that exposure to EMF is potentially harmful even if its intensity is very low. It has been proved that thermal factors are not responsible for these effects, therefore nowadays, they are called 'non-thermal effects'. Our paper deals with three different aspects of biological effects of non-ionizing radiation, bioelectromagnetism, electromagnetobiology and electromagnetic bioinformation. Firstly, we describe how EMF and photons can be produced within a living cell, how biological cycles are controlled, and what are the features of endogenous electromagnetic radiation. Secondly, we discuss various facets of external EMF interactions with living matter, focusing on extremely-low-frequencies, radio- and microwaves. Possible mechanisms of these interactions are also mentioned. Finally, we present a short overview of current theories which explain how electromagnetic couplings may control an open and dissipative structure, namely the living organism. The theory of electromagnetic bioinformation seems to explain how different physiological processes are triggered and controlled, as well as how long-range interactions may possibly occur within the complex biological system. The review points out that the presented research data must be assessed very carefully since its evaluation is crucial to set the proper limits of EMF exposure, both occupational and environmental. The study of biological effects of non-ioinizing radiation may also contribute to the development of new diagnostic and therapeutic methods.

[Electrosmog as a health risk factor: sources of artificial electromagnetic fields, evaluation of health risk, prevention methods]

In recent years we have observed how electromagnetic (EM) radiation enters our daily life. The strength of man-made EM field is often far above the natural level and this finding has encouraged a large group of researchers to investigate its possible health effect. Non-ionizing radiation and extremely low-frequency electric and magnetic fields have been the subject of intensive theoretical and experimental works since Adey published his observations concerning non-linear and non-thermal biological effects. At the same time an epidemiological material appeared suggesting that EM field generates various diseases including leukemia and brain tumors. Possible mechanisms of EM field interactions with living matter remain unknown although theoretical models have been proposed by many authors. In vitro and in vivo studies as well as epidemiological data have not provided the ground for decisive conclusions. Nevertheless, the relationship between EM fields and biological effects seems to be most likely. Any international standards for safety limits have not as yet been established and regulations in this regard vary in different countries. However, occupational and residential exposure to EM field can be efficiently measured using an appropriate equipment and such measurements should become a standard procedure wherever electrosmog is suspected to be a pathogenic factor.

Acute toxicity, subchronic dermal toxicity, and delayed contact sensitization evaluations of dicyclopentenyloxyethyl methacrylate in rabbits and guinea pigs

The subchronic dermal toxicity of dicyclopentenyloxethyl methacrylate (DPOMA) was evaluated in young adult New Zealand White rabbits, and its potential to produce delayed contact sensitization was evaluated in Harley guinea pigs by a modified Buehler's closed patch technique. In addition, studies were conducted to evaluate the acute systemic toxicity of DPOMA in rats (oral) and rabbits (dermal), and its eye and skin irritancy in rabbits. In the subchronic dermal toxicity study, 4 groups of rabbits were treated percutaneously with DPOMA at 0 (acetone), 10, 107, and 1067 (undiluted) mg/kg X day in a volume of 1 ml/kg, over a 4-wk period. The application sites were unoccluded. No deaths occurred, and no signs of systemic toxicity were observed. No treatment-related effects were seen on body weights, hematology, clinical chemistry, urinalysis, organ weights, or histopathology (except the treated skin). The only treatment-related effect was slight to moderate skin irritation in the mid- and high-dose groups. The severity of skin irritaton was dependent on the number of applications and the concentration of DPOMA. Maximal skin irritation occurred after 1 wk. No skin irritation was seen in the control and low-dose group. In the DCS study, guinea pigs received 6 induction doses of 0.5 ml 100% DPOMA and were challenged with 0.5 ml of 50% (w/v) DPOMA in acetone 2 wk after the last induction treatment. No erythema or edema was observed in any of the challenged guinea pigs in either the treated and control groups. These acute toxicity studies indicate that DPOMA is practically nontoxic by a single exposure via both oral and dermal routes (the oral LD50 in rat and dermal LD50 in rabbits were greater than 5.0 g/kg body weight), slightly irritating to the skin, and inconsequentially irritating to the eyes. The no-observed-effect level (NOEL) for systemic toxicity of DPOMA applied repeatedly to rabbits skin is at least 1067 mg/kg X d. DPOMA is not a strong or moderate skin sensitizer in guinea pigs.