Postural Orthostatic Tachycardia Syndrome (POTS): A critical assessment.

Although diagnostic criteria have been developed characterizing postural orthostatic tachycardia syndrome (POTS), no single set of criteria is universally accepted. Furthermore, there are gaps in the present criteria used to identify individuals who have this condition. The reproducibility of the physiological findings, the relationship of symptoms to physiological findings, the presence of symptoms alone without any physiological findings and the response to various interventions confuse rather than clarify this condition. As many disease entities can be confused with POTS, it becomes critical to identify what this syndrome is. What appears to be POTS may be an underlying condition that requires specific therapy. POTS is not simply orthostatic intolerance and symptoms or intermittent orthostatic tachycardia but the syndrome needs to be characterized over time and with reproducibility. Here we address critical issues regarding the pathophysiology and diagnosis of POTS in an attempt to arrive at a rational approach to categorize the syndrome with the hope that it may help both better identify individuals and better understand approaches to therapy.

Impact of defibrillation threshold testing on burden of heart failure hospitalizations.

Background: Defibrillation threshold testing (DT) following implantable cardioverter defibrillator (ICD) implantation has not shown to improve mortality. However, the impact of DT on burden of heart failure (HF) hospitalisations has not been well defined.Methods: We studied retrospectively consecutive patients who underwent ICD implantation or generator change between 2008 and 2014. Primary outcome was burden of HF hospitalisations within 30 days following implantation. Secondary outcomes were mortality, stroke, and ICD shock within 30 days and one-year mortality.Results: Three hundred and eleven of 501 patients (62%) were in DT+ group versus 190 (38%) were in DT- group. The percentage of new implantations was higher in DT+ group than in DT- group (69% vs 39%, p < .001) but the distributions of NYHA function classes were similar between two groups. The burden of HF hospitalisations at 30-days was significantly higher in DT+ group than in DT- group (17.4% vs 4.7%, HR 0.842, 95% CI 0.774-0.915, p < .0001). No difference in mortality, stroke or ICD shocks was found between two groups at 30 days and mortality at 1 year.Conclusions: DT after new ICD or generator replacement was associated with increased HF hospitalisation rates at 30 days after ICD implant in a non-trial HF population. However, there was no association between DT and mortality, stroke and ICD shocks at 30 days or mortality at 1 year. The increased burden of HF hospitalisation in this observational study requires validation by randomised studies.

Assessment of the 2017 AHA/ACC/HRS Guideline Recommendations for Implantable Cardioverter-Defibrillator Implantation in Cardiac Sarcoidosis.

BACKGROUND: Implantable cardioverter-defibrillators are used to prevent sudden cardiac death in patients with cardiac sarcoidosis. The most recent recommendations for implantable cardioverter-defibrillator implantation in these patients are in the 2017 American Heart Association/American College of Cardiology/Heart Rhythm Society Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. These recommendations, based on observational studies or expert opinion, have not been assessed. We aimed to assess them. METHODS: We performed a large retrospective cohort study of patients with biopsy-proven sarcoidosis and known or suspected cardiac sarcoidosis that underwent cardiovascular magnetic resonance imaging. Patients were followed for a composite end point of significant ventricular arrhythmia or sudden cardiac death. The discriminatory performance of the Guideline recommendations was tested using time-dependent receiver operating characteristic analyses. The optimal cutoff for the extent of late gadolinium enhancement predictive of the composite end point was determined using the Youden index. RESULTS: In 290 patients, the class I and IIa recommendations identified all patients who experienced the composite end point during a median follow-up of 3.0 years. Patients meeting class I recommendations had a significantly higher incidence of the composite end point than those meeting class IIa recommendations. Left ventricular ejection fraction (LVEF) >35% with >5.7% late gadolinium enhancement on cardiovascular magnetic resonance imaging was as sensitive as and significantly more specific than LVEF >35% with any late gadolinium enhancement. Patients meeting 2 class IIa recommendations, LVEF >35% with the need for a permanent pacemaker and LVEF >35% with late gadolinium enhancement >5.7%, had high annualized event rates. Excluding 2 class IIa recommendations, LVEF >35% with syncope and LVEF >35% with inducible ventricular arrhythmia, resulted in improved discrimination for the composite end point. CONCLUSIONS: We assessed the Guideline recommendations for implantable cardioverter-defibrillator implantation in patients with known or suspected cardiac sarcoidosis and identified topics for future research.

Ambulatory electrocardiogram monitoring for syncope and collapse: a comparative assessment of clinical practice in UK and Germany.

Aims: Diagnostic ambulatory electrocardiogram (AECG) monitoring is widely used for evaluating syncope/collapse. In Europe, two sets of practice guidelines [National Institute for Health and Clinical Excellence (NICE) and European Society of Cardiology (ESC)] provide recommendations concerning optimal selection of AECG devices. However, whether practising physicians' select AECGs based on published guidelines is unclear. This study examined AECG use by Emergency Department (EDs) physicians and cardiologists in two European countries: Germany (D) and United Kingdom (UK). Methods and Results: A quantitative survey was undertaken in which 177 respondents participated (ED: UK 33, Germany 40; Cardiology: UK 54, Germany 50). The choice of AECG technology varied by specialty. Thus, among EDs, despite patients having daily symptoms, 20% (UK), 31% (D) of respondents chose an AECG other than Holter monitor. Conversely, when monitoring for infrequent events (

Trends of hospitalizations for syncope/collapse in the United States from 2004 to 2013-An analysis of national inpatient sample.

INTRODUCTION: Syncope/collapse is a common reason for emergency department visits, and approximately 30-40% of these individuals are hospitalized. We examined changes in hospitalization rates, in-hospital mortality, and cost of syncope/collapse-related hospital care in the United States from 2004 to 2013. METHODS: We used the US Nationwide Inpatient Sample (NIS) from 2004 to 2013 to identify syncope/collapse-related hospitalizations using ICD-9, code 780.2, as the principal discharge diagnosis. Data are presented as mean ± SEM. RESULTS: From 2004 to 2013, there was a 42% reduction in hospitalizations with a principal discharge diagnosis of syncope/collapse from 54,259 (national estimate 253,591) in 2004 to 31,427 (national estimate 156,820) in 2013 (P < 0.0001). The mean length of hospital stays decreased (2.88 ± 0.04 days in 2004 vs. 2.54 ± 0.02 in 2013; P < 0.0001), while in-hospital mortality did not change (0.28% in 2004 vs. 0.18% in 2013; P  =  0.12). However, mean charges (inflation adjusted) for syncope/collapse-related hospitalization increased by 43.6% from $17,514 in 2004 to $25,160 in 2013 (P < 0.0001). The rates of implantation of permanent pacemakers and implantable cardioverter defibrillator remained low during these hospitalizations, and decreased over time (P for both < 0.0001). CONCLUSIONS: Hospitalization rates for syncope/collapse have decreased significantly in the US from 2004 to 2013. Despite a modest reduction in length of stay, the cost of syncope/collapse-related hospital care has increased.

Ambulatory diagnostic ECG monitoring for syncope and collapse: An assessment of clinical practice in the United States.

INTRODUCTION: Diagnostic ambulatory electrocardiogram (AECG) monitoring is widely used for evaluating syncope and collapse, and practice guidelines provide recommendations regarding optimal AECG device selection. However, whether physicians utilize AECGs in accordance with the pertinent guidelines is unclear. This study assessed utilization of AECG monitoring systems for syncope and collapse diagnosis by physicians in the United States. METHODS AND RESULTS: A quantitative survey was undertaken of physicians comprising multiple specialties (emergency department, n = 35; primary care, n = 35; hospitalists, n = 30; neurologists, n = 30; nonimplanting, n = 34, and implanting-cardiologists, n = 35). Depending on specialty, respondents reported that neural-reflex and orthostatic causes accounted for 17-23%, cardiac causes for 12-20%, and "neurological causes" (specifically psychogenic pseudo-syncope/pseudo-seizures and acute cerebrovascular conditions) for 7-12% of their syncope/collapse cases. The choice of AECG technology varied by specialty. Thus, despite patients having daily symptoms, 25% of respondents chose an AECG technology other than a Holter-type monitor. Conversely, when monitoring for infrequent events (e.g., less than monthly), 12-18% indicated that they would choose a 24- to 48-hour Holter, 20-34% would choose either a conventional event recorder or a mobile cardiac telemetry system, and only 53-65% would select an insertable cardiac monitor. CONCLUSIONS: In evaluation of syncope/collapse, most U.S. clinicians across specialties use AECGs appropriately, but in a substantial minority there remains discordance between choice of AECG technology and guideline-based recommendations.

Rationale for the Assessment of Metoprolol in the Prevention of Vasovagal Syncope in Aging Subjects Trial (POST5).

BACKGROUND: Vasovagal syncope (VVS) is a common problem associated with a poor quality of life, which improves when syncope frequency is reduced. Effective pharmacological therapies for VVS are lacking. Metoprolol is a ß-adrenergic receptor antagonist that is ineffective in younger patients, but may benefit older (≥40 years) VVS patients. Given the limited therapeutic options, a placebo-controlled clinical trial of metoprolol for the prevention of VVS in older patients is needed. STRUCTURE OF STUDY: The POST5 is a multicenter, international, randomized, placebo-controlled study of metoprolol in the prevention of VVS in patients ≥40 years old. The primary endpoint is the time to first recurrence of syncope. Patients will be randomized 1:1 to receive metoprolol 25 to 100 mg BID or matching placebo, and followed up for 1 year. Secondary end points include syncope frequency, presyncope, quality of life, and cost analysis. Primary analysis will be intention to treat, with a secondary on-treatment analysis. POWER CALCULATIONS: A sample size of 222, split equally between the groups achieves 85% power to detect a hazard rate of 0.3561 when the event rates are 50% and 30% in the placebo and metoprolol arms. Allowing for 10% dropout, we propose to enroll 248 patients. IMPLICATIONS: This study will be the first adequately powered trial to determine whether metoprolol is effective in preventing VVS in patients ≥40 years. If effective, metoprolol may become the first line pharmacological therapy for these patients.

Syncope: Assessment of risk and an approach to evaluation in the emergency department and urgent care clinic.

Syncope is among the most frequent forms of transient loss of consciousness (TLOC), and is characterized by a relatively brief and self-limited loss of consciousness that by definition is triggered by transient cerebral hypoperfusion. Most often, syncope is caused by a temporary drop of systemic arterial pressure below that required to maintain cerebral function, but brief enough not to cause permanent structural brain injury. Currently, approximately one-third of syncope/collapse patients seen in the emergency department (ED) or urgent care clinic are admitted to hospital for evaluation. The primary objective of developing syncope/TLOC risk stratification schemes is to provide guidance regarding the immediate prognostic risk of syncope patients presenting to the ED or clinic; thereafter, based on that risk assessment physicians may be better equipped to determine which patients can be safely evaluated as outpatients, and which require hospital care. In general, the need for hospitalization is determined by several key issues: i) the patient's immediate (usually considered 1 week to 1 month) mortality risk and risk for physical injury (e.g., falls risk), ii) the patient's ability to care for him/herself, and iii) whether certain treatments inherently require in-hospital initiation (e.g., pacemaker implantation). However, at present no single risk assessment protocol appears to be satisfactory for universal application, and development of a consensus recommendation is an essential next step.

Syncope risk assessment in the emergency department and clinic.

The initial assessment of patients who present with presumed syncope is challenging. Syncope has many possible causes ranging from relatively benign to potentially life-threatening, and sorting through the possibilities may not be feasible given time limitations in an urgent care setting. Therefore, the physician almost always must determine whether the affected individual needs in-hospital evaluation or can be safely referred to an outpatient syncope evaluation clinic. In instances when the etiology of syncope has been diagnosed with confidence at the initial clinical evaluation, the hospitalization question is readily addressed and the appropriateness of hospitalization versus timely outpatient evaluation (preferably in a dedicated syncope management clinic) is clear. In those cases in which the diagnosis is uncertain, risk stratification schemes such as those summarized in this communication become more essential. However, at present no single risk assessment protocol appears to be satisfactory for universal application. The development of a consensus recommendation is an essential next step.

Approach to the patient with syncope: venues, presentations, diagnoses.

Syncope is a frequent cause for presentation to emergency departments and urgent-care clinics. The physician should establish a confident causal diagnosis, assess prognostic implications, and provide appropriate advice to prevent recurrences. An organized approach is needed to the assessment of the patient with syncope, including a careful initial examination as well as application of specialized syncope evaluation units and structured questionnaires for history taking. The initial patient evaluation, particularly a detailed medical history, is the key to identifying the most likely diagnosis. Based on these findings, subsequent diagnostic tests can be chosen to confirm the clinical suspicion.

Epidemiology and economic impact of cardiac syncope in western countries.

This article updates our current understanding of the epidemiology and economic impact of syncope in western countries. Unfortunately, both of these aspects of syncope are inadequately understood; in part the problem is due to the difficulty in public health data separating 'true syncope' from conditions that cause other forms of transient loss of consciousness. However, in certain respects, the epidemiology of syncope is becoming clearer. Similarly, we have come to understand that the economic impact of syncope is substantial and is much larger than is necessary, primarily because management, especially excessive hospitalization, often remains suboptimal.

Relationship of paroxysmal atrial tachyarrhythmias to volume overload: assessment by implanted transpulmonary impedance monitoring.

BACKGROUND: Clinical experience suggests that atrial tachyarrhythmias (ATs) are a frequent comorbidity in heart failure patients with left ventricular systolic dysfunction and that volume overload may increase AT susceptibility. However, substantiating this apparent relationship in free-living patients is difficult. Recently, certain implantable cardioverter-defibrillators provide, by measuring transpulmonary electric bioimpedance, an index of intrathoracic fluid status (OptiVol index [OI]). The goal of this study was to determine whether periods of greater intrathoracic fluid congestion (as detected by OI) correspond with increased AT event frequency. METHODS AND RESULTS: This analysis retrospectively assessed the relation between AT events and OI estimate of volume overload in patients with left ventricular systolic dysfunction and OI-capable implantable cardioverter-defibrillators. OI values were stratified into 3 levels: group 1, <40; group 2, 40 to 60; and group 3, >60. An OI threshold-crossing event was defined as OI > or = 60, a value previously associated with clinically significant volume overload. Findings in 59 patients (mean left ventricular ejection fraction, 24%) with 225 follow-up visits (mean, 3.8 visits per patient) were evaluated. AT prevalence was 73%. AT frequency (percent of patients visits with at least 1 episode of AT since previous device interrogation) was greater in group 3 versus group 1 (P=0.0342). Finally, in terms of temporal sequence, AT episodes preceded OI threshold-crossing event in 43% of incidences, followed threshold-crossing event in 29%, and was simultaneous or indeterminate in the remainder. CONCLUSIONS: These findings not only support the view that worsening pulmonary congestion is associated with increased AT frequency in patients with left ventricular dysfunction but also suggest that AT events may be responsible for triggering episodic pulmonary congestion more often than previously suspected.

Subcutaneous bioimpedance recording: assessment of a method for hemodynamic monitoring by implanted devices.

BACKGROUND: Diagnostic evaluation of patients with suspected symptomatic arrhythmias is limited by inability to assess the hemodynamic impact of a detected rhythm. OBJECTIVE: To address this limitation, we utilized closely spaced subcutaneous electrodes, small enough to incorporate within an implantable monitor, to detect blood flow-induced pectoral muscle bioimpedance (Z) changes in a swine model of hemorrhage-induced hypotension. METHODS: In seven anesthetized and ventilated adult pigs, small ring electrodes (current electrodes 5 cm apart; voltage electrodes 3.5 cm apart) were positioned on the left pectoral muscle. Z signals (Biopac system) and invasive arterial blood pressures were recorded. Hypotension was induced by hemorrhage (50% blood volume reduction). Mean arterial pressure (MAP) and pulse pressure (PP) with corresponding pulse Z (DeltaZ) and base Z (Z(o)) were measured. A longitudinal mixed model with a first-order autoregressive error structure was used to test for associations (change in DeltaZ vs change in MAP and change in DeltaZ vs change in PP) taking into account within pig correlation. RESULTS: During bleeding-induced hypotension, Z(o) increased. Changes of DeltaZ correlated with both a change in MAP (coefficient = 1.17, P < 0.0001) and change in PP (coefficient = 0.98, P < 0.0001). A change in DeltaZ of 1-2 orders of magnitude corresponded to an approximate 40-70% drop in MAP and PP in a porcine model in which the baseline MAP was 69-70 mmHg. CONCLUSION: Our findings suggest that closely spaced subcutaneous electrodes identify changes in local tissue/vascular bioimpedance that correlate well with direct invasive measures of induced hypotension in a porcine model.

Management of syncope in adults: an update.

Syncope is a clinical syndrome characterized by transient loss of consciousness and postural tone that is most often due to temporary and spontaneously self-terminating global cerebral hypoperfusion. A common presenting problem to health care systems, the management of syncope imposes a considerable socioeconomic burden. Clinical guidelines, such as the European Society of Cardiology Guidelines on Management of Syncope, have helped to streamline its management. In recent years, we have witnessed intensive efforts on many fronts to improve the evaluation process and to explore therapeutic options. For this update, we summarized recent active research in the following areas: the role of the syncope management unit and risk prediction rules in providing high-quality and cost-effective evaluation in the emergency department, the implementation of structured history taking and standardized guideline-based evaluation to improve diagnostic yield, the evolving role of the implantable loop recorder as a diagnostic test for unexplained syncope and for guiding management of neurally mediated syncope, and the shift toward nonpharmacological therapies as mainstay treatment for patients with neurally mediated syncope. Syncope is a multidisciplinary problem; future efforts to address critical issues, including the publication of clinical guidelines, should adopt a multidisciplinary approach.

Assessment of percutaneous coronary intervention on regional and global left ventricular function in patients with chronic total occlusions.

BACKGROUND: The improvement of regional and global ventricular function following percutaneous coronary intervention (PCI) with reperfusion of the artery supplying the infarct area in acute myocardial infarction is well-described. However, little is known of the potential effects of late recanalization of chronic coronary artery occlusion on left ventricular function. OBJECTIVE: To determine whether PCI improves regional and global left ventricular function in patients with chronic coronary artery occlusions. PATIENTS AND METHODS: Thirty-five patients having at least one coronary artery occluded for six weeks or longer were included in the present prospective study. Exercise thallium-201 myocardial perfusion scintigraphy, multiple-gated acquisition ventriculography and two-dimensional echocardiography were performed in 19 patients (16 men; mean age of 58+/-5 years) who underwent a successful PCI to assess both regional and global left ventricular function before and six weeks following the procedure. RESULTS: The mean ejection fractions before and after reperfusion were 51+/-7% and 58+/-6% using Simpson's method (P<0.001) by echocardiography, and 45+/-1% and 53+/-1% (P=0.01) by multiple-gated acquisition ventriculography, respectively. The echocardiographic wall motion score was 24+/-9 before and 15+/-6 after PCI (P<0.001). The exercise perfusion score (21+/-1 and 14+/-1 [P=0.01]), rest perfusion score (15+/-1 and 12+/-1 [P=0.02]) and reinjection perfusion score (14+/-1 and 11.1+/-1 [P=0.07]) also improved after PCI. The presence of angina was strongly associated with an improvement in left ventricular function and wall motion score (P<0.01). CONCLUSIONS: PCI significantly improved the regional and global left ventricular function in patients with chronic total coronary occlusion. This procedure may provide symptom benefits in selected patients.