Relationship of Paroxysmal Atrial Tachyarrhythmias to Volume Overload

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, \u3c40; group 2, 40 to 60; and group 3, \u3e60. An OI threshold-crossing event was defined as OI \u3e 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

Initial Evaluation of Patients with Presumed Syncope

Syncope is a common clinical problem, but nevertheless is but one element of the broader issue of ‘transient loss of consciousness’ (TLOC). The first step is to ascertain whether the patient actually suffered a syncopal episode, and thereafter the goal must be to determine the basis of symptoms with sufficient confidence to assess prognosis and initiate an effective treatment strategy. The initial evaluation of these patients, which usually takes place in an emergency department (ED. or acute care facility, is challenging since patients are usually asymptomatic when they come for medical attention, may have little or no recall of the event, and witnesses, if any, often cannot provide reliable information. Given these circumstances, it is understandable that frontline physicians often tend to take a seemingly ‘safe’ approach, and admit both high-risk and intermediate-risk syncope patients to hospital. This strategy has many implications, including life-style and economic concerns for the patient, and health care management issues for physicians, hospital administrators and the overall health care system. The European Society of Cardiology (ESC. guidelines and several clinical studies provide helpful advice regarding “risk stratification” to help guide physicians in selecting patients for either early hospital admission or later oupatient subspeciality evaluation. The utility of syncope management units in the ED, and a guideline-based approach to the syncope patient, has tended to both diminish the number of undiagnosed cases and reduce the hospital admission rate. In this review, we have attempted to both highlight a cost-effective diagnostic pathway beginning with the initial evaluation of the patient with suspected syncope, and to provide criteria which may help frontline physicians better base their decisions regarding need for in-hospital versus outpatient clinic evaluation of syncope patients

Ambulatory electrocardiogram monitoring devices for evaluating transient loss of consciousness or other related symptoms

Capturing electrocardiograms (ECGs) during spontaneous events is the most powerful available tool to identify or exclude an arrhythmic cause of symptoms, and often can elucidate the definite diagnosis for different conditions, such as transient loss of consciousness (T-LOC), lightheadedness, or palpitations. Current ambulatory ECG monitoring technologies include 24-hour Holter, wearable event recorder, external loop recorder (ELR), and insertable cardiac monitoring (ICM). Of them, Holter ECG is most frequently used in daily practice in Japan, while ELR and ICM are less frequently used. However, the appropriate monitor choice should be based on the expected frequency of symptoms. Frequent events may be adequately detected by Holter ECG, but less frequent symptoms are more effectively assessed by longer-term monitoring (i.e., ELR or ICM). In this report, based on our clinical experience, we review the usefulness of ambulatory ECG monitoring devices, especially of ELR, for evaluating T-LOC and other potentially arrhythmia-related symptoms. Specifically, we focus on the use of ELR and ICM for evaluating Japanese patients with T-LOC. Keywords: Transient loss of consciousness, Syncope, Insertable cardiac monitoring, External loop recorder, Holter electrocardiogra

Syncope and the risk of sudden cardiac death: Evaluation, management, and prevention

Syncope is a clinical syndrome defined as a relatively brief self-limited transient loss of consciousness (TLOC) caused by a period of inadequate cerebral nutrient flow. Most often the trigger is an abrupt drop of systemic blood pressure. True syncope must be distinguished from other common non-syncope conditions in which real or apparent TLOC may occur such as seizures, concussions, or accidental falls. The causes of syncope are diverse, but in most instances, are relatively benign (e.g., reflex and orthostatic faints) with the main risks being accidents and/or injury. However, in some instances, syncope may be due to more worrisome conditions (particularly those associated with cardiac structural disease or channelopathies); in such circumstances, syncope may be an indicator of increased morbidity and mortality risk, including sudden cardiac death (SCD). Establishing an accurate basis for the etiology of syncope is crucial in order to initiate effective therapy. In this review, we focus primarily on the causes of syncope that are associated with increased SCD risk (i.e., sudden arrhythmic cardiac death), and the management of these patients. In addition, we discuss the limitations of our understanding of SCD in relation to syncope, and propose future studies that may ultimately address how to improve outcomes of syncope patients and reduce SCD risk. Keywords: Syncope, Sudden cardiac death, Risk assessmen