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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.

Voluntary stretching of upper back and shoulder muscles is often associated with a sense of well‐being of unknown cause. The goal of this study was to examine the impact of shoulder/upper back stretching on heart rate (HR) and blood pressure (BP) responses in healthy individuals. Twenty‐four healthy individuals underwent continuous beat‐to‐beat HR and BP monitoring during active standing (AS) and during shoulder/upper back extension stretching. Measurements were compared using appropriate statistical tests. With AS, HR increased (median 24 bpm) and systolic BP decreased (median − 28 mmHg). Shoulder/upper back stretching elicited a similar BP drop but a lesser HR increment (p < 0.001). The HR increase per mmHg BP fall (∆HR/∆BP) was significantly lower during stretch than during AS (0.34 vs. 1.1 beats/min/mmHg; p < 0.001). Thus, the HR response with stretch‐induced BP fall averaged only 30.9% of that seen with AS. Shoulder/upper back muscle stretching induces transient BP reduction with only limited compensatory tachycardia compared to hypotension during AS. These findings suggest a neural reflex mechanism possibly initiated by muscle mechanoreceptors, with predominant vasodepression that may contribute to relaxation and a sense of well‐being.

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 β-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. 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. 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. 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.

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.

Background Practice guidelines provide clinicians direction for the selection of ambulatory ECG (AECG) monitors in the evaluation of syncope/collapse. However, whether patients’ understand differences among AECG systems is unknown. Methods and Results A survey was conducted of USA (n = 99), United Kingdom (UK)/Germany (D) (n = 75) and Japan (n = 40) syncope/collapse patients who underwent diagnostic AECG monitoring. Responses were quantitated using a Likert‐like 7‐point scale (mean ± SD) or percent of patients indicating a Top 2 box (T2B) for a particular AECG attribute. Patient ages and diagnosed etiologies of syncope/collapse were similar across geographies. Patients were queried on AECG attributes including the ability to detect arrhythmic/cardiac causes of collapse, instructions received, ease of use, and cost. Patient perception of the diagnostic capabilities and ease of use did not differ significantly among the AECG technologies; however, USA patients had a more favorable overall view of ICM/ILRs (T2B: 42.4%) than did UK/D (T2B: 28%) or Japan (T2B: 17.5%) patients. Similarly, US patient rankings for education received regarding device choice and operation tended to be higher than UK/D or Japan patients; nevertheless, at their best, the Likert scores were low (approximately 4.7‐6.0) suggesting need for education improvement. Finally, both US and UK/D patients were similarly concerned with ICM costs (T2B, 31% vs 20% for Japan). Conclusions Patients across several geographies have a similar but imperfect understanding of AECG technologies. Given more detailed education the patient is likely to be a more effective partner with the clinician in establishing a potential symptom‐arrhythmia correlation. We surveyed syncope/collapse patients from three geographical regions (United States, United Kingdom/Germany and Japan) who underwent AECG monitoring. Patients across several geographies have similar, albeit imperfect, understanding of AECG technologies, and warrant more complete education regarding AECG devices selected for their care.

Whether the risk factors for cardiovascular (CV) outcomes are different in primary versus secondary prevention implantable cardioverter-defibrillator (ICD) patients is unclear. We sought to identify predictors of CV outcomes in ICD recipients for primary (G1) versus secondary prevention (G2). Consecutive patients who had ICD implanted during August 2005 to December 2009 were included. The primary outcome was a composite of appropriate shock, acute coronary syndrome, ischemic stroke, coronary revascularization, heart failure exacerbation, CV hospitalization, or all-cause death. We used Cox proportional hazards model and a stepwise selection method to fit the most parsimonious model to predict the primary outcome in all patients and separately for G1 and G2 patients. We followed 223 (184 G1 and 39 G2, mean age 61 years) patients through December 31, 2012; 141 (63.2%) developed the primary outcome. In all patients, atrial fibrillation (AF; hazard ratio 6.72, 95% CI 4.20 to 10.75; p <0.001), use of antiarrhythmic drug (1.55, 1.02 to 2.36; p = 0.04), and lower estimated glomerular filtration rate (0.99, 0.98 to 0.997; p = 0.01) were associated with increased risk of the primary outcome; the attributable risks were 21.6%, 16.0%, and 15.9%, respectively. In G1, AF, hypertension, and lower estimated glomerular filtration rate were associated with increased risk, whereas in G2, AF, use of antiarrhythmic drug, and nonischemic cardiomyopathy were associated with increased risk. In conclusion, although risk factors are different for primary and secondary prevention patients, AF is a strong and consistent risk factor for adverse outcomes in both populations.

Frequent ventricular premature complexes (VPCs), particularly those without troublesome palpitations, are often regarded as a benign arrhythmia and are not treated other than with reassurance. However, VPCs can contribute to left ventricular (LV) dysfunction in the absence of symptoms. The present study was designed to investigate whether catheter ablation of VPCs can improve LV dysfunction in patients with and without troublesome palpitations. Of 80 consecutive patients who underwent catheter ablation of frequent VPCs, 24 (aged 60 ± 15 years) were found to have a reduced LV ejection fraction at baseline (<48%) and included in the present study. No important procedure-related complications occurred in these patients. During a median follow-up of 8 months, the VPC burden after ablation had decreased from 15 ± 6% to 1 ± 1% (p <0.001), and the left ventricular ejection fraction had increased from 32 ± 15% to 43 ± 14% (p <0.001). Ten patients (42%) had no palpitations before ablation. In the other 14 patients, the palpitations were improved or entirely resolved after ablation. No significant difference was found in the extent of LV ejection fraction improvement after ablation between patients with and without palpitations (+11 ± 12% vs +11 ± 11%, p = 0.941) or between patients with different locations of VPC origin. In conclusion, VPCs might not necessarily be associated with palpitations in many patients with LV dysfunction. Successful ablation of frequent VPCs in these “asymptomatic” patients is associated with an improvement in LV function similar to that observed in “symptomatic” patients.

Catheter‐based radiofrequency (RF) ablation targeting segments of the cardiac conduction system and/or selected regions of myocardium is an accepted treatment for many cardiac arrhythmias. On the other hand, while purposeful extension of RF ablation to include nearby cardiac neural elements, particularly epicardial ganglionated plexi (GP), remains a subject of ongoing study, inadvertent stimulation of such structures may occur during an otherwise conventional RF ablation procedure. Thus, asystolic pauses have been observed during RF ablation of left ventricular free‐wall accessory pathways, slow AV node pathways, and the left superior pulmonary vein. In this report, sinus arrest occurred within 3.3 s of RF application (40 W at 50°C) along the coronary sinus roof for treatment of an atypical “slow–slow” atrioventricular nodal reentrant tachycardia. Energy delivery was immediately terminated, but asystole persisted for 4.7 s followed by sinus bradycardia. The procedure was temporarily halted, but later was successfully resumed. Given the latency from terminating RF to return of sinus node function, the sinus arrest was likely a centrally mediated reflex vagal response. Consequently, while parasympathetic ganglia near the CS os are believed to principally innervate the AV node, not the sinus node, our observation highlights the neural cross‐communications that likely exist in this region of the heart.