Endothelial dysfunction: its clinical value and methods of assessment

Endothelial dysfunction (ED) is a systemic disorder characterized by reduced production of nitric oxide. This pathologic condition, which impairs vascular homeostasis, leads to the loss of protective properties of endothelial cells and is related to the pathogenesis of cardiovascular diseases. ED may affect every vascular bed, accounting for several clinical implications, particularly when the coronary bed is affected. Although the reliability of ED as a cardiovascular disease surrogate is still debated, many methods for its assessment have been proposed. In this review, we underline the clinical value of ED in the cardiovascular field and summarize the principal methods currently available for its assessment.

Troponin-I is a predictor of a delayed diagnosis of atrial fibrillation in acute ischemic stroke and transient ischemic attack

BACKGROUND

Prolonged cardiac monitoring detects higher rates of atrial fibrillation (AF) in ischemic stroke and transient ischemic attack (TIA) but is costly and has practical implications. The use of admission troponin-I (TnI) level to identify patients at high risk of delayed AF detection was investigated.

METHODS

Consecutive ischemic stroke and TIA cases presenting to our institute over a 13-month period were identified from the Irish Stroke and TIA Register. Electronic databases and case notes were examined. "Delayed" AF was diagnosed after a sinus rhythm admission electrocardiogram and no documented history. Group comparisons were made by AF status. The association between TnI and AF was investigated using a multivariate regression model.

RESULTS

A total of 185 cases (130 ischemic stroke) were analyzed. Mean age (standard deviation) was 73.3 (13.9) years, 47% female. Sixty-two cases (33.5%) had AF. The first documented presentation of AF was found in 21 cases, on admission electrocardiogram (n = 11) or inpatient telemetry (delayed, n = 10). TnI was higher in those with delayed AF than in those without AF (W = 194; P = .036). A higher proportion of those with an elevated TnI (30%) than those with a normal TnI (6.1%) had delayed diagnosis of AF (χ(2) = 6.41, P = .011). Having an abnormal TnI was a significant independent predictor of delayed AF detection (odds ratio, 5.8; P = .037).

CONCLUSIONS

TnI elevation is associated with a higher likelihood of subsequent AF diagnosis. Identification of these higher risk stroke and TIA cases for more intensive cardiac monitoring may improve stroke secondary prevention practices.

New directions in cardiac arrhythmia management: present challenges and future solutions

Cardiac arrhythmias are a major contributor to population morbidity and mortality. Enormous advances in arrhythmia management have occurred over the 60 years since the founding of the Montreal Heart Institute, but important challenges remain. The purpose of this article is to identify the areas of cardiac arrhythmia therapy that need improvement and to discuss the evolving approaches that promise solutions. Challenges in diagnosis, detection, and risk-stratification include difficulties in separating benign from high-risk syncope and pinpointing the underlying causes, the detection of silent atrial fibrillation in patients at risk of stroke, and inadequate identification of sudden-death risk. Implantable devices are limited by the need for battery and device replacements, device complications like infection and dysfunction, and lead complications like fracture, infection, or displacement. Antiarrhythmic drug therapy, although widely used, is plagued by a very limited range of available agents, supply issues, insufficient efficacy, and significant adverse effect risk. Health economic concerns include the high cost of new technologies, challenges in establishing cost effectiveness, and restrictive practices of government or third-party payers. Major improvements in arrhythmia management can be expected from new discoveries and technological developments in genetics, innovative diagnostic tools for arrhythmia monitoring, imaging and analysis, new approaches to antiarrhythmic drug development, biological therapies, and continuing improvement in implantable device technology like further miniaturization, leadless technology, and use of novel energy sources. As exciting as the developments in arrhythmia management have been in the past, we can look forward to exponential improvement in our ability to manage arrhythmia patients in the near future.

Phone-delivered mindfulness training for patients with implantable cardioverter defibrillators: results of a pilot randomized controlled trial

BACKGROUND

The reduction in adrenergic activity and anxiety associated with meditation may be beneficial for patients with implantable cardioverter defibrillators.

PURPOSE

This study aims to determine the feasibility of a phone-delivered mindfulness intervention in patients with defibrillators and to obtain preliminary indications of efficacy on mindfulness and anxiety.

METHODS

Clinically stable outpatients were randomized to a mindfulness intervention (eight weekly individual phone sessions) or to a scripted follow-up phone call. We used the Hospital Anxiety and Depression Scale and the Five Facets of Mindfulness to measure anxiety and mindfulness, and multivariate linear regression to estimate the intervention effect on pre-post-intervention changes in these variables.

RESULTS

We enrolled 45 patients (23 mindfulness and 22 control; age, 43-83; 30 % women). Retention was 93 %; attendance was 94 %. Mindfulness (beta = 3.31; p = 0.04) and anxiety (beta = -1.15; p = 0.059) improved in the mindfulness group.

CONCLUSIONS

Mindfulness training can be effectively phone-delivered and may improve mindfulness and anxiety in cardiac defibrillator outpatients.

The Reveal LINQ insertable cardiac monitor

Insertable cardiac monitors (ICMs) are leadless subcutaneous devices that continuously monitor the heart rhythm and record events over a timeframe measured in years, allowing for the diagnosis of infrequent rhythm abnormalities that can be the cause of palpitations, syncope and stroke. To date, ICMs have primarily been used in the work-up and management of syncope; however, their use in other areas of rhythm evaluation, particularly atrial fibrillation monitoring, is increasing. The Reveal LINQ™ is the smallest and most versatile ICM available and represents a dramatic leap forward in ICM technology that has the potential to transform patient care in a number of circumstances. Device miniaturization, simplified implant procedure and enhanced automation vastly increase physician and patient acceptance. The next 5 years can be expected to bring a greatly increased use of ICMs for disease diagnosis and management in a variety of clinical settings.

All-cause mortality and cardiovascular events with nicorandil in patients with IHD: systematic review and meta-analysis of the literature

BACKGROUND

Nicorandil is able to protect the cardiomyocytes from ischemic damage, but clear benefits of nicorandil in all-cause mortality and cardiovascular events were not consistently reported in patients with ischemic heart disease (IHD).

MATERIALS AND RESULTS

Cochrane, PubMed, EMBASE, CBM, CNKI and Wangfang databases were searched for randomized controlled trials. Data on all-cause mortality and cardiovascular events were collected. Nicorandil groups were pooled to perform a comparison with control groups and to get the pooled odds ratios (ORs) and associated 95% confidence intervals (CIs) for all-cause mortality, relative risks (RRs), and associated 95% CIs for cardiovascular events. STATA 11.0 software was used for all-cause mortality and cardiovascular events statistics. We retrieved 17 randomized controlled studies enrolling a total of 7305 patients. The addition of nicorandil treatment significantly reduced cardiovascular events (13.83% versus 18.01%; RR, 0.77; 95% CI, 0.69 to 0.86). No differences in all-cause mortality (3.83% versus 4.70%; OR, 0.81; 95% CI, 0.64 to 1.02), and repeat revascularization rate (13.06% versus 13.54%; RR, 0.95; 95% CI, 0.70 to 1.29) were observed. There was a weak linear association between cardiovascular events and nicorandil in IHD with diabetes (P=0.099).

CONCLUSIONS

The results suggest that nicorandil as an adjunct therapy to IHD is associated with reduced cardiovascular events in patients with IHD.

Characteristics of Patients With Diabetes Having Normal Coronary Arteries

We evaluated the association between risk variables in diabetic patients with normal and diseased coronary arteries in a retrospective cohort study conducted at Rashid Hospital, Dubai. A total of 4446 patients underwent coronary angiography due to various indications; 43% had type 2 diabetes mellitus (T2DM). Among the diabetic patients, 94% had diseased coronary arteries and the remaining 6% had absolutely normal arteries. The normal coronary group had significantly lower low-density lipoprotein cholesterol (LDL-C) and a higher high-density lipoprotein cholesterol (HDL-C) levels than the diseased group. Patients with normal coronaries were more likely to be females, have T2DM for a shorter duration, and were nonsmokers and non-South Asians. They also had lower levels of LDL, hemoglobin A1c, and fasting glucose and higher levels of HDL-C. Apart from these variables, genetic or environmental factors could protect these patients from atherosclerosis.

Evaluation of endothelial function by peripheral arterial tonometry and relation with the nitric oxide pathway

Endothelial dysfunction is an important component in the development of cardiovascular diseases. Endothelial function may be evaluated by peripheral arterial tonometry (PAT) which measures the vasodilator function in the microvasculature of the fingertip during reactive hyperaemia. The reactive hyperaemia index (RHI) is decreased in the presence of cardiovascular risk factors and thus far several studies have shown that PAT-RHI may provide reliable prediction of outcome. The technique is operator independent and easy to perform. Abnormalities measured by PAT follow the same trend as those measured by flow-mediated dilation in the brachial artery, but the two methods are not interchangeable. We have reviewed the recent literature in an effort to evaluate peripheral arterial tonometry as a method to assess the function of the endothelium and additionally suggest directions for future research. Special attention will be directed to the nitric oxide dependency of the reactive hyperaemia index obtained by peripheral arterial tonometry.

Appropriate duration of driving restrictions after inappropriate therapy from implantable cardiac shock devices-interim analysis of the Nippon Storm Study

BACKGROUND

Little is known regarding the appropriate duration for driving restrictions after inappropriate implantable cardiac shock device (ICSD) therapy.

METHODS AND RESULTS

We evaluated the Nippon Storm Study data, and found that inappropriate ICSD therapy occurred in 114 (7.6%) patients during a median follow-up of 464 days. Among those patients, 25 experienced further inappropriate ICSD therapy during a subsequent median follow-up of 380 days. Time-dependent recurrence of inappropriate ICSD therapy occurred in 19 (76%) patients within 180 days.

CONCLUSIONS

The interval for driving restrictions after inappropriate ICSD therapy can be reduced.

Microglia are selectively activated in endocrine and cardiovascular control centres in streptozotocin-induced diabetic rats

Type 1 and 2 diabetes are associated with dysfunction in multiple hormone systems, as well as increased sympathetic nerve activity, which may contribute to the development of diabetic complications. In other pathologies, such as myocardial infarction, increased sympathetic drive is associated with neuroinflammation and microglial activation in the hypothalamic paraventricular nucleus (PVN), a brain region that regulates sympathetic drive and multiple endocrine responses. In the present study, we used immunohistochemistry to study microglial and neuronal activation in the PVN and related brain regions in streptozotocin (STZ)-induced diabetic rats. As expected, STZ treatment was associated with elevated blood glucose within 1 week. STZ injections also caused neuronal activation in the PVN and superoptic nucleus (SON) but not in the nucleus tractus solitarius (NTS), which was evident by 6 weeks. STZ-treated rats showed increased plasma osmolarity, which would be expected to activate PVN and SON neurones. There was no apparent increase in histochemical markers of microglial activation, including phospho-p38, phospho-extracellular signal regulated kinase, P2X4 receptor or interleukin 1-β even at 10 weeks after STZ-treatment. However, we did see a significant increase in the percentage of microglia with an activated morphology in the PVN, SON and NTS, although not in surrounding hypothalamic, brainstem or cortical regions. These morphological changes included a significant reduction in microglial process length and were evident by 8 weeks but not 6 weeks. The delayed onset of microglial changes compared to neuronal activation in the PVN and SON suggests the over-excitation of neurones as a mechanism of microglial activation. This delayed microglial activation may, in turn, contribute to the endocrine dysregulation and the elevated sympathetic nerve activity reported in STZ-treated rats.

Feasibility and efficacy of a remote real-time wireless ECG monitoring and stimulation system for management of ventricular arrhythmia in rabbits with myocardial infarction

The purpose of this study was to explore the feasibility of continuous remote monitoring, and the induction and termination of malignant ventricular arrhythmias (VAs) by a novel implantable electronic cardiovascular device (IECD) system in rabbits with myocardial infarction (MI). The IECD was implanted and MI was induced by ligation of the left anterior descending coronary artery in 20 adult rabbits. Internet-based remote electrocardiogram (ECG) monitoring and ventricular stimulation were conducted in remote locations with internet access. The voltage amplitudes of the stimulation signals were recorded synchronously by remote and surface ECG. Programmed stimulation with regular stimuli and regular stimuli with an added extra stimulus were performed prior to and following the MI surgery to induce and terminate VAs. IECD implantation and MI surgery, as well as qualified remote and bidirectional signal communications between the implanted IECD and extracorporeal system, were successfully achieved in 18 rabbits. The voltage of the stimulation signals recorded by the remote and surface ECGs showed a good correlation with the stimulation current (remote ECG, r=0.972 and surface ECG, r=0.988; P<0.001). Sustained ventricular tachycardia (VT) was induced in five rabbits (5/20, 25%) prior to MI induction and in 12 rabbits (12/16, 75%) following MI induction. Of the 17 induced VTs, 16 were successfully terminated by remote ventricular stimulation. The novel IECD system provides qualified remote wireless ECG monitoring and possesses the potential to induce and terminate VAs by remote ventricular pacing in this rabbit model of MI. Thus, this model of MI may be used to test the efficacy of novel drugs and devices for the management of VAs.

QT prolongation in a child with thyroid storm

A 12-year-old girl presented with an acute confusional state and a 2-year history of weight loss, anxiety, agitation and recurrent fever. Thyroid function tests confirmed severe hyperthyroidism, and a diagnosis of thyroid storm was made (Burch and Wartofsky score=75). ECG showed a prolonged QTc interval of 506 ms. Acute treatment for thyroid storm consisted of Lugol's iodine, prednisolone, carbimazole and propranolol. She made a steady recovery and by 3 months her thyroid function had normalised; a repeat ECG showed a QTc within the normal range (430 ms). There was no relevant family history. This is a case of QTc prolongation with hyperthyroidism and normalisation with euthyroidism. It is not commonly recognised that hyperthyroidism in children may be associated with QTc prolongation. QTc measurement should be incorporated into management protocols for hyperthyroidism.

Clinical utility of implantable loop recorders

Implantable loop recorders provide the highest sensitivity and accuracy of diagnosing cardiac arrhythmia that results in cardiac syncope. When bradyarrhythmia or tachyarrhythmia, including atrial fibrillation, is detected, appropriate secondary prevention therapy will be implemented, which will impact the long-term clinical outcome. An implantable loop recorder enables the clinician to record for a longer period of time, which increases the likelihood of detecting cardiac arrhythmia. Currently, this technology is being evaluated to diagnose a cardiac etiology of ischemic stroke and to optimize atrial fibrillation management that will predict the success of rhythm control and prevent thromboembolic events. This article reviews implantable loop recorder technology, and discusses the current indications, the outcomes of clinical studies and ongoing current studies, and future technological improvements.

Intermittent short ECG recording is more effective than 24-hour Holter ECG in detection of arrhythmias

Background

Many patients report symptoms of palpitations or dizziness/presyncope. These patients are often referred for 24-hour Holter ECG, although the sensitivity for detecting relevant arrhythmias is comparatively low. Intermittent short ECG recording over a longer time period might be a convenient and more sensitive alternative. The objective of this study is to compare the efficacy of 24-hour Holter ECG with intermittent short ECG recording over four weeks to detect relevant arrhythmias in patients with palpitations or dizziness/presyncope.

Methods

Design: prospective, observational, cross-sectional study. Setting: Clinical Physiology, University Hospital. Patients: 108 consecutive patients referred for ambiguous palpitations or dizziness/presyncope. Interventions: All individuals underwent a 24-hour Holter ECG and additionally registered 30-second handheld ECG (Zenicor EKG® thumb) recordings at home, twice daily and when having cardiac symptoms, during 28 days. Main outcome measures: Significant arrhythmias: atrial fibrillation (AF), paroxysmal supraventricular tachycardia (PSVT), atrioventricular (AV) block II–III, sinus arrest (SA), wide complex tachycardia (WCT).

Results

95 patients, 42 men and 53 women with a mean age of 54.1 years, completed registrations. Analysis of Holter registrations showed atrial fibrillation (AF) in two patients and atrioventricular (AV) block II in one patient (= 3.2% relevant arrhythmias [95% CI 1.1–8.9]). Intermittent handheld ECG detected nine patients with AF, three with paroxysmal supraventricular tachycardia (PSVT) and one with AV-block-II (= 13.7% relevant arrhythmias [95% CI 8.2–22.0]). There was a significant difference between the two methods in favour of intermittent ECG with regard to the ability to detect relevant arrhythmias (P = 0.0094). With Holter ECG, no symptoms were registered during any of the detected arrhythmias. With intermittent ECG, symptoms were registered during half of the arrhythmia episodes.

Conclusions

Intermittent short ECG recording during four weeks is more effective in detecting AF and PSVT in patients with ambiguous symptoms arousing suspicions of arrhythmia than 24-hour Holter ECG.

Physical activity in the prevention of peripheral artery disease in the elderly

Aging is a well-known cardiovascular risk factor and cardiovascular diseases (CVD) are estimated to be the most common cause of death in the elderly. Peripheral arterial disease (PAD) represents an important clinical manifestation of CVD leading to increase morbidity and mortality, especially in elderly population. The correct management of PAD population includes the prevention of cardiovascular events and relief of symptoms, most commonly intermittent claudication. Progressive physical activity is an effective treatment to improve walking distance and to reduce mortality and cardiovascular events in patients with PAD, however the ability to effectively engage in physical activity often declines with increasing age. The maintenance and increase of reserve functional capacity are important concepts in the elderly population. Ultimately, the goal in participation of physical activity in the healthy elderly population is maintenance and development of physical functional reserve capacity. Therefore, for individuals suffering of PAD, appropriate physical activity in the form of supervised exercise may serve as a primary therapy. Although there are few direct comparisons of therapeutic exercise programs vs. pharmacological or surgical interventions, these increases in walking distance are greater than those reported for the most widely used agents for claudication, pentoxyphylline, and cilostazol. Despite a reduction in mortality and improvement of quality of life caused by physical activity in the PAD population, the molecular, cellular, and functional changes that occur during physical activity are not completely understood. Therefore, this review article aims at presenting an overview of recent established clinical and molecular findings addressing the role of physical activity on PAD in the older population.

The effect of late adoption of Canadian innovations: a case for implantable cardiac monitors

Syncope is a sudden and generally momentary loss of consciousness, which can have serious adverse events. The outcomes of the syncope episode can vary from a fall to fatal accidents. Syncope has a major negative effect on the patient's health-related quality of life. The economic burden of syncope on healthcare systems is considerable. There are no clear diagnostic pathways for identifying the cause of syncope; patients can be admitted to hospital and undergo expensive and often repeated and inconclusive diagnostic tests. Implantable cardiac monitors have been available for more than a decade to help early diagnosis of syncope in unexplained cases. However, despite being a Canadian invention, the use of the implantable cardiac monitors has been suboptimal in the Canadian healthcare system. This study provides an overview of syncope, its management, and presents the estimated potential cost savings per diagnosis of systematic use of implantable cardiac monitors in Ontario.

Role of extended external loop recorders for the diagnosis of unexplained syncope, pre-syncope, and sustained palpitations

AIMS

To assess the diagnostic yield of new external loop recorders (ELRs) in patients with history of syncope, pre-syncope, and sustained palpitations.

METHODS AND RESULTS

Since 2005, we have established a registry including patients who consecutively received ELR monitoring for unexplained syncope or pre-syncope/palpitations. The registry included 307 patients (61% females, age 58 ± 19 years, range 8-94 years) monitored by high-capacity memory ELR of two subsequent generations: SpiderFlash-A(®) (SFA(®), Sorin CRM), storing two-lead electrocardiogram (ECG) patient-activated recordings by loop-recording technique (191 patients, 54 patients with syncope, years 2005-09), and SpiderFlash-T(®) (SFT(®)), adding auto-trigger detection for pauses, bradycardia, and supraventricular/ventricular arrhythmias (116 patients, 38 patients with syncope, years 2009-12). All the patients previously underwent routine workup for syncope or palpitation, including one or more 24 h Holter, not conclusive for diagnosis. Mean monitoring duration was 24.1 ± 8.9 days. Among 215 patients with palpitations, a conclusive diagnosis was obtained in 184 patients (86% diagnostic yield for palpitation). Among 92 patients with syncope, a conclusive diagnosis was obtained in 16 patients (17% clinical diagnostic yield for syncope), with recording during syncope of significant arrhythmias in 9 patients, and sinus rhythm in 7 patients. Furthermore, asymptomatic arrhythmias were de novo detected in 12 patients (13%), mainly by auto-trigger detection, suggesting an arrhythmic origin of the syncope.

CONCLUSIONS

The diagnostic yield of ELR in patients with syncope, pre-syncope, or palpitation of unknown origin after routine workup was similar to implantable loop recorder (ILR) within the same timeframe, therefore, ELR could be considered for patients candidate for long-term ECG monitoring, stepwise before ILR.

Implant evaluation of an insertable cardiac monitor outside the electrophysiology lab setting

Background

To date, insertable cardiac monitors (ICM) have been implanted in the hospital without critical evaluation of other potential settings. Providing alternatives to in-hospital insertion may increase access to ICM, decrease waiting times for patients awaiting diagnosis, and reduce hospital resources.

Methods

This was a prospective, non-randomized, clinical trial involving nine clinical sites throughout the United States designed to assess the feasibility of ICM implants in a non-hospital setting. Other than the Reveal® ICM, implant supplies and techniques were left to physician discretion in patients who met indications. Patients were followed up to 90 days post-implant. The primary objective was to characterize the number of procedure-related adverse events that required surgical intervention within 90 days.

Results

Sixty-five patients were implanted at nine out-of-hospital sites. The insertion procedure was well tolerated by all patients. There were no deaths, systemic infections or endocarditis. There were two (3%) procedure-related adverse events requiring device explant and four (6%) adverse events not requiring explant. ICM use led to 16 diagnoses (24.6%) with 9 patients proceeding to alternate cardiac device implants during the course of the 90-day follow up.

Conclusion

Out-of-hospital ICM insertion can be accomplished with comparable procedural safety and represents a reasonable alternative to the in-hospital setting.

Clinicaltrials.gov registration number:NCT01168427

Impaired endothelial function in female adolescents with type 1 diabetes measured by peripheral artery tonometry

BACKGROUND

The reactive hyperemia peripheral artery tonometry (RH-PAT) is a newly developed method for non-invasive endothelial function assessment.

OBJECTIVE

The goal of this study is to determine whether a significant difference in RH-PAT score is present between adolescents with type 1 diabetes (T1D) in comparison with controls.

SUBJECTS AND METHODS

Thirty-four adolescents with T1D and 25 control subjects (age 12-20 years) underwent RH-PAT endothelial function testing after an overnight fast. Height, weight, body mass index (BMI), blood pressure (BP), fasting lipid profile, Tanner stage, and glucose level were determined in each child.

RESULTS

Adolescents with T1D had significantly lower RH-PAT scores compared to healthy controls, and this difference remained significant when overweight cases were not considered (p < 0.05). This difference was also observed in the female subgroup (p = 0.005). The interindividual variability in RH-PAT observations in T1D cases was not explained by BMI standard deviation score (SDS), BP SDS, age, duration of T1D, hemoglobin A1c, triglycerides, and pubertal stage, respectively.

CONCLUSIONS

The RH-PAT technique is used as a non-invasive test to assess for early vascular changes in high-risk patient groups. Endothelial dysfunction, measured by RH-PAT, was present in diabetic adolescent, especially in the female subgroup. Although additional longitudinal studies are required, early detection of this reversible process may have therapeutic and prognostic implications.

Usefulness of an implantable loop recorder in patients with syncope of an unknown cause

PURPOSE

The mechanisms underlying syncope remain unknown in about 20% of patients with recurrent syncope. The implantable loop recorder (ILR) has been shown to be a useful diagnostic tool in patients with unexplained syncope even after negative initial evaluations. Nevertheless, ILR has rarely been used in clinical practice.

MATERIALS AND METHODS

This study included 18 consecutive patients who had an ILR implanted at our center because of recurrent unexplained syncope after extensive diagnostic tests between February 2006 and June 2011.

RESULTS

Diagnosis was confirmed in 10 (55.6%) of the 18 enrolled patients (13 males, 61±15 years). The confirmed diagnoses included sick sinus syndrome (n=6, 60%), advanced atrioventricular block (n=2, 20%) and ventricular tachyarrhythmia (n=2, 20%). The mean follow-up durations of the total study subjects and the diagnosed patients were 11.3±10.6 months and 5.6±9.2 months, respectively. Of the 10 diagnosed patients, 8 (80%) were diagnosed within 6 months of loop recorder implantation.

CONCLUSION

ILR may be a valuable and effective diagnostic tool for patients with unexplained syncope.

Thyroid hormones and electrocardiographic parameters: findings from the third national health and nutrition examination survey

Introduction

Altered thyroid status exerts a major effect on the heart. Individuals with hypo- or hyperthyroidism showed various changes in electrocardiograms. However, little is known about how variations in thyroid hormone levels within the normal range affect electrical activities of the heart in the general population.

Methods and Results

We conducted a cross-sectional analysis of 5,990 men and women from the Third National Health and Nutrition Examination Survey. Serum total T4 was measured by immunoassay and TSH was measured by chemiluminescent assay. We categorized T4 and TSH into 7 groups with cut-offs at the 5^th, 20^th, 40^th, 60^th, 80^th, and 95^th percentiles of the weighted population distribution. Electrocardiographic parameters were measured from the standard 12-lead electrocardiogram. We found a positive linear association between serum total T4 level and heart rate in men, and a U-shape association between T4 and PR interval in men and women. TSH level was positively associated with QRS interval in men, while a U-shape association between TSH and QRS was observed in women. No clear graded association between thyroid hormones and corrected QT or JT was found, except that men in the highest category of T4 levels appeared to have longer corrected QT and JT, and men in the lowest category of T4 appeared to have shorter corrected QT and JT.

Conclusions

Variation in thyroid hormone levels in the general population, even within the normal range, was associated with various ECG changes.

Transient ischemic dilation in SPECT myocardial perfusion imaging for prediction of severe coronary artery disease in diabetic patients

BACKGROUND

Transient ischemic dilation (TID) of the left ventricle during stress myocardial perfusion SPECT (MPS) has been shown to be a useful marker of severe coronary artery disease (CAD). However, investigations in diabetic patients with available coronary angiographic data are still limited. We evaluated the incremental diagnostic value of TID in identifying the presence of angiographically severe CAD in diabetic patients.

METHODS AND RESULTS

TID ratio values were automatically derived from rest-stress MPS in 242 diabetic patients with available coronary angiography data. A cutoff of ≥1.19 was considered to represent TID. Severe CAD (≥70% stenosis in the proximal left anterior descending artery or the left main artery, or ≥90% stenosis in two or three vessels) was identified in 69 (29%) patients. At multivariate analysis, the best independent predictors of severe CAD were summed stress score and TID (both P < .001). At incremental analysis, the addition of TID improved the power of a model including clinical data and summed stress score, increasing the global χ(2) value from 14.3 to 28.2 (P < .01). The best cutoff of summed stress score for identifying patients with severe CAD was ≥8. When the TID ratio was considered in patients with summed stress score between 3 and 7, the sensitivity for diagnosing severe CAD significantly improved from 71% to 77% (P < .05). In the overall study population, the net reclassification improvement by adding TID to a model including clinical data and summed stress score in the prediction of severe CAD was 0.40 (P < .005).

CONCLUSIONS

TID ratios obtained from rest-stress MPS provide incremental diagnostic information to standard perfusion analysis for the identification of severe and extensive CAD in diabetic patients.

Inappropriate ICD shocks caused by T-wave oversensing due to acute alcohol intoxication

T-wave oversensing can be a serious problem that often results in inappropriate device therapy. We report here a patient with binge alcohol use who received multiple, inappropriate ICD shocks due to T-wave oversensing from repolarization changes induced by acute alcohol intoxication and no other relevant metabolic derangements. Following recovery from his alcohol intoxication a few days later, the T-wave amplitude decreased so the device no longer inappropriately sensed or delivered therapies. This case represents an uncommon, but reversible, cause of T-wave oversensing that should be considered before more aggressive measures are taken to correct the abnormality.

Cardiac Resynchronization Therapy With and Without Defibrillator in a Commercial Truck Driver with Ischemic Cardiomyopathy and New York Heart Association Class III Heart Failure

Commercial drivers warrant tighter restrictions to their driving privileges than private drivers. Patients with cardiac disease who are at risk of consciousness-impairing arrhythmias are not allowed to drive commercially. Patients with left ventricular systolic dysfunction and/or heart failure symptoms are permanently disqualified from commercial driving. A biventricular pacemaker without defibrillator can improve symptoms and mortality in selected patients with heart failure. Biventricular pacing may have antiarrhythmic effects that may reduce the added benefit of a defibrillator. Motor vehicle collisions resulting from arrhythmic events are infrequent. The interests of public safety must outweigh individual liberties when driving safety is in question.

Current and emerging indications for implantable cardiac monitors

Implantable cardiac monitors (ICMs) continuously monitor the patient's electrocardiogram and perform real-time analysis of the heart rhythm, for up to 36 months. The current clinical use of ICMs involves the evaluation of transitory symptoms of possible arrhythmic origin, such as unexplained syncope and palpitations. Moreover, ICMs can also be used for the evaluation of difficult cases of epilepsy and unexplained falls, though current indications for their application in these sectors are less clearly defined. Finally, the ability of new-generation ICMs to automatically record arrhythmic episodes suggests that these devices could also be used to study asymptomatic arrhythmias, and thus could be proposed for the long-term evaluation of the total (symptomatic and asymptomatic) arrhythmic burden in patients at risk of arrhythmic events. In particular, ICMs may have an emerging role in the management of patients with atrial fibrillation and in those at risk of ventricular arrhythmias.

[Internet therapy for ICD-patients]

Implantable cardioverter-defibrillators (ICD) are increasingly used for the prevention of potentially lethal cardiac arrhythmias due to their confirmed superior medical efficiency. Nevertheless, ICD-patients often suffer from psychosocial problems, e.g., anxiety and depression. These issues are rarely addressed in routine medical follow-up care. Due to the limited mobility of many ICD-patients, Internet-based care may be ideal for delivering psychosocial care to patients in their homes. Our pilot study and case studies illustrate prospects and challenges of this approach. We developed icd-forum.de, a 6-week internet-based prevention program that provides a platform for information, a virtual self-help group, and a professionally moderated chat room in order to help decrease anxiety and to improve quality of life. A critical evaluation in the context of other published studies on the subject allows recommendations for the implementation of future internet-based psychosocial programs for ICD-patients to be deduced. It is the authors' opinion that such programs offer advantages specifically for heart failure patients and they recommend their broader use. Prior to this, conclusive evaluation studies are needed.

Inappropriate asystole detection in early postoperative phase after loop recorder implantation

The implantable loop recorder is a useful diagnostic tool for patients with unexplained syncope. The capability to automatically detect and store arrhythmic events, implemented in the last generations of these devices, can further improve the diagnostic yield, but this feature can be compromised by inappropriate detection of false arrhythmias. We herein report the case of a patient in which several inappropriate activations of long-lasting asystole occurred in the two days following the implant, probably because of an intermittently loose contact between the device and subcutaneous tissue for a small pocket haematoma.

Thromboembolic events during the perioperative period in patients undergoing permanent pacemaker implantation

BACKGROUND

Thromboembolism (TE) is one of the most serious complications after pacemaker implantation. It has been demonstrated that several patient characteristics and different pacing modes are related to an increased risk of TE events during long-term follow-up.

HYPOTHESIS

We propose that TE events occurring during the perioperative period of pacemaker implantation may be associated with certain clinical characteristics.

METHODS

The potential risk factors of TE events were analyzed in 406 consecutive patients who underwent pacemaker implantation.

RESULTS

We identified TE events in 11 patients (2.7%) within 7 days after pacemaker implantation. Four of the 11 (36.4%) patients died of complications of TE. Univariate analysis revealed that an age of >75 years (4.56 odds ratio [OR], P = 0.031), hypertension (3.59 OR, P = 0.028), diabetes (8.89 OR, P < 0.001), coronary heart disease (4.8 OR, P = 0.005), atrial fibrillation (AF) (5.68 OR, P = 0.006), persistent AF (10.36 OR, P < 0.001), and a history of stroke or transient ischemic attack (5.62 OR, P = 0.002) were associated with an increased risk of TE events. Multivariate logistic analysis showed that persistent AF (9.8 OR, P < 0.001) was independently associated with TE. The incidence of perioperative TE was not significantly different between patients with single- and dual-chamber pacemakers.

CONCLUSIONS

We found TE events during the perioperative period in patients undergoing pacemaker implantation were not uncommon. Because persistent AF during the perioperative period was the only independent risk factor for perioperative TE, appropriate anticoagulation therapy may be necessary in those patients. © 2012 Wiley Periodicals, Inc. J. Liu, MD, is co-first author. The authors have no funding, financial relationships, or conflicts of interest to disclose.

Graves' disease complicated by ventricular fibrillation in three men who were smokers

BACKGROUND

Thyrotoxicosis is known to be associated with sinus tachycardia and supraventricular tachyarrhythmias, but rarely with ventricular fibrillation (Vf), which has only occurred in some patients with hypokalemic periodic paralysis or ischemic heart disease.

PATIENT FINDINGS

We present three men who were transferred to our hospital with Graves' disease who developed idiopathic Vf. None of them had hypokalemic periodic paralysis or ischemic heart disease but all were smokers. None of other patients with thyrotoxicosis (587 females and 155 males) who were seen at our hospital, in the period during which the three men were seen, had idiopathic Vf. In our three men with thyrotoxicosis and idiopathic Vf, there was no identifiable underlying heart disease. One of the three patients died of hypoxic encephalopathy. The other two men did not have recurrent Vf after their thyroid function normalized.

SUMMARY

These cases and a review of similar cases in the literature imply that improving thyrotoxicosis seems to be effective for treating idiopathic Vf in some patients.

CONCLUSIONS

Our findings suggest that thyroid hormone excess might play a direct role in the development of Vf in susceptible individuals. Our experience with these three patients suggests that smoking men with thyrotoxicosis likely have an increased risk for Vf, even if they do not have other predisposing factors.

Driving restrictions after implantable cardioverter defibrillator implantation: an evidence-based approach

Aims

Little evidence is available regarding restrictions from driving following implantable cardioverter defibrillator (ICD) implantation or following first appropriate or inappropriate shock. The purpose of the current analysis was to provide evidence for driving restrictions based on real-world incidences of shocks (appropriate and inappropriate).

Methods and results

A total of 2786 primary and secondary prevention ICD patients were included. The occurrence of shocks was noted during a median follow-up of 996 days (inter-quartile range, 428–1833 days). With the risk of harm (RH) formula, using the incidence of sudden cardiac incapacitation, the annual RH to others posed by a driver with an ICD was calculated. Based on Canadian data, the annual RH to others of 5 in 100 000 (0.005%) was used as a cut-off value. In both primary and secondary prevention ICD patients with private driving habits, no restrictions to drive directly following implantation, or an inappropriate shock are warranted. However, following an appropriate shock, these patients are at an increased risk to cause harm to other road users and therefore should be restricted to drive for a period of 2 and 4 months, respectively. In addition, all ICD patients with professional driving habits have a substantial elevated risk to cause harm to other road users during the complete follow-up after both implantation and shock and should therefore be restricted to drive permanently.

Conclusion

The current analysis provides a clinically applicable tool for guideline committees to establish evidence-based driving restrictions.

[Cardiac syncope : diagnosis and therapy]

The second most frequent category of syncope is cardiac syncope. In contrast to syncope of noncardiac causes, the 1-year mortality of patients presenting with cardiac syncope without treatment is as high as 33%. Therefore, immediate diagnosis and treatment are necessary. Bradyarrhythmias or tachyarrhythmias are the most common causes of cardiac syncope. In many cases, an initial evaluation including history, physical examination, and electrocardiogram identifies the cause of syncope, so that specific treatment can be initiated immediately. In the remainder of cases, implantable loop recorders are useful to identify arrhythmias, while the presence or absence of structural cardiac disease is diagnosed by echocardiography. Syncope due to arrhythmias is typically treated with implantation of a pacemaker or an implantable cardioverter-defibrillator; treatment of syncope of other cardiac causes requires therapy of the underlying heart disease.

Diagnostic and prognostic value of electrophysiologic study in patients with nondocumented palpitations

The 12-lead electrocardiogram helps to define the arrhythmic mechanism in patients with palpitations. However, in the setting of nondocumented palpitations the value of the electrophysiologic study (EPS) needs additional investigation. We investigated the utility of the EPS in patients with nondocumented palpitations. A total of 172 patients with normal electrocardiographic findings and nondocumented palpitations underwent an EPS. The clinical and electrophysiologic characteristics were assessed. The symptoms were long-lasting (>5 minutes) in 56%. Sudden onset was present in 99%, and termination was rapid in 65%. Neck palpitations were reported in 36%. The EPS findings were normal in 86 patients (50%); atrioventricular nodal reentrant tachycardia was induced in 43, orthodromic reentrant tachycardia in 9, and nonsustained atrial tachycardia/fibrillation (AT/AF) in 34. Long-lasting episodes, sudden termination, and neck palpitations predicted positive EPS findings and were associated with reentrant supraventricular tachycardia (p<0.001). The induction of AT/AF was associated with age >50 years and structural heart disease (p<0.001). After 53 ± 36 months of follow-up, 92% of patients with negative EPS findings were symptom free. Only 32% of patients with induced AT/AF remained free of symptoms (p<0.001). The recurrence of palpitations was more prevalent among patients with structural heart disease and aged >50 years (p<0.001). In conclusion, 50% of patients with nondocumented palpitations had positive EPS findings. A long duration, sudden termination, and neck palpitations, together with structural heart disease and age >50 years, predicted tachycardia inducibility and recurrence and could help in selecting patients suitable for EPS and ablation.

Sports and arrhythmias: a report of the International Workshop Venice Arrhythmias 2009

This article is a report of an international symposium, endorsed by the Section on Sports Cardiology of the European Association for Cardiovascular Prevention and Rehabilitation, the Italian Society of Sports Cardiology, and the Italian Federation of Sports Medicine, which was held within the 11th International Workshop on Cardiac Arrhythmias (Venice Arrhythmias 2009, Venice, Italy, October 2009). The following main topics were discussed during the symposium: the role of novel diagnostic examinations to assess the risk of sudden death in athletes, controversies on arrhythmic risk evaluation in athletes, controversies on the relationship between sports and arrhythmias, and controversies on antiarrhythmic treatment in athletes.

Approach to patients with implanted pacemaker and scheduled surgical or diagnostic procedure

Application of cardiac electrostimulation in strictly defined indications has been on the increase over the last few decades. Frequent use of this therapy as well as the fact that it is applied predominantly in patients in the seventh decade of life, implies possible signifficant comorbidities and need for various diagnostic and surgical procedures. These are the reasons we decided to point out certain specific features in approaching this patient group in preparation and implementation of these procedures. Preoperative approach starts with usual patient history, with additional information on the type of pacemaker, last pacemaker check and electrocardiogram. This general approach is not substantialy different for pacemaker or ICD patients. What is specific is the possible interferrence caused by devices used in diagnostic or therapeutic procedures (diathermy, lithotripsy). Complications that may arise are usually related to the underlying disease rather than the pacemaker malfunction, but still, careful approach and pacemaker check are warranted, especially in the group marked as "pacemaker dependent". Adequate preoperative assessment, only slightly different from the usual, represents a sufficient guarantee for safe procedures diagnostic, therapeutic or surgical.

Efficacy of diagnostic tools for detecting cardiac arrhythmias: systematic literature search

BACKGROUND/OBJECTIVES

Symptoms suggestive of cardiac arrhythmias are a challenge to the diagnosis. Physical examination and a 12-lead ECG are of limited value, as rhythm disturbances are frequently of a paroxysmal nature. New technologies facilitate a more accurate diagnosis. The objective of this study was to review the medical literature in an effort to define a guide to rational diagnostic testing.

METHODS

Primary studies on the use of a diagnostic tool in the evaluation of palpitations were searched in MEDLINE, and EMBASE with an additional reference check.

RESULTS

TWO TYPES OF STUDIES WERE FOUND: descriptive and experimental studies, which compared the yield of two or more devices or diagnostic strategies. Holter monitors seemed to have less diagnostic yield (33 to 35%) than event recorders. Automatically triggered recorders detect more arrhythmias (72 to 80%) than patient-triggered devices (17 to 75%). Implantable devices are used for prolonged monitoring periods in patients with infrequent symptoms or unexplained syncope.

CONCLUSION

The choice of the device depends on the characteristics of the symptoms and the patient. Due to methodological shortcomings of the included studies no evidence-based diagnostic strategy can be proposed. (Neth Heart J 2010;18:543-51.).