Coexistence of atrioventricular nodal reentrant tachycardia with other forms of arrhythmias.

OBJECTIVE: The aim of this retrospective study was to investigate the association of atrioventricular nodal reentrant tachycardia (AVNRT) with other forms of arrhythmia in individual patients and its consequences for treatment. SUBJECTS AND METHODS: This study comprised 493 consecutive patients aged 16-88 years (296 women and 197 men) who were diagnosed with a form of AVNRT via a standard 4-catheter electrophysiological study (EPS). Patients were clinically followed (range 0.5-12 years) at a single center. RESULTS: Coexistence of AVNRT with other types of tachycardias was observed in 197 (40%) patients. Atrial fibrillation was found most frequently in 94 (19%) patients as follows: focal atrial tachycardia, n = 40 (8%); atrial flutter, n = 32 (6%), and AV reentrant tachycardia, n = 22 (4%). Double tachycardia was present in 140 (30%) patients, and more than 2 different types of tachycardias were present in 57 (12%) patients. Transitions between AVNRT and other tachycardias occurred in 25 (5%) patients. Two or more tachycardias were ablated in 42 (9%) patients. The majority of patients were free of symptoms at the first follow-up, whereas 130 (26%) patients reported a variety of symptoms. CONCLUSION: Coexistence of AVNRT with other types of arrhythmias was a common finding among these patients. The most frequently observed double tachycardia was the combination of AVNRT with atrial tachyarrhythmias, such as atrial fibrillation, with a potential significance for further patient management.

Cardiac MRI after Sudden Cardiac Arrest: A Systematic Review.

Purpose To perform a systematic review to assess the diagnostic and prognostic value of cardiac MRI after sudden cardiac arrest (SCA). Materials and Methods PubMed and Cochrane Library databases were systematically searched for studies investigating cardiac MRI after SCA in adult patients (≥18 years of age). The time frame of the encompassed studies spans from January 2012 to January 2023. The study protocol was preregistered in OSF Registries (www.osf.io/nxaev), and the systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of the included studies was evaluated using the Newcastle-Ottawa quality assessment scale. Results Fourteen studies involving 1367 individuals, 1257 (91.9%) of whom underwent cardiac MRI, were included. Inconsistent findings were reported on the diagnostic value of cardiac MRI-specific findings. The included studies demonstrated the following main findings: (a) cardiac MRI led to a new or alternative diagnosis in patients with SCA; (b) cardiac MRI identified pathologic or arrhythmogenic substrates; (c) cardiac MRI helped detect myocardial edema (potentially reversible); (d) cardiac MRI provided evidence for the occurrence of adverse events; and (e) functional markers or ventricular dimensions were considered prognostically relevant in a few studies. Relevant challenges in this systematic review were the lack of comparators and reference standards relative to cardiac MRI as the index test and patient selection bias. Conclusion Cardiac MRI following SCA can contribute to the diagnostic process and offer supplementary information essential for treatment planning. Limitations of the review include studies with insufficient comparators and potential bias in patient selection. Systematic review registration link: osf.io/nxaev Keywords: Cardiac MRI, Cardiovascular Disease, Cardiomyopathy, Ischemia, Myocardial Edema, Sudden Cardiac Arrest © RSNA, 2024.

Harmonizing Heartbeats: The Mosaic of Cardiac Resynchronization Therapy Responders-A Comprehensive Exploration of Diverse Criteria and Predictors.

Background: Heart failure (HF) remains a challenging healthcare issue necessitating innovative therapies like cardiac resynchronization-defibrillation therapy (CRT-D). However, the definition of a CRT-D response lacks uniformity, impeding effective clinical evaluation. This study explores diverse CRT-D responder definitions encompassing functional, echocardiographic and laboratory criteria. Materials & Methods: A single-center study involving 132 CRT-D patients scrutinized responder criteria including NYHA stage, LVEF increase and proBNP decrease. Statistical analyses such as Kaplan-Meier curves and Cox hazard regression were employed to evaluate responder characteristics and survival outcomes. Results: Responder rates varied across criteria, revealing nuanced patient profiles. CRT-D responders defined by NYHA decrease, LVEF increase or proBNP decrease exhibit improved survival rates after 2 and 3 years (p < 0.050). Young age, absence of recent myocardial infarction and normal right ventricular echocardiographic parameters emerge as predictors for positive response. In part, drug-based HF therapy correlates with increased responder rates. Cox regression identified LVEF ≥ 5% and proBNP decrease ≥ 25% as independent predictors of extended survival. Conclusions: CRT-D responder definitions exhibit considerable variability, emphasizing the need for a nuanced patient-centered approach. Factors like right ventricular function, drug therapy, atrial fibrillation and renal function influence responses. This study enriches our understanding of CRT-D response and contributes to the foundation for personalized HF management.

Mode and Characteristics of Arrhythmia Initiation in Idiopathic Ventricular Fibrillation: A THESIS Substudy.

BACKGROUND: There is limited information on the mode of arrhythmia initiation in idiopathic ventricular fibrillation (IVF). A non-pause-dependent mechanism has been suggested to be the rule. OBJECTIVES: The aim of this study was to assess the mode and characteristics of initiation of polymorphic ventricular tachycardia (PVT) in patients with short or long-coupled PVT/IVF included in THESIS (THerapy Efficacy in Short or long-coupled idiopathic ventricular fibrillation: an International Survey), a multicenter study involving 287 IVF patients treated with drugs or radiofrequency ablation. METHODS: We reviewed the initiation of 410 episodes of ≥1 PVT triplet in 180 patients (58.3% females; age 39.6 ± 13.6 years) with IVF. The incidence of pause-dependency arrhythmia initiation (prolongation by >20 ms of the preceding cycle length) was assessed. RESULTS: Most arrhythmias (n = 295; 72%) occurred during baseline supraventricular rhythm without ambient premature ventricular complexes (PVCs), whereas 106 (25.9%) occurred during baseline rhythm including PVCs. Nine (2.2%) arrhythmias occurred during atrial/ventricular pacing and were excluded from further analysis. Mode of PVT initiation was pause-dependent in 45 (15.6%) and 64 (60.4%) of instances in the first and second settings, respectively, for a total of 109 of 401 (27.2%). More than one type of pause-dependent and/or non-pause-dependent initiation (mean: 2.6) occurred in 94.4% of patients with ≥4 events. Coupling intervals of initiating PVCs were <350 ms, 350-500 ms, and >500 ms in 76.6%, 20.72%, and 2.7% of arrhythmia initiations, respectively. CONCLUSIONS: Pause-dependent initiation occurred in more than a quarter of arrhythmic episodes in IVF patients. PVCs having long (between 350 and 500 ms) and very long (>500 ms) coupling intervals were observed at the initiation of nearly a quarter of PVT episodes.

High incidence of echocardiographic abnormalities of the interatrial septum in patients undergoing ablation for atrial fibrillation.

BACKGROUND: Atrial fibrosis or fatty deposition is known to increase the propensity for the development of atrial fibrillation (AF). Apart from the pulmonic veins, the interatrial septum (IAS) might play a role in the maintenance of AF. In contrast to left atrial anatomy and adjacent veins, the IAS cannot be visualized in detail with computed tomography. Thus, preprocedural transesophageal echocardiography (TEE) may provide important morphologic information beyond exclusion from atrial thrombi. METHODS: The study comprised 108 consecutive patients (mean age 60 ± 11 years; 98 men). AF was paroxysmal in 91 (84%) and persistent in 17 (16%) patients. We investigated the morphological characteristics of the IAS by TEE in patients who underwent radiofrequency ablation of AF. RESULTS: The IAS was structurally abnormal in 46 (43%) patients, showing the following echocardiograhic findings: atrial septal hypermobility or aneurysm (n = 27) associated with a patent foramen ovale (PFO) (n = 11) or with a small atrial septal defect (ASD) (n = 2), a septal flap associated with a PFO or an ASD (n = 8), and an abnormally thickened IAS (n = 12). A thrombus in the left atrial appendage was discovered in only 2 (2%) patients. CONCLUSIONS: A structurally abnormal IAS was diagnosed in nearly half of the patients undergoing ablation therapy for AF. The information obtained by TEE is mandatory to exclude left atrial thrombi prior the ablation procedure. Moreover, detailed knowledge of morphologic characteristics of the IAS facilitates an optimized and safe performance of the transseptal puncture using long sheaths with large diameters.

Impact of cavotricuspid isthmus ablation for typical atrial flutter and heart failure in the elderly-results of a retrospective multi-center study.

Introduction: While in the CASTLE-AF trial, in patients with atrial fibrillation and heart failure with reduced ejection fraction, interventional therapy using pulmonary vein isolation was associated with outcome improvement, data on cavotricuspid isthmus ablation (CTIA) in atrial flutter (AFL) in the elderly is rare. Methods: We included 96 patients between 60 and 85 years with typical AFL and heart failure with reduced or mildly reduced ejection fraction (HFrEF/HFmrEF) treated in two medical centers. 48 patients underwent an electrophysiological study with CTIA, whereas 48 patients received rate or rhythm control and guideline-compliant heart failure therapy. Patients were followed up for 2 years, with emphasis on left ventricular ejection fraction (LVEF) over time. Primary endpoints were cardiovascular mortality and hospitalization for cardiac causes. Results: Patients with CTIA showed a significant increase in LVEF after 1 (p < 0.001) and 2 years (p < 0.001) in contrast to baseline LVEF. Improvement of LVEF in the CTIA group was associated with significantly lower 2-year mortality (p = 0.003). In the multivariate regression analysis, CTIA remained the relevant factor associated with LVEF improvement (HR: 2.845 CI:95% 1.044-7.755; p = 0.041). Elderly patients (≥ 70 years) further benefited from CTIA, since they showed a significantly reduced rehospitalization (p = 0.042) and mortality rate after 2 years (p = 0.013). Conclusions: CTIA in patients with typical AFL and HFrEF/HFmrEF was associated with significant improvement of LVEF and reduced mortality rates after 2 years. Patient age should not be a primary exclusion criterion for CTIA, since patients ≥70 years also seem to benefit from intervention in terms of mortality and hospitalization.

Case report: Short-long-short mechanism triggering sustained ventricular tachycardia in a patient with a single-chamber ICD but inhibiting antitachycardia therapy.

Introduction: Short-long-short (SLS) sequences are an important cause of ICD pro-arrhythmia and can initiate both polymorphic and monomorphic ventricular tachycardias (VT). Depending on the programming of a single-chamber ICD, the interplay between SLS sequences and combined VT detection criteria can be responsible for withholding adequate anti-tachycardia pacing (ATP) or shock therapy. Methods: A 78-year-old patient with ICD was admitted to our emergency department after external cardioversion of a long-lasting VT with hemodynamic compromise. The interrogation of the ICD revealed an SLS sequence initiating a monomorphic VT at a rate of 171 bpm (350 ms). The VT discrimination of the implanted single-chamber ICD was based on the onset and stability criteria as the patient had a history of paroxysmal atrial fibrillation. The ICD was programmed that both criteria had to be met for VT detection and initiation of anti-tachycardia therapy. Results: Due to the SLS sequence in combination with the programmed VT detection interval, the onset threshold was not fulfilled and inhibited adequate therapy. Some relatively slow VT beats following the SLS sequence resulted finally in a considerable delay in the declaration of the episode onset. As a first step, the threshold for VT detection was programmed to 150 instead of 160 bpm. To avoid SLS sequences and pause-dependent ventricular tachyarrhythmias, VVI backup stimulation was increased from 35 to 55 ppm. Besides, a device-specific algorithm called rate smoothing was activated as a potential preventive feature. On the 3-month follow-up, all sustained VT episodes were detected adequately by the reprogrammed device, resulting in appropriate anti-tachycardia pacing. After further refinement and less aggressive programming of rate smoothing, the patient remained free of symptoms and arrhythmias over a follow-up of more than 2.5 years, particularly since progression to permanent atrial fibrillation and pacing at a lower rate of 60 ppm. Conclusions: SLS sequences may initiate or trigger VT episodes. Misclassification of the true onset may occur in some ICD devices due to specific programming of VT detection criteria. If both criteria "Onset and Stability" have to be fulfilled, ICD therapy is not delivered despite ongoing VT. Anti-bradycardia backup pacing at a very low stimulation rate may facilitate SLS sequences in patients with ICD resembling a potential pro-arrhythmic mechanism. In case of gradual VT onset with some intervals slower than the programmed VT threshold, the detection rate has to be adjusted down to guarantee appropriate identification of the onset.

Left Atrial Ejection Fraction Assessed by Prior Cardiac CT Predicts Recurrence of Atrial Fibrillation after Pulmonary Vein Isolation.

Assuming that atrial fibrillation (AF) is associated with left atrial remodeling and dysfunction, we hypothesize that left atrial and left atrial appendage ejection fractions (LAEF and LAAEF) are useful and may be more sensitive outcome predictors of pulmonary vein isolation (PVI). Fifty patients who underwent PVI at our institution with available pre-interventional cardiac computed tomography (CT) for procedure planning were included in this retrospective study. The patients were separated into two groups by recurrence and non-recurrence of AF and subgroups of paroxysmal and persistent AF. Semiautomatic volumetric analysis of the left atrium was used to calculate morphological and functional parameters and optimal cut-offs were calculated using the Youden index. LAEF (accuracy 94%, sensitivity 67%) and LAAEF (accuracy 90%, sensitivity 67%) were significantly reduced in patients with AF recurrence (16% vs. 36%, p = 0.00002; 16% vs. 42%, p = 0.000002), and in the subgroup analysis, the functional parameters were independent from AF type (paroxysmal and persistent). With a cut-off of <23% for both LAEF and LAAEF (area under the curve (AUC) 0.94, 95%CI 0.84-0.99 and AUC 0.96, 95%CI 0.86-0.99, respectively), AF recurrence occurred in 77.8%, within a mean follow-up period of 229 days. In conclusion, left atrial function on prior cardiac CT offers useful parameters for predicting AF recurrence after PVI.

Thinking fast and slow: lactate and MELD-XI (model for end-stage liver disease excluding INR) are useful for estimating mortality after cardiopulmonary resuscitation.

BACKGROUND: Intensivists keep getting challenged with prognostication after cardiopulmonary resuscitation (CPR). The model for end-stage liver disease, excluding INR (MELD-XI) Score has proven valuable for assessing illness severity. Serum lactate is a readily available and established indicator of general stress and tissue hypoxia. We aimed to evaluate the prognostic value of MELD-XI combined with serum lactate in patients after CPR. METHODS: A retrospective analysis on 106 patients after CPR was performed. Multivariable Cox regression was performed to evaluate associations with 30-day mortality and neurological outcome by means of cerebral performance category (CPC). An optimal cut-off was calculated by means of the Youden Index. Patients were then divided into subgroups based on the optimal cut-offs for MELD-XI and serum lactate. RESULTS: MELD-XI and lactate were independently associated with mortality. The respective cut-offs were MELD-XI>12 and lactate ≥2.5 mmol/L. Patients were split into three groups: lactate <2.5 mmol/L and MELD-XI≤12 (low-risk; N.=32), lactate ≥2.5 mmol/L or MELD-XI>12 (medium-risk; N.=39), and lactate ≥2.5 mmol/L and MELD-XI >12 (high-risk; N.=33). The mortality rates were 6%, 26% and 61% in the low, medium and high-risk group. This combined model yielded in the highest predictive abilities (AUC=0.78 95%CI: 0.68-0.85; P=0.03 vs. AUC=0.66 for SOFA Score). Worse neurological outcome (CPC 3 or 4) was more common in the medium and high-risk group (6.25%, 10.3% and 9.1%). CONCLUSIONS: The combination of MELD-XI and lactate concentration at ICU admission was superior to the more complex SOFA Score for prediction of mortality after CPR.

Infective endocarditis - A review of current therapy and future challenges.

Etiological, microbiological and epidemiological factors changed over time, but mortality rates remain high in infective endocarditis (IE). Healthcare-associated IE is nowadays responsible for a significant proportion of cases due to increasing numbers of cardiac devices. Cardiac implantable electronic devices, transcatheter aortic valve replacement, and percutaneous valve repair are meanwhile used, especially in old and sick patients. In suspected IE modified Duke criteria, integrating clinical results, imaging, and biomarkers are traditionally applied. Newer imaging technologies such as multi-slice computed tomography, photon-emission computed tomography, and magnetic resonance imaging might add value to conventional echocardiography in diagnosis and management of IE. Treatment consists of long-term antibiotic therapy, infectiological source control and/or cardiac surgery. Recently, antibiotic parenteral outpatient regimens and partial oral treatment strategies were shown to shorten hospital stays in patients suffering from IE. However, it remains unclear how to best select patients for partial oral therapy. This review describes new trends in diagnosing, imaging, and treating IE in a changing patient collective with particular focus on patients with implantable cardiac devices.

Higher Incidence of Stroke in Severe COVID-19 Is Not Associated With a Higher Burden of Arrhythmias: Comparison With Other Types of Severe Pneumonia.

Aims: Thromboembolic events, including stroke, are typical complications of COVID-19. Whether arrhythmias, frequently described in severe COVID-19, are disease-specific and thus promote strokes is unclear. We investigated the occurrence of arrhythmias and stroke during rhythm monitoring in critically ill patients with COVID-19, compared with severe pneumonia of other origins. Methods and Results: This retrospective study included 120 critically ill patients requiring mechanical ventilation in three European tertiary hospitals, including n =60 COVID-19, matched according to risk factors for the occurrence of arrhythmias in n = 60 patients from a retrospective consecutive cohort of severe pneumonia of other origins. Arrhythmias, mainly atrial fibrillation (AF), were frequent in COVID-19. However, when compared with non-COVID-19, no difference was observed with respect to ventricular tachycardias (VT) and relevant bradyarrhythmias (VT 10.0 vs. 8.4 %, p = ns and asystole 5.0 vs. 3.3%, p = ns) with consequent similar rates of cardiopulmonary resuscitation (6.7 vs. 10.0%, p = ns). AF was even more common in non-COVID-19 (AF 18.3 vs. 43.3%, p = 0.003; newly onset AF 10.0 vs. 30.0%, p = 0.006), which resulted in a higher need for electrical cardioversion (6.7 vs. 20.0%, p = 0.029). Despite these findings and comparable rates of therapeutic anticoagulation (TAC), the incidence of stroke was higher in COVID-19 (6.7.% vs. 0.0, p = 0.042). These events also happened in the absence of AF (50%) and with TAC (50%). Conclusions: Arrhythmias were common in severe COVID-19, consisting mainly of AF, yet less frequent than in matched pneumonia of other origins. A contrasting higher incidence of stroke independent of arrhythmias also observed with TAC, seems to be an arrhythmia-unrelated disease-specific feature of COVID-19.

Polymorphisms associated with ventricular tachyarrhythmias: rationale, design, and endpoints of the 'diagnostic data influence on disease management and relation of genomics to ventricular tachyarrhythmias in implantable cardioverter/defibrillator patients (DISCOVERY)' study.

Implantable cardioverter-defibrillator (ICD) therapy is effective in primary and secondary prevention for patients who are at high risk of sudden cardiac death. However, the current risk stratification of patients who may benefit from this therapy is unsatisfactory. Single nucleotide polymorphisms (SNPs) are DNA sequence variations occurring when a single nucleotide in the genome differs among members of a species. A novel concept has emerged being that these common genetic variations might modify the susceptibility of a certain population to specific diseases. Thus, genetic factors may also modulate the risk for arrhythmias and sudden cardiac death, and identification of common variants could help to better identify patients at risk. The DISCOVERY study is an interventional, longitudinal, prospective, multi-centre diagnostic study that will enrol 1287 patients in approximately 80 European centres. In the genetic part of the DISCOVERY study, candidate gene polymorphisms involved in coding of the G-protein subunits will be correlated with the occurrence of ventricular arrhythmias in patients receiving an ICD for primary prevention. Furthermore, in order to search for additional sequence variants contributing to ventricular arrhythmias, a genome-wide association study will be conducted if sufficient a priori evidence can be gathered. In the second part of the study, associations of SNPs with ventricular arrhythmias will be sought and a search for potential new biological arrhythmic pathways will be investigated. As it is a diagnostic study, DISCOVERY will also investigate the impact of long-term device diagnostic data on the management of patients suffering from chronic cardiac disease as well as medical decisions made regarding their treatment.

Exercise-related T-wave oversensing: an underestimated cause of reduced exercise capacity in a pacemaker-dependent patient-a case report and review of the literature.

A 62-year-old pacemaker-dependent patient presented to our department with a sudden onset of reduced physical capacity. While initial physical and pacemaker evaluations remained without specific findings, Holter-ECG monitoring revealed an abnormal rate response with unusual pauses during physical exercise. Consequently, closer evaluation of the pacemaker system revealed intermittent, exercise-related T-wave oversensing (TWOS). While TWOS remains a significant burden in ICD-patients, it might be an underestimated but clinically significant event in pacemaker patients. Further studies should evaluate the impact of TWOS in this patient population.

Safe application of extensive radiotherapy to a cardiac resynchronization device.

Patients with cardiac implantable electronic devices undergoing radiotherapy (RT) are prone to the risk of device failure. Guidelines and manufacturer's instructions are lacking practical recommendations for cumulative radiation doses to pacemakers or implantable cardioverter defibrillators. The present case demonstrates the effect of RT of a Merkel cell carcinoma near the location of a cardiac resynchronization therapy pacemaker. Despite guideline recommendations, surgical relocation or de novo implantation of the device on the contralateral side was avoided to prevent the dissemination of tumour cells, inflammation, and wound healing complications. A total dose of 47.25 Gy applied in very close proximity to the cardiac resynchronization therapy pacemaker was carried out safely without jeopardizing the patient and any device malfunction during and after treatment within >1.5 years of follow-up period. The present case demonstrates that high-dose RT near to a cardiac resynchronization therapy device can be carried out safely. Special precautions during RT as well as close device follow-up interrogations are mandatory. Large-scale studies are needed for the true frequency of adverse events.

Classic and Novel Biomarkers as Potential Predictors of Ventricular Arrhythmias and Sudden Cardiac Death.

Sudden cardiac death (SCD), most often induced by ventricular arrhythmias, is one of the main reasons for cardiovascular-related mortality. While coronary artery disease remains the leading cause of SCD, other pathologies like cardiomyopathies and, especially in the younger population, genetic disorders, are linked to arrhythmia-related mortality. Despite many efforts to enhance the efficiency of risk-stratification strategies, effective tools for risk assessment are still missing. Biomarkers have a major impact on clinical practice in various cardiac pathologies. While classic biomarkers like brain natriuretic peptide (BNP) and troponins are integrated into daily clinical practice, inflammatory biomarkers may also be helpful for risk assessment. Indeed, several trials investigated their application for the prediction of arrhythmic events indicating promising results. Furthermore, in recent years, active research efforts have brought forward an increasingly large number of "novel and alternative" candidate markers of various pathophysiological origins. Investigations of these promising biological compounds have revealed encouraging results when evaluating the prediction of arrhythmic events. To elucidate this issue, we review current literature dealing with this topic. We highlight the potential of "classic" but also "novel" biomarkers as promising tools for arrhythmia prediction, which in the future might be integrated into clinical practice.

Incidence and predictability of amiodarone-induced thyrotoxicosis and hypothyroidism.

OBJECTIVES: To determine the incidence and predictability of amiodarone-induced thyrotoxicosis (AIT) and hypothyroidism (AIH) in patients with cardiomyopathy. PATIENTS AND METHODS: A total of 72 patients (mean age 69 +/- 11 years) living in an area previously endemic for thyroid disease but with currently sufficient iodine intake were enrolled in this prospective study. All participants were treated with amiodarone for the first time. The course of thyroid function in patients with normal thyroid morphology and in those with goiter was monitored over a median follow-up period of eight months in 71 (98.6%) patients. RESULTS: Of 72 participants, 18 (25.0%) had a morphologically normal thyroid gland as evidenced by sonography. The prevalence of thyroid dysfunction before initiation of amiodarone was 37.6% (27 of 72) with almost equal distribution between hypothyroidism and hyperthyroidism (14 and 13 patients). After treatment with amiodarone, thyroid dysfunction was diagnosed in 56.8% (25 of 44) of the patients without preexisting dysfunction. Of these 25 patients, nine (36%) developed either subclinical or overt AIH and 16 (64.0%) developed either subclinical or overt AIT. Although 61.1% (44 of 72) had normal thyroid function before initiation of amiodarone, this number decreased to 26.7% (19 of 71, P < 0.001) after treatment. Factors such as (99m)Tc-pertechnetate scan uptake, thyroid autoimmunity, age, thyroid autonomy or abnormal thyroid morphology were not significantly associated with the development of thyroid dysfunction. CONCLUSIONS: Prevalence of thyroid dysfunction was high in elderly patients treated with amiodarone. Cases of AIT and AIH occurred in patients with and without preexisting thyroid disorders. Because of the high incidence of amiodarone-induced thyroid dysfunction, regular testing of thyroid function is mandatory during and following amiodarone treatment.

High incidence of tachyarrhythmias detected by an implantable loop recorder in patients with unexplained syncope.

BACKGROUND: Syncope is a complex clinical syndrome that may be challenging with respect to a definite diagnosis. The implantable loop recorder (ILR) is a useful tool to define but also to exclude an arrhythmic aetiology. AIM: To investigate the causes of recurrent syncope or near-syncope with respect to underlying arrhythmias in non-selected consecutive patients monitored with an ILR. METHODS: A retrospective study was conducted including 55 patients (34 men, 21 women; age 60+/-19 years) with unexplained syncope who received an ILR for prolonged monitoring at our institution between April 1998 and October 2006. RESULTS: Forty (73%) patients had a recurrence of syncope or near-syncope. Structural heart disease was present in 18 (33%) patients, 4 of them having an ejection fraction <35%. An arrhythmia was detected as the cause of syncope in 25 (46%) patients. The ILR was successful in establishing a symptom-rhythm correlation in 63%. The mean follow-up period from implantation to occurrence of the detected arrhythmias was 9+/-8 months. Bradyarrhythmias were recorded in 12 (22%) patients, whereas tachyarrhythmias were found in 13 (24%) patients. Narrow QRS tachycardia was the underlying arrhythmia in 6 patients and wide QRS tachycardia in 7 patients. A pacemaker was implanted in all 12 patients with bradyarrhythmias. Implantable cardioverter defibrillator (ICD) therapy was indicated in 6 patients with adjunctive catheter ablation in 3 of them. Four patients presenting with paroxysmal supraventricular tachycardia were treated with radiofrequency catheter ablation. CONCLUSION: The ILR helped efficaciously to determine the correct diagnosis and appropriate treatment of recurrent syncope. A considerably high proportion of tachyarrhythmias was detected in this non-selected consecutive population. The majority of patients with tachyarrhythmic syncope required defibrillator implantation and/or radiofrequency ablation.

Spontaneous automaticity arising from a successfully ablated Mahaim fiber.

The authors describe a 22-year-old woman with regular and irregular arrhythmias exhibiting left bundle branch block (LBBB) morphology at various heart rates. An atriofascicular fiber was diagnosed as the underlying mechanism for the antidromic reciprocating tachycardia. In addition, spontaneous automaticity of the Mahaim fiber was present during electrophysiologic study. The accessory pathway was ablated successfully, targeting a Mahaim potential at the supero-anterior tricuspid valve annulus. Relatively slow automatic rhythms with identical LBBB morphology were recorded immediately after ablation, as well as during long-term follow-up in a more sporadic and subclinical form. Abnormal automaticity arising from the distal portions of the remnant pathway was considered to be the origin of the slow ventricular rhythms in this peculiar case.

Gender-specific effect of metabolic syndrome on rate adjusted QT interval in middle-aged participants of an atherosclerosis prevention program.

INTRODUCTION: The metabolic syndrome is a matter of immense public concern for atherosclerosis prevention. Key features are visceral obesity, dyslipidemia, hyperglycemia in the non-diabetic range, and arterial hypertension. Subclinical atherosclerosis is the clinical consequence of metabolic syndrome, which may influence the QT interval. The aim was to investigate the rate corrected QT interval in subjects with metabolic syndrome in comparison to those without cardiometabolic risk factor clusters, and to explore gender differences in cardiac repolarization between the two groups. PATIENTS, MATERIALS AND METHODS: Heart rate and QT interval were automatically measured from surface ECG in 1086 participants (767 men, 319 women) from the Salzburg-Atherosclerosis-Prevention-program-in-subjects-at-High-Individual-Risk (SAPHIR). To omit the QT adjustment bias inherent in Bazett's formula we used a QT adjustment method with linear scaling as described by Rautaharju. RESULTS: The prevalence of metabolic syndrome was 13.8% among males and 10% among females. Mean rate adjusted QT (QTa) intervals were longer in women than in men. Presence of metabolic syndrome, however, was associated with significantly prolonged QTa only in men but not in women. Adjustment for relevant confounders reduced the difference of mean QTa in men from 9.24 to 5.83 ms (95% CI 0.9-10.8), but this difference was still statistically significant (p = 0.021). The effect of metabolic syndrome on QTa was only partly mediated by hypertension and insulin resistance. In females, however, no relevant differences were detected for QTa interval between subjects categorized by presence or absence of metabolic syndrome. CONCLUSIONS: The findings indicate a significant association between metabolic syndrome and rate-invariant QT in middle-aged men after adjustment for other risk factors. QT measurement may provide additive diagnostic and prognostic information in populations undergoing cardiovascular risk screening. However, the effect of metabolic and hormonal factors on ventricular repolarization seems to differ between the sexes.