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Aims Amiodarone and digitalis are frequently used drugs in patients with heart failure. Both have separately been linked to reduced post‐transplant survival, but their combined impact on mortality after HTX remains uncertain. This study investigated the effects of combined amiodarone and digitalis use before HTX on post‐transplant outcomes. Methods and results This registry study analysed 600 patients receiving HTX at Heidelberg Heart Center between 1989 and 2016. Patients were stratified by amiodarone and digitalis use before HTX. Analysis included patient characteristics, medication, echocardiographic features, heart rates, permanent pacemaker implantation, atrial fibrillation, and post‐transplant survival including causes of death. One hundred eighteen patients received amiodarone before HTX (19.7%), hereof 67 patients with digitalis (56.8%) and 51 patients without digitalis before HTX (43.2%). Patients with and without amiodarone before HTX showed a similar 1 year post‐transplant survival (72.0% vs. 78.4%, P = 0.11), but patients with combined amiodarone and digitalis before HTX had a worse 1 year post‐transplant survival (64.2%, P = 0.01), along with a higher percentage of death due to transplant failure (P = 0.03). Echocardiographic analysis of these patients showed a higher percentage of an enlarged right ventricle (P = 0.02), left atrium (P = 0.02), left ventricle (P = 0.03), and a higher rate of reduced left ventricular ejection fraction (P = 0.03). Multivariate analysis indicated combined amiodarone and digitalis use before HTX as a significant risk factor for 1 year mortality after HTX (hazard ratio: 1.69; 95% confidence interval: 1.02–2.77; P = 0.04). Conclusions Combined pre‐transplant amiodarone and digitalis therapy is associated with increased post‐transplant mortality.

Die Lebensqualitat von Patienten mit implantierbarem Kardioverter-Defibrillator (ICD) wird von therapiebedingten Faktoren beeinflusst. Die Studienlage ist jedoch heterogen und validierte krankheitsspezifische Messgrosen der krankheits- oder indikationsspezifischen Lebensqualitat (DRQoL) von ICD-Patienten fehlen. Das Ziel der Studie war es, ein erweitertes Verstandnis der langfristigen DRQoL von ICD-Patienten zu erlangen. Ein besonderer Fokus lag auf Stressoren und kognitiven Bewaltigungsstrategien im Alltag. Die Datenerhebung erfolgte mittels semi-strukturierter leitfadengestutzter Interviews. In dieser monozentrischen qualitativen Studie wurden zehn ICD-Patienten mit primar- und sekundarprophylaktischer Indikation eingeschlossen. Drei Facharzte waren beteiligt. Die Daten wurden unter Berucksichtigung von salutogenetischen Ansatzen (Antonovsky) qualitativ ausgewertet. Der ICD schrankt die Patienten im Alltag mehrheitlich nicht ein. Die Patienten entwickeln Bewaltigungsstrategien, um die ICD-Indikation zu verstehen und ihr eine Sinnhaftigkeit zuzuschreiben. Die salutogenetische Betrachtung verdeutlicht, dass der ICD die DRQoL individuell positiv oder negativ durch Koharenz- und Widerstandsfaktoren beeinflusst. Es wurde eine salutogenetische Konzeptualisierung zur Analyse der DRQoL von ICD-Patienten entwickelt. Anhand dieser konnen Patienten mit hohem Risiko, geringer Koharenz und Widerstandsfahigkeit identifiziert werden. Unter Berucksichtigung der individuellen Lebenswelten ist es moglich, eine positive Bewaltigung der ICD-Indikation im Versorgungsprozess zu erzielen.

Background Postcardiac injury syndrome (PCIS) is an inflammatory complication that derives from injury to the epicardium, myocardium, or endocardium. It occurs after trauma, myocardial infarction, percutaneous coronary intervention, cardiac surgery, intracardiac ablation, and implantation of cardiac implantable electronic device (CIED). In this study we assessed the incidence of PCIS after CIED implantation and its possible risk factors. Material and methods All patients who received CIED implantation at Heidelberg University Hospital between 2000 and 2014 were evaluated (n = 4989 patients). Clinical data including age, sex, underlying cardiac disease, type of implanted CIED, location of electrode implantation, clinical symptoms, time of symptom onset of PCIS, therapy, and outcome were extracted and analyzed. Results We identified 19 cases of PCIS in 4989 patients, yielding an incidence of 0.38%. The age of patients with PCIS ranged from 39 to 86 years. Dilated cardiomyopathy (DCM) as underlying cardiac disease and right atrial (RA) lead implantation had a significant association with occurrence of PCIS (p = 0.045 in DCM and p Conclusion To the best of our knowledge, this is the largest cohort evaluating the incidence of PCIS after CIED implantation. The data show that PCIS is a rare complication after CIED implantation and occurs more frequently in patients with DCM and those with RA lead implantation. Although rare and mostly benign, PCIS can lead to potentially lethal complications and physicians must be aware of its symptoms.

Aims Remote patient monitoring (RPM) systems offer a promising alternative to conventional In-Clinic check-ups, hereby reducing unnecessary clinic visits. Especially with the rise of the COVID-19 pandemic, this reduction is of paramount importance. Regarding the association between RPM and clinical outcomes, findings of previous studies have been inconsistent. The aim of this study is to elucidate the effect of partly substituting In-Clinic visits by RPM on clinical outcomes in implantable cardioverter-defibrillator (ICD) patients. Methods and results The study included 595 heart failure patients (LVEF ≤35%; NYHA Class II/III) implanted with an ICD compatible with the Boston Scientific LATITUDE™ system. Participants were randomized to RPM plus an annual In-Clinic visit or 3–6 months In-Clinic check-ups alone. The investigated endpoints after 2 years of follow-up included a composite of all-cause mortality and cardiac hospitalization, mortality and cardiac hospitalization as independent endpoints and ICD therapy. The incidence of mortality and hospitalization did not differ significantly as independent, nor as composite endpoint between the RPM and In-Clinic group (all Ps, Graphical Abstract Graphical Abstract

The inSighT study was designed to determine the prevalence of ischemic changes as recorded by implantable cardioverter-defibrillator (ICD) ST deviations in intracardiac electrocardiograms (EGM) over the 24 h preceding malignant ventricular arrhythmias (VT/VF).The study enrolled patients with known coronary artery disease (CAD) or high risk of future development of CAD implanted with an ICD equipped with an ST monitoring feature (Ellipse™/Fortify Assura™, St. Jude Medical). Device session records were collected at each in-clinic follow-up. EGM ST levels of the beats over the 15 minutes prior to VT/VF events were compared using a t test with those from a baseline period of 23-24 h prior to the VT/VF event. All events with p .05 were visually inspected to confirm they were evaluable; additional criteria for exclusion from further analysis included inappropriate therapy, aberrant conduction, and occurrence of VT/VF within 24h prior to the current event.The study enrolled 481 ICD patients (64 ± 11 years, 83% male) in 14 countries and followed them for 15±5 months. A total of 165 confirmed VT/VF episodes were observed, of which 71 events (in 56 patients, 34% of all patients with VT/VF) were preceded by significant (p .05) ST-segment changes unrelated to known non-ischemic causes. None of the analyzed demographic and clinical factors proved to be associated with greater odds of presenting with ST-segment changes prior to VT/VF episode.In this exploratory study, characteristic ST-segment changes, likely representative of ischemic events, were observed in 34% of all patients with VT/VF episodes.

AimsThe European REMOTE-CIED study is the first randomized trial primarily designed to evaluate the effect of remote patient monitoring (RPM) on patient-reported outcomes in the first 2 years after implantation of an implantable cardioverter-defibrillator (ICD).Methods and resultsThe sample consisted of 595 European heart failure patients implanted with an ICD compatible with the Boston Scientific LATITUDE® RPM system. Patients were randomized to RPM plus a yearly in-clinic ICD check-up vs. 3–6-month in-clinic check-ups alone. At five points during the 2-year follow-up, patients completed questionnaires including the Kansas City Cardiomyopathy Questionnaire and Florida Patient Acceptance Survey (FPAS) to assess their heart failure-specific health status and ICD acceptance, respectively. Information on clinical status was obtained from patients’ medical records. Linear regression models were used to compare scores between groups over time. Intention-to-treat and per-protocol analyses showed no significant group differences in patients’ health status and ICD acceptance (subscale) scores (all Ps > 0.05). Exploratory subgroup analyses indicated a temporary improvement in device acceptance (FPAS total score) at 6-month follow-up for secondary prophylactic in-clinic patients only (P ConclusionLarge clinical trials have indicated that RPM can safely and effectively replace most in-clinic check-ups of ICD patients. The REMOTE-CIED trial results show that patient-reported health status and ICD acceptance do not differ between patients on RPM and patients receiving in-clinic check-ups alone in the first 2 years after ICD implantation.ClinicalTrials.gov Identifier: NCT01691586.

BackgroundPatient satisfaction with remote patient monitoring (RPM) of implantable cardioverter defibrillators (ICDs) seems to be high, yet knowledge on long‐term patient experiences is limited. The European REMOTE‐CIED study explored patients' experiences with RPM, examined patient's preferences for ICD follow‐up, and identified determinants of patient's preferences in the first 2 years postimplantation.MethodsEuropean heart failure patients (N = 300; median age = 66 years [interquartile range (IQR) = 59‐73], and 22% female) with a first‐time ICD received a Boston Scientific LATITUDE RPM system (Marlborough, MA, USA) and had scheduled in‐clinic follow‐ups once a year. Patients completed questionnaires at 1‐2 weeks and also at 3, 6, 12, and 24 months postimplantation and clinical data were obtained from their medical records. Patient evaluation data were analyzed descriptively, and Student's t‐tests/Man‐Whitney U tests or Chi‐square tests/Fisher's exact tests were performed to examine determinants of patient preferences.ResultsAt 2 years postimplantation, the median patient satisfaction score with the RPM system was 9 out of 10 (IQR = 8‐10), despite 53% of the patients experiencing issues (eg, failure to transmit data). Of the 221 patients who reported their follow‐up preferences, 43% preferred RPM and 19% preferred in‐clinic follow‐up. Patients with a preference for RPM were more likely to be higher educated (P = 0.04), employed (P = 0.04), and equipped with a new LATITUDE model (P = 0.04), but less likely to suffer from chronic obstructive pulmonary disease (P = 0.009).ConclusionIn general, patients were highly satisfied with RPM, but a subgroup preferred in‐clinic follow‐up. Therefore, physicians should include patients’ concerns and preferences in the decision‐making process, to tailor device follow‐up to individual patients’ needs and preferences.

The wearable cardioverter-defibrillator (WCD) was introduced to provide protection from sudden cardiac death (SCD) in patients with transiently elevated risk or during ongoing risk stratification. Benefits and clinical characteristics of routine WCD use remain to be assessed in larger patient populations. This study aims to identify determinants of WCD compliance, therapies, and inappropriate alarms in a real-life cohort. A total of 106 cases (68.9% male) were included between 11/2010 and 04/2016. WCD therapies, automatically recorded arrhythmia episodes, inappropriate WCD alarms, patient compliance, and outcome after WCD prescription were analyzed. Median duration of WCD use was 58.5 days. Average daily wearing time was 22.7 h. Compliance was reduced in patients ≤ 50 years. Three patients received WCD therapies (2.8%). In one case ventricular fibrillation (VF) was appropriately terminated with the first shock. Two patients received inappropriate WCD therapies due to WCD algorithm activation during ventricular pacemaker stimulation. One patient died of asystole while carrying a WCD (0.9%). Additional arrhythmias detected comprised self-terminating sustained ventricular tachycardia (VT; 2.8%), non-sustained VT (2.8%), and supraventricular arrhythmias (5.7%). Inappropriate WCD alarms due to over-/undersensing occurred in 77/106 patients (72.6%), of which 41 (38.7%) experienced ≥ 10 inappropriate WCD alarms during the prescription period. Thirteen patients (12.3%) displayed a mean of > 1 inappropriate alarms/day. WCD use was associated with high compliance and provided protection from VT/VF-related SCD. The majority of patients experienced inappropriate WCD alarms. Alterations in QRS morphology during pacemaker stimulation require consideration in WCD programming to prevent inappropriate alarms.

Background Studies have shown that remote patient monitoring (RPM) of implantable cardioverter defibrillators (ICDs) is at least comparable to in-clinic follow-up with regard to clinical outcomes and might be cost-effective, yet RPM is not standard clinical practice within Europe. Better insight into the patient perspective on RPM may aid in its acceptance, implementation, and reimbursement. This narrative review (1) summarizes existing evidence on the impact of RPM on patient-reported outcomes and (2) discusses future directions in examining the patient perspective. Methods and results Literature review indicated that only five randomized trials on RPM in ICD patients included patient-reported outcomes, with inconclusive results. Observational studies show a trend toward good patient satisfaction and acceptation of RPM. Yet, results should be interpreted with caution due to a number of limitations including a potential selection bias, use of generic/nonvalidated questionnaires, relatively short follow-up durations, and a lack of subgroup identification. Conclusion Although RPM seems to be safe, effective, timely, and efficient, the patient perspective has received little attention so far. The scarce evidence on patient-reported outcomes in RPM studies seems to be positive, but future trials with a follow-up of ≥12 months and validated patient-reported outcome measures are needed. The REMOTE-CIED study from our group is the first prospective randomized controlled trial primarily designed to examine the patient perspective on RPM, and is powered to identify characteristics associated with RPM satisfaction and benefit. Results are expected in 2018 and will add valuable information to the current evidence.

Background Post cardiac injury syndrome (PCIS) is an inflammatory process, which occurs in the setting of injury to the pericardium, epicardium or myocardium. It may follow cardiac surgery, myocardial infarction, trauma, intracardiac ablation, percutaneous coronary intervention, and implantation of heart rhythm devices (HRD). In this study we aimed to assess the incidence of PCIS after HRD implantation and its possible risk factors. Material and methods All patients who received HRD implantation at our University Hospital between the years 2000 to 2014 were evaluated (n=4,989 patients) for developing PCIS. Clinical data including age, sex, underlying cardiac disease, type of implanted HRD, location of electrode implantation, clinical symptoms, time of symptom onset of PCIS, therapy, and outcome were extracted and analysed. Results 19 cases of PCIS were identified in altogether 4,989 patients resulting in an incidence of 0.38%. The age in patients with PCIS ranged from 39 to 86 years. Dilated cardiomyopathy (DCM) as underlying cardiac disease and right atrial (RA) lead implantation showed significant association to occurrence of PCIS (p=0.045 in DCM and p Conclusion To the best of our knowledge, this is the thus far largest cohort evaluating the incidence of PCIS after HRD implantation. PCIS remains a rare, but potentially lethal complication of heart rhythm device implantation. It should be considered particularly in patients with right atrial lead active fixation and DCM as underlying cardiac disease.

Left bundle branch block (LBBB) has a predictive value for response to cardiac resynchronization therapy as reported by Zareba et al. (Circulation 123(10):1061–1072, 2011). However, based on ECG criteria, the discrimination between complete LBBB and nonspecific intraventricular conduction delay is challenging. We tested the hypothesis that discrimination can be performed using standard electrophysiological catheters and a simple stimulation protocol. Fifty-nine patients were analyzed retrospectively. Patients were divided into groups of narrow QRS (n = 20), wide QRS of right bundle branch block (RBBB) morphology (n = 14), and wide QRS of LBBB morphology (n = 25). Using a diagnostic catheter placed in the coronary sinus, left ventricular activation was assessed during intrinsic conduction as well as during right ventricular (RV) stimulation. In patients with narrow QRS and RBBB, the Q-LV/QRS ratio was 0.43 ± 0.013 (n = 20) and 0.41 ± 0.026 (n = 14), respectively. In patients with LBBB morphology, the Q-LV/QRS split up into a group of patients with normal (0.43 ± 0.022, n = 7) and a group with delayed left ventricular activation (0.75 ± 0.016, n = 18). By direct comparison of the Q-LV/QRS ratio during intrinsic conduction with the Q-LV/QRS ratio during RV pacing leading to a functional LBBB, a clear distinction between a group of “true LBBB” and another group of “apparent LBBB”/nonspecific intraventricular conduction delay (NICD) could be generated. We present a novel and practical method that might facilitate discrimination between patients with apparent LBBB and true LBBB by comparing Q-LV/QRS ratios during intrinsic activation and during RV stimulation. Although this method can already be directly applied, validation by 3D electrical mapping and prospective correlation to cardiac resynchronization therapy (CRT) response will be required for further translation into clinical practice.

BackgroundEvidence on psychological distress in patients living with an implantable cardioverter defibrillator (ICD) is inconclusive. The current study is the first to examine the prevalence and risk markers of anxiety and/or depression in a large international cohort of European ICD patients with or without cardiac resynchronization therapy (CRT).MethodHeart failure patients (N = 569) from France, Germany, Spain, Switzerland and the Netherlands participating in the REMOTE-CIED study completed a set of questionnaires 1–2 weeks post ICD-implantation, including the 7-item Generalized Anxiety Disorder scale and the 9-item Patient Health Questionnaire to assess anxiety and depressive symptoms, respectively. Patients' clinical data were obtained from their medical records.ResultsThe prevalence of anxiety was 16% and that of depression 19%, with 25% of patients reporting one or both types of distress. Multivariable logistic regression analysis showed that age < 60 years (odds ratio (OR) = 2.5[95% confidence interval = 1.2–5.0]), having a threatening view of heart failure (OR = 4.7[2.7–8.2]), a high level of ICD-related concerns (OR = 2.9[1.7–5.1]), Type D personality (OR = 2.4[1.3–4.4]), poor patient-reported health status (OR = 2.2[1.3–3.9]) and receiving psychotropic medication (OR = 3.0[1.5–5.9]) were positively associated with distress, while attending cardiac rehabilitation (OR = 0.3[0.2–0.7]) was negatively associated with distress.ConclusionsA significant subset of European ICD and CRT-defibrillator patients reports anxiety and/or depression in the first weeks post implantation. Patients' psychological characteristics, especially negative perceptions about their illness and treatment, were the strongest associates of distress. Timely identification of these patients is essential as they may benefit from psychological interventions and cardiac rehabilitation in terms of improved quality of life and prognosis.

Post cardiac injury syndrome (PCIS) is an inflammatory process that occurs in the setting of injury to the pericardium, epicardium or myocardium. It may follow cardiac surgery, myocardial infarction, trauma, intracardiac ablation, percutaneous coronary intervention or implantation of a pacemaker or cardioverter–defibrillator. In this paper, we report the first case of PCIS after implantation of a “Cardiac Resynchronization Therapy Defibrillator” (CRT-D) device and review systematically the available literature. To obtain information on PCIS after implantation of heart rhythm devices (HRD), we performed a systematic review of Medline, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). The collected data included age, gender, initial diagnosis, procedure type, time to PCIS, symptoms, clinical manifestations, therapy and outcome. Included were reports in English, French and Spanish. In our systematic review, we found PCIS after HRD implantation in 17 additional cases. The age ranged from 23 to 84 years. Symptoms developed within 1 day–4 months after implantation. The use of active-fixation atrial leads was reported in nine cases. Fever, dyspnoea, chest pain, tachypnoea, tachycardia, palpitation, malaise, ankle edema, dry cough, night sweats, nausea and vomiting were reported as associated symptoms. PCIS should be considered as a rare, but serious complication of HRD implantation, may cause recurrent hospitalization and can be life threatening. The incidence and possible causes of PCIS after HRD, such as active fixation leads and specific lead positions as well as its treatment deserve further investigation in prospective studies.

Objectives This study sought to test the hypothesis that inducing an autoimmune response against the cardiac sodium channel (NaV1.5) induces arrhythmias. Background Sporadic evidence supports the concept that autoantibodies may cause cardiac arrhythmias but substantial experimental investigations using in vivo models have been lacking to date. The NaV1.5 is essential for cardiac impulse propagation and its dysfunction has been linked to conduction disease. Methods Rats were immunized with a peptide sequence derived from the third extracellular loop of the first domain of NaV1.5. After 28 days, we evaluated in vivo both the electrical and mechanical parameters of cardiac function. Histopathology, myocardial gene and protein expression were assessed. Whole-cell patch-clamp was used to measure sodium current (INa) density in isolated cardiomyocytes. Results NaV1.5-immunized rats had high titers of autoantibodies against NaV1.5. On ECG recording, NaV1.5-immunized animals showed significantly prolonged PR-intervals. During Holter ECG-monitoring we observed repeated prolonged episodes of third-degree atrioventricular and sinoatrial block in every NaV1.5-immunized animal, but not in controls. Immunization had no effect on cardiac function. In comparison to controls, myocardial NaV1.5 mRNA and protein levels were decreased in immunized rats. INa density was reduced in cardiomyocytes incubated with sera from NaV1.5-immunized rats and from patients with idiopathic atrioventricular block (AVB) in comparison to sera from respective controls. In patients with idiopathic AVB, we observed autoantibodies against NaV1.5 that were absent in sera from healthy controls. Conclusions Provocation of an autoimmune response against NaV1.5 induces conductance defects probably caused by a reduced expression level and an inhibition of NaV1.5 by autoantibodies, resulting in decreased INa.

SUMMARY Flavonoids are a class of naturally occurring polyphenols abundant in edibles and beverages of plant origin. Epidemiological studies consistently associate high flavonoid intake with a reduced risk for the development of cardiovascular diseases. So far these beneficial effects have been mainly attributed to nonspecific antioxidant and antiinflammatory properties. However, there is an increasing body of evidence that flavonoids specifically target molecular structures including cardiovascular ion channels. Playing a pivotal role in the regulation of vascular tone and cardiac electric activity, ion channels represent a major target for the induction of antihypertensive and cardioprotective effects. Thus, pharmacological properties of flavonoids on cardiovascular ion channels, ion currents and tissue preparations are being increasingly addressed in experimental studies. Whereas it has become clear that cardiovascular ion channels represent an important molecular target of flavonoids, the published data have not yet been systematically reviewed.

Background— Genetic predisposition is believed to be responsible for most clinically significant arrhythmias; however, suitable genetic animal models to study disease mechanisms and evaluate new treatment strategies are largely lacking. Methods and Results— In search of suitable arrhythmia models, we isolated the zebrafish mutation reggae ( reg ), which displays clinical features of the malignant human short-QT syndrome such as accelerated cardiac repolarization accompanied by cardiac fibrillation. By positional cloning, we identified the reg mutation that resides within the voltage sensor of the zebrafish ether-à-go-go –related gene (zERG) potassium channel. The mutation causes premature zERG channel activation and defective inactivation, which results in shortened action potential duration and accelerated cardiac repolarization. Genetic and pharmacological inhibition of zERG rescues recessive reg mutant embryos, which confirms the gain-of-function effect of the reg mutation on zERG channel function in vivo. Accordingly, QT intervals in ECGs from heterozygous and homozygous reg mutant adult zebrafish are considerably shorter than in wild-type zebrafish. Conclusions— With its molecular and pathophysiological concordance to the human arrhythmia syndrome, zebrafish reg represents the first animal model for human short-QT syndrome.

Background and aims Hesperetin belongs to the flavonoid subgroup classified as citrus flavonoids and is the main flavonoid in oranges. A high dietary intake of flavonoids has been associated with a significant reduction in cardiovascular mortality. HERG potassium channels play a major role in cardiac repolarisation and represent the most important pharmacologic target of both antiarrhythmic and proarrhythmic drugs. Methods and results We used the two-microelectrode voltage-clamp technique to analyse inhibitory effects of hesperetin on hERG potassium channels heterologously expressed in Xenopus oocytes. Hesperetin blocked hERG potassium channels in a concentration dependent manner. Onset of block was fast and completely reversible upon wash-out. There was no significant effect of hesperetin on channel kinetics. Affinity of hesperetin to mutant F656A hERG channel was significantly decreased compared to WT hERG, indicating a binding site in the channel pore cavity. In contrast, affinity of hesperetin to Y652A hERG was not different from the affinity to WT hERG. Conclusion We found an antagonist of cardiac hERG channels that modulates hERG currents by accessing the aromatic pore binding site, particularly amino acid phe-656. Regarding high hesperetin concentrations found in oranges and the increasing consumption of oranges and orange juice in Europe, potential effects of hesperetin on cardiac electrophysiology in vivo deserve further investigation.

To compare outcome between patients with and without super-response to cardiac resynchronization therapy-defibrillator (CRT-D). In this cohort study, 167 consecutive CRT-D candidates were included. Super-response to CRT-D was defined clinically [improvement of ≥1 New York Heart Association (NYHA) class or ≥50 m in six-minute walk distance (6MWD)] and echocardiographically [increase of left ventricular ejection fraction (LVEF) ≥1 category (LVEF

The last decade has seen rapid progress in our understanding of the molecular basis of arrhythmias, particularly concerning hereditary arrhythmia syndromes. This has led to significant improvement regarding differentiation, risk stratification and therapy in these patients and their families. However, there is mounting evidence that the knowledge obtained by studying these rare monogenic disorders will also enable us to dissect the molecular mechanisms underlying polygenetic and multi-factorial arrhythmias that are by far more common in clinical practice. The goal of this review is to give a brief overview of current knowledge on the molecular basis of primary electrical heart diseases. A focus is on the long QT syndrome.

The antiarrhythmic potential of betablockers contributes to their beneficial effects in the treatment of cardiac diseases, although the molecular basis of their class II antiarrhythmic action has not been clarified yet.To investigate a putative functional link between beta-adrenoreceptors and the fast component of cardiac delayed rectifier K(+) channels (I(Kr)), whole-cell patch-clamp experiments were performed with isolated guinea-pig ventricular myocytes. Tail currents of I(Kr) were measured at -40 mV after short (200 ms) test pulses to +40 mV.After application of the unspecific beta-receptor agonist isoproterenol (10 microM) for 12 min, the I(Kr) tail current was decreased by 72%, with an IC(50) of 1.4 microM. The specific beta(1)-blocker CGP207120A (10 microM) significantly attenuated the isoproterenol effect (net 24% decrease). The specific beta(1)-agonist xamoterol (10 microM), could mimic the isoproterenol effect (58% decrease). Modulators of beta(2)- or beta(3)-adrenoreceptors were far less effective. When isoproterenol or xamoterol were combined with KT5720 (2.5 microM), a specific inhibitor of protein kinase A (PKA), their effects were drastically reduced, indicating that PKA presumably mediates the beta(1)-adrenergic inhibition of I(Kr). Tail current reductions by cAMP, forskolin, PKA catalytic subunit and a combination of PKA holoenzyme and cAMP support an involvement of PKA in the regulation of I(Kr).The functional link between I(Kr) and the beta(1)-adrenergic receptor involving PKA may play an important role in arrhythmogenesis and contribute to the antiarrhythmic action of clinically used beta(1)-blockers.

Chromanol 293B and dofetilide are inhibitors of IKs and IKr, i.e., of the slow and the rapid component of the delayed rectifier potassium current. The specificity of these drugs was tested by investigating their effects on the delayed rectifier potassium current in vascular smooth muscle, regulating the tone of blood vessels. Using depolarizing step protocols with asymmetrical potassium concentrations (135/4.5 mM K+ in pipette/bath), voltage-dependent K+ currents (IKv) of enzymatically dispersed guinea pig portal vein cells were studied in the whole-cell patch-clamp technique. Peak currents were obtained within 20 ms (at +50 mV) after activation. During a 10 s test pulse to +60 mV, these currents exhibited a relatively fast inactivation with time constants of 384 ms (Tfast) and 4505 ms (Tslow). Dofetilide was totally ineffective in modulating currents; in contrast, after application of chromanol 293B, a steady-state block of IKv developed within 135 s. The block was concentration-dependent with an IC50 of 7.4 microM. Chromanol did not produce any shift in the normalized steady-state activation and inactivation curves and the recovery from inactivation was not significantly changed. Chromanol 293B similarly inhibited delayed rectifier K+ channels whether in their closed or open state, and produced an "apparent" acceleration of inactivation, i.e., the drug accelerated the faster time constant of inactivation during a 10 s test pulse from 384 ms (control) to 149 ms (100 microM chromanol). In recent studies, chromanol was described as a specific blocker of slowly activating delayed rectifier potassium channels (IKs) in cardiomyocytes. The results of this study, however, extend the inhibitory spectrum of the drug and demonstrate block of closed and open state delayed rectifier K+ currents in portal vein vascular smooth muscle. Such a block could possibly contribute to the generation of portal hypertension.

Background The discrimination between atrial flutter (AFlu) and atrial fibrillation (AFib) can be made difficult by an irregular ventricular response owing to complex conduction phenomena within the atrioventricular (AV) node, known as multilevel AV block. We tested the hypothesis that a mathematical algorithm might be suitable to discriminate both arrhythmias. Objectives To discriminate AFlu with irregular ventricular response from AFib based on the sequence of R-R intervals. Methods Intracardiac recordings of 100 patients (50 patients with AFib and 50 patients with AFlu) were analyzed. On the basis of a numerical simulation of variable flutter frequencies followed by 2 levels of AV block in series, a given sequence of R-R intervals was analyzed. Results Although the ventricular response displays absolute irregularity in AFib, the sequences of R-R intervals follow certain rules in AFlu. We find that using a mathematical simulation of multilevel AV block, based on the R-R sequence of 16 ventricular beats, a stability of atrial activation could be predicted with a sensitivity of 84% and a specificity of 74%. When limiting the ventricular rate to 125 beats/min, discrimination could be performed with a sensitivity of even 89% and a specificity of 80%. In cases of AFlu, the atrial cycle length could be predicted with high accuracy. Conclusion On the basis of the electrophysiological mechanism of multilevel AV block, we developed a computer algorithm to discriminate between AFlu and Afib. This algorithm is able to predict the stability and cycle length of atrial activation for short R-R sequences with high accuracy.

A 49-year-old man consulted our department 3 months after having several implantable cardioverter-defibrillator (ICD) shocks with subsequent syncope. A CRT-D device (Boston Scientific, Cognis 100-D) and a single-element subcutaneous array (Medtronic, model 6996 SQ) had been implanted 2 years previously for primary prevention of sudden cardiac death caused by symptomatic (New York Heart Association class III) nonischemic dilated cardiomyopathy with severely impaired left ventricular function (left ventricular ejection fraction, 10%) and a left bundle-branch block (QRS width, 176 ms). ICD interrogation revealed a prolonged episode of tachyarrhythmia starting with a fast monomorphic ventricular tachycardia (Vt cycle length, 230 ms). Antitachycardia pacing (ATP) during charging led to discrete Vt acceleration, followed by degeneration into ventricular fibrillation (VF) caused by the first 41-J shock. Another 5 ineffective ICD shocks were delivered. Eventually, the seventh shock was able to terminate VF (Figure 1). Chest radiographic examination revealed a dislodged SQ array requiring surgical revision (Figure 2). After positioning of a new SQ array, the intraoperative defibrillation threshold (DFT) was determined at 21 J. No perioperative complications occurred, and the patient could be discharged home after recovery. On follow-up 6 weeks later, the patient remained in stable condition with no arrhythmia recurrence. Figure 1. Ventricular tachycardia episode storage from a CRT-D device (Boston Scientific, Cognis 100-D) is shown. Shown are the atrial …

article i nfo The transient outward current Ito is an important determinant of the early repolarization phase. Ito and its molecular basis Kv4.3 are regulated by adrenergic pathways including protein kinase C. However, the exact regulatory mechanisms have not been analyzed yet. We here analyzed isoenzyme specific regulation of Kv4.3 and Ito by PKC. Kv4.3 channels were expressed in Xenopus oocytes and currents were measured with double electrode voltage clamp technique. Patch clamp experiments were performed in isolated rat cardiomyocytes. Unspecific PKC stimulation with PMA resulted in a reduction of Kv4.3 current. Similar effects could be observed after activation of conventional PKC isoforms by TMX. Both effects were reversible by pharmacological inhibition of the conventional PKC isoenzymes (Go6976). In contrast, activation of the novel PKC isoforms (ingenol) did not significantly affect Kv4.3 current. Whereas TMX-induced PKC activation was not attenuated inhibition of PKCβ, inhibition of PKCα with HBDDE prevented inhibitory effects of both PMA and TMX. Accordingly, stimulatory effects of PMA and TMX could be mimicked by the α-isoenzyme selective PKC activator iripallidal. Further evidence for the central role of PKCα was provided with the use of siRNAs. We found that PKCα siRNA but not PKCβ siRNA abolished the TMX induced effect. In isolated rat cardiomyocytes, PMA dependent Ito reduction could be completely abolished by pharmacologic inhibition of PKCα. In summary we show that PKCα plays a central role in protein kinase C dependent regulation of Kv4.3 current and native Ito. These results add to the current understanding of isoenzyme selective ion channel regulation by protein kinases.

Inhibition of I(K1) currents by adrenergic alpha(1) receptors has been observed in cardiomyocytes and has been linked to arrhythmogenesis in an animal model. Both PKC-dependent and PKC-independent pathways have been implied in this regulation. The underlying molecular mechanisms, however, have not been elucidated to date. The molecular basis of native I(K1) current is mainly formed by Kir2.1 (KCNJ2), Kir2.2 (KCNJ12) and Kir2.3 (KCNJ4) channels that are differentially regulated by protein kinases. We therefore sought to investigate the role of those different Kir2.x channel subunits in this regulation and to identify the major signalling pathways involved. Adrenergic alpha(1A) receptors (the predominant cardiac isoform) were co-expressed with cloned Kir2.1, Kir2.2 and Kir2.3 channels in Xenopus oocytes and electrophysiological experiments were performed using two-microelectrode voltage clamp. Native I(K1) currents were measured with the whole-cell patch clamp technique in isolated rat ventricular cardiomyocytes. Activation of co-expressed adrenergic alpha(1A) receptors by phenylephrine induced differential effects in Kir2.x channels. No effect was noticed in Kir2.1 channels. However, a marked inhibitory effect was observed in Kir2.2 channels. This regulation was not attenuated by inhibitors of PKC, CamKII and PKA (chelerythrine, KN-93, KT-5720), and mutated Kir2.2 channels lacking functional phosphorylation sites for PKC and PKA exhibited the same effect as Kir2.2 wild-type channels. By contrast, the regulation could be suppressed by the general tyrosine kinase inhibitor genistein and by the src tyrosine kinase inhibitor PP2 indicating an essential role of src kinases. This finding was validated in rat ventricular cardiomyocytes where co-application of PP2 strongly attenuated the inhibitory regulation of I(K1) current by adrenergic alpha(1) receptors. The inactive analogue PP3 was tested as negative control for PP2 and did not reproduce the effects of PP2. In Kir2.3 channels, a marked inhibitory effect of alpha(1A) receptor activation was observed. This regulation could be attenuated by inhibition of PKC with chelerythrine or with Ro-32-0432, but not by tyrosine kinase inhibition with genistein. In summary, on the molecular level the inhibitory regulation of I(K1) currents by adrenergic alpha(1A) receptors is probably based on effects on Kir2.2 and Kir2.3 channels. Kir2.2 is regulated via src tyrosine kinase pathways independent of protein kinase C, whereas Kir2.3 is inhibited by protein kinase C-dependent pathways. Src tyrosine kinase pathways are essential for the inhibition of native I(K1) current by adrenergic alpha(1) receptors. This regulation may contribute to arrhythmogenesis under adrenergic stimulation.

Background— A high intake of dietary flavonoids, which are abundant in fruits, vegetables, tea, and wine, is known to reduce cardiovascular mortality. The effects of flavonoids on cardiac electrophysiology, which theoretically may have both antiarrhythmic and proarrhythmic consequences, have not been studied systematically to date. Methods and Results— We screened a broad spectrum of flavonoids for their inhibitory activity on HERG channels by using heterologous expression in Xenopus oocytes. At a concentration of 1 mmol/L, 10 compounds caused a significant inhibition of HERG currents, whereas 11 other flavonoids had no effect. The IC 50 value for HERG block by naringenin, the most potent inhibitor, was 102.3 μmol/L in Xenopus oocytes and 36.5 μmol/L in HEK cells. To demonstrate the physiological relevance of these findings, we studied the effects of pink grapefruit juice, which contains large amounts of naringenin glycosides (>1000 μmol/L), in human volunteers. In 10 persons, we observed a peak QTc prolongation of 12.5±4.2 ms 5 hours after oral ingestion of 1 L of grapefruit juice. This effect was significant ( P =0.02). Conclusions— We found a significant QTc prolongation by grapefruit juice in healthy volunteers, probably caused by block of HERG channels by flavonoids. These findings reveal new perspectives on the potential for dietary modification of cardiac electrophysiology.

Objective: The cardiac inwardly rectifying potassium current I K1 and its molecular correlates Kir2.1 and Kir2.2 play an important role in cardiac repolarisation and in the pathogenesis of hereditary long-QT syndrome (LQTS-7). Protein kinases A (PKA) and C (PKC) are key enzymes in adrenergic signal transduction, inducing arrhythmias in heart disease. This study investigated the regulation of Kir2.2 (KCNJ12) by PKA. Methods: Cloned Kir2.2 channels were expressed heterologously in Xenopus oocytes and currents were measured with the double-electrode voltage–clamp technique. Results: After activation of PKA by forskolin (100 μmol/l) or Ro-20-1724 (100 μmol/l), wild type currents at −120 mV were increased by 93.7% and 79.0%, respectively. Coapplication of the PKA inhibitor KT-5720 (2.5 μmol/l) attenuated this effect. No significant changes were apparent after mutation of the single PKA consensus site S430. In addition, removal of all four PKC consensus sites in Kir2.2 induced a phorbolester-mediated current increase which could be suppressed by PKA inhibitors H-89 (50 μmol/l) and KT-5720 (2.5 μmol/l). Conclusions: This study demonstrates antagonistic effects of PKA and PKC in the regulation of Kir2.2. Phosphorylation by PKC has been shown to cause an inhibition of Kir2.2 currents, whereas activation of PKA leads to current upregulation.

Background: Cardiac inwardly rectifying IK1 current drives terminal repolarisation. Inhibition of IK1 current can suppress re-entry based arrhythmias and has been demonstrated to exert anti-fibrillatory effects. Human IK1 current is mainly formed by heterotetrameric assembly of three subunits: Kir2.1, Kir2.2 and Kir2.3 channels. Amiodarone and dronedarone have been shown to inhibit cardiac IK1 current, but the molecular basis of these effects has not been elucidated to date. Methods: Human Kir2.1 - Kir2.3 channels were expressed in Xenopus oocytes and current recordings were performed using the double-electrode voltage-clamp technique. Results: Amiodarone and dronedarone exerted differential inhibitory effects on Kir2.1, Kir2.2 and Kir2.3 channels, respectively. Both drugs inhibited only Kir2.1 channels without an effect on Kir2.2 and Kir2.3 channels. We analyzed effects of dronedarone in detail. Onset of inhibition was slow, but the effect was completely reversible upon washout. Biophysical current characteristics such as inwardly-rectifying properties and reversal potential of Kir2.1 currents were not modified. The inhibitory effect did not exhibit frequency dependence. Interestingly, dronedarone inhibited Kir2.1 currents mainly at negative potentials. Conclusions: Amiodarone and dronedarone both inhibit only Kir2.1 channels without affecting Kir2.2 and Kir2.3 channels. In view of the functional significance of Kir2.1 channels, this effect probably underlies the observed inhibition of IK1 current by both compounds and may contribute to their anti-fibrillatory efficacy.

Background: The cardiac inwardly rectifying potassium current IK1 stabilises the diastolic resting membrane potential of ventricular cardiomyocytes. Protein kinase A (PKA) induces an inhibition of IK1 current which strongly promotes focal arrhythmogenesis under increased catecholamine levels. The molecular mechanisms underlying this regulation have only partially been elucidated to date. Furthermore, the role of A Kinase Anchoring Proteins (AKAPs) in this regulation has not been examined yet. The objective of this project was to elucidate the molecular mechanisms underlying the inhibition of IK1 by PKA and to identify novel molecular targets for antiarrhythmic therapy downstream β-adrenoreceptors. Methods: Cardiac IK1 current was measured in isolated rat ventricular cardiomyocytes using whole-cell patch clamp. Kir2.x channels and AKAPs were expressed in Xenopus oocytes and current recordings were performed using the double-electrode voltage-clamp technique. Association of channels and AKAPs was examined with the use of co-immunoprecipitation and immunofluorescent confocal microscopy in isolated cardiomyocytes and in mammalian cell lines. Results: In patch clamp experiments, activation of PKA inhibited IK1 current in rat ventricular cardiomyocytes. This regulation was markedly attenuated by disrupting PKA-binding to AKAPs with the peptide inhibitor AKAP-IS. In expression systems, we observed functional and spatial coupling of the plasma membrane-associated AKAP15/18 and AKAP79 to Kir2.1 and Kir2.2 channel subunits, but not to Kir2.3 channels, which underly IK1 currents. In contrast, AKAPyotiao had no functional effect on the PKA regulation of Kir channels. AKAP15/18 and AKAP79 co-immunoprecipitated with and co-localized to Kir2.1 and Kir2.2 channel subunits in ventricular cardiomyocytes. Conclusions: In this study, we provide evidence for the functional and spatial coupling of cardiac Kir2.1 and Kir2.2 subunits as molecular components of IK1 current with the plasma membrane-bound AKAPs 15/18 and 79. Cardiac membrane-associated AKAPs are a functionally essential part of the regulatory cascade determining IK1 current function and may be novel molecular targets for antiarrhythmic therapy downstream from β-adrenoreceptors.

In a routine ECG from a young asymptomatic woman, changes in P-wave morphology and the frontal plane atrial vector were noted. Two-dimensional echocardiography revealed a large atrial septal aneurysm as probable underlying cause. This case report demonstrates that non-specific right atrial ECG signs may be indicative of lone atrial septal aneurysm.

Background: Inwardly rectifying potassium current IK1 stabilizes the diastolic resting membrane potential. On the molecular level it is composed by heterotetrameric assembly of Kir2.1, Kir2.2 and Kir2.3 channels. Dysfunction of IK1 current strongly predisposes to focal ventricular ectopy. Protein kinase A (PKA) is a key enzyme in adrenergic signal transduction that is involved in catecholaminergic arrhythmogenesis. Targeted protein phosphorylation through PKA is mediated by A Kinase Anchoring Proteins (AKAPs). To date, however, only little is known about the AKAPs that are of functional relevance for the regulation of cardiac IK1 potassium current. Methods: Cardiac IK1 current was measured in isolated rat ventricular cardiomyocytes using whole-cell patch clamp. Kir2.x channels and AKAPs were expressed in Xenopus oocytes and current recordings were performed using the double-electrode voltage-clamp technique. Association of channels and AKAPs was examined with the use of co-immunoprecipitation and immunofluorescent confocal microscopy in isolated cardiomyocytes and in mammalian cell lines. Results: IK1 current in isolated rat ventricular cardiomyocytes was inhibited by activation of protein kinase A. This regulation was markedly attenuated by disrupting PKA-binding to AKAPs with the peptide Ht31 in the expression system. We observed functional coupling of AKAP15 and AKAP79 to Kir2.1 and Kir2.2 channels, but not to Kir2.3 channels. Kir2.1 channels were only sensitive to PKA regulation if membrane-associated AKAPs were co-expressed. Kir2.2 channels exhibited the strongest sensitivity to PKA regulation that was even further increased after co-expression of AKAPs. By contrast, Kir2.3 channels were insensitive to PKA regulation even after co- expression of AKAPs. When co-expressing the AKAP-IS related inhibitor peptide Ht31 together with AKAPs and Kir2.1 and Kir2.2 channels, PKA- dependent effects were almost completely suppressed. Both AKAP79 and AKAP15 co-immunoprecipitate and co-localize with Kir2.1 and Kir2.2 in cardiomyocytes indicating co-assembly in membrane-bound signalling complexes. Conclusion: In this project, we provide evidence for the functional and biochemical coupling of cardiac Kir2.1 and Kir2.2 channels to the membrane-associated anchoring proteins AKAP15 and AKAP79. Membrane-associated AKAPs may provide novel molecular targets for antiarrhythmic therapy downstream from the cardiac beta1-adrenoreceptor.

INHIBITION OF HETEROMERIC KIR2.X CHANNELS BY ALPHA1A ADRENERGIC RECEPTORS: CRUCIAL ROLE OF PROTEIN KINASE C DEPENDENT REGULATION OF KIR2.3 SUBUNITS Claudia Kiesecker, MS, Edgar Zitron, Daniel Scherer, Sonja Lueck, Ramona Bloehs, Eberhard P. Scholz, Sven Kathofer, MD, Dierk Thomas, MD, Volker A. Kreye, MD, Johann Kiehn, MD, Wolfgang Schols, MD, Hugo A. Katus, MD and Christoph A. Karle, MD. Medical University Hospital Heidelberg, Heidelberg, Germany and University of Heidelberg, Heidelberg, Germany.