[Syncope]. / Synkope.

Syncope is a frequent disorder, sometimes due to life-threatening causes. The uncertainty in its diagnosis requires a standardized approach. According to the 2018 European Society of Cardiology (ESC) guidelines, new aspects in evaluation and treatment include risk stratification and decision-making strategies during the initial evaluation in the emergency department, a reconsideration of diagnostic tests, algorithms for the treatment of reflex syncope, indications for an implantable cardioverter/defibrillator in high risk patients for sudden cardiac death, and organizational aspects such as interdisciplinary syncope units. The 2018 ESC guideline and the 2019 commentaries of the German Society of Cardiology (DGK) are an excellent and comprehensive instruction for safe, effective and efficient evaluation and therapy. However, some aspects require critical appraisal. The inadequate availability and reimbursement of pivotal diagnostic tests, such as tilt table testing and the implantable loop recorder is emphasized.

[The Wearable Cardioverter-Defibrillator (WCD)]. / Der tragbare Kardioverter-Defibrillator.

While the implantable cardioverter-defibrillator (ICD) has been proven to be the best choice for patients with long-term risk for sudden cardiac arrest/sudden cardiac death (SCA/SCD), the question is how to manage patients with only temporary risk, e.g., during the guidelines-recommended waiting period until the decision for an ICD can be made. These patient groups should be monitored around the clock to guarantee a lifesaving shock within a few minutes, if necessary.These conditions can be accomplished by the wearable cardioverter-defibrillator (WCD) in the outpatient sector. The WCD is worn on the skin and consists of four nonadhesive ECG electrodes as well as three defibrillation electrodes-two at the back and one at the front-embedded in a garment. The defibrillation unit is connected via a cord and can be worn over the shoulder or on a belt. Cardiac events can be recorded and retrospectively analyzed by the treating physician.The WCD is a safe and effective measure to terminate potentially lethal ventricular tachycardia and ventricular fibrillation. It may be used early after myocardial infarction with reduced left ventricular ejection fraction (LVEF), as well as for patients with acute heart failure in nonischemic cardiomyopathy with uncertain cause and prognosis. In addition, it may be used for patients waiting for heart transplantation, for patients who cannot be implanted an ICD due to comorbidities, and for patients after explantation of their ICD, e.g., because of infection until reimplantation.One may expect that risk stratification of patients with the WCD will lead to even better selection for ICD use.

[Differentiated antiplatelet therapy for acute coronary syndromes]. / Differenzierte antithrombozytäre Therapie bei akutem Koronarsyndrom.

Dual antiplatelet therapy is the cornerstone of maintenance medication following invasive treatment of patients with acute coronary syndromes (ST elevation myocardial infarction, non-ST elevation myocardial infarction, unstable angina). Over the last decade, P2Y12 inhibition in addition to low-dose acetylsalicylic acid has been intensively debated. The debate was enriched by the results of the large phase III clinical trials for prasugrel (TRITON) and ticagrelor (PLATO) compared to clopidogrel in patients with acute coronary syndromes. This article summarizes the critical details und subanalyses of both study programmes and highlights on clinical decision making when using the three P2Y12 blockers in acute coronary syndromes. A special focus is on higher risk patients such as those with ST elevation myocardial infarction and those with coexisting diabetes, but also on minimizing relevant bleedings, which are common during more intense platelet inhibition.

[Recommendations of the Working Group of Arrhythmias of the German Society of Cardiology on the approach to patients with Riata® and Riata ST® leads (St. Jude Medical). Nucleus of the Working Group of Arrhythmias of the German Society of Cardiology]. / Empfehlungen der Deutschen Gesellschaft für Kardiologie (Arbeitsgruppe Rhythmologie) zum Umgang mit Patienten mit ICD-Elektroden Riata® und Riata ST® der Firma St. Jude Medical. Nucleus der AG Rhythmologie der Deutschen Gesellschaft für Kardiologie.

Riata® and Riata ST® implantable cardioverter defibrillator (ICD) leads (St. Jude Medical, Sylmar, CA) show an increased incidence of insulation defects, particularly "inside-out" lead fracture where inner, separately insulated cables penetrate through the surrounding silicone of the lead body. The exact incidence of Riata® lead problems is not clear and seems to range between 2-4% per year in the first 5 years after implantation according to new registry data. We recommend beyond a detailed information the following care of patients with Riata® and Riata ST® leads: 1) Activation of automatic ICD alerts, 2) remote monitoring with automatic daily alerts whenever possible, 3) monthly ICD controls in patients at high risk (pacemaker dependency, history of ventricular tachyarrhythmias) and high or moderate lead-related risk (8F, 7F single coil), 3-monthly controls in moderate patient and lead-related risk, 3 to 6-monthly controls in low patient and lead-related risk (no bradycardia, no history of ventricular tachyarrhythmia). Every ICD control should include meticulous analysis of oversensing artifacts in stored electrograms (EGMs) of sustained and non-sustained ventricular tachyarrhythmias and registration of EGMs during provocation testing (pectoral muscle activity, arm movements). If electrical abnormalities are observed, reoperation with addition of a new ICD lead is recommended; lead extraction only if indicated according to current guidelines. Fluoroscopy should only be performed if electrical abnormalities are found by an experienced electrophysiologist and a high frame rate and resolution. Management of fluoroscopic abnormalities in the absence of electrical abnormalities is not clear. Therefore, routine fluoroscopy of patients with Riata® leads without electrical abnormalities is not recommended.

Clinical significance of microvolt T-wave alternans.

Several studies have recently proven that primary preventive therapy of sudden arrhythmogenic death is possible in selected patients with congestive heart failure, particularly in the setting of ischemic cardiomyopathy [1, 2]. However, a number needed to treat between 11 and 17 to save one life over three years in these studies indicates that a more accurate identification of high risk patients is desirable in order to avoid unnecessary implants of cardioverter/defibrillators (ICD). Since currently available risk stratification methods have limited predictive accuracy, development of new techniques is important in order to non-invasively assess arrhythmogenic risk in patients prone to sudden death. Microvolt level T-wave alternans (mTWA) has recently been proposed to assess abnormalities in ventricular repolarization favoring the occurrence of reentrant arrhythmias [3, 4]. In 1994, a first clinical study by Rosenbaum and coworkers [5] convincingly demonstrated that mTWA is closely related to arrhythmia induction in the electrophysiology (EP) laboratory as well as to the occurrence of spontaneous ventricular tachyarrhythmias during follow-up [5]. More recently, a number of clinical studies has examined its clinical applicability [4-7]. The present review summarizes currently available clinical data on TWA with a particular focus on risk stratifying patients with congestive heart failure and myocardial infarction.

Use of telemedicine in the diagnosis of paroxysmal atrial fibrillation and to monitor the effect of antiarrhythmic drug therapy.

We present the case of a patient with highly symptomatic tachyarrhythmias for 2 years without any arrhythmia documentation despite numerous ECG and Holter registrations. By means of telemedicine, it was possible to document the arrhythmia--in this case atrial fibrillation--within 10 days and to start antiarrhythmic drug treatment with flecainide and metoprolol. This case demonstrates the diagnostic potential of telemedicine in patients with recurrent episodes of tachyarrhythmias in whom episodes are not sufficiently frequent to allow diagnosis by Holter monitoring. Telemedicine may also be advantageous for ECG monitoring during the early phase after cardioversion or initiation of specific antiarrhythmic pharmacotherapy in order to detect potential drug-induced proarrhythmic changes.

[Resuscitation in ventricular fibrillation: what is essential?]. / Reanimation bei Kammerflimmern: Worauf kommt es an?

Prognosis of prehospital cardiac arrest due to ventricular fibrillation is dependent on the first minutes, as survival decreases by 10% for each minute by which resuscitation attempts are delayed. Thus, early defibrillation plays a key role in improving outcome of cardiac arrest victims. The effectiveness of automated external defibrillators (AEDs) in this setting has been proven by several clinical trials. There remains controversy with regard to using AEDs in the in-hospital setting, as well as the approach of "public access" defibrillation. Whereas the use of intravenous antiarrhythmic drugs, particularly amiodarone, remains controversial, new data support the use of vasopressine instead of epinephrine as vasopressor drug in cardiac arrest patients. The present review aims to focus on the above mentioned aspects as well as on the changes to the present ILCOR guidelines which have led to modification of the resuscitation guidelines of the European Resuscitation Council (ERC).

[Resuscitation after prehospital cardiovascular arrest]. / Reanimation nach prähospitalem Herz-Kreislauf-Stillstand.

Initiation of effective cardiopulmonary resuscitation (CPR) at the earliest possible moment is the most important determinant of prognosis for prehospital cardiac arrest. The prognosis is essentially defined by two parameters: survival to hospital admission and survival to discharge. In connection with prehospital cardiac arrest, early defibrillation is particularly important, including the widespread availability of (semi)automatic defibrillators. Further aspects of CPR have recently received increased attention: on the one hand, changed study status regarding the use of antiarrhythmic agents (especially amiodarone), on the other hand, administration of vasopressin during resuscitation, and finally, the efficacy of mild hypothermia following prehospital cardiac arrest. These aspects represent the main subject of the present overview, which also addresses the latest revision of the International Liaison Committee on Resuscitation (ILCOR) guidelines on CPR that resulted in corresponding changes in the European Resuscitation Council (ERC) guidelines.

Effect of metoprolol and d,l-sotalol on microvolt-level T-wave alternans. Results of a prospective, double-blind, randomized study.

OBJECTIVES: The study evaluated the effects of metoprolol, a pure beta-blocker, and d,l-sotalol, a beta-blocker with additional class III antiarrhythmic effects, on microvolt-level T-wave alternans (TWA). BACKGROUND: Assessment of TWA is increasingly used for purposes of risk stratification in patients prone to sudden death. There are only sparse data regarding the effects of beta-blockers and antiarrhythmic drugs on TWA. METHODS: Patients with a history of documented or suspected malignant ventricular tachyarrhythmias were eligible. All patients underwent invasive electrophysiologic (EP) testing including programmed ventricular stimulation and determination of TWA at increasing heart rates using atrial pacing. Reproducibility of TWA at two consecutive drug-free baseline measurements was tested in a random patient subset. Following baseline measurements, all patients were randomized either to double-blind intravenous infusion of sotalol (1.0 mg/kg) or metoprolol (0.1 mg/kg). Results of TWA assessment at baseline and after drug exposure were compared. RESULTS: Fifty-four consecutive patients were studied. In 12 patients, repetitive baseline measurement of TWA revealed stable alternans voltage (V(alt)) values (9.1 +/- 5.8 microV vs. 8.5 +/- 5.7 microV, p = NS). After drug administration, V(alt) decreased by 35% with metoprolol (7.9 +/- 6.0 microV to 4.9 +/- 4.2 microV; p < 0.001) and by 38% with sotalol (8.6 +/- 6.8 microV to 4.4 +/- 2.3 microV; p = 0.001). In eight patients with positive TWA at baseline, repeated measurement revealed negative test results. CONCLUSIONS: In patients prone to sudden cardiac death, there is a reduction in TWA amplitude following the administration of antiadrenergic drugs. This result indicates that TWA is responsive to the pharmacologic milieu and suggests that, to assess a patient's risk of spontaneous ventricular arrhythmia, the patient should be tested while maintaining the pharmacologic regimen under which the risk of arrhythmia is being assessed. This applies particularly for beta-blocker therapy.

Association between atrial fibrillation and appropriate implantable cardioverter defibrillator therapy: results from a prospective study.

INTRODUCTION: Atrial fibrillation (AF) is associated with significant morbidity and mortality that may be related to hemodynamic impairment, thromboembolic events, or enhanced electrical instability of the ventricular myocardium. There is, however, a lack of data concerning the association of AF and ventricular tachyarrhythmias. METHODS AND RESULTS: Consecutive patients with indication for an implantable cardioverter defibrillator (ICD) were classified for the presence or absence of persistent AF at the time of device implantation. Incidence of device therapy, stored electrograms, and clinical events during follow-up were evaluated prospectively. Two hundred fifty patients were included. During follow-up (20+/-14 months), patients in AF experienced appropriate device therapy for recurrent ventricular arrhythmias more frequently compared with patients in sinus rhythm (SR) (63% vs 38%, P = 0.01). On multivariate analysis, AF was an independent predictor of appropriate ICD therapy (relative risk 1.8; 95% confidence interval [CI] 1.2 to 2.9) and inappropriate device therapy (relative risk 2.3; 95% CI 1.2 to 4.5). Predefined clinical events (cluster endpoint: death, syncope, and hospitalizations) were observed more frequently in AF than in SR patients (55% vs 31%, P = 0.01). Analysis of device-stored electrograms revealed a higher incidence of short-long-short cycles preceding ventricular arrhythmias in AF compared with SR patients (50% vs 16%, P = 0.002). Baseline heart rate preceding ventricular arrhythmias did not differ between the two groups. CONCLUSION: AF is an independent predictor of recurrent ventricular arrhythmias in ICD recipients. The underlying electrophysiologic mechanism seems to be irregular rather than rapid ventricular activation, with a high incidence of short-long-short sequences preceding ventricular tachyarrhythmias in AF patients.

Rate-dependence of QT dispersion and the QT interval: comparison of atrial pacing and exercise testing.

OBJECTIVES: The study was done to determine whether variables of QT dispersion from the 12-lead electrocardiogram (ECG) are dependent on heart rate. BACKGROUND: The dispersion of the QT interval is under evaluation as a risk marker in patients at risk for ventricular arrhythmias. Assuming that a similar rate correction is necessary as for the QT interval itself, investigators have frequently reported QTc-dispersion values utilizing the Bazett formula. It is not known whether there is a physiologic basis for such a rate correction in the human heart. METHODS: In 35 patients referred for evaluation of ventricular arrhythmias, digital 12-lead ECGs recorded at various heart rates during submaximal exercise testing and again during atrial pacing upon electrophysiologic testing were submitted to computerized interactive analysis of several ECG dispersion variables. RESULTS: Data from 11 patients were excluded due to incomplete high-quality analysis possible at all heart rates. From the remaining 24 patients, a total of 193 ECG recordings at various heart rates (ranging from 76 +/- 17 beats/min to 117 +/- 14 beats/min during atrial pacing and from 78 +/- 18 beats/min to 110 +/- 14 beats/min during exercise testing) were available. A highly significant linear relationship with heart rate was found for both the QT interval and the Q-to-T-peak interval. By contrast, standard QT interval dispersion (QTmax - QTmin), the T-peak-to-T-end interval, and the average area under the T wave did not change with increasing heart rates. CONCLUSIONS: Dispersion of the QT interval and other ECG variables of dispersion of ventricular repolarization are independent of heart rate. Therefore, it is not necessary to rate-correct these measurements.

[Postural orthostatic tachycardia syndrome (POTS): etiology, diagnosis and therapy]. / Posturales orthostatisches Tachykardiesyndrom (POTS): Atiologie, Diagnose und Therapie.

BACKGROUND: Since the renaissance of tilt table testing in clinical cardiology some 15 years ago, the syndromes of autonomic dysfunction with orthostatic intolerance underwent improved differentiation and classification. In the present review a variant of autonomic dysfunction with orthostatic intolerance--POTS (postural orthostatic tachycardia syndrome)--will be discussed. DIAGNOSIS AND TREATMENT: The affected patients present with orthostatic intolerance, postural tachycardia, exercise intolerance, fatigue, dizziness and in some cases with other dysautonomic symptoms such as gastrointestinal or sudomotor dysfunction. Together with the clinical history, tilt table testing is the cornerstone of diagnostic evaluation by which the syndrome can be distinguished from typical neurocardiogenic disorders. POTS is characterized by different subtypes; accordingly, therapy for relief of symptoms is variable and includes beta blockers for patients with the hyperadrenergic type and alphamimetics for those with partial dysautonomia. CONCLUSION: Although it is now possible to differ POTS from other forms of autonomic dysfunction, further research is warranted to clarify the pathophysiology of this syndrome and its subtypes and to improve therapeutic interventions.

Analysis of 12-lead T-wave morphology for risk stratification after myocardial infarction.

BACKGROUND: The stratification of post-myocardial infarction (MI) patients at risk of sudden cardiac death remains important. The aim of the present study was to assess the prognostic value of novel T-wave morphology descriptors derived from resting 12-lead ECGs. METHODS AND RESULTS: In 280 consecutive post-MI patients, a 12-lead ECG was recorded before discharge, optically scanned, and digitized. For the present study, 5 T-wave morphology descriptors were automatically calculated after singular value decomposition of the ECG signal. The total cosine R-to-T (TCRT [describes the global angle between repolarization and depolarization wavefront]) and the T-wave loop dispersion were univariately associated (P:=0.0002 and P:<0.002, respectively, U: test) with 27 prospectively defined clinical events in 261 patients (mean follow-up 32+/-10 months). Kaplan-Meier event probability curves for strata above and below the median confirmed the strong risk discrimination by TCRT and T-wave loop dispersion (P:<0.003 and P:<0.001, respectively, log-rank test). On Cox regression analysis, with the entering of age, left ventricular ejection fraction, heart rate, QRS width, reperfusion therapy, beta-adrenergic-blocker treatment, and standard deviation of R-R intervals on 24-hour Holter monitoring, TCRT (P:<0.03) yielded independent predictive value, whereas T-wave loop dispersion was of borderline independence (P:=0.064). Heart rate (P:<0.02), left ventricular ejection fraction (P:<0.02), and reperfusion therapy (P:<0.02) also remained in the final model. CONCLUSIONS: Computerized T-wave morphology analysis of the 12-lead resting ECG permits independent assessment of post-MI risk and an improved risk stratification when combined with other risk markers.

Predictive value of T-wave alternans for arrhythmic events in patients with congestive heart failure.

Measurement of microvolt level T-wave alternans in the surface electrocardiogram is a novel way to assess the risk of ventricular arrhythmias. Seven tests of arrhythmic risk, including T-wave alternans, were undertaken in 107 consecutive patients with congestive heart failure and no history of sustained ventricular arrhythmias; the patients were followed up for arrhythmic events during the next 18 months. Of the patients with events, 11 had positive and two indeterminate T-wave alternans results; there were no arrhythmic events among patients with negative T-wave alternans results. Of the seven tests, only T-wave alternans was a significant (p=0.0036) and independent predictor of arrhythmic events.

[Microvolt level T wave alternans: a new marker for noninvasive risk stratification]. / Mikrovolt-T-Wellen-Alternans--ein neuer Marker zur nichtinvasiven Risikostratifikation.

Prospective identification of patients with structural heart disease who could profit from prophylactic ICD therapy is hampered by the low predictive power of the currently available risk stratification parameters. Microvolt T wave alternans measured noninvasively is a new promising parameter to assess impaired ventricular repolarization which has been associated with an increased incidence of ventricular tachyarrhythmias. T wave alternans is rate-dependent; to induce alternans, heart rate may be increased by atrial stimulation during invasive EP testing or noninvasively by exercise stress testing. The first clinical validation with respect to prediction of inducibility of ventricular tachyarrhythmias and of arrhythmic events during follow-up in patients undergoing invasive EP testing was reported in 1994. Subsequently, a good concordance between the results of invasive and noninvasive assessment of T wave alternans was demonstrated by our group. The first prospective evaluation of the noninvasive alternans measurement using submaximal exercise testing was performed in patients surviving prehospital ventricular fibrillation or sustained ventricular tachycardia referred to our institution. The occurrence of T wave alternans in this patient population was predictive of future tachyarrhythmic events with subsequent appropriate ICD therapy. The results of the currently performed prospective trials in various patient populations will help to establish the utility of T wave alternans assessment as a risk stratifier in clinical practice.