Internal Versus External Electrical Cardioversion of Atrial Arrhythmia in Patients With Implantable Cardioverter-Defibrillator: A Randomized Clinical Trial.

BACKGROUND: Atrial arrhythmias are common in patients with implantable cardioverter-defibrillator (ICD). External shocks and internal cardioversion through commanded ICD shock for electrical cardioversion are used for rhythm-control. However, there is a paucity of data on efficacy of external versus internal cardioversion and on the risk of lead and device malfunction. We hypothesized that external cardioversion is noninferior to internal cardioversion for safety, and superior for successful restoration of sinus rhythm. METHODS: Consecutive patients with ICD undergoing elective cardioversion for atrial arrhythmias at 13 centers were randomized in 1:1 fashion to either internal or external cardioversion. The primary safety end point was a composite of surrogate events of lead or device malfunction. Conversion of atrial arrhythmia to sinus rhythm was the primary efficacy end point. Myocardial damage was studied by measuring troponin release in both groups. RESULTS: N=230 patients were randomized. Shock efficacy was 93% in the external cardioversion group and 65% in the internal cardioversion group (P<0.001). Clinically relevant adverse events caused by external or internal cardioversion were not observed. Three cases of pre-existing silent lead malfunction were unmasked by internal shock, resulting in lead failure. Troponin release did not differ between groups. CONCLUSIONS: This is the first randomized trial on external vs internal cardioversion in patients with ICDs. External cardioversion was superior for the restoration of sinus rhythm. The unmasking of silent lead malfunction in the internal cardioversion group suggests that an internal shock attempt may be reasonable in selected ICD patients presenting for electrical cardioversion. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03247738.

A randomized study of remote monitoring and fluid monitoring for the management of patients with implanted cardiac arrhythmia devices.

AIMS: Only limited comparative data exist on the benefits of fluid monitoring (FM) combined with remote monitoring (RM) regarding morbidity and mortality of heart failure (HF) patients. This prospective single-centre randomized pilot study aimed to estimate the influence of RM in combination with FM on HF hospitalizations as well as ventricular tachyarrhythmias and mortality. METHODS AND RESULTS: Patients with standard indication for implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy and defibrillator were implanted with devices capable of RM and FM, and were followed for 15 months. Subjects were randomly allocated to RM including OptiVol and predefined management of alerts (remote group), or standard in-office visits every 3 months (control group). A total of 176 patients (77% male; 66 ± 12 years; left ventricular ejection fraction (LVEF) 32 ± 11%; ischemic cardiomyopathy 50%; CRT device 50%; primary prevention 85%) were analysed. Cox proportional hazard analysis on the time to first HF-related hospitalization showed a hazard ratio of 1.23 [0.62-2.44] (P = 0.551) favouring the control group. In the remote group, 13 patients (15%) experienced ICD shocks vs. 10 patients (11%) in the control group (P = 0.512). The average time to first ICD shock was 212 ± 173 days in the remote arm and 212 ± 143 days in the control arm (P = 0.994). The Kaplan-Meier estimate of mortality after 1 year was 8.6% (eight deaths) in the remote group vs. 4.6% in the control group (six deaths; P = 0.502). CONCLUSION: In a single-centre randomized pilot study of RM in combination with FM, no significant influence on HF-related hospitalizations, ICD shocks, or mortality was found.

Passive-fixation lead failure rates and long-term patient mortality in subjects implanted with Sprint Fidelis electrodes.

AIMS: To evaluate passive-fixation lead failure rates and long-term patient survival in subjects implanted with Sprint Fidelis electrodes. METHODS AND RESULTS: We identified 748 subjects who received a Sprint Fidelis (n = 429; Medtronic models 6948: 94.8%, 6949: 2.6%, 6930: 1.9%, 6931: 0.7%) or a Sprint 'non-Fidelis' implantable cardioverter defibrillator lead (n = 319, Medtronic models 6944: 68.6%, 6947: 17.9%, 6942: 7.8%, 6943: 3.4%, 6945: 2.2%) at our centre between 1998 and 2008. Kaplan-Meier patient survival was lower in the Fidelis group than in the Control cohort (68.4 vs. 77.0% at 5 years, P = 0.0061), but multivariate analyses revealed no significant association between mortality and implanted lead type. Passive-fixation lead failure rate at 5 years was 14.4% (95% confidence interval (CI) [9.2, 19.3]) in the Fidelis (n = 414) group and 1.8% (95% CI [0.0-3.8]) in the Control (n = 241) cohort (P < 0.001 upon multivariate comparison). CONCLUSION: Failure rates of passive-fixation Sprint Fidelis leads are increased and similar to those previously reported for active-fixation Fidelis electrodes. Despite the elevated risk for lead failure and its potential sequelae, the Sprint Fidelis has no obvious impact on long-term mortality.

Measurement of Left Atrial Pressure is a Good Predictor of Freedom From Atrial Fibrillation.

BACKGROUND: It is suggested that an elevated left atrial pressure (LAP) promotes ectopic beats emanating in the pulmonary veins (PVs) and that LAP might be a marker for structural remodeling. This study aimed to identify if the quantification of LAP correlates with structural changes of the LA and may therefore be associated with outcomes following pulmonary vein isolation (PVI). METHODS: We analysed data from 120 patients, referred to PVI due to drug-refractory atrial fibrillation (AF) (age 63±8; 57% men). The maximum (mLAP) and mean LAP (meLAP) were measured after transseptal puncture. RESULTS AND CONCLUSIONS: Within a mean follow-up of 303±95 days, 60% of the patients maintained in sinus rhythm after the initial procedure and 78% after repeated PVI. Performing univariate Cox-regression analysis, type of AF, LA-volume (LAV), mLAP and the meLAP were significant predictors of recurrence after PVI (p=0.03; p=0.001; p=0.01). In multivariate analysis mLAP>18mmHg, LAV>100 ml and the presence of persistent AF were significant predictors (p=0.001; p=0.019; p=0.017). The mLAP >18 mmHg was associated with a hazard ratio of 3.8. Analyzing receiver-operator characteristics, the area under the curve for mLAP was 0.75 (p<0.01). mLAP >18 mmHg predicts recurrence with a sensitivity of 77 % and specificity of 60 %. There was a linear correlation between the LAV from MDCT and mLAP (p = 0.01, R2 = 0.61). The mLAP measured invasively displays a significant predictor for AF recurrence after PVI. There is a good correlation between LAP and LAV and both factors may be useful to quantify LA remodeling.

Pulmonary vein anatomy predicts freedom from atrial fibrillation using remote magnetic navigation for circumferential pulmonary vein ablation.

AIMS: Multidetector computed tomography (MDCT) is frequently used to guide circumferential pulmonary vein ablation (PVA) for treatment of atrial fibrillation (AF) as it offers accurate visualization of the left atrial (LA) and pulmonary vein (PV) anatomy. This study aimed to identify if PV anatomy is associated with outcomes following PVA using remote magnetic navigation (RMN). METHODS AND RESULTS: We analysed data from 138 consecutive patients and 146 ablation procedures referred for PVA due to drug-refractory symptomatic AF (age 63 ± 11 years; 57% men; 69% paroxysmal AF). The RMN using the stereotaxis system and open-irrigated 3.5 mm ablation catheters was used in all procedures. Prior to PVA, all patients underwent electrocardiogram-gated 64-MDCT for assessment of LA dimensions, PV anatomy, and electro-anatomical image integration during the procedure. Regular PV anatomy was found in 68%, a common left PV ostium was detected in 26%, and variant anatomy of the right PVs was detected in 6%. After a mean follow-up of 337 ± 102 days, 63% of the patients maintained sinus rhythm after the initial ablation, and 83% when including repeat PVA. Although acutely successful PV isolation did not differ between anatomical subgroups (regular 3.5 ± 0.8 vs. variant 3.2 ± 1.3; P = 0.31), AF recurrence was significantly higher in patients with non-regular PV anatomy (P = 0.04, hazard ratio 1.72). Pulmonary vein anatomy did not influence complication rates. CONCLUSION: Pulmonary vein anatomy assessed by MDCT is a good predictor of AF recurrence after PVA using RMN.

Rationale, objectives, and design of the EUTrigTreat clinical study: a prospective observational study for arrhythmia risk stratification and assessment of interrelationships among repolarization markers and genotype.

AIMS: The EUTrigTreat clinical study has been designed as a prospective multicentre observational study and aims to (i) risk stratify patients with an implantable cardioverter defibrillator (ICD) for mortality and shock risk using multiple novel and established risk markers, (ii) explore a link between repolarization biomarkers and genetics of ion (Ca(2+), Na(+), K(+)) metabolism, (iii) compare the results of invasive and non-invasive electrophysiological (EP) testing, (iv) assess changes of non-invasive risk stratification tests over time, and (v) associate arrythmogenomic risk through 19 candidate genes. METHODS AND RESULTS: Patients with clinical ICD indication are eligible for the trial. Upon inclusion, patients will undergo non-invasive risk stratification, including beat-to-beat variability of repolarization (BVR), T-wave alternans, T-wave morphology variables, ambient arrhythmias from Holter, heart rate variability, and heart rate turbulence. Non-invasive or invasive programmed electrical stimulation will assess inducibility of ventricular arrhythmias, with the latter including recordings of monophasic action potentials and assessment of restitution properties. Established candidate genes are screened for variants. The primary endpoint is all-cause mortality, while one of the secondary endpoints is ICD shock risk. A mean follow-up of 3.3 years is anticipated. Non-invasive testing will be repeated annually during follow-up. It has been calculated that 700 patients are required to identify risk predictors of the primary endpoint, with a possible increase to 1000 patients based on interim risk analysis. CONCLUSION: The EUTrigTreat clinical study aims to overcome current shortcomings in sudden cardiac death risk stratification and to answer several related research questions. The initial patient recruitment is expected to be completed in July 2012, and follow-up is expected to end in September 2014. Clinicaltrials.gov identifier: NCT01209494.

Cardiovascular magnetic resonance imaging patterns of acute COVID-19 mRNA vaccine-associated myocarditis in young male patients: A first single-center experience.

Background: The risk of myocarditis after mRNA vaccination against COVID-19 has emerged recently. Current evidence suggests that young male patients are predominantly affected. In the majority of the cases, only mild symptoms were observed. However, little is known about cardiac magnetic resonance (CMR) imaging patterns in mRNA-related myocarditis and their differences when compared to classical viral myocarditis in the acute phase of inflammation. Methods and results: In total, 10 mRNA vaccination-associated patients with myocarditis were retrospectively enrolled in this study and compared to 10 patients suffering from viral myocarditis, who were matched for age, sex, comorbidities, and laboratory markers. All patients (n = 20) were hospitalized and underwent a standardized clinical examination, as well as an echocardiography and a CMR. Both, clinical and imaging findings and, in particular, functional and volumetric CMR assessments, as well as detailed tissue characterization using late gadolinium enhancement and T1 + T2-weighted sequences, were compared between both groups. The median age of the overall cohort was 26 years (group 1: 25.5; group 2: 27.5; p = 0.57). All patients described chest pain as the leading reason for their initial presentation. CMR volumetric and functional parameters did not differ significantly between both groups. In all cases, the lateral left ventricular wall showed late gadolinium enhancement without significant differences in terms of the localization or in-depth tissue characterization (late gadolinium enhancement [LGE] enlargement: group 1: 5.4%; group 2: 6.5%; p = 0.14; T2 global/maximum value: group 1: 38.9/52 ms; group 2: 37.8/54.5 ms; p = 0.79 and p = 0.80). Conclusion: This study yielded the first evidence that COVID-19 mRNA vaccine-associated myocarditis does not show specific CMR patterns during the very acute stage in the most affected patient group of young male patients. The observed imaging markers were closely related to regular viral myocarditis in our cohort. Additionally, we could not find any markers implying adverse outcomes in this relatively little number of patients; however, this has to be confirmed by future studies that will include larger sample sizes.

Transthoracic echocardiography to rule out paroxysmal atrial fibrillation as a cause of stroke or transient ischemic attack.

BACKGROUND AND PURPOSE: We assessed whether echocardiography can predict paroxysmal atrial fibrillation (PAF) in patients with cerebral ischemia presenting in sinus rhythm. METHODS: Within the prospective Find-AF cohort, 193 consecutive patients with cerebral ischemia and sinus rhythm on presentation had evaluation of echocardiographic parameters of left atrial size and function. PAF was diagnosed by 7-day Holter monitoring. RESULTS: In 26 patients with PAF, late diastolic Doppler (A) and tissue Doppler (a') velocities were lower whereas left atrial diameter, left atrial volume index (LAVI), LAVI/A, and LAVI/a' were larger (P<0.05 for all) than they were in 167 patients without PAF. In multivariate models A, a', LAVI/A, and LAVI/a' predicted the presence of PAF. Area under the receiver operating characteristic curve to diagnose PAF was highest for LAVI/a' (0.813 [0.738; 0.889]). A previously suggested cut-off of LAVI/a'<2.3 had 92% sensitivity, 55.8% specificity, and 98% negative predictive value for PAF. CONCLUSIONS: LAVI/a'<2.3 can effectively rule out PAF in patients with cerebral ischemia.

Acute and long-term feasibility of contralateral transvenous lead placement with subcutaneous, pre-sternal tunnelling in patients with chronically implanted rhythm devices.

AIMS: A growing number of patients with implanted rhythm devices require new or additional leads, e.g. in cases of electrode defect or planned device upgrade. If the ipsilateral subclavian vein is occluded, transvenous electrode placement from the contralateral side with subcutaneous, pre-sternal lead tunnelling (TUN) is one potential option that has been described in anecdotal reports. The aim of this retrospective study was to determine the acute and long-term feasibility of this approach. METHODS AND RESULTS: We identified 18 subjects (67% male, 66±14 years) who underwent TUN at our institution between the years 1995 and 2009. Implantation protocols and patient files were reviewed for peri-operative complications and long-term lead performance. Furthermore, patients were interviewed for symptoms related to the tunnelled lead. Twenty transvenous leads (seven implantable cardioverter defibrillator leads; five left ventricular, four right ventricular, four right atrial pace/sense electrodes) were successfully tunnelled without significant peri-operative complications. The follow-up duration was 29±36 (3-162) months. Electrical parameters remained stable in 95% (19/20) of the tunnelled leads. In one right ventricle pace/sense lead, ventricular oversensing was documented 10 months after TUN, and the lead was replaced because a structural defect could not be excluded. Five patients died without causal relationship to the procedure 4-48 months after TUN. One patient reported discomfort related to the tunnelled lead. CONCLUSION: Contralateral transvenous lead implantation with subcutaneous, pre-sternal TUN appears to be a feasible option in selected patients with an implanted rhythm device and ipsilateral subclavian vein occlusion.

Sudden cardiac death after implantation of a cardiac resynchronization therapy pacemaker: a case report illustrating that not always less is more.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves symptoms and survival in selected patients with systolic heart failure and ventricular conduction delay. In subjects without prior life-threatening ventricular arrhythmia, clinicians have to select between implanting a CRT pacemaker (CRT-P) or a more complex device with additional defibrillator capability (CRT-D). This individual decision can be challenging in light of the available evidence and the potential risks and benefits. CASE SUMMARY: A 76-year-old male with non-ischaemic cardiomyopathy, heart failure New York Heart Association Class III, left bundle branch block (QRS duration 185 ms) and a left ventricular ejection fraction of 30% despite optimal medical therapy was indicated for CRT. In light of the patient characteristics and clinical condition, a CRT-P device was implanted. No complication occurred, and the patient was discharged after an appropriate device function was confirmed. Despite the clinical improvement, he died suddenly without prior symptoms approximately 2 months thereafter. Post-mortem device interrogation provided no evidence for device malfunction and confirmed sudden cardiac death (SCD) due to spontaneous ventricular fibrillation. DISCUSSION: Patients indicated for CRT often have overlapping internal cardioverter defibrillator indication for the primary prevention of SCD. By weighing individual risks and potential benefits, clinicians have to decide whether to implant a CRT-P (less is more) or a more complex and costly CRT-D device. Despite careful consideration of patient characteristics and clinical conditions, however, SCD can occur in subjects categorized as low risk and implanted with a CRT-P. More data from randomized clinical trials are needed to better support physicians in the often challenging process of selecting the most appropriate device for CRT.

Generation and cardiac differentiation of an induced pluripotent stem cell line from a patient with arrhythmia-induced cardiomyopathy.

Arrhythmia-induced cardiomyopathy (AIC) is characterized by left-ventricular systolic dysfunction caused by persistent arrhythmia. To date, genetic or pathological drivers causing AIC remain unknown. Here, we generated induced pluripotent stem cells (iPSCs) from an AIC patient. The AIC-iPSCs exhibited full pluripotency and differentiation characteristics and maintained a normal karyotype after reprogramming. The AIC-iPSCs differentiated into functional beating AIC-iPSC-cardiomyocytes (CMs), which represents the cell-type of interest to study molecular, genetic and functional aspects of AIC.

Enhanced detection of paroxysmal atrial fibrillation by early and prolonged continuous holter monitoring in patients with cerebral ischemia presenting in sinus rhythm.

BACKGROUND AND PURPOSE: Diagnosis of paroxysmal atrial fibrillation is difficult but highly relevant in patients presenting with cerebral ischemia yet free from atrial fibrillation on admission. Early initiation and prolongation of continuous Holter monitoring may improve diagnostic yield compared with the standard of care including a 24-hour Holter recording. METHODS: In the observational Find-AF trial (ISRCTN 46104198), consecutive patients presenting with symptoms of cerebral ischemia were included. Patients free from atrial fibrillation at presentation received 7-day Holter monitoring. RESULTS: Two hundred eighty-one patients were prospectively included. Forty-four (15.7%) had atrial fibrillation documented by routine electrocardiogram on admission. All remaining patients received Holter monitors at a median of 5.5 hours after presentation. In those 224 patients who received Holter monitors but had no previously known paroxysmal atrial fibrillation, the detection rate with early and prolonged (7 days) Holter monitoring (12.5%) was significantly higher than for any 24-hour (mean of 7 intervals: 4.8%, P = 0.015) or any 48-hour monitoring interval (mean of 6 intervals: 6.4%, P = 0.023). Of those 28 patients with new atrial fibrillation on Holter monitoring, 15 (6.7%) had been discharged without therapeutic anticoagulation after routine clinical care (ie, with data from 24-hour Holter monitoring only). Detection rates were 43.8% or 6.3% for short supraventricular runs of ≥ 10 beats or prolonged episodes (> 5 hours) of atrial fibrillation, respectively. Diagnostic yield appeared to be only slightly and not significantly increased during the first 3 days after the index event. CONCLUSIONS: Prolongation of Holter monitoring in patients with symptoms of cerebral ischemic events increases the rate of detection of paroxysmal atrial fibrillation up to Day 7, leading to a relevant change in therapy in a substantial number of patients. Early initiation of monitoring does not appear to be crucial. Hence, prolonged Holter monitoring (≥ 7 days) should be considered for all patients with unexplained cerebral ischemia.

Ventricular oversensing due to manufacturer-related differences in implantable cardioverter-defibrillator signal processing and sensing lead properties.

AIMS: Ventricular oversensing remains a significant problem in modern implantable cardioverter-defibrillator (ICD) systems. The role of manufacturer-related differences in device-based signal processing on the one hand and sensing lead properties on the other is largely unknown. This retrospective study aimed to evaluate and compare the incidence and mechanisms of ventricular oversensing in single- or dual-chamber ICD systems from Biotronik (BTK), Guidant (GDT), and Medtronic (MDT). METHODS AND RESULTS: In 245 consecutive patients, device function, stored episodes, and lead parameters were evaluated at implant and during 243 ± 18 days of follow-up. Oversensing occurred in 3.3% of the patients [four T-wave oversensing (TWO), three R-wave double-sensing, and one diaphragmatic myopotentials]. The incidence of ventricular oversensing was generally low if an ICD device and an ICD lead were from one identical manufacturer (BTK: 2/68, GDT: 1/80, and MDT: 1/69; P = 0.67). In the subgroup of ICDs connected to leads from other manufacturers, however, ventricular oversensing was observed in none of 19 GDT and MDT ICDs but in 4 of 9 BTK devices (44.4%, P = 0.012). These four cases of oversensing (three R-wave double-sensing and one TWO) all occurred in BTK ICDs connected to integrated bipolar ICD leads from other manufacturers. CONCLUSION: Significant manufacturer-related differences exist in the incidence of ventricular oversensing in single- and dual-chamber ICD systems. Biotronik devices connected to integrated bipolar ICD leads from other manufacturers have an increased risk for R-wave double-sensing.

Interference of remote magnetic catheter navigation and ablation with implanted devices for pacing and defibrillation.

AIMS: Remote magnetic catheter navigation (RMN) may facilitate catheter ablation. However, as the system uses permanent magnets, interference (INF) with devices for pacing [pacemaker (PM)], defibrillation [implantable cardioverter defibrillators (ICD)], or cardiac resynchronisation [cardiac resynchronization therapy (CRT)] may occur. We investigated the effects of the RMN system on implanted arrhythmia devices in a prospective series. METHODS AND RESULTS: Prior to RMN-guided electrophysiological procedures, devices were fully interrogated and programmed to VVI 40/min with tachycardia detection off (if applicable). Periprocedural device performance was monitored by 12-lead electrocardiogram, and duration and effect of asynchronous stimulation resulting from INF were evaluated. Following the procedure, devices were again interrogated and system integrity verified. A total of 21 procedures in 18 patients with implanted devices [PM n = 12, ICD n = 3, CRT-pacemaker (P) n = 1, CRT-defibrillation (D) n = 2] were evaluated. No relevant changes in lead parameters or device programming were observed after the procedure. No INF was noted in ICD/CRT-D devices (tachycardia detection off) and in 2 PMs, whereas 10 PMs and 1 CRT-P switched to asynchronous stimulation for 1.8 ± 0.3 h (63 ± 13% of RMN duration) without clinical adverse effects. In one patient, ventricular tachycardia (VT) degenerating in ventricular fibrillation occurred, but no causal relation between INF and VT initiation could be ascertained. CONCLUSION: This prospective data provide no evidence that using RMN in patients with implanted arrhythmia devices may cause persistent device dysfunction. Asynchronous PM stimulation is common without negative clinical consequences. Although a causal role of INF for the VT observed seems unlikely, risks and benefits of RMN utilization should carefully be weighed for each patient with an implanted arrhythmia device.

[Safety and efficiency of interventional electrophysiology utilizing the German "Belegarztsystem"]. / Effizienz und Sicherheit einer interventionellen Elektrophysiologie im kooperativen Belegarztsystem.

INTRODUCTION: Electrophysiology study (EPS) and catheter ablation (abl.), in particular for atrial fibrillation, are increasingly performed in Germany. Therefore, measures and steps to ensure quality assurance are indicated. Most of the procedures are performed by physicians employed by hospitals; however, some are also carried out by attending cardiologists on contract in private practice, applying the so-called Belegarztsystem. The aim of this study was to determine the safety and efficiency of an interventional electrophysiology performed in a German Belegarztsystem. METHODS: Based on a prospective registry, we analyzed procedure-related data from 1400 consecutive EPS/abl. performed at our center between 2014 and 2018. One-year follow-up data (arrhythmia recurrences, complications, deaths) were collected for all procedures carried out during the first 2 years. RESULTS: In the total study cohort, no periprocedural death occurred, and there was a low cumulative incidence of groin complications (0.9%). The most common procedure (n = 772) was complex ablation for atrial fibrillation/flutter (55%). In this group, the success rate was 98% (acute) and 65% (1 year), and the cumulative rate of complications was 5.0% (transient ischemic attack/stroke 0.1%, pericardial tamponade 0.4%, relevant pericarditis/pericardial effusion 1.1%, groin complication 1.5%, other 1.9%). For the other procedures, rates for success and complications were comparable, and procedure times and x­ray doses tended to be lower in our analysis as compared to prior reports. CONCLUSION: Interventional electrophysiology, carried out by experienced operators and qualified staff, can be performed safely and effectively by attending physicians in a Belegarztsystem.

Cardiac resynchronization therapy and atrial overdrive pacing for the treatment of central sleep apnoea.

AIMS: The combined therapeutic impact of atrial overdrive pacing (AOP) and cardiac resynchronization therapy (CRT) on central sleep apnoea (CSA) in chronic heart failure (CHF) so far has not been investigated. We aimed to evaluate the effect of CRT alone and CRT + AOP on CSA in CHF patients and to compare the influence of CRT on CHF between CSA positive and CSA negative patients. METHODS AND RESULTS: Thirty patients with CRT indication underwent full night polysomnography, echocardiography, exercise testing, and neurohumoral evaluation before and 3 months after CRT implantation. In CSA positive patients (60%), two additional sleep studies were conducted after 3 months of CRT, with CRT alone or CRT + AOP, in random order. Cardiac resynchronization therapy resulted in significant improvements of NYHA class, left ventricular ejection fraction, N-terminal pro-brain natriuretic peptide, VO(2)max, and quality of life irrespective of the presence of CSA. Cardiac resynchronization therapy also reduced the central apnoea-hypopnoea index (AHI) (33.6 +/- 14.3 vs. 23.8 +/- 16.9 h(-1); P < 0.01) and central apnoea index (17.3 +/- 14.1 vs. 10.9 +/- 13.9 h(-1); P < 0.01) without altering sleep stages. Cardiac resynchronization therapy with atrial overdrive pacing resulted in a small but significant additional decrease of the central AHI (23.8 +/- 16.9 vs. 21.5 +/- 16.9 h(-1); P < 0.01). CONCLUSION: In this study, CRT significantly improved CSA without altering sleep stages. Cardiac resynchronization therapy with atrial overdrive pacing resulted in a significant but minor additional improvement of CSA. Positive effects of CRT were irrespective of the presence of CSA.

Arrhythmia-Induced Cardiomyopathy.

BACKGROUND: Heart failure affects 1­2% of the population and is associated with elevated morbidity and mortality. Cardiac arrhythmias are often a result of heart failure, but they can cause left-ventricular systolic dysfunction (LVSD) as an arrhythmia-induced cardiomyopathy (AIC). This causal relationship should be borne in mind by the physician treating a patient with systolic heart failure in association with cardiac arrhythmia. METHODS: This review is based on pertinent publications retrieved by a selective search in PubMed (1987­2017) and on the recommendations in current guidelines. RESULTS: The key criterion for the diagnosis of an AIC is the demonstration of a persistent arrhythmia (including pathological tachycardia) together with an LVSD whose origin cannot be explained on any other basis. Nearly any type of tachyarrhythmia or frequent ventricular extrasystoles can lead, if persistent, to a progressively severe LVSD. The underlying pathophysiologic mechanisms are incompletely understood; the increased ventricular rate, asynchronous cardiac contractions, and neurohumoral activation all seem to play a role. The most common precipitating factors are supraventricular tachycardias in children and atrial fibrillation in adults. Recent studies have shown that the causal significance of atrial fibrillation in otherwise unexplained LVSD is underappreciated. The treatment of AIC consists primarily of the treatment of the underlying arrhythmia, generally with drugs such as beta-blockers and amiodarone. Depending on the type of arrhythmia, catheter ablation for long-term treatment should also be considered where appropriate. The diagnosis of AIC is considered to be well established when the LVSD normalizes or improves within a few weeks or months of the start of targeted treatment of the arrhythmia. CONCLUSION: An AIC is potentially reversible. The timely recognition of this condition and the appropriate treatment of the underlying arrhythmia can substantially improve patient outcomes.