Implantable cardiac devices in adult patients with repaired tetralogy of Fallot.

OBJECTIVES: Implantable cardiac devices are common in patients with tetralogy of Fallot (ToF) (18.3-21.3%) according to previous reports from large centres. We conducted this study to investigate the prevalence and incidence of cardiac devices in a less selected population of patients with ToF and assess factors other than arrhythmia associated with having a device. Design: 530 adult (≥18 years) patients with repaired ToF were identified in the national registry of congenital heart disease (SWEDCON) and matched with data from the Swedish pacemaker registry. Patients with implantable cardiac devices were compared with patients without devices. Results: Seventy-five patients (14.2%) had a device; 51 (9.6%) had a pacemaker and 24 (4.5%) had an implantable cardioverter defibrillator. The incidence in adult age (≥18 years) was 5.9/1000 patient years. Estimated device free survival was 97.5% at twenty, 87.2% at forty and 63.5% at sixty years of age. Compared with previous studies, the prevalence of devices was lower, especially for ICD. In multivariate logistic regression, cardiovascular medication (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.8-6.8), impaired left ventricular function, (OR 2.6, 95%CI 1.3-5.0) and age (OR 1.02, 95%CI 1.002-1.05) were associated with having a device. Conclusion: The prevalence of devices in our population, representing a multicenter register cohort, was lower than previously reported, especially regarding ICD. This can be due to differences in treatment traditions with regard to ICD in this population, but it may also be that previous studies have reported selected patients with more severe disease.

A decade of catheter ablation of cardiac arrhythmias in Sweden: ablation practices and outcomes.

AIMS: Catheter ablation is considered the treatment of choice for many tachyarrhythmias, but convincing 'real-world' data on efficacy and safety are lacking. Using Swedish national registry data, the ablation spectrum, procedural characteristics, as well as ablation efficacy and reported adverse events are reported. METHODS AND RESULTS: Consecutive patients (≥18 years of age) undergoing catheter ablation in Sweden between 01 January 2006 and 31 December 2015 were included in the study. Follow-up (repeat ablation and vital status) was collected through 31 December 2016. A total of 26 642 patients (57 ± 15 years, 62% men), undergoing a total of 34 428 ablation procedures were included in the study. In total, 4034 accessory pathway/Wolff-Parkinson-White syndrome (12%), 7358 AV-nodal re-entrant tachycardia (21%), 1813 atrial tachycardia (5.2%), 5481 typical atrial flutter (16%), 11 916 atrial fibrillation (AF, 35%), 2415 AV-nodal (7.0%), 581 premature ventricular contraction (PVC, 1.7%), and 964 ventricular tachycardia (VT) ablations (2.8%) were performed. Median follow-up time was 4.7 years (interquartile range 2.7-7.0). The spectrum of treated arrhythmias changed over time, with a gradual increase in AF, VT, and PVC ablation (P < 0.001). Decreasing procedural times and utilization of fluoroscopy with time, were seen for all arrhythmia types. The rates of repeat ablation differed between ablation types, with the highest repeat ablation seen in AF (41% within 3 years). The rate of reported adverse events was low (n = 595, 1.7%). Death in the immediate period following ablation was rare (n = 116, 0.34%). CONCLUSION: Catheter ablations have shifted towards more complex procedures over the past decade. Fluoroscopy time has markedly decreased and the efficacy of catheter ablation seems to improve for AF.

Two Cases of LQT Syndrome with Malignant Syncope after Switch from Propranolol to Bisoprolol.

Propranolol in slow-release form has been the first-line treatment in long QT (LQT) until it was withdrawn from the market. We describe two cases where a switch to bisoprolol resulted in worsening of arrhythmia control: A man with LQT2, asymptomatic on propranolol, experienced syncope after switching to bisoprolol 5 mg daily. He switched back to propranolol and has remained asymptomatic during subsequent 12 months. A man with classical Jervell Lange-Nielsen syndrome, previous gangliectomy, and ICD implantation, switched to bisoprolol 5 mg daily. Four months later he experienced a tachycardia storm. He switched back to propranolol and has remained free from arrhythmias during subsequent 12 months.

Detection of paroxysmal atrial fibrillation in 994 patients with a cerebrovascular event by intermittent 21-day ECG-monitoring and 7-day continuous Holter-recording.

Background: The detection of paroxysmal atrial fibrillation (AF) is of importance in stroke care. The method used is continuous electrocardiogram (ECG)-monitoring or multiple short ECG-recordings during an extended period. Their relative efficiency is a matter of discussion. In a retrospective cohort study on 994 patients with an ischemic stroke or transient ischemic attack (TIA), we have compared continuous 7-day monitoring to intermittent recording 60 sec three times daily with a handheld device during 3 weeks. We related the result to subsequent occurrence of AF as detected in 12-lead ECG recordings. Methods: The patients were identified in the local database of cardiovascular investigations. Their clinical profile and vital status during the follow-up were obtained from the Swedish Stroke Register and the Swedish general population registry. For comparison, we used an age- and sex-matched population with no known cerebrovascular event and a population with a cerebrovascular event that was not screened. Results: AF was detected in 7.1% by continuous screening and in 5.1% by intermittent screening (P = 0.3). During follow-up of 32 months, AF in 12-lead ECG was found in 7.0%. In the subgroup with positive screening, 46.3% had AF compared with 6.7% in the subgroup with negative screening (P < 0.0001). Conclusions: The two screening approaches had a similar yield of arrhythmia, in spite of the group with intermittent monitoring having a more favorable clinical profile. A positive screening was highly predictive of AF in ECG during the follow-up.

Right ventricular lead positioning does not influence the benefits of cardiac resynchronization therapy in patients with heart failure and atrial fibrillation.

AIMS: Little is known about the optimal right ventricular (RV) pacing site in cardiac resynchronization therapy (CRT). This study compares bi-ventricular pacing at the left ventricular (LV) free wall combined with two different RV stimulation sites: RV outflow tract (RVOT+LV) vs. RV-apex (RVA+LV). METHODS AND RESULTS: Thirty-three patients (32 males) with chronic heart failure, NYHA class III-IV, optimal drug therapy, QRS-duration ≥150 ms, and chronic atrial fibrillation (AF) received CRT with two different RV leads, in the apex (RVA) or outflow tract (RVOT), together with an LV lead, all connected to a bi-ventricular pacemaker. Randomization to pacing in RVOT+LV or RVA+LV was made 1 month after implantation and cross-over to the alternate pacing configuration occurred after 3 months. The median age of patients was 69 ± 10 years, the mean QRS was 179 ± 23 ms, and 58% of patients had ischaemic heart disease. Seven patients had pacemaker rhythm at inclusion and 60% were treated with atrioventricular-junctional ablation before randomization. In the RVA+LV and RVOT+LV pacing modes, 67 and 63% (nonsignificant) responded symptomatically with a decrease of at least 10 points in the Minnesota Living with Heart Failure score. The secondary end-points (6-min walk test, peak oxygen uptake, N-Terminal fragment of B-type Natriuretic Peptide, and left ventricular ejection fraction) showed significant improvement between baseline and CRT, but not between RVOT+LV and RVA+LV. CONCLUSION: In this randomized controlled study, the exact RV pacing site, either apex or outflow tract, did not influence the benefits of CRT in a group of patients with chronic heart failure and AF. ClinicalTrials.gov ID: NCT00457834.

Two automatic QT algorithms compared with manual measurement in identification of long QT syndrome.

BACKGROUND: Long QT syndrome (LQTS) is an inherited disorder that increases the risk of syncope and malignant ventricular arrhythmias, which may result in sudden death. METHODS: We compared manual measurement by 4 observers (QT(manual)) and 3 computerized measurements for QT interval accuracy in the diagnosis of LQTS: 1. QT measured from the vector magnitude calculated from the 3 averaged orthogonal leads X, Y, and Z (QTVCG) and classified using the same predefined QTc cut-points for classification of QT prolongation as in manual measurements; 2. QT measured by a 12-lead electrocardiogram (ECG) program (QTECG) and subsequently classified using the same cut-points as in (1) above; 3. The same QT value as in (2) above, automatically classified by a 12-lead ECG program with thresholds for QT prolongation adjusted for age and sex (QTinterpret). The population consisted of 94 genetically confirmed carriers of KCNQ1 (LQT1) and KCNH2 (LQT2) mutations and a combined control group of 28 genetically confirmed noncarriers and 66 unrelated healthy volunteers. RESULTS: QT(VCG) provided the best combination of sensitivity (89%) and specificity (90%) in diagnosing LQTS, with 0.948 as the area under the receiver operating characteristic curve. The evaluation of QT measurement by the 4 observers revealed a high interreader variability, and only 1 of 4 observers showed acceptable level of agreement in LQTS mutation carrier identification (kappa coefficient >0.75). CONCLUSION: Automatic QT measurement by the Mida1000/CoroNet system (Ortivus AB, Danderyd, Sweden) is an accurate, efficient, and easily applied method for initial screening for LQTS.

Ablation procedures in Sweden during 2007: results from the Swedish Catheter Ablation Registry.

AIMS: Catheter ablation research is reported extensively. Much less is known about the clinical practice in the field. Study databases and surveys target selected populations. A general registry is needed to evaluate the actual results of routine catheter ablation. We present statistics from the Swedish Catheter Ablation Registry. METHODS AND RESULTS: The registry is a nation-wide database collecting data from all the eight centres serving the country's population of 9.18 million inhabitants. During each ablation procedure, the data are entered into a local database. On demand, the data are transferred to the central data management facility. The central SQL-database presently covers 7018 ablations performed in 5885 patients during 2004-07. In 2007, 2314 ablation procedures [521 for atrial fibrillation (AF)] were performed (252 ablations per million inhabitants and 57 AF procedures per million inhabitants). Mean procedure and fluoroscopy times ranked from 75 and 12 min, respectively, for atrioventricular junction ablation to 224 and 43 min, respectively, for AF ablation. The incidence of complications during 2007 was 1.8%. One death after a procedure for AF was reported, due to a cerebrovascular embolus. CONCLUSION: The report presents prospective-gathered annual data from a nation-wide ablation register with voluntary participation. Several major complications have been reported, but the overall complication rate was low.

U22, a protocol to quantify symptoms associated with supraventricular tachycardia.

BACKGROUND: The main indication for ablation of supraventricular tachyarrhythmias (SVTA) is symptomatic relief. Specific paroxysmal symptoms cannot be quantified with general measures of quality of life, such as with the SF-36 questionnaire. U22 is a new protocol which measures the effects of arrhythmia on well-being, the intensity of discomfort during an episode, the type and temporal characteristics of dominant symptoms, and the duration and frequency of episodes. Discrete 0-10 scales are used. Unlike SF-36, U22 can be used in individual patients. METHODS: U22 and SF-36 protocols were used in the symptomatic evaluation of 88 patients (mean age = 49.6 +/- 16.4 years; 43 men), who underwent catheter ablation of SVTA. RESULTS: The U22 scores (SD) for (a) well-being (10 being best), (b) effects of arrhythmia on well-being (10 being worst), and (c) discomfort during arrhythmia (10 being worst) were 5.6 (2.7), 7.5 (2.8), and 8.0 (2.4), respectively. For comparison, the physical and mental component summaries of SF-36 were 45.3 (11.0) and 45.2 (12.1), respectively, slightly lower than the expected normal of 50. The intensity of dominant symptom scored by U22 was 9.7 (1.2), 10 being worst. In 29% of patients > or =4 symptoms were equally dominant. Multiple dominant symptoms in U22 were associated with a low general well-being in SF-36. CONCLUSION: We found U22 useful to quantify symptoms associated with SVTA.

Nondipolar content of T wave derived from a myocardial source simulation with increased repolarization inhomogeneity.

BACKGROUND: Several conditions with repolarization disturbances are associated with increased level of nondipolar components of the T wave. The nondipolar content has been proposed as a measure of repolarization inhomogeneity. This computer simulation study examines the link between increased nondipolar components and increased repolarization inhomogeneity in an established model. METHODS: The simulation was performed with Ecgsim software that uses the equivalent double-layer source model. In the model, the shape of transmembrane potential is derived from biological recordings. Increased repolarization inhomogeneity was simulated globally by increasing the variance in action potential duration and locally by introducing changes mimicking acute myocardial infarction. We synthesized surface ECG recordings with 12, 18, and 300 leads. The T-wave residue was calculated by singular value decomposition. The study examined the effects of the number of ECG leads, changes in definition of end of T wave and random noise added to the signal. RESULTS: Normal myocardial source gave a low level of nondipolar content. Increased nondipolar content was observed in the two types of increased repolarization inhomogeneity. Noise gave a large increase in the nondipolar content. The sensitivity of the result to noise increased when a higher number of principal components were used in the computation. CONCLUSIONS: The nondipolar content of the T wave was associated with repolarization inhomogeneity in the computer model. The measure was very sensitive to noise, especially when principal components of high order were included in the computations. Increased number of ECG leads resulted in an increased signal-to-noise ratio.

Increased risk of late pacemaker implantation after ablation for atrioventricular nodal reentry tachycardia: A 10-year follow-up of a nationwide cohort.

BACKGROUND: Catheter ablation of the slow pathway is the standard treatment of atrioventricular nodal reentry tachycardia (AVNRT) with a well described low risk of periprocedural atrioventricular block. Less is known about the risk of pacemaker implantation late after ablation. OBJECTIVE: We aimed to quantify the risk of late pacemaker implantation in a countrywide cohort undergoing first-time ablation for AVNRT. METHODS: All patients undergoing first-time ablation for AVNRT in Sweden from 2004 to 2014 were identified from the Swedish catheter ablation registry and matched against the Swedish Pacemaker and ICD registry. The cohort was compared to patients ablated for an accessory pathway (AP) and to matched controls. RESULTS: During follow-up of 2039 days, pacemaker was implanted later than 30 days after ablation in 96 of 6842 patients with AVNRT (1.4%), 29 of 4065 patients with AP (0.7%) (P = .001), and 124 of 33,270 controls (0.4%) (P < .00001). A periprocedural pacemaker (≤30 days postablation) was implanted in 32 of 6877 patients with AVNRT (0.5%) and 9 of 4079 patients with AP (0.2%) (P = .05). With cryoablation, 5 patients needed periprocedural pacemaker implantation. Pacemakers were implanted before ablation in 88 of 6977 patients with AVNRT (1.3%) and 11 of 4100 patients with AP (0.3%); the prevalence of pacemaker implants in controls was 124 of 33,270 (0.4%) (P < .00001 for both comparisons). CONCLUSION: The risk of late pacemaker implantation after AVNRT ablation was low but 3 times higher than that in the control population and 3 times higher than the risk of periprocedural pacemaker implantation. Similar results were observed with cryoablation and radiofrequency ablation. Ablation may not be the cause of increased late pacemaker implantation risk.

Entrapment of circular mapping catheter in the mitral valve.

BACKGROUND: Ablation procedures in the left atrium for treatment of atrial fibrillation are becoming increasingly common. The procedure often involves placing one or two circular mapping catheters in the left atrium. Entrapment of an ablation catheter in the mitral valve during ablations of left-sided accessory pathways by the retrograde approach has been described in two earlier published reports. More recently, several reports describe similar entrapment of a mapping catheter. In a recently published review, however, only one case of unspecified valve damage was registered among 8745 atrial fibrillation procedures. OBJECTIVE: The purpose of this study was to evaluate patients with entrapment. METHODS: Retrospective analysis of electrophysiological results. RESULTS: We describe three patients with entrapment during ablations for atrial fibrillation. The entrapments occurred with three different operators at three different electrophysiological laboratories within 2 years. The complication described here may be more common than is widely appreciated. CONCLUSIONS: From our figures, we estimate the incidence of the complication to 0.9% (95% confidence interval, 0.2-2.5%).

Cardioversion of atrial fibrillation does not affect obstructive sleep apnea.

BACKGROUND: Sleep apnea is common in patients with atrial fibrillation, but the effect of the cardioversion of atrial fibrillation to sinus rhythm on central and obstructive apneas is mainly unknown. The primary aim of the study was to analyze the association between cardioversion of atrial fibrillation and sleep apneas, to investigate whether obstructive or central sleep apneas are reduced following cardioversion. A secondary objective was to study the effect on sleep quality. METHODS: Twenty-three patients with atrial fibrillation were investigated using overnight polysomnography, including esophagus pressure monitoring and ECG, before and after the cardioversion of persistent atrial fibrillation. RESULTS: Obstructive sleep apnea occurred in 17/23 patients (74%), and central sleep apnea in 6/23 patients (26%). Five patients had both obstructive and central sleep apnea. Sinus rhythm at follow-up was achieved in 16 patients. The obstructive apnea-hypopnea index, central apnea-hypopnea index, and the number of patients with obstructive or central sleep apnea did not differ before and after restoration of sinus rhythm. Sleep time, sleep efficiency, time in different sleep stages, and subjective daytime sleepiness were normal and unaffected by cardioversion. CONCLUSIONS: Both obstructive and central sleep apneas are highly prevalent in patients with persistent atrial fibrillation. Obstructive sleep apneas are unaffected by the cardioversion of atrial fibrillation to sinus rhythm. The sleep pattern is normal and unaffected by cardioversion in patients with atrial fibrillation. CLINICAL TRIAL REGISTRATION: Trial number NCT00429884.

Assessment of Use vs Discontinuation of Oral Anticoagulation After Pulmonary Vein Isolation in Patients With Atrial Fibrillation.

Importance: Pulmonary vein isolation (PVI) is a recommended treatment for patients with atrial fibrillation, but it is unclear whether it results in a lower risk of stroke. Objectives: To investigate the proportion of patients discontinuing anticoagulation treatment after PVI in association with the CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years [doubled], diabetes, stroke [doubled], vascular disease, age 65-74 years, sex category [female]) score, identify factors predicting stroke after PVI, and explore the risk of cardiovascular events after PVI in patients with and without guideline-recommended anticoagulation treatment. Design, Setting, and Participants: A retrospective cohort study was conducted using Swedish national health registries from January 1, 2006, to December 31, 2012, with a mean-follow up of 2.6 years. A total of 1585 patients with atrial fibrillation undergoing PVI from the Swedish Catheter Ablation Register were included, with information about exposure to warfarin in the national quality register Auricula. Data analysis was performed from January 1, 2015, to April 30, 2016. Exposures: Warfarin treatment. Main Outcomes and Measures: Ischemic stroke, intracranial hemorrhage, and death. Results: In this cohort of 1585 patients, 73.0% were male, the mean (SD) age was 59.0 (9.4) years, and the mean (SD) CHA2DS2-VASc score was 1.5 (1.4). Of the 1585 patients, 1175 were followed up for more than 1 year after PVI. Of these, 360 (30.6%) discontinued warfarin treatment during the first year. In patients with a CHA2DS2-VASc score of 2 or more, patients discontinuing warfarin treatment had a higher rate of ischemic stroke (5 events in 312 years at risk [1.6% per year]) compared with those continuing warfarin treatment (4 events in 1192 years at risk [0.3% per year]) (P = .046). Patients with a CHA2DS2-VASc score of 2 or more or those who had previously experienced an ischemic stroke displayed a higher risk of stroke if warfarin treatment was discontinued (hazard ratio, 4.6; 95% CI, 1.2-17.2; P = .02 and hazard ratio, 13.7; 95% CI, 2.0-91.9; P = .007, respectively). Conclusions and Relevance: These findings indicate that discontinuation of warfarin treatment after PVI is not safe in high-risk patients, especially those who have previously experienced an ischemic stroke.

Non-dipolar content of the T-wave as a measure of repolarization inhomogeneity in ST-elevation myocardial infarction.

The non-dipolar content of the T-wave, i.e. the component of the signal, which cannot be explained by a dipolar model, has been suggested as a measure of the local repolarization inhomogeneity. Our purpose was to study the non-dipolar content of the T-wave during the initial course of ST-elevation myocardial infarction (STEMI), when local repolarization inhomogeneity presumably is markedly increased. Twelve-lead ECG was semicontinuously collected in 211 patients with STEMI, treated with a thrombolytic agent. The T-wave was processed by principal component analysis. The absolute and relative T-wave residues were used as measures of the non-dipolar content. The median values for each hour and for the entire monitoring time were computed. Changes in the parameters were closer studied in two windows, 0-10 respectively, 11-24 h after start of ECG-monitoring. The median of the absolute T-wave residue during the entire monitoring period was 25 000 units in the STEMI-group and 13 500 units in the comparison group. The median for hour 1 was 36 500 units and 28 800 units for hour 2. The decrease was greater in patients with >or=50% resolution of the ST-elevation at 60 min. The moment of change, identified by cumulative sum-method, showed no correlation to the time for 50% ST-resolution. We conclude, that patients with thrombolysed STEMI have an increased non-dipolar content of the T-wave. Resolution of the ST-elevation is associated with a decrease. The increased non-dipolar content reflects a property of the repolarization phase, which is related to but separated from the ST-elevation.

[No evidence of positive effects of pacemaker use in paroxysmal atrial fibrillation]. / Inga bevis för nytta av pacemaker vid paroxysmalt förmaksflimmer.

Sixteen randomised controlled studies examining the use of pacemakers for the therapeutic prevention of atrial fibrillation were investigated. Four studies dealt with patients without conventional pacemaker indication. A minor positive effect was observed in one study. The validity of the observation is however limited due to a small number of patients and a short follow-up period. Five studies assessed the effect of overdrive pacing and different preventive pacing algorithms. A small, statistically significant positive effect was found in one of these studies. Six studies investigated dual site pacing or septal pacing. Five of these indicated a possible positive effect. Before this approach is implemented clinically, further studies are nevertheless required.