Effect of flecainide on the extension and localization of complex fractionated electrogram during atrial fibrillation

AIMS

Complex fractionated electrogram (CFE) ablation in addition to pulmonary vein isolation is an accepted strategy for the treatment of non-paroxysmal atrial fibrillation (AF). We sought to determine the effect of flecainide on the distribution and extension of CFE areas.

METHODS

Twenty-three non-paroxysmal AF patients were enrolled in this prospective study. A first CFE map was obtained under baseline conditions by sampling 5 s of continuous recording from the distal electrodes of the ablation catheter. Intravenous flecainide (1 mg/kg) was administered over 10 min and followed by 30-min observation time. A second CFE map was obtained with the same modalities. CFE-mean values, CFE areas, and atrial electrogram amplitude were retrieved from the electro-anatomical mapping system (Ensite NavX).

RESULTS

After flecainide administration, CFE-mean values increased (111.5 ± 55.3 vs. 132.3 ± 65.0 ms, p < 0.001) with a decrease of CFE area (32.9%) in all patients. Atrial electrogram amplitude decreased significantly (0.30 ± 0.31 vs. 0.25 ± 0.20 mV, p < 0.001). We observed 80.9% preservation of CFE areas. A CFE mean of 78 ms was the best cutoff for predicting stable CFE areas.

CONCLUSIONS

Flecainide reduces the extension of CFE areas while preserving their spatial localization. A CFE-mean value <80 ms may be crucial to define and locate stable CFE areas.

Long-term outcomes of adjunctive complex fractionated electrogram ablation to pulmonary vein isolation as treatment for non-paroxysmal atrial fibrillation

PURPOSE

The adjunctive ablation of areas of complex fractionated electrogram (CFE) to pulmonary vein isolation (PVI) is an emerging strategy for patients with non-paroxysmal atrial fibrillation (AF). We studied the long-term outcomes of this approach.

METHODS

Sixty-six patients (mean age 58 ± 9, 86.4 % male) with non-paroxysmal AF underwent ablation procedures consisting of PVI plus extensive CFE ablation. Post-ablation atrial tachycardia (AT) was also targeted if presented. All patients were followed up regularly on an ambulatory basis by means of ECG and Holter recordings.

RESULTS

After a mean follow-up period of 40 ± 14 months and 1.7 ± 0.7 procedures, 38 patients (57.6 %) were free of arrhythmias, 15 (22.7 %) displayed clinical improvement and 13 (19.7 %) suffered recurrences of persistent AF/AT. Females displayed poorer long-term outcomes than males (arrhythmia-free 22.2 vs. 63.2 %, p < 0.05). Multivariate analysis demonstrated that long duration of uninterrupted AF prior to the procedure was an additional predictor of long-term failure (odds ratio 1.49, p < 0.01). ROC analysis (area under curve 0.80; p < 0.001) estimated 3.5 years as the optimal cut-off point for predicting long-term failure (sensitivity 85 %, specificity 74 %). The cumulative data showed a significantly higher percentage of arrhythmia-free patients when the duration of AF had been ≤ 2 years (69.7 %) and ≤ 4 years (68.9 %) than when it was > 4 years (33.3 %; p < 0.01).

CONCLUSIONS

PVI + CFE ablation in non-paroxysmal AF appears to provide a reasonable proportion of arrhythmia-free patients during long-term follow-up. Poorer long-term results can be expected among female patients and those with an uninterrupted AF duration of > 4 years.

Ventricular arrhythmias originating from the aortomitral continuity: an uncommon variant of left ventricular outflow tract tachycardia

AIMS

Ventricular arrhythmias arising from the fibrous rings have been demonstrated, but knowledge about the aortomitral continuity (AMC) as a source of the arrhytmias is still limited. The objective is to describe the characteristics of ventricular arrhythmias originating from the AMC in patients without structural heart disease.

METHODS AND RESULTS

Ten patients with ventricular tachycardia (VT) and/or premature ventricular contractions, who had been successfully treated by catheter ablation at the AMC beneath the aortic valve, were enrolled. Clinical data and electrocardiographic characteristics were analysed. Three of the 10 patients had previously registered episodes of supraventricular tachycardia and had undergone catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT). In four patients with anterior AMC location, early R/S wave transition was found in the precordial leads, with equal R and S amplitudes in V2, rS in V1, and R in V3. In six patients whose VT arose from the middle part of the AMC, we demonstrated a special ('rebound') transition pattern, with which equal R and S amplitudes occurred in V2, and high R waves in V1 and V3. In the anterior AMC location, the S/R ratios in leads V1 and V2 were >1 and statistically significantly higher than those located in the middle (V1: 1.59 vs. 0.23, P< 0.001; V2: 1.52 vs. 0.41, P< 0.01).

CONCLUSIONS

We report a series of ventricular arrhythmias arising from the AMC with different R/S wave transition patterns in the precordial leads on the electrocardiogram. There may be a relationship between ventricular arrhythmias from AMC and AVNRT.

Remote magnetic versus manual catheters: evaluation of ablation effect in atrial fibrillation by myocardial marker levels

Background

A remote magnetic navigation (MN) system is available for radiofrequency ablation of atrial fibrillation (AF), challenging the conventional manual ablation technique. The myocardial markers were measured to compare the effects of the two types of MN catheters with those of a manual-irrigated catheter in AF ablation.

Methods

AF patients underwent an ablation procedure using either a conventional manual-irrigated catheter (CIR, n = 65) or an MN system utilizing either an irrigated (RMI, n = 23) or non-irrigated catheter (RMN, n = 26). Levels of troponin T (TnT) and the cardiac isoform of creatin kinase (CKMB) were measured before and after ablation.

Results

Mean procedure times and total ablation times were longer employing the remote magnetic system. In all groups, there were pronounced increases in markers of myocardial injury after ablation, demonstrating a significant correlation between total ablation time and post-ablation levels of TnT and CKMB (CIR r = 0.61 and 0.53, p < 0.001; RMI r = 0.74 and 0.73, p < 0.001; and RMN r = 0.51 and 0.59, p < 0.01). Time-corrected release of TnT was significantly higher in the CIR group than in the other groups. Of the patients, 59.6% were free from AF at follow-up (12.2 ± 5.4 months) and there were no differences in success rate between the three groups.

Conclusions

Remote magnetic catheters may create more discrete and predictable ablation lesions measured by myocardial enzymes and may require longer total ablation time to reach the procedural endpoints. Remote magnetic non-irrigated catheters do not appear to be inferior to magnetic irrigated catheters in terms of myocardial enzyme release and clinical outcome.

[Magnetic navigation for ablation of cardiac arrhythmias]

BACKGROUND

The first use of magnetic navigation for radiofrequency ablation of supraventricular tachycardias, was published in 2004. Subsequently, the method has been used for treatment of most types of tachyarrhythmias. This paper provides an overview of the method, with special emphasis on usefulness of a new remote-controlled magnetic navigation system.

MATERIAL AND METHODS

The paper is based on our own scientific experience and literature identified through a non-systematic search in PubMed.

RESULTS

The magnetic navigation system consists of two external electromagnets (to be placed on opposite sides of the patient), which guide an ablation catheter (with a small magnet at the tip of the catheter) to the target area in the heart. The accuracy of this procedure is higher than that with manual navigation. Personnel can be quickly trained to use remote magnetic navigation, but the procedure itself is time-consuming, particularly for patients with atrial fibrillation. The major advantage is a considerably lower radiation burden to both patient and operator, in some studies more than 50 %, and a corresponding reduction in physical strain on the operator. The incidence of procedure-related complications seems to be lower than that observed with use of manually operated ablation catheters. Work is ongoing to improve magnetic ablation catheters and methods that can simplify mapping procedures and improve efficacy of arrhythmia ablation. The basic cost for installing a complete magnetic navigation laboratory may be three times that of a conventional electrophysiological laboratory.

INTERPRETATION

The new magnetic navigation system has proved to be applicable during ablation for a variety of tachyarrhythmias, but is still under development.

Complications with permanent endocardial electrode systems

The different complications of endocardial electrode systems in 185 patients during the last seven years are discussed. The surgical technique for the now routinely used cephalic route is described. The choice of anaesthesia is discussed. In the last 39 implantations there have not been any displacements or retractions. Of the total number of patients only 3 required replacement of endocardial by myocardial electrodes. This was caused by unstable position and high stimulation threshold. Fracture of the electrode occurred in 4 cases. Stimulation of the diaphragm occurred in 10%, displacement and retraction of the electrodes in 6,5% and heart penetration or perforation in 3,8% of the patients. There was one death from cardiac tamponade due to electrode perforation of the right ventricle. One case had irreversible brain damage due to prolonged asystole during pulse generator replacement. Unimportant wound infections and haematomas occurred in 5 patients and phlebitis in 3 patients. More or less serious electrode complications have been seen in 56 of the 185 patients, 18 patients having more than one complication.

Patients with high-grade atrioventricular block treated and not treated with a pacemaker

One-hundred and eighty-one patients with chronic and with intermittent high-grade atrioventricular block (AVB) were studied retrospectively. Seventy-one were treated with fixed-rate, 51 with demand-type pacemaker, 59 were treated conservatively. Observation time was three years minimum and 14.5 years maximum. The mean age was about seven years higher, and 8.7% more patients had chronic AVB in the conservatively treated than in the pacemaker-treated group. About 12% more patients had Adams-Stokes attacks in the pacemaker group than in the conservatively treated group. There were 7% more patients with coronary heart disease (CHD) in the pacemaker group, and 10% more with aortic valve disease among the conservatively treated. Totally 4.4% of the patients had a calcification of the mitral annulus fibrosus. The two groups were comparable as regards functional class (NYHA) and heart size. Survival showed 31% more sudden deaths in the conservatively treated than in the pacemaker group. Sudden deaths were not more frequent among the patients with CHD than in those without. Long-term survival showed the more favourable result for the patients with than without pacemaker treatment. There were eight (11.3%) unexplained sudden deaths among the patients treated with fixed-rate pacemaker, only three (5.9%) among those treated with a demand unit. The fixed-rate and the demand units showed a mean longevity of 37.2 and 34.6 months, respectively.

Sudden death caused by heart block in a patient with multiple myeloma and cardiac amyloidosis

A patient with multiple myeloma and amyloidosis was admitted to hospital following successful cardiopulmonary resuscitation at home. No disturbances in heart rhythm were seen during the first 48 hours of continuous telemetric ECG recording. The patient died from ventricular asystole due to complete atrioventricular block, while he was on a 24-hour Holter monitoring the fifth night in hospital. Patients with known cardiac amyloidosis and syncope should undergo long-term ECG recordings, preferably by telemetry. Repeated registrations may be necessary to discover disturbances in heart rhythm.

Acute hemodynamic and long-term clinical effects of prazosin in the treatment of chronic congestive heart failure

The effect of prazosin in congestive heart failure was assessed in 10 patients (age 39--69) years) with ischemic heart disease or cardiomyopathy in functional class II-IV (NYHA). All patients were treated with digitalis and diuretics in optimal doses. Mean (+/- S.E.M.) cardiac index (CI) was 2.2 +/- 0.2 l/min/m2 before and 2.3 +/- 0.1 one hour after oral administration of 2--4 mg prazosin (given as tablets) (p less than 0.10). Mean pulmonary capillary wedge pressure (PWP) fell from 24 +/- 4 to 20 +/- 4 mmHg (p greater than 0.10). Prazosin seemed to have a more beneficial effect on patients with markedly elevated PWP or reduced CI before prazosin administration. The effect of prazosin on heart rate and systolic blood pressure was insignificant. During a follow-up period of 1--20 months (mean 7.3), 2 of 7 patients treated with prazosin (2--4 mg daily) improved their clinical condition, one patient was unchanged and 4 patients died in progressive cardiac failure. The results indicate that some patients with severe heart failure may benefit from prazosin when conventional treatment has failed.

Permanent pacemaker treatment in older age groups

Of 693 patients on permanent pacemaker treatment between 1962 and 1981, 282 (40.7%) were above the age of 75. Of this number, 142 patients were 75-79 years, 95 80-84 years and 45 85-93 (mean 87) years old at the time of the first pacemaker implantation. The patients were followed for 13-154 months (mean 37.1) with special attention being paid to morbidity and mortality after the implantation. Complications occurred in 65 (23%) of the elderly patients, with no significant difference between the three age groups. Excessive threshold rise with stimulation failure (6%) and infections or skin erosions (4.9%) were the most frequent complications. Mortality increased in all age groups during the first 6-12 months compared with the age- and sex-matched Norwegian population. Five-year survival rates were 56, 32 and 25% respectively. We conclude that cardiac pacemaker treatment in the elderly is a safe symptom-relieving therapeutic procedure and that the prognosis for these patients is similar to that for their fellow senior citizens after the first year of treatment.

Sick sinus syndrome treated with permanent pacemaker in 109 patients. A follow-up study

During the last decade implantation of permanent pacemakers has become the treatment of choice for patients suffering from the sick sinus syndrome (SSS). We have followed up 112 SSS patients treated with permanent pacemakers in Haukeland Hospital in the period 1966--76. The pacemakers were later removed from three of the patients. In the remaining 109 patients the SSS was characterized by tachy-bradyarrhythmias (TBA) in 44 and bradyarrhythmias (BA) in 65. Before implantation, 68 patients had syncopes and 27 severe dizziness. After implantation, symptomatic improvement was apparent in 104 patients; only three still had syncopes. During the follow-up period (mean 34.4 months), 29 patients died (yearly mortality 9.3%). There was no significant difference in total mortality between patients with TBA and with BA. Concomitant disturbances in atrioventricular (AV) conduction occurred in 35.8% of the patients. Among 79 of 80 patients still alive, five had developed total AV block, 19 had stable atrial fibrillation, 12 of these were possibly pacemaker-independent (ventricular rate greater than 60/min). Systemic embolization was observed in 16 patients, more frequently in the TBA (12/44) than in the BA group (4/65) (p less than 0.001). It is concluded that permanent pacemakers have an excellent symptomatic effect in patients with SSS. The prognosis is mainly determined by the presence or absence of coronary heart disease and/or heart failure.

Interference with cardiac pacemaker function

A survey is given of the factors affecting cardiac pacemaker function. Whereas it was earlier considered that external interference was a frequent cause of a pacemaker failure, more recent studies indicate that this is of minor importance. It would appear that failure of pacemaker function due to changes in the QRS-complex, i.e. voltage change, intraventricular conduction defects and frequency changes, intraventricular conduction defects and frequency changes, are more important. A lesser known cause of failure in demand function is the inhibition which arises from skeletal muscle postentials. This appears to be a major problem in some types of pacemaker. Manufacturing defects are unavoidable, and it can still be assumed that electronic component defects may develop in 1 of 1000 pulse generators. Cases with the problem of early run-away pacemaker are still being reported and two such cases are discussed. In one of the patients the run-away phenomenon was intermittent, and was accompanied by a variation in run-away frequency. This possibility should thus always be taken into consideration in a pacemaker patient presenting with snycope. In a patient with a QRS-inhibited pacemaker a double stimulation phenomanen has been observed.

Atrio-pulmonary vein conduction delay during pulmonary vein isolation for atrial fibrillation is related to vein anatomy, age, and focal activity

BACKGROUND

During pulmonary vein isolation for treatment of atrial fibrillation (AF), a significant delay in atrio-pulmonary vein (PV) conduction is often observed. We sought to investigate this conduction delay in various PV in individual patients.

METHODS

We studied 385 AF patients (mean age: 54 +/- 11 years, 74 women) who underwent segmental PV isolation (PVI). A circular decapolar catheter was used to record electrograms at the PV ostia. The time delay from local atrial potential to PV potential was measured in each vein. Conduction delay (CD) was defined as the longest time interval >20 ms observed during PVI.

RESULTS

For patients treated for the first time, CD was more frequently observed in the left common and the right and left superior PVs (84.2%, 67.9%, and 66.2%, respectively) and less frequently in the left and right inferior and right middle PVs (54.3%, 40.0%, and 30.8%, respectively). Veins with CD required more ablation applications (12.4 vs 9.9) and a higher ablated segmental fraction (72.3% vs 63.7%). CD was observed in 75.2% (109/145) of the PVs in which focal activity was detected. Older patients had a higher incidence of PVs with CD than younger patients. There were no gender differences.

CONCLUSIONS

The incidence of CD was highest in the left common and superior PVs, in older patients and in PVs with focal activity. PVs with CD required more ablation applications and a larger area of ablation around the ostia. These observations were not found during repeat procedures.

[Catheter ablation of tachyarrhythmias in children and adolescents]

BACKGROUND

Catheter ablation has been increasingly applied in children and adolescents with tachyarrhythmias. The aim of this article is to assess the results of ablation therapy of tachycardias in patients below 18 years of age at Haukeland University Hospital.

MATERIAL AND METHODS

141 patients (70 boys and 71 girls, aged 5-17 (13.5 +/- 3.5 ) years with tachyarrhythmias underwent an electrophysiologic study and catheter ablation in the period 1992-2007.

RESULTS

Ablation was successfully performed in 138/141 (98%) patients., The procedure was repeated (3 patients twice) until the arrhythmia substrate disappeared in 16 of 138 patients. 81/141 (57%) patients had accessory pathways; 52 (37%) had double atrioventricular nodal pathways, 48 had concealed and 33 patients had overt (classical Wolff-Parkinson-White-syndrome) atrioventricular pathways. 8 (6%) patients had other atrial or ventricular tachyarrhythmias and 4 (3%) had organic heart disease. Use of a 3D mapping system was decisive for success for ablation in patients with complex cardiac diseases. Procedure-related complications were observed in 2/141 (1.4%) patients of whom one had a temporary third degree and one had a permanent first-degree atrioventricular block which did not entail further treatment.

CONCLUSION

Catheter ablation of tachycardia in children and adolescents is a safe treatment method with a high success rate and few complications and should be preferred before drug therapy.

Significance of Late Recurrence of Atrial Fibrillation during Long-Term Follow-Up after Pulmonary Vein Isolation

BACKGROUND AND STUDY OBJECTIVE

Patients with paroxysmal or persistent atrial fibrillation (AF) can be treated by pulmonary vein (PV) isolation. Although the recurrence rate after the procedure is relatively high, the long-term outcomes after initially recurrence-free procedures remains unclear. We examined the rates of recurrence of AF after PV isolation.

METHODS

Our study included 278 consecutive patients with drug-refractory AF (mean age = 53 +/- 11 years, 228 men). PV isolation was based on the disappearance of PV potentials recorded from a circumferential catheter after segmental ostium ablation. Cavo-tricuspid isthmus lines and additional atrial lines were performed in 124 and 28 patients, respectively. Patients were monitored for a mean of 26 +/- 11 months (range 12-56). Recurrence was defined as >/= 1 episodes of symptomatic or asymptomatic AF > 1 month after the procedure.

RESULTS

A total of 120 (34) patients had >/= 1 recurrence of AF > 1 month after the procedure, of whom 14 (4) had a first recurrence > 6 months after the procedure. There was a significantly higher recurrence rate among patients with persistent AF.

CONCLUSIONS

A relatively high AF recurrence rate was observed after PV isolation. AF may recur late after the ablation procedure, though the majority of recurrences occurred within 6 months after the first procedure. There were no differences in incidence or time of occurrence of late recurrences between patients with paroxysmal versus persistent AF.

Device treatment of atrial tachycardia—minor additional effect of repeating pacing sequences

PURPOSE

Ramp and burst pacing as treatment for atrial tachycardia (AT), one known trigger mechanism of atrial fibrillation (AF) are available in permanent pacemakers to reduce the burden of AF. An analysis of the success rate of three consecutive antitachycardia pacing sequences is presented.

METHOD

The AT 500 (Medtronic) pacemaker was implanted in 36 patients (18 female, mean age 77+/-11 years) with pacemaker indication due to tachybrady arrhythmias (n=34), and other indications (n=2). A standardized AT treatment of 8 sequences of ramp followed by six and four sequences burst pacing was programmed on after 1 month of tachycardia detection only. 5 consecutive sinus beats or 3 min with atrial rhythm not classified as AF or AT defined treatment success and was registered at 3 months follow-up.

RESULTS

2979 episodes (mean 85+/-316) in 17 patients (7 female) were treated and analyzed. The overall treatment success increased from 42+/-27% to 44+/-31% and 45+/-31% during the consecutive ATP sequences (ns). The average ATP success of the first ramp pacing sequences was 95+/-10%, the second ramp ATP sequence was successful in 3+/-6%, and the last ramp ATP sequence in 2+/-5%.

CONCLUSION

95% of the 45% treatment success of a standard AT treatment was achieved by the first ramp pacing sequence. Further antitachycardia pacing sequences did not increase the success rate significantly.

A clinical study of patients with and without recurrence of paroxysmal atrial fibrillation after pulmonary vein isolation

Patients with paroxysmal atrial fibrillation (PAF) can be treated by pulmonary vein (PV) isolation. However, the recurrence rate after this procedure is relatively high. We sought to evaluate the quality of life (QOL) of patients with PAF recurrence after PV isolation and to analyze factors related to recurrences. Seventy-two drug-refractory PAF patients (59 men, 13 women, mean age 52 +/- 10) were included. PV isolation was based on the disappearance of PV potentials recorded from a Lasso catheter after segmental ostium ablation. Automatic foci were observed in 47 patients (65.3%) during the procedure. A mean of 3.1 +/- 0.9 PVs was isolated. Patients were followed for a mean of 10.3 +/- 5.1 months, during which 27 experienced >1 episode of PAF. QOL was scored from 0 (situation before ablation) to 10 (no episode after ablation) based on a questionnaire completed by 69 patients (95.8%). QOL was judged very good in 26 patients (none with PAF recurrences), better in 30 (15 with PAF recurrences), unchanged in 11 (10 with recurrences), and worse in 2 patients with PAF recurrences. Longer histories of PAF and a lower percentage of patients with automatic foci identified during the procedure were observed in the group with, than in the group without recurrences (P < 0.05). PV isolation improved QOL in patients with PAF, including in patients with recurrences. The length of PAF history and observation of automatic foci may be of importance for recurrences of PAF during long-term follow-up.

Reducing atrial tachycardia and atrial fibrillation episodes with a prevention and treatment device and tailored treatment

BACKGROUND

Pacemaker treatment of known trigger mechanisms for atrial tachyarrhythmias (AT) and atrial fibrillation (AF) has shown reduction in the incidence of AF. A new arrhythmia management device, which included storage of AT/AF (for tailoring treatment) and three prevention algorithms and one for treatment, was examined in order to identify the influence on arrhythmia episodes over a 12-month follow-up (FU) period.

METHODS

Twenty-three consecutive patients with known tachybradyarrhythmias were examined. Seven patients had to be excluded (two outliers, four developed permanent AF, one had no detection algorithm turned on at implantation). The remaining 16 patients showed 2723 episodes (675 treated episodes) for evaluation of the effect on episodes/month/patient (e/m/p), treatment success, duration of episodes, circadian distribution and quality of life.

RESULTS

The AT/AF e/m/p were reduced from 37 +/- 102 e/m/p at 1-month FU to 16 +/- 48 e/m/p at 3-month FU, 15 +/- 48 e/m/p at 6-month FU and 10 +/- 28 e/m/p at 12-month FU (p < 0.05), according to fewer subjective symptoms. Treatment success remained stable during the observation period (29-40%). Only minor changes in the duration of episodes and the distribution of start times were observed.

CONCLUSION

Tailoring treatment by the pacemaker examined with several prevention and treatment algorithms reduces e/m/p and might be a promising supplement in the treatment of selected patients with known AT/AF and bradycardia.