P1020Persistent AF patients with limited areas of low voltage have a similar benefit from pulmonary vein isolation as compared to paroxysmal AF patients: insight from the SMOP study

Background

Pulmonary vein isolation (PVI) performed with radio-frequency catheter ablation (CA) is an effective therapy for atrial fibrillation (AF). However previous data have suggested that PVI is less effective in persistent (PER) vs. paroxysmal (PAR) AF. Atrial fibrosis and scar, indeed, are an important substrate involved in persistent AF, and some author correlate them to an increased rate of recurrences after CA. For this reason several adjunctive ablation strategies have been suggested for invasive treatment in PER AF pts. However, there is a lack of evidence on their effectivness in current literature.

Objective

the aim of our study was to assess the rate of AF recurrences in PAR and PER AF patients after a first pulmonary vein isolation (IVP) procedure, and their relationship with low voltage areas of the left atrium assessed by means of high density mapping performed before CA.

Methods

we analyzed 214 patients of the SMOP-AF study (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric registry enrolling patients with both PAR and PER AF undergoing a first radio-frequency CA procedure aimed to obtain permanent PVI . High-density mapping was performed in sinus rhythm using the CARTO system before PVI. Areas with less than 0,5 mV on mapping were defined as low voltage zone (LVZ); LVZ was indexed on the atrial area. Comparisons were made by cross-tables and Chi-square test or Student T test.

Results

Patients with PER AF (n = 44, 21%) were older (63 ± 9 vs 58 ± 10 yrs, p = 0.01), but notably with no difference in LVEF and atrial dimensions as compared to pts with PAR AF. In addition no statistical difference was observed in procedural variables, except for a greater LVZ area on atrial mapping (8 ± 18 % vs. 5 ± 15 %, p = 0.04) and a longer p wave duration (115 ± 21 msec vs. 103 ± 18 msec, p = 0.01) in pts with PER AF. The incidence of recurrence in the overall population was 15.3% at 3 months and 13.7% from 3 to 12 months: there was no statistical difference in success-rate between PER and PAR pts (respectively 79,5% vs 86% p value = 0.315 in blanking period and 85,3% vs 86,5% p value = 0.8 at 3-12 months follow-up). No statistical difference was observed for ablation variables (number of lesion, contact force, force time integral) in pts with vs. without recurrences.

Conclusion

Our study showed that pulmonary vein isolation alone seems to be as effective in paroxismal and persistent AF patients with low degree of left atrial fibrosis. Our data call into question the idea that PVI alone is not effective in PER AF. High density mapping of the LA could help to identify a subset of PER AF patients with a limited extension of low voltage areas (i.e around 10% of the overall LA surface) that could benefit from PVI without adjunctive ablation strategies. Our data needs to be confirmed in a longer follow-up.

P1896Single-procedure success-rate of pulmonary vein isolation using point-by-point tagging lesions algorithm based on contact force technology: preliminary results of the multicentric SMOP study

Background

Pulmonary veins isolation (PVI)is an effective therapy for atrial fibrillation (AF), recommended by current guidelines. However, recurrences after first radio-frequency (RF) catheter ablation (CA) are still high. PV reconnection could be due to ineffective transmural lesions; automated ablation lesion tags (the VisiTag algorithm) based on predefined parameters of catheter stability and contact force (CF) have been developed to allow the detection of ineffective ablation lesion, nevertheless there is a lack of multicenter studies exploring this technology.

Objective

the aim of our study was to assess the rate of recurrence after a first PVI procedure in a large, multicentric Italian population and to explore the efficacy of Visitag algorithm (CARTO 3) used to guide RF ablation of AF.

Methods

we analyzed 214 patients of the SMOP-AF study (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric study enrolling patients with paroxysmal and persistent AF undergoing a first PVI procedure after an high-density mapping during sinus rhythm. During the procedure, ablation was guided by an automated annotation system in which tag based on predefined parameters were displayed real-time in each lesion site on the electroanatomical map. Visitag settings for the catheter position stability were a 2,5 mm distance limit for at least 7 sec and a minimum CF of 5 g over 30% of the ablation and a FTI>400 g*s. Where available (n=106, 49.5%), Ablation Index (AI), which also incorporates information on delivered RF power, was used instead of FTI to guide RF ablation with a threshold range of 400–550 for anterior/roof and 330–420 for posterior/inferior segments. Minimum and mean contact force, time and power values for each RF-lesion were recorded while both FTI and AI values were calculated automatically by the CARTO system. Comparison between groups were made by cross-tables, Mann-Whitney or Student T test as appropriated.

Results

the mean age of the enrolled population was 59±9 years, left ventricular ejection fraction was 59±9%. AF was paroxysmal in 89.7%, persistent in 10.3% of the patients and refractory to at least one anti-arrhythmic drug in 86.4% of the population. At 3 months follow-up 85% of the patients were free from AF recurrences and the success rate increased to 90.8% at 3–6 months, and 86.3% at 3–12 months follow-up. The mean ablation time was shorter in AI-guided vs. FTI-guided procedures (31±9 vs 46±29 min; p<0.001). There was a trend toward a reduction in AF recurrences when AI vs. FTI was used, both at 6 and 12 months (respectively 5,4% vs 13.6%; p 0.06 and 9.6% vs 18.5%; p 0.08).

Conclusion

PVI isolation using dedicated algorithms developed to guide the effectiveness of RFCA leads to a very high success-rate after a single procedure. The use of AI, which integrates contact force information with delivered power, reduces the procedural time and increases the overall success-rate

P1037Relationship between left atrium low voltage areas and atrial fibrillation radiofrequency ablation success-rate: preliminary results of the SMOP study

Background

radio frequency catheter ablation (CA) is an effective therapy for atrial fibrillation (AF). Some authors have described a potential relationship between the presence of areas of fibrosis in the left atrium (LA) and the success of CA, nevertheless there is a lack of multicenter studies in this field.

Objective

the aim of our study was to assess the relationship between the of presence of low voltage areas of the LA detected during subtrate mapping at the time of the procedure and recurrences of AF after CA.

Methods

we analyzed 214 patients of the SMOP-AF (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric study enrolling patients with both paroxysmal and persistent AF undergoing a first radio-frequency CA procedure. High-density mapping was performed in sinus rhythm using the CARTO system before performing pulmonary vein isolation. Areas with less than 0,5 mV on mapping were defined as low voltage zone (LVZ), while between 0,5 mV and 1,5 mV intermediate voltage zone (IVZ). IVZ and LVZ were expressed as a percentage of the LA surface. Comparisons were made by Pearson correlation, cross-tables and Chi-square test or Student T test.

Results

the mean age of the enrolled population was 59±9 years, left ventricular ejection fraction was 59±9%, 86.4% of the pts had tested at least one anti-arrhythmic drug. Persistent atrial fibrillation was present in 10.3% of patients. The rate of documented AF recurrence at 3 months was 15,3% (n=29). There was a statistical significant correlation between the presence of IVZ and the rate of recurrences at 3 months (r=0.16, p value 0.03). Patients with IVZ greater than 4% of the left atrium surface showed a higher risk of recurrences (19.5% vs. 8,7%, p value 0.04). No statistical difference was observed in other procedural variables (number of lesions, contact force, force-time integral) among patients with or without recurrences.

Conclusion

Our study showed a relationship between CA short-term success rate and the presence of areas of intermediate voltage zone detected with high-density substrate mapping at the time of the procedure. The presence of areas of intermediate voltage zone greater than 4% of the LA determines a 2.5 folds increased risk of short-term recurrence. Our data needs to be confirmed in a longer follow-up.

Bystander cavo-tricuspid isthmus activation during post-incisional intra-atrial reentrant tachycardia

We describe a case of post-incisional atrial tachycardia resembling typical atrial flutter on the surface ECG. Typical atrial flutter reentry was ruled out by the results of activation and entrainment mapping. Nevertheless, overdrive pacing from the lateral edge of the cavo-tricuspid isthmus produced tachycardia entrainment with concealed fusion associated with post-pacing and stimulus-to-P wave onset intervals exactly matching the tachycardia cycle length duration and the electrogram-to-P wave onset interval, respectively. Therefore, that site was firstly severed by sequential radiofrequency pulses. However, a transformation of the tachycardia P wave morphology and endocardial activation sequence, not associated with tachycardia termination or cycle length modification occurred. After additional mapping manoeuvres, a relatively small reentrant circuit was identified in the low and mid aspect of the lateral right atrium with the critical isthmus located between the lower border of a cannulation atriotomy and the crista terminalis, close to the inferior vena cava orifice. A single radiofrequency pulse at that site terminated the tachycardia. Both the electrocardiographic pattern and the endocardial mapping data obtained in our case might be explained by a split of the reentrant wavefront into a secondary wavelet which freely propagated through the cavo-tricuspid isthmus without completing the peritricuspid loop. In conclusion, bystander cavo-tricuspid isthmus activation during atrial tachycardia may simulate a typical atrial flutter pattern on the surface ECG. Further studies should evaluate the prevalence of this propagation pattern in post-incisional atrial reentry and atypical atrial flutters, and identify its implications for ablation strategy.

Iterative atrial tachycardia originating from the coronary sinus musculature

A case of iterative atrial tachycardia leading to dilated cardiomyopathy is reported. During electrophysiologic study, the tachycardia showed a markedly irregular cycle length associated with changes in atrial activation breakthrough as demonstrated by coronary sinus (CS) recordings and frequently degenerated into self-terminating atrial fibrillation. Left atrial transseptal mapping demonstrated the earliest endocardial atrial activation close to the posterolateral mitral annulus, but this was invariably later than that recorded within the CS, where low-energy radiofrequency applications eliminated the tachycardia. No acute vessel damage was observed at postablation CS angiography. In accordance with previously published experimental data, we hypothesized that the muscular sleeves surrounding the CS might be involved in the genesis of this tachycardia. During 6-month follow-up, the patient remained asymptomatic without tachycardia recurrences and with complete recovery of left ventricular function, confirming the reversible nature of the tachycardia-induced cardiomyopathy.

Radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia: selective approach to the slow pathway via the superior vena cava

Selective radiofrequency catheter ablation of the slow atrioventricular nodal pathway is currently considered the first-line therapy for patients suffering from recurrent symptomatic atrioventricular nodal reentry tachycardia. In most cases slow pathway conduction may be selectively eliminated or modified by the application of radiofrequency current at the posterior portion of Koch's triangle. The ablation site is usually targeted by careful mapping of this area performed using an ablation catheter advanced via the inferior vena cava approach. In this report we describe 2 cases in which the conventional approach to the target site was either impossible owing to the presence of an atresic inferior vena cava (case 1), or contraindicated in view of a history of common femoral vein thrombosis, subsequently extended up to the inferior vena cava (case 2). In both patients a superior vena cava approach was utilized and the slow pathway was successfully ablated. In case of arrhythmias necessitating slow pathway mapping and ablation, such an approach may be considered as a feasible and safe alternative whenever, owing to the presence of anomalies and/or diseases of the inferior vena cava, the conventional approach cannot be employed.

[Cardiac rhythm disturbances in hypertensive cardiopathy]

Patients with hypertensive heart disease are at a significantly increased risk for cardiovascular morbidity and mortality. Ultrastructural and gross anatomical cardiac changes, combined with hemodynamic and neurovegetative balance fluctuations, are frequently responsible for cardiac arrhythmias of atrial and/or ventricular origin. The prevalence, the pathophysiologic mechanism and the prognostic significance of cardiac rhythm disturbances occurring in hypertensive heart disease are discussed in this review.

Overdrive atrial stimulation during transesophageal electrophysiological study: usefulness of post-pacing VA interval analysis in differentiating supraventricular tachycardias with 1:1 atrio-ventricular relationship

We evaluated the feasibility and usefulness of overdrive atrial pacing to identify the relationship between atrial and ventricular activation in supraventricular tachycardias with a stable 1:1 atrio-ventricular (AV) conduction ratio during a transesophageal electrophysiological investigation. Overdrive atrial stimulation was performed in 42 consecutive patients (11 males and 31 females; mean age 49 +/- 17 years) during AV junctional reentrant tachycardia, orthodromic AV reentrant tachycardia and ectopic atrial tachycardia (22, 13 and seven subjects, respectively). Trains of 12 stimuli at a constant rate were introduced starting at a cycle length 10 ms shorter than the tachycardia cycle length; stimulation was repeated with a 10-ms decrement in pacing cycle length at each step until tachycardia terminated and/or second-degree AV block occurred. The difference between the VA interval duration at baseline and in the first post-pacing tachycardia beat was measured at each step and provided identification of the AV relationship. At least one post-pacing VA interval was evaluable in 90% of the cases and measured 2 +/- 4 and 1 +/- 3 ms in AV junctional and AV reentrant tachycardia groups, respectively, and 83 +/- 42 ms in the ectopic atrial tachycardia group (P < 0.0000001 ectopic atrial tachycardia group vs. others). When three or more post-pacing VA intervals were obtained during the same tachycardia, a curve was constructed by plotting their values against the corresponding pacing cycle lengths. A curve could be constructed in 36% of the cases and was flat in all patients with AV junctional and AV reentry, while it was completely irregular in the ectopic atrial tachycardia group (P < 0.003). The analysis of post-pacing VA interval behaviour in response to overdrive atrial stimulation provides a rapid and reliable differentiation between supraventricular tachycardias with 1:1 AV conduction ratio during a transesophageal electrophysiological study.

["Double nodal pathway" as a common electrogenic pathway at the base of first and second degree paroxysmal atrioventricular node and nodal reentrant tachycardia]

The combined occurrence of conduction disturbances and reentry in subjects with a dual atrioventricular nodal pathway is extremely rare and poorly documented, only by means of short electrocardiographic strips. This case report deals with a young woman with frequent episodes of paroxysmal first- and second-degree type I atrioventricular block due to a dual atrioventricular nodal pathway at Holter monitoring, and atrioventricular nodal reentrant tachycardia inducible at transesophageal electrophysiologic study. This case confirms that some paroxysmal first- and second-degree atrioventricular block and the atrioventricular nodal reentrant tachycardia may share the same electrogenetic substrate represented by a dual atrioventricular nodal pathway. This finding may be of clinical significance because of its potential therapeutical implications. Further studies are needed in order to explain the rarity of this association.

Unusual resetting patterns in response to single atrial extrastimuli during AV junctional reentrant tachycardia

INTRODUCTION

Two unusual resetting patterns were observed in two patients with slow-fast AV junctional reentrant tachycardia (AVJRT) submitted to an electrophysiologic study.

METHODS AND RESULTS

After AVJRT induction, resetting was evaluated by introducing single extrastimuli at progressively shorter coupling intervals from the high right atrium (HRA) and the proximal coronary sinus (CS). An alteration in the return cycle length duration allowed demonstration of resetting. In the first patient, during and AVJRT with a large excitable gap, properly timed extrastimuli delivered both from the HRA and CS simultaneously reset the tachycardia and advanced the H electrogram of the preceding tachycardia beat. In the second patient, both HRA and CS stimulation apparently failed to reset AVJRT (return cycle length unchanged), but, at critical coupling intervals, the cycle length duration of the tachycardia beat following the return cycle was consistently shortened.

CONCLUSION

During slow-fast AVJRT, single atrial stimulation from sites remote to the reentrant circuit may result in unusual resetting patterns. Further studies are required to evidence the full spectrum of resetting in AVJRT.

Radiation-induced heart disease

The recent improvement in radiation techniques and the associated significant prolongation of survival have resulted in a widespread utilization of mediastinal irradiation in patients with various neoplasms. However, a large number of experimental and clinical studies have clearly demonstrated that high-dose therapeutic mediastinal irradiation can produce delayed, severe cardiovascular disease. This review presents the data from the Literature regarding the pathogenesis, pathology, prevalence and clinical manifestation of the radiation-related heart disease.

Intra-atrial and atrioventricular nodal reentrant tachycardia in the same subject diagnosed at transesophageal electrophysiologic study

The case report deals with a young woman with frequent episodes of paroxysmal narrow QRS tachycardia of uncertain etiology at Holter monitoring in whom a transesophageal electrophysiologic study was carried out in order to identify the electrogenetic mechanism of the presenting arrhythmia. During the electrophysiologic study, 2 different types of supraventricular tachycardia were induced and diagnosed as intra-atrial and atrioventricular nodal reentrant tachycardia. This association represents a rare finding and can provide a possible explanation to the intriguing electrocardiographic pattern observed at Holter monitoring. Therefore, transesophageal electrophysiologic study proved to be a valuable method for evaluating subjects with complex supraventricular tachycardias.

Ventricular premature beats in young subjects without evidence of cardiac disease: histological findings

This report describes the results of right ventricle endomyocardial biopsies from 26 subjects (mean age 27 +/- 10 years) with premature ventricular beats and normal cardiac anatomy and mechanical function. Light microscopy examination revealed normal myocardium in 10 subjects (38%), acute myocarditis in two (7%), borderline myocarditis in one (3.5%), non-specific histological abnormalities including cellular hypertrophy, fibrosis and degenerative changes in 11 (42%), vasculitis in one (3.5%) and findings compatible with right ventricular dysplasia in the final subject (3.5%). The frequency of ventricular premature beats, as assessed by Holter monitoring, and the results of electrophysiological testing did not correlate with histopathological findings and their severity. These data indicate that some young subjects with premature ventricular beats of unknown origin have abnormal right ventricular biopsy findings. Adequate follow-up will probably demonstrate the clinical utility of these observations.

Management of keloids and hypertrophic scars

Keloids and hypertrophic scars may complicate elective foot surgery. Differentiation between these two entities is important before treatment is contemplated. The authors review current theories on the etiology of these lesions and outline various treatment options.

[Localization of the accessory pathways using surface ECG in Wolff-Parkinson-White syndrome]

During recent years criteria for localization of bypass tracts in the Wolff-Parkinson-White syndrome from the conventional ECG have been acquired utilizing epicardial and endocardial mapping data. The polarity of delta wave and QRS in the frontal and horizontal plane and the morphology of retrograde P waves during orthodromic reciprocating tachycardia, are the most indicative elements. An accurate analysis of QRS complexes during atrial fibrillation confirms the site of pre-excitation and could suggest the presence of 2 or more accessory pathways with sufficient spatial separation. Some criteria for identifying multiple accessory pathways are discussed.

Electrophysiologic evaluation of intravenous L-propionylcarnitine in man

L-propionylcarnitine, a short-chain acylcarnitine, has been shown in experimental studies to induce, during acidic and hypoxic conditions, some electrophysiological changes such as an increase of duration of the action potential and of the effective refractory period. In this study, the acute electrophysiological effects of intravenous L-propionylcarnitine (30 mg/kg in 3 min) were studied in 12 subjects with estimated normal function of the sinus node and normal parameters for atrioventricular conduction. Statistically significant changes were observed 2 min after infusion. The sinus cycle length shortened (866 +/- 138 vs 818 +/- 124 msec, P less than 0.05) while refractory periods of the atrioventricular node increased (effective by 30-50 msec in four cases; functional from 425 +/- 52 to 436 +/- 55 msec, P less than 0.05). Sinuatrial conduction time, atrial refractory periods, infranodal conduction, bundle branch, His-Purkinje system and ventricular refractoriness were unchanged. Systolic and diastolic blood pressure were also unchanged. Because of the limited effects on electrophysiological parameters, L-propionylcarnitine should be used as a metabolic drug even in patients with mild disturbances of conduction.

Electrocardiographic patterns during Holter monitoring in patients with first and second degree A-V block due to 'dual A-V nodal pathways'

The electrocardiographic patterns, observed during 24-h Holter monitoring, of 10 patients (mean age 35 +/- 22 years) with first and second degree A-V block due to dual A-V nodal pathways are reported. Recordings were selected according to the presence of: sudden and persistent prolongation of the PR interval: sudden normalization of the PR interval: 'atypical' Wenckebach sequences showing sudden and pronounced prolongation of any PR interval prior to the blocked P wave. Besides the already recognized pattern, new aspects were identified: (1) Wenckebach sequences in the slow and fast pathways characterized by a progressive increase in the PR interval until a blocked P wave occurred during long and short PR interval periods, respectively; (2) Wenckebach periods first in the slow and then in the fast pathway; (3) 2:1 A-V block with a normal PR interval in the conducted beat after a Wenckebach sequence in the slow pathway; (4) Wenckebach in the fast pathway and, subsequently, in the slow one characterized by a slight prolongation of the PR interval for some beats followed by a sudden and pronounced increase in the PR interval of one beat and a subsequent progressive slight PR prolongation until a blocked P wave occurred; (5) Wenckebach sequence in the fast pathway with subsequent conduction over the slow pathway without a blocked P wave; (6) blocked P waves during both long and short PR interval periods with slight prolongation of the preceding PR interval. The electrophysiological mechanisms involved in these electrocardiographic patterns together with the nature (anatomical or functional) of the intranodal pathways and the clinical significance of this type of block are discussed.

Transesophageal versus intracardiac atrial stimulation in assessing anterograde conduction properties of the accessory pathway in Wolff-Parkinson-White syndrome

Electrophysiologic intracardiac and noninvasive transesophageal testing, used to evaluate parameters of anterograde conduction across the accessory pathway, the refractory period and shortest atrial cycle length with 1:1 conduction over the pathway, were compared to assess the reliability of the noninvasive technique in identifying patients with Wolff-Parkinson-White syndrome, at risk of rapid ventricular response during atrial fibrillation when this arrhythmia is not inducible. Sixteen patients with Wolff-Parkinson-White syndrome were submitted both to invasive and transesophageal atrial stimulation. We evaluated both the functional and effective refractory periods of the accessory pathway, using the same drive cycle length, and the shortest cycle length with 1:1 atrioventricular conduction over the accessory pathway. There were no differences between the parameters obtained by intracardiac atrial stimulation and by transesophageal atrial stimulation. The two approaches correlated well: mean functional refractory periods of the accessory pathway were 285 +/- 42 msec and 289 +/- 32 msec, respectively (NS, r = 0.88); mean effective refractory periods of the accessory pathway were 267 +/- 41 msec and 271 +/- 32 msec, respectively (NS, r = 0.89); mean shortest cycle lengths with 1:1 conduction over the accessory pathway were 255 +/- 48 msec and 255 +/- 44 msec, respectively (NS, r = 0.94). These data demonstrate the reliability of transesophageal atrial stimulation in estimating the parameters for anterograde conduction across an accessory pathway. These results, and the already documented ability of transesophageal atrial stimulation to induce atrial fibrillation, suggest this noninvasive technique should be taken as a first approach in screening patients with Wolff-Parkinson-White syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical use of transoesophageal atrial stimulation in terminating ventricular tachycardia

This study was performed to evaluate whether transoesophageal atrial pacing could also stop ventricular tachycardias with low rates and no haemodynamic impairment. Prior to resorting to ventricular endocardial pacing, seven male patients, aged between 15 and 73 years, were treated by transoesophageal atrial pacing for 10 spontaneous episodes of sustained ventricular tachycardia at rates between 105 and 160 beats per minute, without haemodynamic impairment. When atrial pacing did not allow ventricular capture, atropine sulphate was administered. Transoesophageal atrial pacing led to ventricular capture in seven episodes, which made overdriving possible, and blocked six episodes of ventricular tachycardia. In no case did transoesophageal atrial pacing lead to an acceleration of ventricular tachycardia or to degeneration into ventricular fibrillation. Transoesophageal atrial pacing can block low-rate sustained ventricular tachycardias (less than or equal to 150 beats per minute). For low-rate sustained ventricular tachycardias without haemodynamic impairment, transoesophageal atrial pacing can thus be used as the method of choice thanks to its good ratio of risk to efficiency.