Twenty-five years of research in cardiac imaging in electrophysiology procedures for atrial and ventricular arrhythmias

Catheter ablation is nowadays considered the treatment of choice for numerous cardiac arrhythmias in different clinical scenarios. Fluoroscopy has traditionally been the primary imaging modality for catheter ablation, providing real-time visualization of catheter navigation. However, its limitations, such as inadequate soft tissue visualization and exposure to ionizing radiation, have prompted the integration of alternative imaging modalities. Over the years, advancements in imaging techniques have played a pivotal role in enhancing the safety, efficacy, and efficiency of catheter ablation procedures. This manuscript aims to explore the utility of imaging, including electroanatomical mapping, cardiac computed tomography, echocardiography, cardiac magnetic resonance, and nuclear cardiology exams, in helping electrophysiology procedures. These techniques enable accurate anatomical guidance, identification of critical structures and substrates, and real-time monitoring of complications, ultimately enhancing procedural safety and success rates. Incorporating advanced imaging technologies into routine clinical practice has the potential to further improve clinical outcomes of catheter ablation procedures and pave the way for more personalized and precise ablation therapies in the future.

European Society of Cardiology quality indicators for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death

To develop a suite of quality indicators (QIs) for the management of patients with ventricular arrhythmias (VA) and the prevention of sudden cardiac death (SCD). The Working Group comprised experts in heart rhythm management including Task Force members of the 2022 European Society of Cardiology (ESC) Clinical Practice Guidelines for the management of patients with VA and the prevention of SCD, members of the European Heart Rhythm Association, international experts, and a patient representative. We followed the ESC methodology for QI development, which involves (i) the identification of the key domains of care for the management of patients with VA and the prevention of SCD by constructing a conceptual framework of care, (ii) the development of candidate QIs by conducting a systematic review of the literature, (iii) the selection of the final set of QIs using a modified-Delphi method, and (iv) the evaluation of the feasibility of the developed QIs. We identified eight domains of care for the management of patients with VA and the prevention of SCD: (i) structural framework, (ii) screening and diagnosis, (iii) risk stratification, (iv) patient education and lifestyle modification, (v) pharmacological treatment, (vi) device therapy, (vii) catheter ablation, and (viii) outcomes, which included 17 main and 4 secondary QIs across these domains. Following a standardized methodology, we developed 21 QIs for the management of patients with VA and the prevention of SCD. The implementation of these QIs will improve the care and outcomes of patients with VA and contribute to the prevention of SCD.

Impact of pulmonary veins anatomy on the outcomes of radiofrequency ablation for paroxysmal atrial fibrillation in the era of contact force-sensing ablation catheters

BACKGROUND

Pulmonary vein (PV) isolation (PVI) has become the cornerstone of atrial fibrillation (AF) ablation in patients with paroxysmal AF (PAF). PVI durability is influenced by many factors including PVs anatomy. Data regarding the influence of PVs anatomical variations on the outcomes of PAF ablation in the era of contact force-sensing ablation catheters are scarce and contradictory.

METHODS

Consecutive patients referred to our center for a first ablation of PAF using radiofrequency (RF) were included. PVs anatomy was classified into 3 groups: typical anatomy (4 distinct veins), left common ostium (LCO), and right accessory PV (RAPV). The primary outcome was recurrence of atrial arrhythmia episode during a 12-month follow-up after ablation.

RESULTS

Two hundred twenty-three patients were included (mean age 58.4 ± 10.8 years and 70.9% male). Among this cohort, 141 patients (63.2%) had typical PV anatomy, 53 (23.8%) had a LCO, and 29 (13.0%) had a RAPV. The existence of a RAPV was not associated with a higher rate of AF recurrences (22 (14.3%) vs. 7 (10.1%), p = 0.519). After multivariate analysis, the presence of an LCO did not appear to be associated with the AF recurrence rate at 12 months (OR = 1.69, 95%CI 0.95-2.49, p = 0.098). Maintenance of antiarrhythmic drugs after ablation was the only factor independently associated with a decreased risk of AF recurrence at 12 months (OR = 0.76, 95%CI 0.60-0.97, p = 0.046).

CONCLUSION

This study suggests that the presence of an LCO or a RAPV is not associated with a higher rate of AF recurrence at 12 months after radiofrequency PVI using contact force-sensing catheters in PAF patients.

How to use pace mapping for ventricular tachycardia ablation in post-infarct patients

We aim to describe the technical aspects of pace mapping (PM), as well as the two typical patterns of pacing correlation maps during ventricular tachycardia (VT) ablation. The first main pattern is focal, with a gradual and eccentric decrease of the QRS correlation from the area with the best PM correlation. This focal pattern may be associated with two clinical situations: (1) with some endocardial points showing a good correlation compared to VT morphology: true endocardial exit of VT or endocardial breakthrough of either an intramural or an epicardial circuit; (2) without any endocardial points showing a good correlation compared to VT morphology: the VT may originate from the other ventricle, but the presence of an intramural or an epicardial circuit should be considered in patients with a structural heart disease. The second pattern is the presence of PM points exhibiting a good correlation close to other PM points showing a poor correlation compared to VT morphology: this abrupt change in paced QRS morphology over a short distance indicates divergence of activation wavefronts between these sites and suggests the presence of a slow conduction channel: the VT isthmus.

Arrhythmias in Patients With Valvular Heart Disease: Gaps in Knowledge and the Way Forward

The prevalence of both organic valvular heart disease (VHD) and cardiac arrhythmias is high in the general population, and their coexistence is common. Both VHD and arrhythmias in the elderly lead to an elevated risk of hospitalization and use of health services. However, the relationships of the two conditions is not fully understood and our understanding of their coexistence in terms of contemporary management and prognosis is still limited. VHD-induced left ventricular dysfunction/hypertrophy and left atrial dilation lead to both atrial and ventricular arrhythmias. On the other hand, arrhythmias can be considered as an independent condition resulting from a coexisting ischemic or non-ischemic substrate or idiopathic ectopy. Both atrial and ventricular VHD-induced arrhythmias may contribute to clinical worsening and be a turning point in the natural history of VHD. Symptoms developed in patients with VHD are not specific and may be attributable to hemodynamical consequences of valve disease but also to other cardiac conditions including arrhythmias which are notably prevalent in this population. The issue how to distinguish symptoms related to VHD from those related to atrial fibrillation (AF) during decision making process remains challenging. Moreover, AF is a traditional limit of echocardiography and an important source of errors in assessment of the severity of VHD. Despite recent progress in understanding the pathophysiology and prognosis of postoperative AF, many questions remain regarding its prevention and management. Furthermore, life-threatening ventricular arrhythmias can predispose patients with VHD to sudden cardiac death. Evidence for a putative link between arrhythmias and outcome in VHD is growing but available data on targeted therapies for VHD-related arrhythmias, including monitoring and catheter ablation, is scarce. Despite growing evidences, more research focused on the prognosis and optimal management of VHD-related arrhythmias is still required. We aimed to review the current evidence and identify gaps in knowledge about the prevalence, prognostic considerations, and treatment of atrial and ventricular arrhythmias in common subtypes of organic VHD.

Catheter knot around the mitral valve apparatus: An exceptional complication of remote magnetic navigation

Remote magnetic navigation (RMN) is as safe and effective as manual navigation for catheter ablation of ventricular arrhythmias. This case is the first description of a soft-tip ablation catheter entrapment in the mitral valve apparatus during an RMN ablation procedure. The tight knot created by the catheter around a mitral valve chordae required surgical removal. This complication, which has never been reported before, highlights the need for closer fluoroscopic monitoring when performing catheter loops inside the ventricles when using the RMN system.

The prevalence of left and right bundle branch block morphology ventricular tachycardia amongst patients with arrhythmogenic cardiomyopathy and sustained ventricular tachycardia: insights from the European Survey on Arrhythmogenic Cardiomyopathy

AIMS

In arrhythmogenic cardiomyopathy (ACM), sustained ventricular tachycardia (VT) typically displays a left bundle branch block (LBBB) morphology while a right bundle branch block (RBBB) morphology is rare. The present study assesses the VT morphology in ACM patients with sustained VT and their clinical and genetic characteristics.

METHODS AND RESULTS

Twenty-six centres from 11 European countries provided information on 954 ACM patients who had ≥1 episode of sustained VT spontaneously documented during patients' clinical course. Arrhythmogenic cardiomyopathy was defined according to the 2010 Task Force Criteria, and VT morphology according to the QRS pattern in V1. Overall, 882 (92.5%) patients displayed LBBB-VT alone and 72 (7.5%) RBBB-VT [alone in 42 (4.4%) or in combination with LBBB-VT in 30 (3.1%)]. Male sex prevalence was 79.3%, 88.1%, and 56.7% in the LBBB-VT, RBBB-VT, and LBBB + RBBB-VT groups, respectively (P = 0.007). First RBBB-VT occurred 5 years after the first LBBB-VT (46.5 ± 14.4 vs 41.1 ± 15.8 years, P = 0.011). An implanted cardioverter-defibrillator was more frequently implanted in the RBBB-VT (92.9%) and the LBBB + RBBB-VT groups (90%) than in the LBBB-VT group (68.1%) (P < 0.001). Mutations in PKP2 predominated in the LBBB-VT (65.2%) and the LBBB + RBBB-VT (41.7%) groups while DSP mutations predominated in the RBBB-VT group (45.5%). By multivariable analysis, female sex was associated with LBBB + RBBB-VT (P = 0.011) while DSP mutations were associated with RBBB-VT (P < 0.001). After a median follow-up of 103 (51-185) months, death occurred in 106 (11.1%) patients with no intergroup difference (P = 0.176).

CONCLUSION

RBBB-VT accounts for a significant proportion of sustained VTs in ACM. Sex and type of pathogenic mutations were associated with VT type, female sex with LBBB + RBBB-VT, and DSP mutation with RBBB-VT.

Mechanism of ventricular tachycardia in a patient with double-outlet left ventricle

We report the case of ventricular tachycardia (VT) ablation procedure in a patient with history of surgically repaired double-outlet left ventricle. The electrophysiology procedure revealed a re-entry pattern between the right-ventricle to main-pulmonary-artery conduit and the tricuspid annulus. The re-entrant mechanism was most likely promoted by a fibrous remodeling of this area, related to the surgical repair. This case is the first to describe a re-entry mechanism between fixed anatomical barriers in a repaired right ventricle of a double-outlet left ventricle. A pace mapping technique was used to highlight the VT isthmus.

2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy: Executive summary

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia.

An efficient algorithm based on electrograms characteristics to identify ventricular tachycardia isthmus entrance in post-infarct patients

AIMS

Our study assesses the value of electrograms (EGMs) characteristics to identify a ventricular tachycardia (VT) isthmus entrance in patients with post-infarct VT. Post-infarct VTs are mostly due to a re-entrant circuit. A pacemapping (PM) approach is able to localize the VT isthmus during sinus rhythm. Limited data are available about the role of local EGMs in defining VT isthmus location.

METHODS AND RESULTS

Twenty consecutive patients (70% male) referred for post-infarct VT catheter ablation were included in the present study. The VT isthmus was defined according to the PM method. At each recording site, 10 characteristics of the local EGM were assessed to predict the location of the VT isthmus entrance. In total, 924 EGMs were acquired, of which 127 were located in the VT isthmus entrance. Logistic regression analysis showed that bipolar voltage, number of EGM positive peaks, and sQRS interval were independently associated with VT isthmus entrance location. The ROC curve best fitted the model at the cut-off 0.1641 (sensitivity 72%, specificity 75.2%, positive predictive value 31.3%, negative predictive value 94.4%, area under the curve 0.78, P < 0.001). Based upon these results, we developed an algorithm implemented in an automatic calculator to determine the likelihood that an EGM is located at a VT isthmus entrance.

CONCLUSION

Our study suggests that three EGM characteristics: bipolar voltage, number of positive peaks, and sQRS interval can successfully identify a VT isthmus entrance in post-infarct patients.

2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia.

Catheter Treatment of Ventricular Tachycardia: A Reference-Less Pace-Mapping Method to Identify Ablation Targets

OBJECTIVE

A novel method is developed to identify ablation targets for the catheter treatment of ventricular tachycardia (VT).

METHODS

The method is based on pace-mapping, which is a validated technique to determine the catheter ablation targets. Conventionally, it consists of stimulating the heart ventricle from various sites and comparing the resulting activation pathways to that of a clinical VT by the analysis of surface electrocardiograms (ECG). In this paper, a novel pace-mapping method is presented, which does not require a reference ECG recording of the VT. A three-dimensional correlation gradient map is reconstructed by semiautomatic analysis of ECG morphological changes within the network of pace-mapping sites. In these maps, abnormal points are identified by high correlation gradient values (i.e., corresponding to slow propagation of the electric influx, as in the core of the reentrant VT circuit). The relation between the conventional and reference-less method is described theoretically and evaluated in a retrospective study including 24 VT ablation procedures.

RESULTS

The "reference-less" method was able to identify normal points with a high accuracy (negative predictive value: NPV = 97%), and to detect more abnormal points, as predicted by the theory. Correlation gradients computed by the proposed method were significantly higher in ablation zones than in other zones of the ventricle (p < 10^-12), indicating excellent prediction of the ablation targets.

SIGNIFICANCE

The reference-less method might either be used in complement of the conventional method or to treat patients in whom VT cannot be induced during the intervention.

Recommendations for the use of electrophysiological study: Update 2018

The field of cardiac electrophysiology has greatly developed during the past decades. Consequently, the use of electrophysiological studies (EPSs) in clinical practice has also significantly augmented, with a progressively increasing number of certified electrophysiology centers and specialists. Since Zipes et al published the Guidelines for Clinical Intracardiac Electrophysiology and Catheter Ablation Procedures in 1995, no official document summarizing current EPS indications has been published. The current paper focuses on summarizing all relevant data of the role of EPS in patients with different types of cardiac pathologies and provides up-to-date recommendations on this topic. For this purpose, the PubMed database was screened for relevant articles in English up to December 2018 and ESC and ACC/AHA Clinical Practice Guidelines, and EHRA/HRS/APHRS position statements related to the current topic were analyzed. Current recommendations for the use of EPS in clinical practice are discussed and presented in 17 distinct cardiac pathologies. A short rationale, evidence, and indications are provided for each cardiac disease/group of diseases. In conclusion, because of its capability to establish a diagnosis in patients with a variety of cardiac pathologies, the EPS remains a useful tool in the evaluation of patients with cardiac arrhythmias and conduction disorders and is capable of establishing indications for cardiac device implantation and guide catheter ablation procedures.

Isotropic Reconstruction of MR Images Using 3D Patch-Based Self-Similarity Learning

Isotropic three-dimensional (3D) acquisition is a challenging task in magnetic resonance imaging (MRI). Particularly in cardiac MRI, due to hardware and time limitations, current 3D acquisitions are limited by low-resolution, especially in the through-plane direction, leading to poor image quality in that dimension. To overcome this problem, super-resolution (SR) techniques have been proposed to reconstruct a single isotropic 3D volume from multiple anisotropic acquisitions. Previously, local regularization techniques such as total variation have been applied to limit noise amplification while preserving sharp edges and small features in the images. In this paper, inspired by the recent progress in patch-based reconstruction, we propose a novel isotropic 3D reconstruction scheme that integrates non-local and self-similarity information from 3D patch neighborhoods. By grouping 3D patches with similar structures, we enforce the natural sparsity of MR images, which can be expressed by a low-rank structure, leading to robust image reconstruction with high signal-to-noise ratio efficiency. An Augmented Lagrangian formulation of the problem is proposed to efficiently decompose the optimization into a low-rank volume denoising and a SR reconstruction. Experimental results in simulations, brain imaging and clinical cardiac MRI, demonstrate that the proposed joint SR and self-similarity learning framework outperforms current state-of-the-art methods. The proposed reconstruction of isotropic 3D volumes may be particularly useful for cardiac applications, such as myocardial infarction scar assessment by late gadolinium enhancement MRI.

Influence of advancing age on clinical presentation, treatment efficacy and safety, and long-term outcome of inducible paroxysmal supraventricular tachycardia without pre-excitation syndromes: A cohort study of 1960 patients included over 25 years

AIM

To investigate the influence of increasing age on clinical presentation, treatment and long-term outcome in patients with inducible paroxysmal supraventricular tachycardia (SVT) without pre-excitation syndromes.

METHODS

Clinical and electrophysiological study (EPS) data, as well as long-term clinical outcome (mean follow-up 2.4±4.0 years) were collected in patients referred for regular tachycardia with inducible SVT during EPS without pre-excitation.

RESULTS

Among 1960 referred patients, 301 patients (15.4%) were aged ≥70 (70-97). In this subset, anticoagulants were prescribed in 49 patients following an erroneous diagnosis of atrial tachycardia and 14 were previously erroneously diagnosed with ventricular tachycardia because of wide QRS. Ablation was performed more frequently in patients ≥70 despite more frequent failure and complications. During follow-up, higher risks of AF, stroke, pacemaker implantation and death were observed in patients ≥70 whereas SVT recurrences were similar in both age groups. In multivariable analysis, age ≥70 was independently associated with higher risks of SVT-related adverse events prior to ablation (OR = 1.93, 1.41-2.62, p<0.001), conduction disturbances (OR = 11.27, 5.89-21.50, p<0.001), history of AF (OR = 2.18, 1.22-3.90, p = 0.009) and erroneous diagnosis at baseline (OR = 9.14, 5.93-14.09, p<0.001) as well as high rates of procedural complications (OR = 2.13, 1.19-3.81, p = 0.01) and ablation failure (OR = 1.68, 1.08-2.62, p = 0.02). In contrast, age ≥70 was not significantly associated with a higher risk of AF in multivariable analysis.

CONCLUSIONS

A sizeable proportion of patients with inducible SVT without pre-excitation syndromes are elderly. These patients exhibit higher risks of erroneous tachycardia diagnosis prior to EPS as well as failure and/or complication of ablation, but similar risk of SVT recurrence. These results support performing transesophageal EPS in most patients and intracardiac EPS in selected patients. EPS may furthermore prove useful in elderly patients with regular tachycardia, mainly by avoiding treatment based on an erroneous diagnosis.

Pace Mapping to Localize the Critical Isthmus of Ventricular Tachycardia

Most postinfarct ventricular tachycardias (VT) are sustained by a reentrant mechanism. The "protected isthmus" of the reentrant circuit is critical for the maintenance of VTs and the target for catheter ablation. In this article, the authors describe the technique of pace-mapping during sinus rhythm to unmask postinfarct VT isthmuses. A pace-mapping map should be considered as the surrogate of an activation map during VT, in both patients with a normal heart and patients with a structural heart disease. Pace mapping is useful to unmask VT isthmuses in patients with postinfarct reentrant VTs.

Age-related location of manifest accessory pathway and clinical consequences

BACKGROUND

Accessory pathway (AP) ablation is not always easy. Our purpose was to assess the age-related prevalence of AP location, electrophysiological and prognostic data according to this location.

METHODS

Electrophysiologic study (EPS) was performed in 994 patients for a pre-excitation syndrome. AP location was determined on a 12 lead ECG during atrial pacing at maximal preexcitation and confirmed at intracardiac EPS in 494 patients.

RESULTS

AP location was classified as anteroseptal (AS)(96), right lateral (RL)(54), posteroseptal (PS)(459), left lateral (LL)(363), nodoventricular (NV)(22). Patients with ASAP or RLAP were younger than patients with another AP location. Poorly-tolerated arrhythmias were more frequent in patients with LLAP than in other patients (0.009 for ASAP, 0.0037 for RLAP, <0.0001 for PSAP). Maximal rate conducted over AP was significantly slower in patients with ASAP and RLAP than in other patients. Malignant forms at EPS were more frequent in patients with LLAP than in patients with ASAP (0.002) or PSAP (0.001). Similar data were noted when AP location was confirmed at intracardiac EPS. Among untreated patients, poorly-tolerated arrhythmia occurred in patients with LLAP (3) or PSAP (6). Failures of ablation were more frequent for AS or RL AP than for LL or PS AP.

CONCLUSIONS

AS and RLAP location in pre-excitation syndrome was more frequent in young patients. Maximal rate conducted over AP was lower than in other locations. Absence of poorly-tolerated arrhythmias during follow-up and higher risk of ablation failure should be taken into account for indications of AP ablation in children with few symptoms.

Role of electrophysiological studies in predicting risk of ventricular arrhythmia in early repolarization syndrome

BACKGROUND

The early repolarization (ER) pattern is associated with an increased risk of arrhythmogenic sudden death. However, strategies for risk stratification of patients with the ER pattern are not fully defined.

OBJECTIVES

This study sought to determine the role of electrophysiology studies (EPS) in risk stratification of patients with ER syndrome.

METHODS

In a multicenter study, 81 patients with ER syndrome (age 36 ± 13 years, 60 males) and aborted sudden death due to ventricular fibrillation (VF) were included. EPS were performed following the index VF episode using a standard protocol. Inducibility was defined by the provocation of sustained VF. Patients were followed up by serial implantable cardioverter-defibrillator interrogations.

RESULTS

Despite a recent history of aborted sudden death, VF was inducible in only 18 of 81 (22%) patients. During follow-up of 7.0 ± 4.9 years, 6 of 18 (33%) patients with inducible VF during EPS experienced VF recurrences, whereas 21 of 63 (33%) patients who were noninducible experienced recurrent VF (p = 0.93). VF storm occurred in 3 patients from the inducible VF group and in 4 patients in the noninducible group. VF inducibility was not associated with maximum J-wave amplitude (VF inducible vs. VF noninducible; 0.23 ± 0.11 mV vs. 0.21 ± 0.11 mV; p = 0.42) or J-wave distribution (inferior, odds ratio [OR]: 0.96 [95% confidence interval (CI): 0.33 to 2.81]; p = 0.95; lateral, OR: 1.57 [95% CI: 0.35 to 7.04]; p = 0.56; inferior and lateral, OR: 0.83 [95% CI: 0.27 to 2.55]; p = 0.74), which have previously been demonstrated to predict outcome in patients with an ER pattern.

CONCLUSIONS

Our findings indicate that current programmed stimulation protocols do not enhance risk stratification in ER syndrome.

Recurrences of symptoms after AV node re-entrant tachycardia ablation: a clinical arrhythmia risk score to assess putative underlying cause

PURPOSE OF THE RESEARCH

To identify clinical factors associated with the probability for each arrhythmic mechanism causing recurring symptoms after atrioventricular nodal re-entrant tachycardia (AVNRT) ablation. Slow pathway radiofrequency ablation is used to treat AVNRT. After ablation, recurrence of symptoms due to AVNRT or other arrhythmias can occur.

RESULTS

We studied 835 patients successfully treated with AVNRT ablation. Variables associated with each specific arrhythmia underlying symptom recurrence were studied by logistic regression. During a mean follow-up of 2.2 ± 2 years, 136 (16%) patients had a recurrence of symptoms. Following invasive and non-invasive studies, symptoms were mostly attributed to sinus tachycardia, recurrence of AVNRT and atrial arrhythmias (respectively 4.7%, 5.2% and 6.1%). Older age and history of atrial fibrillation were associated with a markedly increased risk of symptom recurrence due to atrial arrhythmias (OR=15.58, 7.09-35.22, p<0.001) whereas younger age was associated with a higher risk of sinus tachycardia. A simple 3-item clinical score based on age categories and atrial fibrillation history efficiently predicted atrial arrhythmia (C-Index=0.82, 0.75-0.89) and sinus tachycardia (C-Index=0.83, 0.75-0.90). 8.3% of patients with scores=0 had atrial arrhythmias whereas 100% of patients with scores ≥4 had atrial arrhythmias.

CONCLUSIONS

While recurrence of symptoms after successful AVNRT ablation is relatively frequent (16%), true AVNRT recurrence accounts for only 1/3 of these recurrences. A simple clinical score based on age and history of atrial fibrillation enables efficient risk stratification for symptom recurrence attributable to atrial arrhythmias and inappropriate sinus tachycardia.

A case series of patients with poorly-tolerated arrhythmias related to a preexcitation syndrome and presenting with atypical ECG

The aim of study was to report different and unusual patterns of preexcitation syndrome (PS) noted in patients referred for studied for poorly-tolerated arrhythmias and their frequency. Electrophysiologic study (EPS) is an easy means to identify a patient with PS at risk of serious events. However the main basis for this diagnosis is the ECG which associates short PR interval and widening of QRS complex with a delta wave.

METHODS

ECGs of 861 patients in whom PS related to an atrioventricular accessory pathway (AP) was identified at electrophysiological study (EPS), were studied.

RESULTS

The most frequent unusual presentation (9.6%) was the PS presenting with a normal or near normal ECG, noted preferentially for left lateral AP and rarely for posteroseptal or right lateral location. More exceptional (0.1%) was the presence of a long PR interval, which did not exclude a rapid conduction over AP. The association of a complete AV block with symptomatic tachycardias was exceptional (0.3%) and was shown related to a rapid conduction over AP after isoproterenol. Most of the presented patients were at high-risk at EPS.

CONCLUSION

The diagnosis of PS is not always evident and symptoms should draw attention to minor abnormalities and lead to enlarge indications of EPS, only means to confirm or not PS.

Incidence and prognostic significance of spontaneous and inducible antidromic tachycardia

AIMS

Orthodromic atrioventricular reentrant tachycardia (ORT) is the most common arrhythmia at electrophysiological study (EPS) in patients with pre-excitation. The purpose of the study was to determine the clinical significance and the electrophysiological characteristics of patients with inducible antidromic tachycardia (ADT).

METHODS AND RESULTS

Electrophysiological study was performed in 807 patients with a pre-excitation syndrome in control state and after isoproterenol. Antidromic tachycardia was induced in 63 patients (8%). Clinical and electrophysiological data were compared with those of 744 patients without ADT. Patients with and without ADT were similar in term of age (33 ± 18 vs. 34 ± 17), male gender (68 vs. 61%), clinical presentation with spontaneous atrioventricular reentrant tachycardia (AVRT) (35 vs. 42%), atrial fibrillation (AF) (3 vs. 3%), syncope (16 vs. 12%). In patients with induced ADT, asymptomatic patients were less frequent (24 vs. 37%; <0.04), spontaneous ADT and spontaneous malignant form more frequent (8 vs. 0.5%; <0.001) (16 vs. 6%; <0.002). Left lateral accessory pathway (AP) location was more frequent (51 vs. 36%; P < 0.022), septal location less frequent (40 vs. 56%; P < 0.01). And 1/1 conduction through AP was more rapid. Orthodromic AVRT induction was as frequent (55.5 vs. 55%), but AF induction (41 vs. 24%; P < 0.002) and electrophysiological malignant form were more frequent (22 vs. 12%; P < 0.02). The follow-up was similar; four deaths and three spontaneous malignant forms occurred in patients without ADT. When population was divided based on age (<20/≥20 years), the older group was less likely to have criteria for malignant form.

CONCLUSION

Antidromic tachycardia induction is rare in pre-excitation syndrome and generally is associated with spontaneous or electrophysiological malignant form, but clinical outcome does not differ.

Imaging in cardiac resynchronization therapy: what does the clinician need?

In the guidelines, criteria to select patients for cardiac resynchronization therapy (CRT) are based only on the QRS duration on surface electrocardiogram (ECG) as a marker of cardiac dyssynchrony. From a theoretical point, imaging techniques would be useful to improve patient's selection with an analysis of the atrio-ventricular, interventricular and intraventricular dyssynchrony. Imaging techniques may also identify physiopathological issues such as the presence of scar, right ventricular dysfunction, or severe pulmonary hypertension. New echocardiographic techniques appear promising, but the role of echocardiography in the identification of mechanical dyssynchrony remains to be clearly defined in prospective multicentre trials. The positioning of left ventricular lead could be optimized using different imaging techniques to assess the site of latest activation and the coronary sinus anatomy. Finally, imaging techniques may have an important role to optimize the programming of the device, especially the different cardiac timings. In the present article, we focused on echocardiography, multislices-computed tomography, and magnetic resonance imaging being discussed elsewhere.

Electroanatomic mapping characteristics of ventricular tachycardia in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Ventricular tachycardia (VT) in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVD) has been previously explored using entrainment mapping techniques but little is know about VT mechanisms and the characteristics of their circuits using an electroanatomical mapping system.

METHODS AND RESULTS

Three-dimensional electroanatomical mapping was performed in 11 patients with well tolerated sustained VT and ARVD. Sinus rhythm mapping of the right ventricle was performed in eight patients showing areas of low bipolar electrogram voltage (<1.2 mV). In total 12 tachycardias (mean cycle length 382+/-62 ms) were induced and mapped. Complete maps demonstrated a reentry mechanism in eight VTs and a focal activation pattern in four VTs. The reentrant circuits were localized around the tricuspid annulus (five VTs), around the right ventricular outflow tract (one VT) and on the RV free lateral wall (two VTs). The critical isthmus of each peritricuspid circuit was bounded by the tricuspid annulus with a low voltage area close to it. The isthmus of tachycardia originating from the right ventricular outflow tract (RVOT) was delineated by the tricuspid annulus with a low voltage area localized on the posterior wall of the RVOT. Each right ventricular free wall circuit showed an isthmus delineated by two parallel lines of block. Focal tachycardias originated on the right ventricular free wall. Linear radiofrequency ablation performed across the critical isthmus was successful in seven of eight reentrant tachycardias. The focal VTs were successfully ablated in 50% of cases. During a follow-up of 9-50 months VT recurred in four of eight initially successfully ablated VTs.

CONCLUSIONS

Peritricuspid ventricular reentry is a frequent mechanism of VT in patients with ARVD which can be identified by detailed 3D electroanatomical mapping. This novel form of mapping is valuable in identifying VT mechanisms and in guiding RF ablation in patients with ARVD.

Noninvasive quantitation of blood flow turbulence in patients with aortic valve disease using online digital computer analysis of Doppler velocity data

Previous experimental studies have demonstrated that aortic valve disease is associated with significant downstream turbulence (T). In this study, we developed a noninvasive method on the basis of Doppler velocity recording for quantitating aortic blood flow T in patients with aortic valve disease. The instantaneous blood velocity at a point in the aorta is equal to the sum of a mean periodic velocity component with a random or turbulent velocity component. According to the ensemble average method, time mean absolute T intensity is the root-mean-square value of turbulent velocity averaged over time and T is better quantitated by the relative T intensity (TIr), which is the ratio of absolute T intensity to the ensemble average velocity averaged over time. We computed TIr in 18 patients with mild to severe aortic stenosis and in 13 healthy volunteers from instantaneous modal velocities of 70 cycle length-matched heart beats recorded in the proximal part of the descending aorta by pulsed Doppler using an ultrasound system with an output port for online digital data transfer into a microcomputer. TIr was greater in patients with aortic valve disease (18.4 +/- 5.1%, range 11.2%-28.9%) than in control patients (7.9 +/- 1.9%, range 4.8%-9.8%; P =.0001). In patients with aortic valve disease, TIr was better linearly related to the ratio of postvalvular aorta to valvular orifice cross-sectional areas (r = 0.89, P =.0001) than to other parameters of valve restriction: transvalvular pressure gradient (r = 0.78, P =.0001); valve area (r = -0.56, P =.01); and valve resistance (r = 0.72, P =.0002). Thus, T that can be computed noninvasively from direct digital transfer of Doppler velocity data appears to be linearly related to indices of aortic valve restriction. Our data support the concept of the postvalvular aorta to valvular orifice cross-sectional areas ratio as a new important hemodynamic parameter in patients with aortic valve disease.

Identification of extremely slow conduction in the cavotricuspid isthmus during common atrial flutter ablation

INTRODUCTION

Complete isthmus block has been used as an endpoint for radiofrequency ablation for common atrial flutter (AF). We sought to systematically evaluate extremely slow conduction (ESC), which is easily misinterpreted as complete block.

METHODS AND RESULTS

We studied 107 consecutive patients (92 men, 15 women, 58 +/- 11 years) who had undergone a successful AF ablation procedure. A 24-pole catheter was positioned along the tricuspid annulus spanning the isthmus. Complete isthmus block was defined as the presence of a complete corridor of double potentials along the ablation line. Activation delay time (AT), activation difference (deltaA) between two adjacent dipoles, maximum activation difference (deltaA(max)), change in polarity (CP) and change in amplitude (CA) of the bipolar atrial electrogram were recorded and P-wave morphology in the surface electrocardiogram was analyzed. ESC was observed in 16 patients. Between ESC and complete block, differences were found on the two lateral dipoles adjacent to the ablation line (AT: 148 +/- 17 vs. 183 +/- 27 ms and 155 +/- 18 vs. 170 +/- 28 ms, P < 0.01; deltaA: -91 +/- 22 vs. -126 +/- 28 ms and -7 +/- 13 vs. 13 +/- 6 ms, P < 0.01). Statistically significant differences in CP were detected on the relevant dipoles (7/16 vs. 14/16 and 6/16 vs.13/16, P < 0.05). No significant difference was found either in CA or in terminal P wave positivity. Mean deltaA(max) were 13.8 +/- 5.0 and 27.8 +/- 9.5 ms (P < 0.001) respectively in ESC and complete block. Two types of ESC, regular and irregular, were demonstrated during the ablation procedure.

CONCLUSIONS

(1) ESC was observed in 15% of the patients during the AF ablation procedure. (2) The parameters of AT, deltaA, and CP may help to differentiate ESC from complete block. DeltaA(max) might be the most powerful indicator. (3) To verify complete block, it is essential to position the mapping catheter across the CTI in order to demonstrate the activation sequence up to the ablation line.

Isthmus characteristics of reentrant ventricular tachycardia after myocardial infarction

BACKGROUND

The reentrant mechanism of postinfarct ventricular tachycardia (VT) has been documented by surgical mapping analysis, but little is known about postinfarct VT circuits and the characteristics of their related protected isthmus with the use of 3D catheter mapping systems.

METHODS AND RESULTS

A 3D electroanatomic mapping was performed in 21 patients with well-tolerated, postinfarct, sustained VT. In total, 33 episodes of tachycardia (mean cycle length 432+/-74 ms) were induced and mapped. Complete maps demonstrated macroreentrant circuits with 1 loop (n=8) or 2 loops (n=25) rotating around a protected isthmus bounded by 2 approximately parallel conduction barriers that consisted of a line of double potentials, a scar area, or the mitral annulus. A total of 26 critical isthmi were identified for the 33 VTs mapped, with the same isthmus being shared by 2 to 4 different tachycardic morphologies in 5 patients. On average, isthmi were 31+/-7 mm long (ranging from 18 to 41 mm) and 16+/-8 mm wide (ranging from 6 to 36 mm) and harbored diastolic electrograms. The isthmus axis was oriented parallel to the mitral annulus plane in perimitral circuits and perpendicular to the mitral annulus plane in all other circuits. Linear radiofrequency ablation performed across the most accessible part of the isthmus prevented the recurrence of tachycardia in 19 patients (90%) with a follow-up at 16+/-8 months.

CONCLUSIONS

Detailed 3D electroanatomic mapping is helpful in reconstructing postinfarct VT circuits and in defining the characteristics of their related protected isthmi. The wide range of isthmus width values supports the need of linear radiofrequency lesions to eliminate the reentrant substrate of postinfarct VTs.