Novel cryo-balloon technology for a successful pulmonary vein isolation: acute outcome and follow-up from a large multicenter Italian clinical setting

Funding Acknowledgements

Type of funding sources: None.

Background

Complete electrical pulmonary vein isolation (PVI) by cryo-balloon approach is a well-established ablation strategy of atrial fibrillation (AF). Recently, a new cryoablation system (POLARx) with unique features has been made available for clinical use. To date, limited data exist on acute and follow-up outcome of this system in a multicentric clinical practice.

Purpose

We reported the preliminary experience of this novel technology in a multicenter Italian registry.

Methods

Consecutive patients (pts) undergoing AF ablation from the CHARISMA registry at 6 Italian centres were included. Protocol-directed cryoablation was delivered for 180 sec or 240 sec according to operator’s preference for isolation achieved in ≤60 sec, or 240 sec if isolation occurred >60 sec or when time to isolation (TTI) was not available. The ablation endpoint was PV isolation as assessed by entrance and exit block. Rhythm monitoring during the follow-up examinations was performed via the clinical assessment of AF recurrence, ECG and Holter monitoring, according to the clinical practice of each center. All patients were followed-up for at least 6 months after the procedure. Arrhythmia recurrences within the first 3 months (blanking period) were classified as early recurrences and were not considered procedural failures

Results

Six-hundred twenty-four cryoapplications from 112 pts (439 PVs) were analyzed (n=89, 79.5% paroxysmal AF, n=23, 20.5% persistent AF, mean age 61.5±9 years, 76% male, 22% with an history of AT, mean LVEF 49±10%). PVI was achieved in all pts using only cryoablation. The mean number of freeze applications per pt was 5.6±2.1 (1.4±1.2 for LSPV, 1.5±1.1 for LIPV, 1.3±0.8 for RSPV and 1.3±0.8 for RIPV), with 318 (72.4%) PVs treated with a single cryoablation (92, 21% with 2 cryoablation; 29, 6.6% with more than 2 cryoablations). Fourty-four (39.3%) pts were treated with a single application to each of the PVs. Over a median of 296[245 to 382] days of follow-up, five (4.5%) patients experienced an early recurrence of AF/AT during the 90-day blanking period. Overall, 12 patients (10.7%) suffered an AF/AT recurrence after the 90-day blanking period (median time to recurrence 200[124 to 297] days). Specifically, 8 (7.1%) patients had AF recurrence only, 3 (2.7%) had AT recurrence only and 1 (0.9%) experienced both events. One (0.9%) patient underwent a repeated ablation procedure. The proportion of patients exhibiting AF/AT recurrences was similar between AF types (10 out 89, 11.2% for paroxysmal AF vs 2 out 23, 8.7% for persistent AF, p=1.00) with a hazard ratio of 0.9 (95%CI: 0.2 to 3.9, log-rank p=0.8894). One transient phrenic nerve palsy was observed, with full recovery in the 48-h post procedure; no major procedure-related adverse events were reported.

Conclusion

In this first multicentric experience, the novel cryo-balloon system proved to be safe and effective and resulted in a very low rate of AF/AT recurrence during follow-up.

P377 CHALLENGING RISK STRATIFICATION IN BRUGADA SYNDROME: A CASE OF VENTRICULAR TACHYCARDIA IN A LOW–RISK PATIENT

A 22–year–old healthy athlete was referred to our hospital for electrocardiographic findings consistent with intermittent type–1 Brugada pattern. A routine electrocardiogram (ECG) performed during a check–up showed sinus rhythm, normal PR interval and QRS duration, rSR’ with a coved type ST–segment elevation in V2 lead (Figure 1).The patients denied history of syncope or palpitations and his family history did not show sudden cardiac death or Brugada syndrome (BrS). Transthoracic echocardiography was normal and a 12–lead Holter monitoring revealed the intermittence of the type–1 Brugada pattern. The patient was hospitalized for further investigation. On admission, ECG showed a type–2 Brugada pattern; therefore, Ajmaline challenge test (1 mg/kg injection in 10 minutes) was performed and resulted positive. Subsequently, the patient underwent an electrophysiological study (EPS) which was negative for induction of sustained arrhythmias. The protocol adopted consisted of double extrastimuli programmed electrical stimulation until refractoriness (drive 600/220 ms and 400/210 ms), at double sites (right ventricle apex and right ventricular outflow tract). Furthermore a genetic test was performed using next–generation sequencing, showing a heterozygous mutation in the SCN5A gene, encoding for sodium channel alpha subunit (variant c.5363delA), not previously described in the literature. Since the low arrhythmic risk, the patient was implanted with a loop recorder (ILR, Medtronic Reveal LINQ), entering a program of home monitoring. After a 15–months follow–up, an episode of ventricular polymorphic tachycardia lasting 2 minutes and 11 seconds, associated with lightheadedness and palpitations, was detected by the remote monitoring (Figure 2). The patient was therefore hospitalized. During the in–hospital stay a cardiac magnetic resonance was performed to exclude other underlying diseases, identifying an enlarged right ventricle (EDVi 114 ml/m2) and abnormal free wall motion (Figure 3), thus reaching one major criteria of arrhythmogenic cardiomyopathy (however not sufficient for the diagnosis). The patient was then implanted with a subcutaneous implantable cardiac defibrillator (Boston Scientific EMBLEM MRI S–ICD). We presented a case of complex arrhythmic risk stratification in a possible overlap of an arrhythmogenic cardiomyopathy and a Brugada Syndrome in a young athlete who experienced a sustained ventricular tachycardia during loop–recorder monitoring.

Novel cryo-balloon ablation technology for pulmonary vein isolation in patients with atrial fibrillation: preliminary experience from a multicenter clinical practice

Funding Acknowledgements

Type of funding sources: None.

Background

Complete electrical pulmonary vein isolation (PVI) by cryo-balloon approach is a well-established ablation strategy of atrial fibrillation (AF). Recently, a new cryoablation system (POLARx) with unique features has been made available for clinical use. To date, no data exist on procedural characteristics of this system in a multicentric clinical practice.

Purpose

We aimed to characterize the initial experience of this technology in the Italian clinical practice.

Methods

Consecutive patients (pts) undergoing AF ablation from the CHARISMA registry at 5 Italian centres were included. Protocol-directed cryoablation was delivered for 180 sec or 240 sec according to operator’s preference for isolation achieved in ≤60 sec, or 240 sec if isolation occurred >60 sec or when time to isolation (TTI) was not available. The ablation endpoint was PV isolation as assessed by entrance and exit block.

Results

Two-hundred sixty-two cryoapplications from 49 pts (194 PVs) were analyzed. PVI was achieved with cryoablation only in all pts. The mean number of freeze applications per pt was 5.3 ± 1.5 (1.3 ± 0.6 for LIPV, LSPV and RSPV, 1.6 ± 1.3 for RIPV), with 143 (73.7%) PVs treated in a single-shot fashion (38, 19.6% with 2 shots; 13, 6.7% with more than 2 shots). Sixteen (33%) pts were treated with a single freeze to each of the PVs. The mean nadir temperature was -55.5 ± 6.9 °C and was colder than -50°C in 83% of the PVs. TTI information was evaluable in 120 (46%) cryoapplications with a median TTI of 47 [32-75] sec (median temperature at TTI = -49 [-53 to -42] °C). The mean time to target -40 °C (TTT) was 30.1 ± 6.9 sec with a TTT < 60 sec achieved in 99.2% of the cryoapplications; the mean thaw time to 0 °C was 18.6 ± 5.8 sec (thaw time >15 sec in 70.3% of the cryoapplications). The mean PV occlusion grade (rank 1-4) was 3.6 ± 0.6 (grade 2 in 5.2% of the cases, grade 3 in 25.6% and grade 4 in 69.2%). No complications were observed at 30 days post-procedure.

Conclusion

In this first multicentric experience in a clinical practice setting, the novel cryo-balloon system proved to be safe and effective and resulted in a high proportion of successful single-freeze isolation. Cooling parameters seem to be slightly different from reference cryo-balloon technology.

Atrial fibrillation ablation in athletes: 5-years experience of a single italian third-level center

Background

The number of master athletes is increasing and treatment of AF is mandatory for sports continuation. However, few data exist about the effectiveness of catheter ablation (CA) in athletes and the feasibility of resuming vigorous exercise afterwards.

Objectives

Aim of our study was to analyze the efficacy and safety of AF CA in athletes and to evaluate the feasibility of resuming vigorous exercise.

Methods

We report a retrospective registry of athletes referred to our center for AF CA in the last five years. All athletes were previously declared non-eligible to competitive sport because of recurrences of AF or evidence of persistent asymptomatic AF. CA was performed as per practice and recurrences were defined as recrudescence of symptoms and/or any documentation of AF lasting more than 30 sec. At the end of the follow-up all pts were asked about resuming sport.

Results

We ablated 40 athletes (38 males, 95%) with a mean age of 48±13 years. Mean left atrium volume was 36±11 ml/m2 and mean ejection fraction was 61±5%. Distribution between AF characteristics was: 31 (78%) paroxysmal AF, 8 (20%) early-persistent AF, 1 (2%) long-persistent AF.

After a median follow-up of 787 days, 62,5% of athletes were free from recurrences after one CA procedure and mostly without antiarrhythmic drugs (87%). 7 athletes underwent a redo procedure and all of them were then free of recurrences with an overall freedom from recurrences of 84%. No major complication was observed. Athletes practicing endurance sports showed a negative trend in terms of recurrences (p = ns).

Most (72%) of the athletes resumed vigorous exercise after at least 3 months from the CA as per Italian sport protocols.

Conclusions

CA is safe and efficient in treating AF also in athletes. Resuming high intensity sports is often possible after 3 months from CA.

Funding Acknowledgement

Type of funding source: None

P1799 The importance of 3D imaging techniques in left atrial appendage closure: landing zone eccentricity influence on peri-device leak incidence and its implication in long-term clinical outcomes

Background

A complex left atrial appendage (LAA) morphology and a non-circular landing zone (LZ) are frequently encountered in patients undergoing percutaneous LAA occlusion (LAAO). Three-dimensional (3D) imaging modalities as 3D transoesophageal echocardiography (3D TOE) and cardiac computed tomography (CCT) should be preferred over two dimensional techniques for better evaluation of LAA diameters, especially for the LZ. In fact, non-circular shape could impair the choice of occluder device size and may be implicated in the occurrence of residual leaks. Incomplete LAA occlusion is recognized to be associated with thromboembolic events.

Purpose

The aim of the study was to evaluate the utility of 3D imaging techniques to predict LAA device size and the landing zone eccentricity index as a potential predictor of residual peri-device leaks and to assess their clinical implications on long-term follow-up.

Methods

It was a retrospective, single-center study including 137 consecutive patients undergoing successful LAAO from January 2010 to July 2018. Pre-procedural 3D TOE and CCT were used to predict device size based upon LZ diameters and quantify LAA orifice eccentricity. Leaks were defined as the presence of peri-device flow at 2D TOE immediately after the device implantation and at 3 months follow-up. Leaks were classified as significant (color jet width ≥4 mm) or minor (<3 mm). A clinical evaluation of thromboembolic events was performed at 48 ± 27 months from the procedure.

Results

LAAO closure was performed implanting either Amulet or Watchman devices (n = 98 and n = 40, respectively). The assessment of LZ measurements with 3D TOE and CCT showed a significant correlation with the device size selected on the basis of 2D techniques (r = 0.82 and r = 0.74, respectively). As concerns the peri-device leaks, the presence of an eccentric LZ (eccentricity index >0.20) was not associated to the development of post-procedural leaks in the overall population; a significant correlation was detected only in the subgroup of patients treated with the Amulet device (p = 0.045). Residual leaks included only 1 significant leak (0.7%) after Amulet device implantation, which was related to a major neurological event (stroke) and 47 (34%) minor leaks (n = 28 in the Amulet group, n = 19 in the Watchman group). In this last population, 2 patients (1.5%) developed minor neurological events (transient ischemic attack).

Conclusions

3D TOE and CCT better predict device size overcoming the limit of 2D imaging techniques undersizing. In eccentric LAA, Watchman device may reduce the incidence of peri-device leaks. The presence of significant residual leaks is uncommon but associated with major clinical events, whilst minor leaks are relatively frequent but do not seem to be related to life-threatining thromboembolic accidents.

P3682Myocardial structural abnormalities in nonischemic patients presenting with ventricular arrhythmias

Background

The diagnosis of concealed cardiomyopathies in patients with ventricular arrhythmias (VAs) is one of the major challenging issues faced by physicians.

Purpose

We aimed at reporting the cardiomyopathic substrate in patients with recurrent arrhythmias of ventricular origin.

Methods

Consecutive patients with unexplained VAs underwent a complete diagnostic work-out, including endomyocardial biopsy (EMB).

Results

Ninety-seven patients were enrolled (76.3% male, age 39.7±13.3 yrs). The presenting arrhythmic manifestation was aborted cardiac arrest in 30 (30.9%) patients, sustained ventricular tachycardia (VT) in 9 (9.3%), nonsustained VT in 15 (15.5%) and frequent premature ventricular complexes in 43 (44.3%). Overall, 350 biopsies were collected (3.6/patient). The incidence of procedure-related complications was 5.1% (n=5): 4 major complications (1 rupture of a tricuspid chorda tendinea w/o hemodynamic impairment, 1 dissection of right external iliac artery treated with stent, 1 thrombotic occlusion of left superficial femoral artery which required surgical treatment, 1 TIA) and 1 minor complication (groin hematoma) occurred. The final diagnosis was arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) (n=41; 42.3%), followed by myocarditis (n=20; 20.6%), dilated cardiomyopathy (n=6; 6.2%), cardiac sarcoidosis (n=6; 6.2%), and myocarditis in ARVD/C (n=5; 5.1%). Among the 25 patients whose final diagnosis was consistent with myocarditis, an acute stage of the disease was documented in 7 (7.2%), while a chronic myocarditis in 18 (18.5%). Additionally, according to medical history and diagnostic workout, in 2 of the 6 patients the dilated cardiomyopathy had a likely post-inflammatory etiology. Absence of myocardial abnormalities was documented in 15 (15.5%) patients: this group included 1 case of methadone-induced torsade de pointes. The remaining 4 (4.1%) patients were diagnosed with a cardiac hypertrophy (n=2, 2.1%, secondary to exercise or Fabry disease), a dilated mitochondrial cardiomyopathy (n=1, 1.0%), a dilated cardiomyopathy in Emery-Dreifuss muscular dystrophy (n=1; 1.0%).

Conclusion

In our series, approximately 45% of patients with unexplained VAs had a final diagnosis of ARVD/C.

P3687Abnormal voltage recordings in patients with ventricular arrhythmias: comparison between right and left cardiomyopathy

Background

Arrhythmogenic Cardio-Myopathy (ACM) is characterized by epi-endocardial fibro-fatty replacement. Depending on the most affected ventricle, right dominant (RDACM) or left dominant (LDACM) phenotypes can be defined. RDACM voltage mapping characteristics have already been described, with late potentials strongly correlating with arrhythmia recurrence risk; LDACM voltage features have not been described yet.

Purpose

To analyze voltage map characteristics in LDACM patients (pts) and compare them with RDACM; to assess if there is any correlation between late potentials and recurrence rate in LDACM as well.

Methods

We retrospectively enrolled all consecutive ACM patients treated c/o our center and diagnosed according to the 2010 Task Force Criteria. Procedural and follow up data were collected. Patient were sorted by ventricular involvement lateralization. Recurrence rates were evaluated and linearly regressed for the presence of late potentials.

Results

89 ACM patients were enrolled (67 RDACM, 22 LDACM; 76% males, 69±4 y.o.) in our study. All patients underwent endocardial voltage mapping; procedurally, 43 (48%) pts underwent catheter ablation, while 46 (52%) were managed conservatively with anti-arrhythmic drugs.

Bipolar pathological potentials were found in 43 (64%) and 13 (59%), unipolar pathological potentials in 45 (67%) and 14 (63%), while late potentials in 19 (31%) and 8 (36%) in the RDACM and LDACM group respectively [p = 0.66, p=0.63, and p=0.33].

The average follow-up was 18 months [14–48]; 15 (22%) in the RDACM and 9 (40%) in LDACM arrhythmic recurrences were respectively encountered; recurrences in both groups were regressed for the presence of late potentials. Results were as follows: the presence of late potentials correlated with recurrences with an 4,3 [1.15–16.1; p=0.03] OR and with an 11 [0.4–85; p=0.022] OR in the RDACM and LDACM group respectively.

Conclusion

Pathologically low unipolar, bipolar and late potentials can be found in comparable % both in RDACM and LDACM; like in RDACM, late potentials represent an important risk factor for arrhythmic recurrence in LDACM as well.

P4652Magnetic resonance and electroanatomical guided endomyocardial biopsy as a diagnostic tool in the clinician's box: a 5 year experience

Background

Percutaneous endo-myocardial biopsy (EMB) is an invasive diagnostic test used to reach or confirm a diagnosis when structural or substrate anomalies are suspected, such as in cardiomyopathies or myocarditis evaluation. In recent years, cardiac magnetic resonance imaging (MRI) and endo-cavitary electro-anatomical mapping (EAM) have been used to localize the most significant myocardial area to sample, therefore increasing EMB overall effectiveness and reliability.

Purpose

To describe and characterize safety, feasibility and anatomical findings of a large cohort of patients (pts) undergoing diagnostic EMB and to assess its impact on the treatment decision making algorithm.

Methods

A cohort of all pts undergoing a percutaneous EMB at our Institution from January 2014 to January 2019 was analyzed. All EMB procedures were guided by a pre-procedural cardiac MRI radiological alteration analysis and an endo-cavitary EAM. Intra-cardiac echography (ICE) was used in all procedures, to directly visualize the sample area and to evaluate in real time post-EBM complications. Demographics, clinical data, MRI data, pathological EMB features, and peri-procedural data were systematically retrieved.

Results

One-hundred and eleven pts were enrolled (78% male, 47±4 y.o., 33% athletes). EMB indication was abnormal MRI findings in 94 (85%), pathological EMB voltages in 10 (9%) and clinical suspect and patient history in 7 (6%) pts.

EMB sample area was determined by both MRI and EAM pathological area analysis in 92 (83%) pts, while by EAM alone in 19 (17%) pts (n=6 pathological unipolar EAM; n=13 bipolar and unipolar pathological EAM). The sample site was the right ventricle in 89 (80%), the left ventricle in 20 (18%), and both in 3 (2%) pts.

In 103 (93%) pts a concomitant electrophysiological induction study was performed (40% positive for sustained ventricular arrhythmias) and 35 (32%) pts underwent a trans-catheter ablation (TCA) (n=8 epicardial TCA; n=2 endo-epicardial TCA; n=25 endocardial ATC). Only 2 (2%) peri-procedural adverse events were witnessed, specifically femoral pseudo-aneurysms, requiring surgical repair. EMB analysis allowed to confirm 58 (52%) pre-procedural diagnosis and to reach 32 (29%) new diagnosis, while resulting inconclusive or non-specific in the diagnostic process only in 21 (19%) cases [Figure1]. A total of 33 (30%) intra-cardiac devices (ICDs) were implanted contextually in the cohort, of which 9 (8%) solely upon EMB indication; in 4 (4%) other patients, biopsy represented a strong decisional factor in the multi-modality decision process for abstaining from ICD implant.

Dashed lines: diagnosis changed upon EMB

Conclusion

MRI and EAM guided EMBs allowed to finely define a large cohort of patients by representing a disease defining parameter in over 80% of the enrolled pts while and a decision shifting parameter in ICD implant algorithm in a high % of pts.

P5560Assessing etiology in a cohort of patients with myocarditis presenting with complex ventricular arrhythmias: can the percutaneous endomyocardial biopsy help?

Background

Myocarditis represents a common but often under-diagnosed disease, with a wide range of clinical presentations; diagnosis is often presumptive and a clear etiology leading to a specific therapeutic approach is usually not identified.

Purpose

To describe and assess disease etiology in a cohort of myocarditis patients (pts) with arrhythmic presentation undergoing an invasive diagnostic work-up.

Methods

All pts with myocarditis presenting with ventricular arrhythmias undergoing an electro-anatomical mapping (EAM) guided endo-myocardial biopsy (EMB) at our institution were enrolled. All enrolled pts also underwent cardiac magnetic resonance imaging (MRI) and an electrophysiological study (EPS). Demographics, arrhythmic presentation, MRI data, arrhythmic inducibility at EPS, EAM and EMB biopsy data were retrieved and analyzed. Molecular biology testing for cardio-tropic virus genome as well as leukocyte immunohistochemical typization were routinely performed on all EMB samples.

Results

Twenty-six pts were enrolled (85% male, 39±6 y.o.). Clinical presentation was an organized ventricular arrhythmia in 16 (62%) pts (n=3 non-sustained ventricular arrhythmia; n=9 sustained ventricular arrhythmia; n=4 ventricular fibrillation) while frequent (>10.000) premature ventricular complexes (PVCs) in the remaining 10 (38%) pts.

MRI showed a late gadolinium enhancement (LGE) pattern consistent with myocarditis in all pts (35% left LGE; 65% right LGE). At the EPS, 10 (38%) pts showed inducibility for SVTs and underwent an intra-cardiac defibrillator (ICD) implant, while 4 (16%) more were implanted for secondary arrhythmic prevention.

EAM was performed in 18 (70%), 6 (22%) and 2 (8%) pts in the right, left and in both ventricle respectively; in all cases, abnormal myocardial voltages were retrieved in the area showing LGE at MRI. Extensive myocardial scarring was detected in 7 (27%) pts.

All EMB were performed without peri-procedural complications; inflammatory infiltrate and substrate alteration consistent with myocarditis were retrieved in 100% of the bioptic samples. Viral genome was identified in 13 (50%) samples (n=5 Human Herpes Virus 6; n=2 Parvovirus B 19; n=3 Adenovirus; n=1 Ebstein Barr Virus; n=1 Cytomegalovirus; n=1 Rhinovirus) and specific human immunoglobulin treatment was undergone by a single pt; eosinophilic infiltration was found in 2 (8%) patients; lymphocite invasion and auto-antibodies consistent with auto-immune myocarditis were detected in 2 (8%) patients and appropriate immunosuppressive therapy was started, while a myocardial band contraction pattern typical of toxic myocarditis was found in a single (4%) patient [Figure 1].

Different Myocarditis Etiology Rates

Conclusion

In our myocarditis cohort, EMB confirmed viruses to represented the first myocarditis etiological agent. Despite an invasive work-out, 31% of the cohort etiology still remains unclear.

P993Diagnostic accuracy of cardiac magnetic resonance and endomyocardial biopsy for arrhythmogenic right ventricular dysplasia/cardiomyopathy and myocarditis

Introduction

Patients with myocarditis may fulfill the cardiac magnetic resonance (CMR) criteria set forth by the 2010 Task Force for arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), thereby increasing the risk of misdiagnosis.

Purpose

We sought to evaluate the role of CMR and endomyocardial biopsy (EMB) in the differential diagnosis between myocarditis and ARVD/C.

Methods

Consecutive patients presenting with ventricular arrhythmias, underwent a complete diagnostic work-out, which included CMR and EMB. The final diagnosis served as the gold standard to assess the diagnostic accuracy of CMR and EMB.

Results

Overall, 74 consecutive patients presenting with VAs underwent a complete diagnostic workout at our institution. The cohort was 70.3% male, with a mean age of 38.9±12.1 years. A final diagnosis of ARVD/C was made in 30 (40.5%) patients, whereas 19 (25.7%) had a diagnosis of myocarditis.

The McNemar's test showed significant differences in the diagnostic performance of EMB and cardiac MRI (p=0.003 for ARVD/C, p=0.04 for myocarditis).

At receiver operating characteristic (ROC) analyses, the area under the curve (AUC) to discriminate between controls and ARVD/C patients was 0.711 (95% CI: 0.59–0.83) for MRI and 0.944 (95% CI: 0.88–1.00) for biopsy (p<0.001). The AUC to discriminate between controls and patients with myocarditis was 0.656 (95% CI: 0.51–0.80) for MRI and 0.893 (95% CI: 0.80–0.99) for biopsy (p=0.006).

Diagnostic performance of CMR and EMB

Conclusion

Even though CMR has good diagnostic performances as single technique, a complete diagnostic work-out including EMB may frequently reduce the risk of misdiagnoses.

P5556Impact of viral genome detection in endo-myocardial biopsy of arrhythmogenic cardiomyopathy substrate

Background

Arrhythmogenic cardiomyopathy (ACM) is a genetically inherited cardiomyopathy characterized by myocardial fibro-fatty replacement. A pathogenetic role of viral myocardial infections in ACM natural history has been proposed over the years, although no definitive conclusion has been reached yet.

Purpose

To describe viral genome presence into a cohort of ACM biopsy proven patients (pts) and its impact on clinical features and outcome.

Methods

A cohort of all ACM pts undergoing an invasive third level evaluation at our institution was enrolled. All pts underwent a cardiac magnetic resonance (MR), an invasive electrophysiological study (EPS) with endo-cavitary electro-anatomical mapping (EAM), and a EAM guided endo-myocardial biopsy (EMB). Viral genome research through molecular biology techniques was performed on all biopsied samples.

According to arrhythmic risk evaluation, a trans-catheter ablation (TCA) and/or an internal cardioverter device (ICD) implant was performed. Clinical arrhythmic presentation, MR data, arrhythmia inducibility at EPS, EAM and EMB characteristic, and arrhythmic events at a 12-month follow up visit were retrieved in all pts and compared between the viral genome positive (v+ACM) and negative group (v-ACM).

Results

Forty-five pts were enrolled in our study (48±13 years; 66% male); the EMB samples of 7 (15%) pts presented a lymphocytic infiltrate and tested positive for viral genome (n=3 B19 Parvovirus; n=2 for Citomegalovirus; n=2 for Ebstein-Bar Virus) [Figure1].

At arrhythmic presentation, complex ventricular arrhythmias (NSVT, SVT and FV) were more frequent in the v+ACM group (86% vs 50%; p=0.039). Both left and right ventricular ejection fraction at MR resulted more depressed in the v+ACM group (44±7 vs 52±2 and 47±2 vs 52±2; p=0.047 and p=0.041). Complex ventricular arrhythmia inducibility at EPS was more frequent in v+ACM (72% vs 34%; p=0.032), while no differences in pathological potentials rate and extension at unipolar and bipolar EAM were found. TCA was performed in 55% and 57% and an ICD was implanted in 29% and 42% in the v+ACM and v-ACM group respectively. No differences in 12-months arrhythmic event rates (39% vs 42%) between the two groups were described.

EBM at different magnifications/stains

Conclusion

In our cohort a viral infection super-imposed to the fibrofatty infiltration was found in 15% of the patients. ACM pts testing positive for viral genome at the EMB had a more severe arrhythmic disease presentation, a more impaired heart function, and a higher rate of complex ventricular arrhythmias at disease presentation, but seemed to respond as well as viral genome negative ACM to ablative and pharmacological treatment

Intracardiac echocardiography in electrophysiology

Intracardiac echocardiography (ICE) is a recent, invaluable tool which can provide real-time anatomical guidance in electrophysiological procedures. By inserting intravenously an ultrasound probe and advancing it into the heart, various different views can be obtained which allow to better visualize patient anatomy, to guide the placement of electrophysiological catheters, and to detect immediately procedural complications as they occur. In atrial fibrillation ablation, ICE proves particularly useful to achieve a safer trans-septal puncture (especially in the presence of anatomical anomalies of the interatrial septum) and to help to monitor the visualization of the mapping catheters (circular, high density), or the monitoring of the balloons catheter (Cryo, Laser) position. In ventricular tachycardia ablation, on the other hand, ICE allows for continuous correlation between electrophysiological and structural findings (such as wall motion anomalies or changes in echodensity), and helps to ensure correct catheter contact and to position it, particularly around delicate structures such as the aortic cusps. In any procedure, ICE is also useful to immediately detect procedural complications, such as thrombus formation along catheters, or pericardial effusion. Thanks to its real-time morphological information, ICE provides an ideal complement to simple fluoroscopy or to more complex electroanatomic mapping techniques and is set to gain a wider role in a broad range of electrophysiological procedures.

Atypical atrial flutter: clinical features, electrophysiological characteristics and response to radiofrequency catheter ablation

AIMS

To evaluate the clinical and electrophysiological features of atypical atrial flutter (AAF) and its response to radiofrequency catheter ablation.

METHODS AND RESULTS

In 90 consecutive patients referred for sustained atrial flutter, bipolar recordings were obtained from the tricuspid annulus, coronary sinus, interatrial septum and left atrium. AAF was defined by the absence of concealed entrainment from the inferior vena cava--tricuspid annulus isthmus. Target sites were identified by early, fragmented or double potentials and by concealed entrainment. Linear lesions were created between target sites and nearby anatomical barriers in a temperature-controlled mode: 20 episodes of AAFs were documented in 19/90 (21%) patients. Mitral valve disease and surgery were significantly more frequent in patients with AAF. Target sites were identified in the right atrial free wall (n=8), interatrial septum (n=6), left atrium (n=4) and coronary sinus (n=2). Effective ablation was obtained in 15/19 patients (79%). After a 15.7 +/- 10.7 month follow-up, AAF recurred in 0/15 patients with a successful and 3/4 (75%) with a failed procedure (P<0.05).

CONCLUSIONS

Conventional mapping techniques enable identification of critical sites of AAF and allow successful ablation in the majority of cases.

Non-contact mapping to guide catheter ablation of untolerated ventricular tachycardia

AIMS

The role of a novel non-contact mapping system (ESI 3000, Endocardial Solutions) to guide radiofrequency catheter ablation of untolerated ventricular tachycardia was investigated in 17 patients; 11 with prior myocardial infarction, three with arrhythmogenic right ventricular dysplasia, and three with idiopathic dilated cardiomyopathy.

METHODS

Twenty-seven monomorphic ventricular tachycardias were induced (mean cycle 320+/-60 ms, range 230-450 ms), mapped for 15-20 s, and terminated by overdrive pacing or DC shock. Off-line analysis of isopotential activation mapping was performed to identify the diastolic pathway and/or the exit point of the ventricular tachycardia reentry circuit. Radiofrequency current was applied to create a line of block across the diastolic pathway or around the exit point.

RESULTS

All 27 ventricular tachycardias were mapped with the non-contact system. The endocardial exit point (-7+/-15 ms before QRS onset) was defined in 21/21 postinfarction ventricular tachycardias, in 3/3 arrhythmogenic right ventricular dysplasia and in 1/3 idiopathic dilated cardiomyopathy ventricular tachycardias, respectively. The diastolic pathway (earliest endocardial diastolic activity: -65+/-49 ms before QRS onset) was identified in 17/21 postinfarction ventricular tachycardias, in 1/3 arrhythmogenic right ventricular dysplasia and in 1/3 idiopathic dilated cardiomyopathy ventricular tachycardias, respectively. Catheter ablation was performed in 25/27 ventricular tachycardias (93%) in 15/17 patients (88%): 16/25 ventricular tachycardias (64%) were successfully ablated in 10/17 patients (59%). Catheter ablation was not performed in two patients or proved unsuccessful in five patients. At a follow-up of 15+/-5 months, there was no recurrence of documented ventricular tachycardia in all 10 patients with successful catheter ablation; in two of them a previously non-documented ventricular tachycardia occurred. A high recurrence of ventricular tachycardia was observed in patients with a failed procedure (5/7: 71%). No major complication or death occurred.

CONCLUSIONS

Non-contact mapping can be effectively used to map and guide radiofrequency catheter ablation of untolerated ventricular tachycardias. Given the favourable acute and clinical long-term results, this approach proves to be more effective in patients with postinfarction ventricular tachycardias, in comparison to patients with arrhythmogenic right ventricular dysplasia and idiopathic dilated cardiomyopathy.

Electrophysiological characteristics and outcome in patients with idiopathic right ventricular arrhythmia compared with arrhythmogenic right ventricular dysplasia

BACKGROUND

Idiopathic right ventricular arrhythmias (IRVA) are responsive to medical and ablative treatment and have a benign prognosis. Arrhythmias caused by right ventricular dysplasia (ARVD) are refractory to treatment and may cause sudden death. It is difficult to distinguish between these two types of arrhythmia.

OBJECTIVE

To differentiate patients with IRVA and ARVD by a conventional electrophysiological study.

METHODS

56 patients with a right ventricular arrhythmia were studied. They had no history or signs of any cardiac disease other than right ventricular dysplasia. They were classified as having IRVA (n = 41) or ARVD (n = 15) on the basis of family history, ECG characteristics, and various imaging techniques. They were further investigated by standard diagnostic electrophysiology.

RESULTS

The two groups were clearly distinguished by the electrophysiological study in the following ways: inducibility of ventricular tachycardia by programmed electrical stimulation with ventricular extrastimuli (IRVA 3% v ARVD 93%, p < 0.0001); presence of more than one ECG morphology during tachycardia (IRVA 0% v ARVD 73%, p < 0.0001); and fragmented diastolic potentials during ventricular arrhythmia (IRVA 0% v ARVD 93%, p < 0.0001). Data from the clinical follow up in these patients supported the diagnosis derived from the electrophysiological study.

CONCLUSIONS

Patients with IRVA or ARVD can be distinguished by specific electrophysiological criteria. A diagnosis of ARVD can be made reliably on the basis of clinical presentation, imaging techniques, and an electrophysiological study.

Incidence and clinical significance of transformation of atrial fibrillation to atrial flutter in patients undergoing long-term antiarrhythmic drug treatment

AIMS

To investigate the rate of transformation of atrial fibrillation to atrial flutter in patients taking antiarrhythmic drugs for the prophylaxis of atrial fibrillation, we retrospectively analysed data from 305 consecutive patients with paroxysmal atrial fibrillation (155 male; mean age 63 +/- 11 years) treated with ventricular rate controlling drugs, antiarrhythmic drugs, or without drugs.

METHODS AND RESULTS

At a mean follow-up of 9 months (range 1-24) all patients experienced recurrence of arrhythmia: 48 (14.6%, Group A) suffered Type 1 atrial flutter, and 257 (85.4%, Group B) atrial fibrillation. The relative rate of recurrence of atrial flutter vs atrial fibrillation was similar in patients without treatment or with ventricular rate controlling drugs (from 6.8% to 14.6%, P=ns). However, recurrence was higher (25%) in patients administered antiarrhythmic drug therapy. The relative risk in these patients was 3.02 times greater, compared with patients without treatment, or treated with rate controlling drugs (P<0.001). There were no differences between groups concerning the baseline clinical characteristics and the clinical consequences of the recurrence; patients with atrial flutter had a lower rate of conversion to sinus rhythm (42% vs 64%) and a higher rate of hospital admission (69% vs 36%) compared with those with atrial fibrillation. Six patients (8.5%) experienced 1:1 atrioventricular conduction during atrial flutter with a ventricular rate of 240-280 beats x min(-1).

CONCLUSION

Our data suggest that the use of antiarrhythmic drugs for the prophylaxis of atrial fibrillation is associated with a threefold increase in the probability of Type 1 atrial flutter recurrence, as opposed to atrial fibrillation, which may have important clinical consequences, but which did not in our study.

Modulation of the atrioventricular node conduction to achieve rate control in patients with atrial fibrillation: long-term results

Modulation of the AV node reduces the ventricular rate during AF, without affecting AV conduction during sinus rhythm. Acute and long-term results of AV node modulation in 75 patients with AF and severe related symptoms of heart failure are presented in this study. The procedure involved, in all cases, the selective ablation of the posterior inputs to the AV node; in a subgroup of 15 patients with poor modification of AV conduction properties, a sequential approach involving subsequent anterior input ablation was performed. The procedure caused acutely a prolongation of the Wenckebach cycle length (38 patients in sinus rhythm) from 334 +/- 88 to 470 +/- 80 ms (P < 0.01), and a reduction of the average ventricular rate (37 patients in AF) from 154 +/- 31 to 88 +/- 40 beats/min (P < 0.01); permanent complete AV block was induced in 9 of 75 patients (12%). Considering the "sequential" approach, an increase of the Wenckebach cycle length from 362 +/- 50 to 530 +/- 45 ms (P < 0.01) and a reduction of the average heart rate in patients with AF from 158 +/- 16 to 81 +/- 20 beats/min (P < 0.01) was obtained in this subgroup of patients, in whom the AH interval prolonged from 93 +/- 12 to 175 +/- 27 ms, and no complete AV block was observed. At a mean follow-up of 23 +/- 9 months (range 2-48), the mean number of hospital admissions per patient per year decreased from 4.2 to 0.2. Five of 49 patients with paroxysmal AF and 3 of 26 patients with chronic AF had high rate recurrences (1 > 120 beats/min) that caused severe palpitations; these patients were considered as late clinical failures (8/75; 11%). All patients reported a substantial subjective improvement and an increased exercise tolerance, as documented by a semiquantitative questionnaire. There were no episodes of late AV block or sudden cardiac deaths. In conclusion, modulation of the AV node--either by slow pathway ablation, or by a "sequential" posterior and anterior approach in refractory patients--allows a long-term control of the ventricular rate and prevents the recurrence of severe clinical symptoms in more than 75% of patients with drug refractory AF.

[Improvement of accessory pathways radiofrequency catheter ablation by arterial or venous epicardial mapping]

Failure of radiofrequency catheter ablation for atrioventricular reciprocating tachycardia may be related to imprecise location of accessory pathways. We have tested the safety and efficacy in improving successful rate of the procedure of a new technique of epicardial mapping of the atrioventricular sulcus by means of a small diameter (2.5F) 16 polar electrode catheter with a soft tip and a minor interelectrode and intercouple distance (2-6-2). The catheter was advanced via a right femoral approach into the coronary sinus or its branches, and the right coronary artery. We report 5 patients who underwent epicardial mapping-guided radiofrequency catheter ablation who had been previously treated with 1 or more (range 1-4) unsuccessful traditional mapping of the atrioventricular sulcus. Epicardial mapping was performed by means of selective catheterization of the coronary sinus in 4 cases, and of the right coronary artery in 1. The accessory pathways was precisely localized and ablated in all patients (mean 8 +/- 1.5 radiofrequency pulses, and 32 +/- 6 min fluoroscopy duration). No procedure or catheterization-related complications were observed. In conclusion, the technique of epicardial mapping used in this study proved to be safe and effective in localizing accessory pathways in selected cases, thereby enhancing radiofrequency catheter ablation success rate. The main advantage of this atraumatic catheter as compared to the traditional ones are the femoral approach and the possibility to advance the catheter to the most anterior aspect of the great cardiac vein. The epicardial mapping is thus a feasible alternative to traditional mapping, particularly in cases in which previous procedures have failed due to a complex arrhythmogenic substrate and or congenital abnormalities.

[Analysis of changes in repolarization for the differential diagnosis of narrow QRS supraventricular tachycardia and the site of the accessory pathway]

In view of the growing role of catheter ablation techniques for the treatment of supraventricular tachycardia, noninvasive determination of tachycardia mechanism and preliminary localization of the accessory pathway (AP) can simplify the cardiac catheterization procedure and reduce fluoroscopic exposure. The purpose of this study was to analyze the diagnostic value of repolarization changes during narrow QRS complex tachycardia (< 0.11 s). In 159 12-lead electrocardiograms during narrow QRS complex tachycardia (13 atrial tachycardias, 57 atrioventricular (AV) node reentrant tachycardias and 89 AV reciprocating tachycardias), the following were evaluated: 1) the tachycardia cycle length; 2) the presence of QRS alternans > or = 1 mm in at least 6 leads; 3) the presence of ST segment depression > or = 2 mm and/or T wave changes (inversion, notching); 4) the duration of retrograde atrial activation during tachycardia (right atrium-coronary sinus interval, in ms); the latter parameter, as well as tachycardia mechanism and accessory pathway location, were determined during an electrophysiologic study. There were no significant differences in mean cycle length among the groups. ST segment depression > or = 2 mm and/or T wave changes were present more often in AV reciprocating tachycardias (51/89) than in the other groups (AV node reentrant tachycardias: 14/57; atrial tachycardias: 1/13; p < 0.001), independently from the cycle length. Distinct patterns of repolarization changes during tachycardia were associated with different location of accessory pathway: ST segment depression from V3 to V6 in left lateral AP; T wave inversion in inferior leads in posterior-posteroseptal AP; T wave changes in V2 in all cases of anteroseptal AP location. The magnitude of ST segment depression, significantly more marked in the AV reciprocating tachycardias (1.3 +/- 1.6 mm) than in AV node reentrant tachycardias (0.7 +/- 0.8 mm, p < 0.005), was directly related to the duration of atrial activation time during tachycardia (80 +/- 20 ms, and 32 +/- 12 ms, p < 0.001, respectively). The finding of ST segment depression and/or T wave changes during narrow QRS tachycardia suggest the presence of an AV reciprocating tachycardia; this phenomenon may be related to a different pattern of retrograde atrial activation. In conclusion, analysis of repolarization changes during narrow QRS tachycardia constitutes an additional electrocardiographic criterion to differentiate the tachycardia mechanism and, furthermore, can guide preliminary location of the AP, even in the absence of ventricular preexcitation.

Value of analysis of ST segment changes during tachycardia in determining type of narrow QRS complex tachycardia

OBJECTIVES

Repolarization changes during narrow QRS complex tachycardia were analyzed to differentiate the tachycardia mechanism and to guide the preliminary location of the accessory pathway.

BACKGROUND

Noninvasive determination of the mechanism of tachycardia is becoming increasingly important in view of the role of catheter ablation techniques for the cure of supraventricular tachycardia.

METHODS

We analyzed 159 12-lead electrocardiograms during narrow QRS complex tachycardia to evaluate 1) the tachycardia cycle; and 2) ST segment depression or T wave inversion, or both. Each patient underwent a complete electrophysiologic evaluation.

RESULTS

There were 13 atrial tachycardias, 57 atrioventricular (AV) node reentrant tachycardias and 89 AV reciprocating tachycardias. The mean RR cycle did not differ among types of tachycardia. ST segment depression >2 mm or T wave inversion, or both, was present more often in AV reciprocating tachycardia (57%) than in AV node tachycardia (25%). The magnitude of ST segment depression was greater in AV reciprocating tachycardia than in AV node tachycardia (mean +/- SD 1.3 +/- 1.6 vs. 0.7 +/- 0.8 mm, p < 0.005). In AV reciprocating tachycardia distinct patterns of repolarization changes and P wave configuration were associated with different sites of the accessory pathway.

CONCLUSIONS

The presence of ST segment depression >2 mm or T wave inversion, or both, during narrow QRS complex tachycardia suggests that AV reentry using an accessory pathway is the mechanism of the tachycardia. The phenomenon may be the consequence of a distinct pattern of retrograde atrial activation. Analysis of repolarization changes can guide preliminary localization of the accessory pathway even in the absence of ventricular preexcitation.

[Modulation of atrioventricular conduction in patients with atrial fibrillation or flutter. Immediate and long-term results]

The modulation of atrioventricular (AV) conduction by radiofrequency catheter ablation of the "slow" AV node pathway reduces the ventricular rate during atrial flutter (AFL) or fibrillation (AF), without affecting AV conduction during sinus rhythm. In this study the acute and long-term effects of AV node modulation in 41 patients with AFL-AF are presented. The arrhythmia was paroxysmal in 34 and chronic in 7 patients, and was responsible in all patients for severe symptoms of heart failure. The procedure was performed during sinus rhythm in 23, AFL in 8, AF in 10 patients, and caused respectively an increase in Wenckebach cycle from 330 +/- 64 to 452 +/- 91 ms (p < 0.001), and a reduction in ventricular rate from 182 +/- 53 to 95 +/- 40 b/min (p < 0.001) and from 170 +/- 40 to 90 +/- 27 b/min (p < 0.001). The arbitrary endpoint of the procedure (Wenckebach cycle > 500 ms during sinus rhythm, maximum heart rate < 100 b/min during AFL-AF) was achieved in 19/41 patients; permanent complete AV block was induced in 6 "non-responder" patients (15%). At a mean follow-up of 15 +/- 7 months (range 1-31) all patients reported a substantial subjective improvement and a better exercise tolerance--as documented by a quantitative questionnaire concerning quality of life--without any recurrence of acute pulmonary edema, syncope or severe hypotension. In 5 patients during paroxysmal AFL-AF, and in 1 patient with chronic AF, a heart rate higher than 120 b/min was documented, and in 3 cases it was associated with severe palpitations. No late AV block occurred. The mean number of hospital-emergency room admissions per patient per year decreased from 3.9 before to 0.2 after the modulation. Considering complete AV block (6 patients, 15%) and clinical failures (6 patients, 15%), the success of the procedure was 70%, and was independent of the rhythm at the time of the procedure; the percentage of AV block was nevertheless higher during AFL-AF (22 vs 9%). Both endpoints of the procedure (Wenckebach cycle > 500 ms; heart rate < 100 b/min) were confirmed to be good predictors of long-term efficacy; on the other hand, a Wenckebach cycle < 430 ms was demonstrated to represent a specific marker of late failure. In conclusion, the study confirms that modulation of AV conduction is feasible in 70% of patients with AFL-AF: in these patients the procedure allows the long-term control of ventricular rate and a substantial improvement in quality of life, avoiding the need for His ablation and pacemaker implantation. "Non-responder" patients can be acutely identified and should be therefore considered condidates for His ablation during the same session.