The Lancet Commission to reduce the global burden of sudden cardiac death: a call for multidisciplinary action

Despite major advancements in cardiovascular medicine, sudden cardiac death (SCD) continues to be an enormous medical and societal challenge, claiming millions of lives every year. Efforts to prevent SCD are hampered by imperfect risk prediction and inadequate solutions to specifically address arrhythmogenesis. Although resuscitation strategies have witnessed substantial evolution, there is a need to strengthen the organisation of community interventions and emergency medical systems across varied locations and health-care structures. With all the technological and medical advances of the 21st century, the fact that survival from sudden cardiac arrest (SCA) remains lower than 10% in most parts of the world is unacceptable. Recognising this urgent need, the Lancet Commission on SCD was constituted, bringing together 30 international experts in varied disciplines. Consistent progress in tackling SCD will require a completely revamped approach to SCD prevention, with wide-sweeping policy changes that will empower the development of both governmental and community-based programmes to maximise survival from SCA, and to comprehensively attend to survivors and decedents' families after the event. International collaborative efforts that maximally leverage and connect the expertise of various research organisations will need to be prioritised to properly address identified gaps. The Commission places substantial emphasis on the need to develop a multidisciplinary strategy that encompasses all aspects of SCD prevention and treatment. The Commission provides a critical assessment of the current scientific efforts in the field, and puts forth key recommendations to challenge, activate, and intensify efforts by both the scientific and global community with new directions, research, and innovation to reduce the burden of SCD worldwide.

Individuals with chronic epilepsy have elevated P-wave heterogeneity comparable to patients with atrial fibrillation

OBJECTIVE

Identification of epilepsy patients with elevated risk for atrial fibrillation (AF) is critical given the heightened morbidity and premature mortality associated with this arrhythmia. Epilepsy is a worldwide health problem affecting nearly 3.4 million people in the United States alone. The potential for increased risk for AF in patients with epilepsy is not well appreciated, despite recent evidence from a national survey of 1.4 million hospitalizations indicating that AF is the most common arrhythmia in people with epilepsy.

METHODS

We analyzed inter-lead heterogeneity of P-wave morphology, a marker reflecting arrhythmogenic nonuniformities of activation/conduction in atrial tissue. The study groups consisted of 96 patients with epilepsy and 44 consecutive patients with AF in sinus rhythm before clinically indicated ablation. Individuals without cardiovascular or neurological conditions (n = 77) were also assessed. We calculated P-wave heterogeneity (PWH) by second central moment analysis of simultaneous beats from leads II, III, and aVR ("atrial dedicated leads") from standard 12-lead electrocardiography (ECG) recordings from admission day to the epilepsy monitoring unit (EMU).

RESULTS

Female patients composed 62.5%, 59.6%, and 57.1% of the epilepsy, AF, and control subjects, respectively. The AF cohort was older (66 ± 1.1 years) than the epilepsy group (44 ± 1.8 years, p < .001). The level of PWH was greater in the epilepsy group than in the control group (67 ± 2.6 vs. 57 ± 2.5 μV, p = .046) and reached levels observed in AF patients (67 ± 2.6 vs. 68 ± 4.9 μV, p = .99). In multiple linear regression analysis, PWH levels in individuals with epilepsy were mainly correlated with the PR interval and could be related to sympathetic tone. Epilepsy remained associated with PWH after adjustments for cardiac risk factors, age, and sex.

SIGNIFICANCE

Patients with chronic epilepsy have increased PWH comparable to levels observed in patients with AF, while being ~20 years younger, suggesting an acceleration in structural change and/or cardiac electrical instability. These observations are consistent with emerging evidence of an "epileptic heart" condition.

Reduction in atrial and ventricular electrical heterogeneity following pulmonary vein isolation in patients with atrial fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) modulates the intrinsic cardiac autonomic nervous system and reduces atrial fibrillation (AF) recurrence.

METHODS

In this retrospective analysis, we investigated the impact of PVI on ECG interlead P-wave, R-wave, and T-wave heterogeneity (PWH, RWH, TWH) in 45 patients in sinus rhythm undergoing clinically indicated PVI for AF. We measured PWH as a marker of atrial electrical dispersion and AF susceptibility and RWH and TWH as markers of ventricular arrhythmia risk along with standard ECG measures.

RESULTS

PVI acutely (16 ± 8.9 h) reduced PWH by 20.7% (from 31 ± 1.9 to 25 ± 1.6 µV, p < 0.001) and TWH by 27% (from 111 ± 7.8 to 81 ± 6.5 µV, p < 0.001). RWH was unchanged after PVI (p = 0.068). In a subgroup of 20 patients with longer follow-up (mean = 47 ± 3.7 days after PVI), PWH remained low (25 ± 1.7 µV, p = 0.01), but TWH partially returned to the pre-ablation level (to 93 ± 10.2, p = 0.16). In three individuals with early recurrence of atrial arrhythmia in the first 3 months after ablation, PWH increased acutely by 8.5%, while in patients without early recurrence, PWH decreased acutely by 22.3% (p = 0.048). PWH was superior to other contemporary P-wave metrics including P-wave axis, dispersion, and duration in predicting early AF recurrence.

CONCLUSION

The rapid time course of decreased PWH and TWH after PVI suggests a beneficial influence likely mediated via ablation of the intrinsic cardiac nervous system. Acute responses of PWH and TWH to PVI suggest a favorable dual effect on atrial and ventricular electrical stability and could be used to track individual patients' electrical heterogeneity profile.

Dual assessment of abnormal cardiac electrical dispersion and diastolic dysfunction for early detection of the epileptic heart condition

BACKGROUND

People with epilepsy (PWE) are at increased risk for premature death due to many factors. Sudden unexpected death in epilepsy (SUDEP) is among the most important causes of death in these individuals and possibly, sudden cardiac death (SCD) in epilepsy is also as important. The possibility of concurrent derangement in electrical and mechanical cardiac function, which could be a marker of early cardiac involvement in PWE, has not been investigated in that population.

METHODS

Electrical dispersion indices (T-wave peak to T-wave end, TpTe; QT dispersion, QTd; QT interval corrected for heart rate, QTc) were analyzed in patients with pharmacoresistant temporal lobe epilepsy and compared to a control group. The electromechanical relationship between those indices and echocardiographic parameters were further assessed in PWE.

RESULTS

In 19 PWE and 21 controls, we found greater TpTe and QTd in PWE (TpTe: 91.6 ± 16.4 ms vs. 65.2 ± 12.1 ms, p < 0.0001; and QTd: 45.3 ± 13.1 ms vs. 19 ± 6.2 ms, p < 0.0001, respectively). QTc was similar between PWE and controls (419.2 ± 31.4 ms vs. 435.1 ± 31.4 ms, p = 0.12). In multivariate linear regression, TpTe, QTc, and epilepsy duration were related to left ventricular mass; QTc was associated with left atrial volume; QTc, the number of seizures per month, epilepsy duration and antiseizure medication explained 81% of E/A mitral wave Doppler ratio.

CONCLUSIONS

This is the first report to demonstrate concurrent electrical dispersion and diastolic dysfunction in PWE. These noninvasive biomarkers could prove useful in early detection of the "Epileptic Heart" condition.

Cardioneuroablation for Vasovagal Syncope and Atrioventricular Block: A Step-by-Step Guide

Catheter based cardioneuroablation is increasingly being utilized to improve outcomes in patients with vasovagal syncope and atrioventricular block due to vagal hyperactivity. There is now increasing convergence amongst enthusiasts on its various aspects, including patient selection, technical steps, and procedural end-points. This pragmatic review aims to take the reader through a step-by-step approach to cardioneuroablation: we begin with a brief overview of the anatomy of intrinsic cardiac autonomic nervous system, before focusing on the indications, pre- and post-procedure management, necessary equipment, and its potential limitations. This article is protected by copyright. All rights reserved.

Very early versus early referral for ablation among young patients for newly diagnosed paroxysmal atrial fibrillation

BACKGROUND

Catheter ablation (CA) has emerged as an effective therapy for the treatment of paroxysmal atrial fibrillation, however it is unclear whether proceeding expeditiously to CA improves clinical outcomes in a real-world population. This study compares outcomes of catheter ablation for new atrial fibrillation (AF) within 6 months of diagnosis (very early) 6 to 12 months after diagnosis (early) and 12 to 24 months after diagnosis (later).

METHODS

A large nationally-representative sample of patients ages 18 to 64 who underwent CA from January 2011 to June 2019 was studied using the IBM MarketScan® Database. The primary outcome was a composite of healthcare utilization over the following 24 months. Propensity score-matching was used to match patients in each cohort. Risk difference in outcomes were compared between matched patients.

RESULTS

2,631 patients were identified post-matching, with 1,649 in the very early cohort and 982 in the early cohort. The very early referral group was less likely to experience the primary composite outcome post-ablation (Absolute risk difference [ARD]: -3.9%; 95% Confidence interval [CI]: -5.8%, -2.0%), with the difference driven by fewer cardioversions (ARD: -2.9%, 95% CI: -5.3%, -0.5%) and outpatient visits (ARD: -6.6%, 95% CI: -10.5%, -2.7%). There was no difference in outcomes between early and later referral groups, with only very early referral showing decreased healthcare utilization.

CONCLUSIONS

Patients who underwent ablation within 6 months of diagnosis had lower healthcare utilization in the ensuing 24 months, driven by fewer outpatient visits and cardioversions, supporting expeditious referral for ablation for symptomatic AF. This article is protected by copyright. All rights reserved.

Computer modeling of radiofrequency cardiac ablation: 30 years of bioengineering research

This review begins with a rationale of the importance of theoretical, mathematical and computational models for radiofrequency (RF) catheter ablation (RFCA). We then describe the historical context in which each model was developed, its contribution to the knowledge of the physics of RFCA and its implications for clinical practice. Next, we review the computer modeling studies intended to improve our knowledge of the biophysics of RFCA and those intended to explore new technologies. We describe the most important technical details of the implementation of mathematical models, including governing equations, tissue properties, boundary conditions, etc. We discuss the utility of lumped element models, which despite their simplicity are widely used by clinical researchers to provide a physical explanation of how RF power is absorbed in different tissues. Computer model verification and validation are also discussed in the context of RFCA. The article ends with a section on the current limitations, i.e. aspects not yet included in state-of-the-art RFCA computer modeling and on future work aimed at covering the current gaps.

Spectrum of clinical applications of interlead ECG heterogeneity assessment: From myocardial ischemia detection to sudden cardiac death risk stratification

Heterogeneity in depolarization and repolarization among regions of cardiac cells has long been recognized as a major factor in cardiac arrhythmogenesis. This fundamental principle has motivated development of noninvasive techniques for quantification of heterogeneity using the surface electrocardiogram (ECG). The initial approaches focused on interval analysis such as interlead QT dispersion and T_peak -T_end difference. However, because of inherent difficulties in measuring the termination point of the T wave and commonly encountered irregularities in the apex of the T wave, additional techniques have been pursued. The newer methods incorporate assessment of the entire morphology of the T wave and in some cases of the R wave as well. This goal has been accomplished using a number of promising vectorial approaches with the resting 12-lead ECG. An important limitation of vectorcardiographic analyses is that they require exquisite stability of the recordings and are not inherently suitable for use in exercise tolerance testing (ETT) and/or ambulatory ECG monitoring for provocative stress testing or evaluation of the influence of daily activities on cardiac electrical instability. The objectives of the present review are to describe a technique that has been under clinical evaluation for nearly a decade, termed "interlead ECG heterogeneity." Preclinical testing data will be briefly reviewed. We will discuss the main clinical findings with regard to sudden cardiac death risk stratification, heart failure evaluation, and myocardial ischemia detection using standard recording platforms including resting 12-lead ECG, ambulatory ECG monitoring, ETT, and pharmacologic stress testing in conjunction with single-photon emission computed tomography myocardial perfusion imaging.

Hemodynamic intolerance and pericardial effusion associated with high-frequency jet ventilation during pulmonary vein isolation

Background

High-frequency jet ventilation (HFJV) is used during pulmonary vein isolation (PVI) to increase catheter stability and improve outcomes. In prior studies, hemodynamic intolerance to HFJV was rare.

Objectives

To evaluate the incidence of hemodynamic or respiratory intolerance of HFJV during PVI.

Methods

Retrospective observational analysis of consecutive patients undergoing PVI performed by 2 operators (PT, JW) at our institution between February 2019 and June 2020 who developed persistent hypotension or abnormal ventilatory parameters in association with HFJV.

Results

Among 194 PVIs, there were 8 cases (4%) of conversion from HFJV to conventional ventilation, 6 for refractory hypotension and 2 for persistently abnormal gas exchange. In 6 patients, including 5 of the 6 patients with refractory hypotension, a new, small pericardial effusion without tamponade was noted just after HFJV was initiated. In patients with persistent hypotension, a decrease in left ventricular filling and systolic function was frequently noted. Both the hemodynamic changes and effusion resolved almost immediately after discontinuation of HFJV. In 4 patients rechallenged with HFJV, the hypotension and/or effusion recurred quickly and again resolved immediately after return to conventional ventilation.

Conclusion

HFJV-associated hypotension and systolic dysfunction, often accompanied by a transient pericardial effusion, is present in a small proportion of patients undergoing PVI, and resolves with cessation of HFJV. The mechanism of these changes is unclear and warrants further study.

EHRA expert consensus statement and practical guide on optimal implantation technique for conventional pacemakers and implantable cardioverter-defibrillators: endorsed by the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), and the Latin-American Heart Rhythm Society (LAHRS)

With the global increase in device implantations, there is a growing need to train physicians to implant pacemakers and implantable cardioverter-defibrillators. Although there are international recommendations for device indications and programming, there is no consensus to date regarding implantation technique. This document is founded on a systematic literature search and review, and on consensus from an international task force. It aims to fill the gap by setting standards for device implantation.

Epicardial and Coronary Sinus Echocardiography

Catheter-based ultrasonography is a widely used tool in cardiac electrophysiology practice, and intracardiac echocardiography is supplanting other forms of imaging to become the dominant imaging modality. Given advances in pericardial access, intrapericardial echocardiography can be performed using ultrasound catheters as well. Intrapericardial echocardiography and echocardiography from the coronary sinus, also an epicardial structure, allows interventionalists to obtain unique views from virtually any vantage point, compared with other forms of echocardiography. Both intrapericardial echocardiography and coronary sinus echocardiography are safe and important alternatives that can be used during complex procedures in the electrophysiology laboratory.

Persistent Atrial Fibrillation Ablation in Females: Insight from the MAGIC-AF Trial

INTRODUCTION

Atrial fibrillation (AF) ablation is less frequently performed in women when compared to men. There are conflicting data on the safety and efficacy of AF ablation in women. The objective of this study was to compare the clinical characteristics and outcomes in a contemporary cohort of men and women undergoing persistent AF ablation procedures.

METHODS AND RESULTS

A total of 182 men and 53 women undergoing a first-ever persistent AF catheter ablation procedure in The Modified Ablation Guided by Ibutilide Use in Chronic Atrial Fibrillation (MAGIC-AF) trial were evaluated. Clinical and procedural characteristics were compared between each gender. The primary efficacy endpoint was the 1-year single procedure freedom from atrial arrhythmia off anti-arrhythmic drugs. Women undergoing catheter ablation procedures were older than men (P < 0.001). The duration of AF and associated co-morbidities were similar between both genders. Single procedure drug-free atrial arrhythmia recurrence occurred in 53% of the cohort with no difference based on gender (men = 54%, women = 53%; P = 1.0). Procedural (P = 0.04), fluoroscopic (P = 0.02), and ablation times (P = 0.003) were shorter in women compared to men. Periprocedural complications and postablation improvement in quality of life were similar between men and women.

CONCLUSION

Women undergoing a first-ever persistent AF ablation procedure were older but had similar clinical outcomes and complications when compared with men.

Pulmonary Vein Isolation Using the Visually Guided Laser Balloon: Results of the U.S. Feasibility Study

INTRODUCTION

Visually guided laser balloon (VGLB) ablation is unique in that the operator delivers ablative energy under direct visual guidance. In this multicenter study, we sought to determine the feasibility, efficacy, and safety of performing pulmonary vein isolation (PVI) using this VGLB.

METHODS

Patients with symptomatic, drug-refractory paroxysmal atrial fibrillation (AF) underwent PVI using the VGLB with the majority of operators conducting their first-ever clinical VGLB cases. The primary effectiveness endpoint was defined as freedom from treatment failure that included: Occurrence of symptomatic AF episodes ≥1 minutes beyond the 90-day blanking, the inability to isolate 1 superior and 2 total PVs, occurrence of left atrial flutter or atrial tachycardia, or left atrial ablation/surgery during follow-up.

RESULTS

A total of 86 patients (mean age 56 ± 10 years, 67% male) were treated with the VGLB at 10 US centers. Mean fluoroscopy, ablation, and procedure times were 39.8 ± 24.3 minutes, 205.2 ± 61.7 minutes, and 253.5 ± 71.3 minutes, respectively. Acute PVI was achieved in 314/323 (97.2%) of targeted PVs. Of 84 patients completing follow-up, the primary effectiveness endpoint was achieved in 50 (60%) patients. Freedom from symptomatic or asymptomatic AF was 61%. The primary adverse event rate was 16.3% (8.1% pericarditis, phrenic nerve injury 5.8%, and cardiac tamponade 3.5%). There were no cerebrovascular events, atrioesophageal fistulas, or significant PV stenosis.

CONCLUSIONS

This multicenter study of operators in the early stage of the learning curve demonstrates that PVI can be achieved with the VGLB with a reasonable safety profile and an efficacy similar to radiofrequency ablation.

Three-Dimensional Cardiac Mapping Characterizes Ventricular Contractile Patterns during Cardiac Resynchronization Therapy Implant: A Feasibility Study

BACKGROUND

Electroanatomic mapping systems track the position of electrodes in the heart. We assessed the feasibility of characterizing left ventricular (LV) performance during cardiac resynchronization therapy (CRT) implant utilizing an electroanatomic mapping system to track the motion of CRT lead electrodes, thus deriving ventricular contractility surrogates.

METHODS

During CRT implant, atrial, right ventricular (RV), and LV leads were connected to the EnSite NavX™ mapping system (St. Jude Medical Inc., St. Paul, MN, USA). The relative displacement of electrodes was averaged over 10 cardiac cycles during RV, LV, and biventricular (BiV) pacing in DOO mode. Three contractility surrogates indicative of ventricular performance were extracted from the RV-LV distance waveform: systolic slope (SS), time to peak systolic contraction (TPSC), and fractional shortening (FS).

RESULTS

In the 20 patients included, there were detectable differences in each of the three contractility surrogates responding to the different pacing configurations. Median SS varied 42%, median TPSC varied 35%, and median FS varied 19% across RV, LV, and BiV pacing interventions. The RV-LV distance waveform showed subtle sensitivity to varying pacing timing cycles when measured in a subset of patients. For all pacing configurations, RV-LV distance waveforms were stable during 2-minute recordings.

CONCLUSIONS

Tracking the motion of CRT pacing electrodes with a mapping system to derive contractility surrogates during implant is feasible.

Occurrence of steam pops during irrigated RF ablation: novel insights from microwave radiometry

BACKGROUND

The disparity between catheter and tissue temperatures during irrigated RF ablation frustrates one's ability to predict steam pops. Microwave radiometry allows for "volumetric" temperature assessment-i.e., within a circumscribed volume around the catheter tip-permitting, direct assessment of temperature during ablation. The aim of this study was to examine (i) the ability of microwave radiometry to predict steam pops, and (ii) compare this to traditional parameters such as power, catheter temperature, and impedance.

METHODS AND RESULTS

Irrigated RF ablation was performed in 8 sheep using the Tempasure ablation catheter in all chambers. Power, impedance, catheter tip, and volumetric temperature were continually monitored. Ablation was terminated after a pop or at 60 seconds. A pop was defined as an audible or visualized pop (intracardiac echocardiography). Predictors of pops were determined by univariate and multivariate GEE logistic regression modeling. A total of 48 pops occurred during 143 lesions applied at 20-50 W. There was no association between the chamber of the heart and the occurrence of pops. The rate of rise of volumetric temperature (greater than 1.5 °C/s) was the single best predictor of pops (OR: 88.8 [95% CI: 12-604], P < 0.0007). Pops only occurred above a maximum volumetric temperature threshold of 89 °C.

CONCLUSIONS

During irrigated RF ablation, steam pop occurrence can be predicted by both, the rate of rise and the maximum volumetric temperature measured by microwave radiometry.

Adjunctive renal sympathetic denervation to modify hypertension as upstream therapy in the treatment of atrial fibrillation (H-FIB) study: clinical background and study design

BACKGROUND

Hypertension is the most important risk factor directly attributable to the high prevalence of atrial fibrillation (AF), and is one of the few modifiable risk factors for AF. Activation and overactivity of the sympathetic nervous system (SNS) have been implicated in the pathogenesis of both essential hypertension and AF. Catheter-based renal sympathetic denervation (RSDN) appears to be an effective adjunctive treatment for refractory hypertension, and may be beneficial in other conditions characterized by SNS overactivity, such as left ventricular hypertrophy and atrial arrhythmias.

OBJECTIVE

The H-FIB study is a multicenter prospective, double-blind, randomized (1:1) controlled trial. The primary efficacy endpoint is antiarrhythmic drug-free freedom from AF recurrence through 12 months.

METHODS

Patients with a history of significant hypertension who are receiving treatment with at least one antihypertensive agent who are planned for a first time ablation for symptomatic paroxysmal or persistent AF will be randomized to either AF ablation alone (control group) or AF ablation + RSDN (study group).

CONCLUSIONS

H-FIB is a multicenter, randomized trial that will test the hypothesis that adjunctive renal sympathetic denervation, at the time of AF ablation, will increase the freedom from recurrent AF.

Safety and efficacy of high-intensity focused ultrasound atop coronary arteries during epicardial catheter ablation

BACKGROUND

Coronary arterial injury continues to be a limitation of epicardial catheter ablation using currently available energy sources. Application of high intensity focused ultrasound (HIFU) energy may avoid such injury due to its theoretical ability to focus energy beyond the ablation element and create lesions at depth.

OBJECTIVE

This study evaluated the safety of HIFU applications delivered directly over the left anterior descending (LAD) artery in an open-chest swine model.

METHODS

Ten swine underwent median sternotomy. A prototype HIFU probe was placed atop the LAD. Forty-three therapies along the LAD (60-seconds/6 watt) were analyzed. Three, 3, and 4 swine were studied at 2, 4, and 8 weeks and subsequently sacrificed. Lesions were scored (0-4) depending on the percent circumferential involvement of arteries.

RESULTS

Lesion area increased minimally from 54.5 ± 18.0 mm(2) at 2 weeks to 56.9 ± 20.6 mm(2) at 8 weeks, and depth increased moderately from 13.2 ± 2.5 mm to 15.5 ± 3.4 mm. At 2, 4, and 8 weeks, the mean injury score of the LAD was 0.8 ± 0.3, 1.5 ± 0.9, and 2.0 ± 0.7. No/minimal arterial injury was seen in 64% of all sections. However, a progressive increase in injury resulted in 89% of all sections showing any injury at 8 weeks. One animal developed occlusion of the distal LAD.

CONCLUSIONS

HIFU has the potential to create deep ventricular lesions with relative sparing of the LAD. The incremental arterial damage noted over time warrants further evaluation to support the viability of focusing ultrasound energy beyond vulnerable critical structures to ablate deeper targets.

Catheter ablation of atrial fibrillation without the use of fluoroscopy

BACKGROUND

In performing catheter ablation of paroxysmal atrial fibrillation (PAF), the advent of electroanatomical mapping (EAM) has significantly reduced fluoroscopy time. Recent advances in the ability of EAM systems to simultaneously visualize multiple catheters have allowed some operators to perform certain procedures, such as catheter ablation of supraventricular tachycardias, with zero fluoroscopy use.

OBJECTIVE

The purpose of this study was to evaluate the feasibility and safety of pulmonary vein (PV) isolation with zero fluoroscopy use, using a combination of three-dimensional EAM and intracardiac echocardiography (ICE).

METHODS

Using the NavX EAM system, the right atrial (RA) and coronary sinus (CS) geometries were created without fluoroscopy. Fluoroless transseptal puncture was performed under ICE guidance. Using a deflectable sheath and a multipolar catheter, the left atrial (LA) and PV anatomies were rendered and, in select cases, integrated with a three-dimensional computed tomography (CT) image. Irrigated radiofrequency ablation was performed to encircle each pair of ipsilateral PVs.

RESULTS

This series included 20 consecutive PAF patients. RA/CS mapping required 5.5 ± 2.6 minutes. In all patients, single (n = 18) or dual (n = 2) transseptal access was successfully achieved. The LA-PV anatomy was rendered using either a circular (14 patients) or penta-array (six patients) catheter in 22 ± 10 minutes; CT image integration was used in 11 patients. Using 49 ± 18 ablation lesions/patient, electrical isolation was achieved in 38/39 ipsilateral PV isolating lesion sets (97%). The procedure time was 244 ± 75 minutes. There were no complications.

CONCLUSION

Completely fluoroless catheter ablation of paroxysmal AF is safely feasible using a combination of ICE and EAM.

Importance of catheter contact force during irrigated radiofrequency ablation: evaluation in a porcine ex vivo model using a force-sensing catheter

INTRODUCTION

Ablation electrode-tissue contact has been shown to be an important determinant of lesion size and safety during nonirrigated ablation but little data are available during irrigated ablation. We aimed to determine the importance of contact force during irrigated-tip ablation.

METHODS AND RESULTS

Freshly excised hearts from 11 male pigs were perfused and superfused using fresh, heparinized, oxygenated swine blood in an ex vivo model. One-minute ablations were placed using one of 3 different power control strategies (impedance control-15 Omega target impedance drop, and 20 W or 30 W fixed power) and 3 different contact forces (2 g, 20 g, and 60 g) to give a grid of 9 ablation groups. The force sensing catheter (Tacticath, Endosense SA) was irrigated at 17 mL/min for all of the ablations. Of a total 101 ablations, no thrombus formation was noted but popping was seen in 17 lesions. The lesion depth and incidence of pops was 5.0 +/- 1.3 mm /0%, 5.0 +/- 1.6 mm /10% and 6.7 +/- 2.5 mm /45% for the 15 Omega, 20 W, and 30 W groups (P < 0.01), respectively, and 4.4 +/- 1.8 mm /3%, 5.8 +/- 1.6 mm /17% and 6.6 +/- 2.0 mm /37% for the 2 g, 20 g, and 60 g groups, respectively (P < 0.01). The impedance drop in the first 5 seconds was significantly correlated to catheter contact force: 9.7 +/- 9.9 Omega, 22.3 +/- 11.0 Omega, and 41.7 +/- 22.1 Omega, respectively, for the 2 g, 20 g, and 60 g groups (Pearson's r = 0.65, P < 0.01).

CONCLUSION

Catheter contact force has an important impact on both ablation lesion size and the incidence of pops.

The permanency of pulmonary vein isolation using a balloon cryoablation catheter

BACKGROUND

Because of its technical feasibility and presumed safety benefits, balloon cryoablation is being increasingly employed for pulmonary vein (PV) isolation. While acute isolation has been demonstrated in most patients, little data are available on the chronic durability of cryoballoon lesions.

METHODS AND RESULTS

Twelve atrial fibrillation patients underwent PV isolation using either a 23-mm or 28-mm cryoballoon. For each vein, after electrical isolation was verified with the use of a circular mapping cathether, 2 bonus balloon ablation lesions were placed. Gaps in balloon occlusion were overcome using either a spot cryocatheter or a "pull-down" technique. A prespecified second procedure was performed at 8-12 weeks to assess for long-term PV isolation. Acute PV isolation was achieved in all PVs in the patient cohort (n = 48 PVs), using the cryoballoon alone in 47/48 PVs (98%); a "pull-down" technique was employed for 5 PVs (1 right superior pulmonary vein, 2 right inferior pulmonary veins, and 2 left inferior pulmonary veins). The gap in the remaining vein was ablated with a spot cryocatheter. During the second mapping procedure, 42 of 48 PVs (88%) remained isolated. One vein had reconnected in 2 patients, while 2 veins had reconnected in another 2 patients. All PVs initially isolated with the "pull-down" technique remained isolated at the second procedure.

CONCLUSIONS

Cryoballoon ablation allows for durable PV isolation with the use of a single balloon. With maintained chronic isolation in most PVs, it may represent a significant step toward consistent and lasting ablation procedures.

Effect of presenting rhythm on image integration to direct catheter ablation of atrial fibrillation

INTRODUCTION

Magnetic resonance (MR) imaging of the left atrium (LA) can be integrated with electroanatomic mapping systems to guide catheter ablation of atrial fibrillation (AF). The usefulness of this technique is dependent on the accuracy of image integration.

OBJECTIVE

The aim of this study is to determine the effect of heart rhythm at the time of pre-procedure MR imaging and heart rhythm at the time of ablation on integration error.

METHODS

Fifty-two consecutive patients who underwent catheter ablation for AF were included. All patients underwent MR imaging of LA and pulmonary veins and image integration with real-time electroanatomic mapping. The rhythm at the time of MR imaging and on the day of ablation was recorded. CARTO-Merge software (Biosense-Webster) was used to calculate the average accuracy of integration of electroanatomic points with MR-derived reconstructions.

RESULTS

There was no significant difference in integration error between patients who were in AF at the time of their MR vs. those who were in sinus rhythm at the time of their MR (1.76 +/- 0.26 vs. 1.88 +/- 0.31 mm, p = 0.15). There was also no significant difference in integration error between patients who were in concordant vs. discordant rhythms at the time of MR vs. day of ablation (1.81 +/- 0.23 vs. 1.89 +/- 0.32 mm, p = 0.40). There was a trend toward less integration error between patients who were in AF on the day of ablation vs. those in sinus rhythm (1.74 +/- 0.26 vs. 1.89 +/- 0.31 mm, p = 0.07).

CONCLUSIONS

Image integration can be performed to direct catheter ablation of AF regardless of the rhythm at the time of imaging and ablation.

Isolating the Posterior Left Atrium and Pulmonary Veins with a "Box" Lesion Set: Use of Epicardial Ablation to Complete Electrical Isolation

Similar to the surgical mini-maze procedure, the posterior "box" lesion set employs linear ablation lesions along the anterior aspects of both sets of PVs connected by a roof line and an inferior line to electrically isolate the PVs and complete posterior LA wall en masse. However, creating fully transmural linear atrial lesions can be difficult to achieve, even with an irrigated ablation catheter. This report details a case wherein a combined endocardial and epicardial approach was required to create an electrically continuous posterior box lesion in a patient with persistent AF.

Combined ventricular endocardial and epicardial substrate mapping using a sonomicrometry-based electroanatomical mapping system

BACKGROUND

Substrate mapping using a magnetic electroanatomical mapping system (MEAM) has been shown to accurately delineate the location/extent of scarred myocardium. This study examined the ability of a sonomicrometry-based electroanatomic mapping system (SEAM) to render endocardial and epicardial substrate maps of infarcted ventricular myocardium.

METHODS AND RESULTS

In 7 swine with healed myocardial infarctions, combined epicardial and endocardial left ventricular (LV) substrate maps were created with both SEAM and MEAM mapping systems using 246+/-68 and 244+/-44 points respectively. Scarred myocardium was identified based upon bipolar electrogram amplitude < 1.5 mV, and radiofrequency ablation lesions were delivered to the scar border as defined by the sonomicrometry mapping system. The LV endocardial chamber volume as defined by SEAM (125+/-46 ml) correlated well with that defined by the MEAM (137+/-45 ml, r=0.77, p < 0.05). The area of infarcted tissue as determined by SEAM was highly correlated with that determined by gross pathology (r=0.96 for endocardial scar and r=0.92 for epicardial scar p < 0.05). The scar area calculated by the SEAM system also correlated well with the scar area determined by the MEAM system (0.91 for endocardial scar and 0.90 for epicardial scar p < 0.05). Finally, the sonomicrometry-based system was able to guide the placement of radiofrequency ablation lesions to the borders of the scar.

CONCLUSIONS

This study demonstrates that the sonomicrometry-based mapping can accurately reconstruct three-dimensional voltage maps of the endocardial and epicardial ventricular surfaces and guide the placement of ablation lesions along the scar border zone.

Pain and anatomical locations of radiofrequency ablation as predictors of esophageal temperature rise during pulmonary vein isolation

INTRODUCTION

Esophageal temperature rise (ETR) during ablation inside left atrium has been reported as a marker for esophageal thermal injury. We sought to investigate the possible relationships between chest pain and ETR during radiofrequency (RF) ablation, and ETR and locations of RF application, in patients undergoing pulmonary vein (PV) isolation under moderate sedation.

METHODS AND RESULTS

We analyzed anatomical locations of each RF application and its association with esophageal temperature and presence/absence of pain. Data from 40 consecutive patients (mean age: 56 +/- 10 years) were analyzed. There were a total of 4,071 RF applications resulting in 291 episodes of pain (7.1%) and 223 ETRs (5.5%). Thirty-five patients (87.5%) experienced at least one pain episode and 32 (80.0%) had at least one ETR. While 77.4% of posterior wall applications that caused pain also corresponded to an ETR (P < 0.0001), only 0.8% of pain-free posterior wall applications were associated with ETRs (P < 0.0001). The sensitivity and specificity of pain during ablation for ETR were 94% and 98%, respectively. No ETRs were observed during anterior wall applications. ETRs occurred more frequently during ablation on the left (86.1%) versus the right (13.9%), and in inferior (70.4%) versus superior (29.6%) segments.

CONCLUSION

In patients undergoing PV isolation, ETR was encountered when ablating in the posterior left atrium with the distribution left > right and inferior > superior. Pain during ablation was associated with ETR, and lack of pain was strongly associated with absence of ETR. Pain during RF ablation may thus serve as a predictor of esophageal heating and potential injury.

Impedance and temperature monitoring improve the safety of closed-loop irrigated-tip radiofrequency ablation

INTRODUCTION

Irrigated-tip catheter ablation allows larger ablation lesions to be created, but also decreases catheter temperature monitoring accuracy. It is unclear which parameters should be monitored to optimize efficacy and safety during irrigated-tip ablation.

METHODS AND RESULTS

Freshly excised hearts from eight male pigs were perfused and superfused using oxygenated swine blood in an ex vivo model. Ablations were performed for 1 minute using one of five different ablation protocols: (1) Temperature Control (42 degrees C 40 W), (2) Fixed Power 20 W, (3) Fixed Power 30 W, (4) Impedance Control (target 10 ohm impedance drop), and (5) Impedance Control (target 20 ohm drop). All ablations were performed with a perpendicular orientation of the catheter to the endocardial surface. Ablation lesions depth was significantly lower in the temperature control group (5.0 +/- 1.7 mm) compared with the fixed power ablation groups (6.5 +/- 1.0 mm for Power 20 W, 6.6 +/- 1.2 mm for Power 30 W). Impedance-controlled ablation created lesions intermediate in depth between fixed power and temperature controlled (6.0 +/- 1.6 for Impedance 10 ohms and 6.2 +/- 1.4 mm for Impedance 20 ohms groups). There was a significantly greater incidence of pops and thrombus formation in the Power 20 W (9/14), Power 30 W (10/14), and Impedance 20 ohms (10/16) groups than the Temperature Control (1/16) and Impedance control 10 ohms (2/16) groups.

CONCLUSION

Temperature control improved the safety profile during irrigated-tip ablation in comparison with fixed-power ablations, but resulted in significantly smaller lesions. Impedance-controlled ablation lesions (target 10 ohm drop) created lesions of comparable size to fixed-power ablations with a significantly better safety profile.

Factors affecting error in integration of electroanatomic mapping with CT and MR imaging during catheter ablation of atrial fibrillation

OBJECTIVE

Integration of 3-D electroanatomic mapping with Computed Tomographic (CT) and Magnetic Resonance (MR) imaging is gaining acceptance to facilitate catheter ablation of atrial fibrillation. This is critically dependent on accurate integration of electroanatomic maps with CT or MR images. We sought to examine the effect of patient- and technique-related factors on integration accuracy of electroanatomic mapping with CT and MR imaging of the left atrium.

MATERIALS AND METHODS

Sixty-one patients undergoing catheter-based atrial fibrillation (AF) ablation procedures were included. All patients underwent cardiac CT (n = 11) or MR (n = 50) imaging, and image integration with real-time electroanatomic mapping of the aorta and left atrium (LA). CARTO-Merge software (Biosense-Webster) was used to calculate the overall average accuracy of integration of electroanatomic points with the CT and MR-derived reconstructions of the LA and aorta.

RESULTS

There was a significant correlation between LA size assessed by electroanatomic mapping (112 +/- 31 ml) and average integration error (1.9 +/- 0.6 mm) (r = 0.46, p = 0.0003). There was also greater integration error for patients with LA volume >/= 110 ml (n = 31) versus < 110 ml (n = 30) (p = 0.004). In contrast, there was no significant association between average integration error and paroxysmal versus persistent AF, left ventricular ejection fraction, days from imaging to electroanatomic mapping, or images derived from CT versus MR.

CONCLUSIONS

Patients with larger LA volume may be prone to greater error during integration of electroanatomic mapping with CT and MR imaging. Strategies to reduce integration error may therefore be especially useful in patients with large LA volume.

Influence of leptin, androgens and insulin sensitivity on increased GH response to clonidine in lean patients with polycystic ovary syndrome

Our aim was to investigate whether insulin sensitivity, leptin, androgen or estradiol levels are associated with disturbed GH response to clonidine in lean patients with polycystic ovary syndrome. Fourteen lean polycystic ovary syndrome patients, 11 ovulatory patients presenting idiopathic hirsutism and 10 non-hirsute, normal women with regular cycles paired for age and BMI were included in a cross-sectional study. Baseline hormonal and metabolic variables were assessed and analyzed in association with GH response to oral administration of 0.3 mg of clonidine. Delta GH was significantly higher in the PCOS group than in the IH and control groups (p = 0.014). The groups were similar in terms of body mass index, insulin, glucose, total and HDL cholesterol, triglycerides and estradiol levels. Free androgen index (r = 0. 454, p = 0.015) and leptin (r = 0.419, p = 0.023) were positively correlated with the homeostasis model assessment. The homeostasis model assessment was the only variable that significantly correlated with GH response to clonidine (r = 0.375, p = 0.029) (vs. estradiol, free androgen index, leptin and LH). Nonetheless, when the analysis was adjusted for leptin levels and free androgen index, the statistical significance of this correlation was lost. The increased GH secretion observed in our lean PCOS patients may be associated with slight changes in insulin sensitivity, even in the absence of clinical evidence of insulin resistance. This association seems to be modulated by leptin and androgen levels.

Pericardial anatomy for the interventional electrophysiologist

Investigators are beginning to exploit the pericardial space for a number of cardiovascular applications, including catheter ablation of cardiac arrhythmias, cardiovascular drug therapy, and cardiac pacing. This review explores the anatomy of the pericardial space and the anatomic variants that may be encountered in this novel approach to the heart.

Probability of occurrence of life-threatening ventricular arrhythmias in Chagas' disease versus non-Chagas' disease

The implantable cardioverter defibrillator (ICD) is highly effective in the treatment of ventricular arrhythmias (VA) responsible for sudden cardiac death. However, the probability of occurrence of these arrhythmic events in presence of cardiomyopathy remains uncertain. The aim of this study was to compare the probability of nonoccurrence of life-threatening VA in ICD recipients with Chagas' versus non-Chagas' heart disease. Over a mean follow-up of 10.5 months, 53 ICD recipients (mean age = 50.1 years, 48 male) were evaluated. Eleven patients had Chagas' heart disease, 19 had idiopathic dilated cardiomyopathy and 23 had ischemic cardiomyopathy. Ventricular tachyarrhythmias with a cycle length < 315 ms were considered life-threatening. The cumulative probability of nonoccurrence of life-threatening VA was examined by Kaplan-Meyer method and the outcomes were submitted to the log rank test. At 2 years, the cumulative probability of life-threatening VA nonoccurrence was 0 in the Chagas' heart disease group versus 40% up to 55 months of follow-up in the non-Chagas' disease group (P = 0.0097). Among patients with cardiomyopathies of different etiologies, those with Chagas' heart disease had the lowest cumulative probability of nonoccurrence of life-threatening VA, confirming its unfavorable prognosis and the importance of preventive measures against sudden death in this disease.

[Reduction of pressure gradients and of ventricular hypertrophy after surgical valvoplasty in aortic stenosis]

BACKGROUND

Relief of gradient is followed by myocardial mass reduction in aortic stenosis. Its degree and speed are under evaluation. Aortic valve repair in calcified aortic stenosis is less well studied than replacement.

METHODS

We evaluated left ventricular hypertrophy reduction by echocardiogram in 11 patients immediately after valve repair in aortic stenosis at a mean of 6.1 +/- 0.9 days post operative.

RESULTS

Septal width was 12.10 +/- 1.66 mm pre and 11.36 +/- 1.12 mm post operative, 6,1% reduction (NS). Parietal width varied 4.4% from 11.70+/-1.41 mm to 11.18 +/- 1,16 mm (NS). Ejection fraction went from 62.02+/-18.59% to 62.50+/-11. 74% (NS). Left ventricular mass varied 6.7%, from 277.65+/-114.80g to 258.93+/- 92.38 g (NS). Mean transvalvar gradient reduced 57%, from 53.56+/-10.30 to 23.0+/-9.1 mmHg (P<0.001).

CONCLUSION

Aortic valve repair reduces gradients adequately and left ventricular hypertrophy shows a trend to regression soon after aortic repair, but is not yet significant in the first post-operatively week.

Predictive factors for persistence of atrial fibrillation after mitral valve operation

BACKGROUND

The majority of patients operated on for mitral valve disease with chronic atrial fibrillation (AF) do not recover sinus rhythm with conventional postoperative treatment. The maze procedure may be used in these circumstances. To define the precise indications for the maze procedure, it would be necessary to identify those patients based on preoperative factors.

METHODS

A retrospective study was undertaken on 100 consecutive patients operated on for mitral valve disease in chronic AF. The return to sinus rhythm was analyzed with relation to age, gender, AF duration, left atrial size, left ventricular ejection fraction, lesion type, valve procedure, associated procedures, and reoperation.

RESULTS

At late follow-up (more than 1 year) 26 (26%) patients presented sinus rhythm and 74 (74%) remained in AF. Statistical single parametric analysis demonstrated that mitral stenosis was a risk factor for maintaining AF, whereas regurgitation was more associated to sinus rhythm recovery. There was no relation with the other parameters with return to sinus rhythm. It should be noted, however, that 96% of this series had AF for more than 6 months preoperatively.

CONCLUSIONS

The majority of patients with mitral valve disease remain in AF and this may justify the association of maze procedure. Pure regurgitation may be a single predictor for return to sinus rhythm after mitral valve operation in chronic AF.

Radiofrequency catheter ablation of ventricular tachycardia guided by nonsurgical epicardial mapping in chronic Chagasic heart disease

We report a case of a 63-year-old women with Chagas' disease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds of application and rendered noninducible afterwards. Two weeks after the procedure, a distinct morphology VT was induced by programmed ventricular stimulation, and the patient was started on amiodarone, remaining asymptomatic 12 months after the procedure.

[Type I atrial flutter radiofrequency ablation. Importance of bidirectional block of isthmus between the inferior vena cava and of tricuspid valve ring]

PURPOSE

To determine the clinical importance of a bi-directional line of block demonstration in the inferior vena cava-tricuspid annulus isthmus as an end-point for radiofrequency (RF) atrial flutter (FL) ablation.

METHODS

Forty consecutive patients (51 +/- 11 years) with type I FL were divided in 2 groups: GI (30 patients) anatomic, non-electrophysiologic isthmus ablation technique (interruption and non-induction FL criteria); and GII (10 patients) anatomic with electrophysiologic evaluation of bi-directional isthmus conduction. The isthmus activation was analyzed before and after anatomic RF ablation with a cateter exploring each side of the line of block, depending on the conduction evaluation (anterograde or retrograde).

RESULTS

FL was interrupted and not reinduced in 26/ 30 (86.6%) GI patients and in 10 (100%) GII patients (p = 0.5558). During follow-up FL recurred in 30% of the patients in both groups. In GII, 6 patients with bi-directional block remained assymptomatic, whereas 3 patients with unidirectional block presented recurrence (p = 0.012).

CONCLUSION

Electrophysiologic demonstration of bidirectional line of block in the isthmus is related to long-term success and should be the criterion for interruption of type I atrial FL RF ablation.

[Relationship between conduction persistence through the slow pathway after atrioventricular nodal reentry tachycardia radiofrequency ablation and its recurrence]

PURPOSE

The aim of this study is to verify whether the persistence of conduction over the slow pathway is related to an increased trend for recurrence.

METHODS

Recurrence rate was retrospectively analyzed in 126 patients who underwent slow pathway radiofrequency (RF) catheter ablation during a follow-up of 20 +/- 12 months. The ablative procedure was interrupted when AVNRT was no longer induced by atrial stimulation after intravenous infusion of isoproterenol. Ninety-eight patients had no evidence of slow pathway whereas 28 patients persisted with AV node jump and atrial echo beat.

RESULTS

There were 15 recurrences: 9% of those who had no evidence of slow pathway (9 of 98 patients) and 21% of those with AV node jump and/or atrial echo beat but this difference was not statistically significant.

CONCLUSION

As long as AVNRT cannot be induced by atrial pacing and isoproterenol infusion after slow pathway RF catheter ablation, the presence of AV node jump and/or atrial echo beat does not increase the risk of recurrence of AVNRT.

Endocardial and epicardial ablation guided by nonsurgical transthoracic epicardial mapping to treat recurrent ventricular tachycardia

INTRODUCTION

An epicardial site of origin of ventricular tachycardia (VT) may explain unsuccessful endocardial radiofrequency (RF) catheter ablation. A new technique to map the epicardial surface of the heart through pericardial puncture was presented recently and opened the possibility of using epicardial mapping to guide endocardial ablation or epicardial catheter ablation. We report the efficacy and safety of these two approaches to treat 10 consecutive patients with VT and Chagas' disease.

METHODS AND RESULTS

Epicardial mapping was carried out with a regular steerable catheter introduced into the pericardial space. An epicardial circuit was found in 14 of 18 mapable VTs induced in 10 patients. Epicardial mapping was used to guide endocardial ablation in 4 patients and epicardial ablation in 6. The epicardial earliest activation site occurred 107+/-60 msec earlier than the onset of the QRS complex. At the epicardial site used to guide endocardial ablation, earliest activation occurred 75+/-55 msec before the QRS complex. Epicardial mid-diastolic potentials and/or continuous electrical activity were seen in 7 patients. After 4.8+/-2.9 seconds of epicardial RF applications, VT was rendered noninducible. Hemopericardium requiring drainage occurred in 1 patient; 3 others developed pericardial friction without hemopericardium. Patients remain asymptomatic 5 to 9 months after the procedure. Interruption during endocardial pulses occurred after 20.2+/-14 seconds (P = 0.004), but VT was always reinducible and the patients experienced a poor outcome.

CONCLUSION

Epicardial mapping does not enhance the effectiveness of endocardial pulses of RF. Epicardial applications of RF energy can safely and effectively treat patients with VT and Chagas' disease.

[Radiofrequency catheter ablation of atrial tachycardia]

BACKGROUND AND OBJECTIVE

Radiofrequency catheter ablation has proved to be highly effective for the treatment of supraventricular tachycardia originating in the AV node or related to atrioventricular accessory pathways. However, experience with ablation of atrial tachycardia is more limited. The purpose of our study was to analyse the success and safety of radiofrequency ablation of atrial tachycardias.

STUDY POPULATION

Ten symptomatic patients with drug refractory atrial tachycardia. Symptoms included palpitations, dizziness, chest pains, shortness of breath, syncope. Five patients had reduced left ventricular ejection fraction (tachycardiomyopathy).

METHODS

Radiofrequency device - Medtronic ATAKRR with temperature monitoring. Temperature ranges from 50 degrees C to 70 degrees C were considered optimal to ablation. Ablation catheter - 7 F CardiorhythmR with a 4 mm2 deflectable tip. Heparin was given intravenously during the procedure (5000 IU bolus + 1000 IU/h). Acetylsalicylic acid 160 mg/day for 1 month after the procedure. Antiarrhythmic drugs were discontinued after the procedure. The sites for ablation were defined during tachycardia by the earliest endocardial atrial activation as compared to the onset of the surface P wave. Criteria of success: Abolition of the tachycardia followed by the inability to reinduce the tachycardia.

FOLLOW-UP

Clinical, ECG and 2D ECHO evaluation in the outpatient's clinic. No complications occurred during the procedure. No reccurrences of the tachycardia were observed during the follow-up. All 5 patients with reduced ejection fraction before ablation had normal left ventricular function during follow-up.

CONCLUSION

Radiofrequency catheter ablation is a safe and effective treatment for drug refractory atrial tachycardia.