Unidirectional conduction characterizing epicardial connections in patients with atrial tachyarrhythmias.

INTRODUCTION: Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. METHODS: This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. RESULTS: Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up. CONCLUSION: A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

Long term prognosis in patients with pulmonary hypertension undergoing catheter ablation for supraventricular tachycardia.

Various forms of supraventricular tachycardia (SVT) occur in patients with severe pulmonary hypertension (PH). Despite the high efficacy of radiofrequency catheter ablation (RFCA) for SVT, insufficient data exist regarding patients with PH. Thirty SVTs in 23 PH patients (age 47 [35-60] years; mean pulmonary artery pressure 44 [32-50] mmHg) were analyzed. Procedural success rate, short- and long-term clinical outcomes, were evaluated during a median follow-up of 5.1 years. Single-procedure success rate was 83%; 94% (17/18) in typical atrial flutter, 73% (8/11) in atrial tachycardia (AT), and 100% (1/1) in atrioventricular nodal reentrant tachycardia. Antiarrhythmic drugs, serum brain natriuretic peptide levels and number of hospitalizations significantly decreased after RFCA than that before (p = 0.002, 0.04, and 0.002, respectively). Four patients had several procedures. After last RFCA, 12 patients had SVT and 8 patients died. Kaplan-Meier curves showed that patients with SVT after the last RFCA had a lower survival rate compared to those without (p = 0.0297). Multivariate analysis identified any SVT after the last RFCA as significant risk factor of mortality (hazard ratio: 9.31; p = 0.016). RFCA for SVT in patients with PH is feasible and effective in the short-term, but SVT is common during long-term follow-up and associated with lower survival.

The prevalence and clinical outcome of supraventricular tachycardia in different etiologies of pulmonary hypertension.

PURPOSE: Patients with pulmonary hypertension (PH) frequently suffer from supraventricular tachycardias (SVT). The main purpose of our study was to identify the cumulative incidence of SVT in patients with different etiologies of PH. The secondary objective was to analyse the clinical impact of SVT. METHODS: We retrospectively studied the prevalence of SVT and the clinical outcome in 755 patients (41% males; 60 ± 15 years; mean follow-up 3.8 ± 2.8 years) with PH of different etiologies. The prevalence of SVT was analysed separately in isolated pre-capillary PH (Ipc-PH) and in patients with combined post- and pre-capillary PH (Cpc-PH). RESULTS: The prevalence of SVT in the Ipc-PH group (n = 641) was 25% (n = 162). The most prevalent arrhythmias were atrial fibrillation followed by a typical atrial flutter (17% and 4.4% of all Icp-PH patients). An excessive prevalence of SVT was found in patients with pulmonary arterial hypertension associated with congenital heart disease (35%, p = 0.01). Out of the overall study population, Cpc-PH was present in 114 (15%) patients. Patients with Cpc-PH manifested a higher prevalence of SVT than subjects with Ipc-PH (58; 51% vs. 162; 25%; p <0.0001) and were more likely to have persistent or permanent atrial fibrillation (38; 29% vs. 61; 10%; p <0.0001). Parameters significantly associated with mortality in a multivariate analysis included age, male gender, functional exercise capacity and right atrial diameter (p < 0.05). Neither diagnosis of SVT nor type of arrhythmia predicted mortality. CONCLUSIONS: The study detected a significant prevalence of SVT in the population of PH of different origins. Different spectrum and prevalence of arrhythmia might be expected in different etiologies of PH. Patients with an elevated post-capillary pressure showed a higher arrhythmia prevalence, predominantly due to an excessive number of atrial fibrillations. The diagnosis of SVT was not associated with mortality.

Chromosome 4q25 variants and biomarkers of myocardial fibrosis in patients with atrial fibrillation.

INTRODUCTION: Little is known about how genetic predisposition and fibrosis relate in atrial fibrillation (AF). Hence, we sought to determine whether the genetic variants and biomarkers for fibrosis enhance prediction of outcomes after catheter ablation. METHODS AND RESULTS: Consecutive patients who underwent catheter ablation of AF (paroxysmal, 158; nonparoxysmal, 137) or supraventricular tachycardia without AF (n = 70) were studied retrospectively. Plasma levels of transforming growth factor ß1 (TGF-ß1), tissue inhibitor of metalloproteinase 1 (TIMP-1), and 4q25 single-nucleotide polymorphisms (SNPs) (rs10033464 and rs220073) were measured. Mean plasma levels of both TGF-ß1 and TIMP-1 were higher in patients with AF than in the control (all P < .001). Plasma levels of TIMP-1 were higher in patients with recurrence compared with those without recurrence (P = .039). Patients with variant alleles of rs10033464 showed increased recurrence after catheter ablation in patients with paroxysmal AF including after adjustment (P = .027). Patients with TIMP-1 < 107 ng/mL and no variant allele (GG) at rs10033464 had lower recurrence rates compared with other groups in those with paroxysmal AF (logrank; P = .007), whereas there was no significant difference among those patients with persistent forms of AF. Inclusion of biomarkers and genotype improved discrimination of AF recurrence in patients with paroxysmal AF (C-statistic .499 vs .600). CONCLUSIONS: The combination of plasma TIMP-1 concentrations less than 107 ng/mL and the absence of a variant allele at rs10033464 was associated with lower recurrence rates in patients with paroxysmal AF. This study suggests that 4q25 SNPs and biomarkers for fibrosis may provide additive value in risk stratification for AF recurrence after catheter ablation.

Sinus node-like pacemaker mechanisms regulate ectopic pacemaker activity in the adult rat atrioventricular ring.

In adult mammalian hearts, atrioventricular rings (AVRs) surround the atrial orifices of atrioventricular valves and are hotbed of ectopic activity in patients with focal atrial tachycardia. Experimental data offering mechanistic insights into initiation and maintenance of ectopic foci is lacking. We aimed to characterise AVRs in structurally normal rat hearts, identify arrhythmia predisposition and investigate mechanisms underlying arrhythmogenicity. Extracellular potential mapping and intracellular action potential recording techniques were used for electrophysiology, qPCR for gene and, Western blot and immunohistochemistry for protein expression. Conditions favouring ectopic foci were assessed by simulations. In right atrial preparations, sinus node (SN) was dominant and AVRs displayed 1:1 impulse conduction. Detaching SN unmasked ectopic pacemaking in AVRs and pacemaker action potentials were SN-like. Blocking pacemaker current If, and disrupting intracellular Ca2+ release, prolonged spontaneous cycle length in AVRs, indicating a role for SN-like pacemaker mechanisms. AVRs labelled positive for HCN4, and SERCA2a was comparable to SN. Pacemaking was potentiated by isoproterenol and abolished with carbachol and AVRs had abundant sympathetic nerve endings. ß2-adrenergic and M2-muscarinic receptor mRNA and ß2-receptor protein were comparable to SN. In computer simulations of a sick SN, ectopic foci in AVR were unmasked, causing transient suppression of SN pacemaking.

Genome-wide association study and meta-analysis identify loci associated with ventricular and supraventricular ectopy.

The genetic basis of supraventricular and ventricular ectopy (SVE, VE) remains largely uncharacterized, despite established genetic mechanisms of arrhythmogenesis. To identify novel genetic variants associated with SVE/VE in ancestrally diverse human populations, we conducted a genome-wide association study of electrocardiographically identified SVE and VE in five cohorts including approximately 43,000 participants of African, European and Hispanic/Latino ancestry. In thirteen ancestry-stratified subgroups, we tested multivariable-adjusted associations of SVE and VE with single nucleotide polymorphism (SNP) dosage. We combined subgroup-specific association estimates in inverse variance-weighted, fixed-effects and Bayesian meta-analyses. We also combined fixed-effects meta-analytic t-test statistics for SVE and VE in multi-trait SNP association analyses. No loci reached genome-wide significance in trans-ethnic meta-analyses. However, we found genome-wide significant SNPs intronic to an apoptosis-enhancing gene previously associated with QRS interval duration (FAF1; lead SNP rs7545860; effect allele frequency = 0.02; P = 2.0 × 10-8) in multi-trait analysis among European ancestry participants and near a locus encoding calcium-dependent glycoproteins (DSC3; lead SNP rs8086068; effect allele frequency = 0.17) in meta-analysis of SVE (P = 4.0 × 10-8) and multi-trait analysis (P = 2.9 × 10-9) among African ancestry participants. The novel findings suggest several mechanisms by which genetic variation may predispose to ectopy in humans and highlight the potential value of leveraging pleiotropy in future studies of ectopy-related phenotypes.

[An analysis of clinical characteristics and acute treatment of supraventricular tachycardia in children from a multicenter study].

Objective: The study assessed the clinical characteristics and response to acute intravenous antiarrhythmic drug therapy of supraventricular tachycardia (SVT) in children. Methods: This was a multicenter prospective descriptive study including 257 children from First Hospital of Tsinghua University, Peking University First Hospital, Children's Hospital Affiliated to Capital Institute of Pediatrics and Beijing Anzhen Hospital who received intravenous antiarrhythmic drug therapy for SVT from July 2014 to February 2017. The clinical and tachycardia features, response to intravenous antiarrhythmic drug therapy of these children were characterized. Statistical analyses were performed using t test, Mann-Whitney U test, χ(2) test and H test. Results: The onset of SVT occurred at any age with a distribution with positive skewness, 57.6% (n=148) children<1 year, 17.5% (n=45) children1~<3 years, 10.5% (n=27) children 3~<6 years and 14.4% (n=37) children ≥ 6 years of age. The percentages of SVT types were 49.4% (n=127) for atrioventricular reentry tachycardia (AVRT), 4.3% (n=11) for atrioventricular nodal reentry tachycardia (AVNRT), 26.8% (n=69) for unclassified paroxysmal SVT and 19.5% (n=50) for atrial tachycardia (AT), respectively. Tachycardia-induced cardionyopathy (TIC) secondary to SVT developed in 30 of 225 (13.3%). Left ventricular ejection fraction (LVEF) of the 27 children attacked by TIC returned to normal after successful control of SVT (41.1%±6.3% vs. 60.3%±9.2%, t=-10.397, P=0.000). Complete termination of SVT by antiarrhythmic drugs was achieved in 164 of 257 (63.8%), partial termination rate was 18.7% (48 of 257) and failure to terminate rate was 17.5% (45 of 257). Propafenone (complete cardioversion in 98 (73.1%) of 134) and amiodarone (complete cardioversion in 23 (76.7%) of 30) showed better efficacy for SVT termination than adenosine (complete cardioversion in 26 (44.1%) 59) (χ(2)=20.524, P=0.000). Paroxysmal SVT had a higher termination rate on pharmacological therapy than AT (67.1% vs. 50.0%, χ(2)=6.337, P=0.042). Patients of different age groups had significantly different response to antiarrhythmic therapy (χ(2)=13.904, P=0.031). Children<1 year of age showed the least response to antiarrhythmic drug therapy with complete termination in 51 (55.4%) of 92. Adverse effects occurred in 9 patients (3.5%): Four patients had severe hypotensive shock using propafenone (n=3) and adenosine (n=1), and 3 patients had sinus arrest using adenosine. Conclusion: Most (57.6%) children with SVT have their first clinical episode within 1 year of age, and AVRT is the most common type. TIC occurs in 13.3% of children with SVT. Intravenous antiarrhythmic drug therapy has a 63.8% complete termination rate for children with SVT and incidence of adverse effects is 3.5%. Propafenone and amiodarone are more effective for SVT termination in children than adenosine. Serious adverse effects may occur when using propafenone.

Experimental, Pathologic, and Clinical Findings of Radiofrequency Catheter Ablation of Para-Hisian Region From the Right Ventricle in Dogs and Humans.

BACKGROUND: Ablation of para-Hisian accessory pathway (AP) poses high risks of atrioventricular block. We developed a pacing technique to differentiate the near-field (NF) from far-field His activations to avoid the complication. METHODS AND RESULTS: Three-dimensional mapping of the right ventricle was performed in 15 mongrel dogs and 23 patients with para-Hisian AP. Using different pacing outputs, the NF- and far-field His activation was identified on the ventricular aspect. Radiofrequency application was delivered at the NF His site in 8 (group 1) and the far-field His site in 7 dogs (group 2), followed by pathologic examination after 14 days. NF His activation was captured with 5 mA/1 ms in 10 and 10 mA/1 ms in 5 dogs. In group 1, radiofrequency delivery resulted in complete atrioventricular block in 3, right bundle branch block with HV (His-to-ventricular) interval prolongation in 1, and only right bundle branch block in 2 dogs, whereas no changes occurred in group 2. Pathologic examination in group-1 dogs showed complete or partial necrosis of the His bundle in 4 and complete necrosis of the right bundle branch in 5 dogs. In group 2, partial necrosis in the right bundle branch was found only in 1 dog. Using this pacing technique, the APs were 5.7±1.2 mm away from the His bundle located superiorly in 20 or inferiorly in 3 patients. All APs were successfully eliminated with 1 to 3 radiofrequency applications. No complications and recurrence occurred during a follow-up of 11.8±1.4 months. CONCLUSIONS: Differentiating the NF His from far-field His activations led to a high ablation success without atrioventricular block in para-Hisian AP patients.

Cilostazol Prevents Atrial Structural Remodeling through the MEK/ERK Pathway in a Canine Model of Atrial Tachycardia.

OBJECTIVES: Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. Atrial structural remodeling (ASR), particularly atrial fibrosis, is an important contributor to the AF substrate. This study aimed to investigate the preventive effects of the phosphodiesterase 3 inhibitor cilostazol on ASR and its potential molecular mechanisms in a canine model of rapid atrial pacing (RAP). METHODS: Thirty dogs were assigned to sham (Sham), paced/ no treatment (Paced) and paced + cilostazol 5 mg/kg/day (Paced + cilo) groups, with 10 dogs in each group. RAP at 500 beats/min was maintained for 2 weeks, while the Sham group was instrumented without pacing. Cilostazol was provided orally during pacing. Western blotting, RT-PCR and pathology were used to assess ASR. RESULTS: Cilostazol attenuated atrial interstitial fibrosis and structural remodeling in canines with RAP. MEK/ERK transduction pathway gene expression was upregulated in the Paced group compared with the Sham group. Cilostazol markedly alleviated these changes in the MEK/ERK pathway. Transforming growth factor-ß1 protein expression in the Paced group was significantly higher than in the Sham group (p < 0.01), and was significantly reduced by cilostazol (p < 0.01). CONCLUSIONS: Our findings suggest that cilostazol is beneficial for prevention and treatment in atrial tachycardia-induced ASR in a canine model of RAP.

Evaluation of a novel high-resolution mapping technology for ablation of recurrent scar-related atrial tachycardias.

BACKGROUND: Rhythmia is a new technology capable of rapid and high-resolution mapping. However, its potential advantage over existing technologies in mapping complex scar-related atrial tachycardias (ATs) has not yet been evaluated. OBJECTIVE: The purpose of this study was to examine the utility of Rhythmia for mapping scar-related ATs in patients who had failed previous ablation procedure(s). METHODS: This multicenter study included 20 patients with recurrent ATs within 2 years after a previous ablation procedure (1.8 ± 0.7 per patient). In all cases, the ATs could not be adequately mapped during the index procedure because of scar with fractionated electrograms, precluding accurate time annotation, frequent change in the tachycardia in response to pacing, and/or degeneration into atrial fibrillation. These patients underwent repeat mapping and ablation procedure with Rhythmia. RESULTS: From a total of 28 inducible ATs, 24 were successfully mapped. Eighteen ATs (75%) terminated during radiofrequency ablation and 4 (16.6%) with catheter pressure or entrainment from the site of origin or isthmus. Two ATs that were mapped to the interatrial septum slowed but did not terminate with ablation. In 21 of 24 ATs the mechanism was macroreentry, while in 3 of 24 the mechanism was focal. Interestingly, in 5 patients with previously failed ablation of an allegedly "focal" tachycardia, high-resolution mapping demonstrated macroreentrant arrhythmia. The mean mapping time was 28.6 ± 17 minutes, and the mean radiofrequency ablation time to arrhythmia termination was 3.2 ± 2.6 minutes. During a mean follow-up of 7.5 ± 3.1 months, 15 of 20 patients (75%) were free of AT recurrences. CONCLUSION: The Rhythmia mapping system may be advantageous for mapping complex scar-related ATs.

A diagnostic algorithm to optimize data collection and interpretation of Ripple Maps in atrial tachycardias.

BACKGROUND: Ripple Mapping (RM) is designed to overcome the limitations of existing isochronal 3D mapping systems by representing the intracardiac electrogram as a dynamic bar on a surface bipolar voltage map that changes in height according to the electrogram voltage-time relationship, relative to a fiduciary point. OBJECTIVE: We tested the hypothesis that standard approaches to atrial tachycardia CARTO™ activation maps were inadequate for RM creation and interpretation. From the results, we aimed to develop an algorithm to optimize RMs for future prospective testing on a clinical RM platform. METHODS: CARTO-XP™ activation maps from atrial tachycardia ablations were reviewed by two blinded assessors on an off-line RM workstation. Ripple Maps were graded according to a diagnostic confidence scale (Grade I - high confidence with clear pattern of activation through to Grade IV - non-diagnostic). The RM-based diagnoses were corroborated against the clinical diagnoses. RESULTS: 43 RMs from 14 patients were classified as Grade I (5 [11.5%]); Grade II (17 [39.5%]); Grade III (9 [21%]) and Grade IV (12 [28%]). Causes of low gradings/errors included the following: insufficient chamber point density; window-of-interest<100% of cycle length (CL); <95% tachycardia CL mapped; variability of CL and/or unstable fiducial reference marker; and suboptimal bar height and scar settings. CONCLUSIONS: A data collection and map interpretation algorithm has been developed to optimize Ripple Maps in atrial tachycardias. This algorithm requires prospective testing on a real-time clinical platform.

Catheter Ablation of Right-Sided Accessory Pathways in Adults Using the Three-Dimensional Mapping System: A Randomized Comparison to the Conventional Approach.

Three-dimensional (3D) mapping and navigation systems have been widely used for the ablation of atrial fibrillation and ventricular tachycardia, but the applicability of these systems for the ablation of supraventricular tachycardia (SVT) due to right-sided accessory pathways (RAPs) remains unknown. The goal of this prospective randomized study was to compare the safety, efficiency, and efficacy of nonfluoroscopic and conventional fluoroscopic mapping techniques in guiding catheter ablation of SVT due to RAPs. Of the 393 consecutive patients with SVT who were randomized to receive either conventional fluoroscopic or Ensite NavX mapping-guided ablation, 64 patients with RAPs were included for analysis. Endpoints for ablation were no evidence of RAP conduction and no inducible atrioventricular reentrant tachycardia (AVRT). The 3D group showed fewer ablation pulses and a shorter total ablation time compared to the conventional group, although the acute procedural success did not differ significantly between the two groups. Total procedure time, electrophysiological study time, total fluoroscopy time, and cumulative radiation doses were also significantly reduced in the 3D group. Patients in the conventional group with a right atrium diameter (RAD) ≥ 47 mm required a longer fluoroscopy time. There was no significant difference in the recurrence rates between the two groups over a follow-up period of 3 to 29 months. There were no permanent complications. The 3D mapping system may be a preferred alternative for patients with AVRT due to RAPs, especially for patients with a large RAD (≥ 47 mm).

Catheter ablation of accessory pathways near the coronary sinus: value of defining coronary arterial anatomy.

BACKGROUND: Accessory pathways can lie near or within the coronary sinus (CS). Radiofrequency catheter ablation of accessory pathways is a well-established treatment option, but this procedure can cause damage to adjacent coronary arteries. OBJECTIVE: The purpose of this study was to evaluate the anatomic relationship between the coronary arteries and the CS. METHODS: Retrospective data of patients who underwent catheter ablation of supraventricular tachycardia between June 2011 and August 2013 was reviewed. In addition, detailed analysis of coronary computed tomographic angiography (CTA) data from 50 patients was performed. RESULTS: Between June 2011 and August 2013, 427 patients underwent catheter ablation of supraventricular tachycardia, of whom 105 (age 28 ± 17 years, 60% male) had accessory pathway-mediated tachycardia. Of these, 23 patients had accessory pathways near the CS, and 60% (N = 14) underwent concurrent coronary angiography. In 4 patients, the posterolateral (inferolateral) branch (PLA) of the right coronary artery was in close proximity to the CS, and 2 patients (18%) had stenosis of the PLA at the site of ablation. On CTA at their closest proximity, the PLA was 1.9 ± 1.3 mm and the left circumflex artery (LCx) was 2.0 ± 0.8 mm from the body of the CS, in right and left coronary artery-dominant patients, respectively. CS ostium and PLA were 3.6 ± 1.9 mm apart. In left-dominant patients, LCx and CS ostium were 3.8 ± 1.2 mm apart. CONCLUSION: The PLA and LCx are in close proximity to the anteroinferior aspect of the CS ostium and proximal CS. The relationship of the CS and coronary arteries should be evaluated before ablation at these sites.

Characterization of thrombogenic, endothelial and inflammatory markers in supraventricular tachycardia: a study in patients with structurally normal hearts.

Patients with atrial fibrillation (AF) are at an increased risk of thromboembolism and stroke primarily from the development of thrombi within the left atrium. Pathological changes in blood constituents and atrial endothelial damage promote left atrial thrombus formation. It is not known whether factors predisposing to left atrial thrombus formation in AF are disease specific or also evident within the normal heart. The present study examined whether there are differences in platelet reactivity, endothelial function and inflammation in blood samples obtained from intracardiac and peripheral sites in subjects within structurally normal hearts. Sixteen patients with diagnosed left-sided supraventricular tachycardia (SVT) undergoing a routine elective electrophysiological study and ablation were investigated. Blood samples were taken simultaneously from the femoral vein, right atrium and left atrium, immediately following trans-septal puncture and prior to heparin bolus administration. Between peripheral and atrial sample sites, patients with SVT showed no change in platelet reactivity or aggregation (P-selectin (CD62P) P = 0.91; platelet-derived soluble CD40 ligand P = 0.9), thrombus formation (thrombin-antithrombin complex; P = 0.55), endothelial function (von Willebrand factor P = 0.75; asymmetric dimethylarginine (ADMA) P = 0.97; nitric oxide P = 0.61), or inflammation (vascular cell adhesion molecule-1 P = 0.59; intercellular adhesion molecule-1 (ICAM-1) P = 0.69). However, SVT patients had lower ADMA and ICAM-1 levels than AF patients. The present study demonstrates, for the first time, that SVT subjects with structurally normal hearts have consistent haemostatic function between atrial and peripheral sites. These results suggest that the atria of SVT patients do not contain predisposing thrombogenic, endothelial or inflammatory factors that promote and/or initiate thrombus formation.

Reversible cardiomyopathy after radiofrequency ablation of 30-year persistent atrial tachycardia.

Tachycardia-induced cardiomyopathy (TIC) is a reversible form of the left ventricular (LV) systolic dysfunction and is believed to be a relatively acute process. We report a TIC case with a 30-year history of long-lasting persistent atrial tachycardia involving a 44-year-old man previously diagnosed with dilated cardiomyopathy and a low LV ejection fraction (LVEF) of 20%. ECG revealed atrial tachycardia at 110-120 bpm. He was hospitalised with a worsening heart failure. His clinical status was New York Heart Association functional class III, and echocardiography revealed LV dilation and an LVEF of 9%. A two-dimensional speckle-tracking strain measurement revealed LV mechanical dyssynchrony. He underwent radiofrequency ablation for atrial tachycardia. After restoring sinus rhythm, his cardiac symptoms improved immediately. The LV mechanical dyssynchrony decreased a week after ablation, without changes in the LV dilation or LVEF. Thereafter, the LV dilation and systolic function gradually improved, and atrial tachycardia and heart failure remained absent.

Diffuse ventricular fibrosis is a late outcome of tachycardia-mediated cardiomyopathy after successful ablation.

BACKGROUND: Successful arrhythmia ablation normalizes ejection fraction (EF) in tachycardia-mediated cardiomyopathy, but recurrent heart failure and late sudden death have been reported. The aim of this study was to characterize the left ventricle (LV) of tachycardia-mediated cardiomyopathy patients long after definitive arrhythmia cure. METHODS AND RESULTS: Thirty-three patients with a history of successfully ablated incessant focal atrial tachycardia 64±36 months prior, and 20 healthy controls were recruited. At ablation, 18 patients had EF<50% (AT-low EF) that recovered within 3 months from 37±12 to 56±4% (P<0.001), whereas 15 patients had EF>55% (AT-normal EF). No subjects had EF of 50% to 55%. Subjects underwent echocardiography with speckle tracking and contrast-enhanced cardiac MRI with ventricular T1 mapping as an index of diffuse fibrosis. Contrast-enhanced cardiac MRI was performed using a clinical 1.5-T scanner and 0.2 mmol/kg gadolinium-diethylene triamine penta-acetic acid for contrast. Subject characteristics were similar across the 3 groups. Compared with AT-normal EF patients and controls, AT-low EF patients had lower EF (60±6 versus 64±4 and 65±4%; P<0.05), greater indexed LV end-diastolic volume (102±34 versus 84±14 and 85±16 mL/m(2); P<0.05), and greater indexed LV end-systolic volume (41±11 versus 31±7 and 30±8 mL/m(2); P<0.01) on contrast-enhanced cardiac MRI. Compared with controls, AT-low EF patients had reduced global LV corrected T1 time (442±53 versus 529±61; P<0.05) consistent with diffuse fibrosis. CONCLUSIONS: Tachycardia-mediated cardiomyopathy patients exhibit differences in LV structure and function including diffuse fibrosis long after arrhythmia cure, indicating that recovery is incomplete.