Chronic atrial fibrillation in patients with rheumatic heart disease: mapping and radiofrequency ablation of flutter circuits seen at initiation after cardioversion

Outcome of tailored therapy in rheumatic heart disease with persistent atrial fibrillation (RHD-AF)

INTRODUCTION

Rheumatic heart disease with persistent atrial fibrillation (RHD-AF) is associated with increased morbidity. However, there is no standardized approach for the maintenance of sinus rhythm (SR) in them. We aimed to determine the utility of a stepwise approach to achieve SR in RHD-AF.

METHODS

Consecutive patients with RHD-AF from July 2021 to August 2023 formed the study cohort. The stepwise approach included pharmacological rhythm control and/or electrical cardioversion (Central illustration). In patients with recurrence, additional options included AF ablation or pace and ablate strategy with conduction system pacing or biventricular pacing. Clinical improvement, NT-proBNP, 6-Minute Walk Test (6MWT), heart failure (HF) hospitalizations, and thromboembolic complications were documented during follow-up.

RESULTS

Eighty-three patients with RHD-AF (mean age 56.13 ± 9.51 years, women 72.28%) were included. Utilizing this approach, 43 (51.81%) achieved and maintained SR during the study period of 11.04 ± 7.14 months. These patients had improved functional class, lower NT-proBNP, better distance covered for 6MWT, and reduced HF hospitalizations. The duration of AF was shorter in patients who achieved SR, compared to those who remained in AF (3.15 ± 1.29 vs 6.93 ± 5.23, p = 0.041). Thirty-five percent (29) maintained SR after a single cardioversion over the study period. Only one underwent AF ablation. Of the 24 who underwent pace and ablate strategy, atrial lead was implanted in 22 (hybrid approach), and 50% of these achieved and maintained SR. Among these 24, none had HF hospitalizations, but patients who maintained SR had further improvement in clinical and functional parameters.

CONCLUSIONS

RHD-AF patients who could achieve SR with a stepwise approach, had better clinical outcomes and lower HF hospitalizations.

Tertiary prevention and treatment of rheumatic heart disease: a National Heart, Lung, and Blood Institute working group summary

Although entirely preventable, rheumatic heart disease (RHD), a disease of poverty and social disadvantage resulting in high morbidity and mortality, remains an ever-present burden in low-income and middle-income countries (LMICs) and rural, remote, marginalised and disenfranchised populations within high-income countries. In late 2021, the National Heart, Lung, and Blood Institute convened a workshop to explore the current state of science, to identify basic science and clinical research priorities to support RHD eradication efforts worldwide. This was done through the inclusion of multidisciplinary global experts, including cardiovascular and non-cardiovascular specialists as well as health policy and health economics experts, many of whom also represented or closely worked with patient-family organisations and local governments. This report summarises findings from one of the four working groups, the Tertiary Prevention Working Group, that was charged with assessing the management of late complications of RHD, including surgical interventions for patients with RHD. Due to the high prevalence of RHD in LMICs, particular emphasis was made on gaining a better understanding of needs in the field from the perspectives of the patient, community, provider, health system and policy-maker. We outline priorities to support the development, and implementation of accessible, affordable and sustainable interventions in low-resource settings to manage RHD and related complications. These priorities and other interventions need to be adapted to and driven by local contexts and integrated into health systems to best meet the needs of local communities.

Outcomes of Mitral Transcatheter Edge-to-Edge Repair in Patients With Rheumatic Heart Disease

Mitral transcatheter edge-to-edge repair (TEER) in patients with rheumatic heart disease (RHD) is challenging owing to leaflet thickening and calcification but is performed in select cases. Limited data exist on its outcomes. The aim of this analysis was to investigate the safety and efficacy of mitral TEER in patients with severe symptomatic rheumatic mitral regurgitation. We queried the Nationwide Readmissions Database for hospitalizations for mitral TEER between 2016 and 2018. Propensity score-weighted regression analysis was conducted to evaluate the association of RHD with in-hospital outcomes and 90-day readmissions after mitral TEER. A total of 18,240 procedures were included in the analysis, including 1,779 in patients with RHD. Mitral TEER in patients with RHD was associated with similar in-hospital mortality to that in patients without RHD (odds ratio [OR] 1.47, 95% confidence interval [CI] 0.94 to 2.30, p = 0.089). However, RHD was associated with higher acute myocardial infarction (OR 1.65, 95% CI 1.07 to 2.56), acute kidney injury (OR 1.58, 95% CI 1.30 to 1.94), ventricular arrhythmia (OR 1.50, 95% CI 1.12 to 2.01), high-degree heart block (OR 1.67, 95% CI 1.25 to 2.23), and conversion to open surgical repair/replacement (OR 2.53, 95% CI 1.02 to 6.30). Mitral TEER in RHD was also associated with higher 90-day all-cause readmission (hazard ratio [HR] 1.19, 95% CI 1.04 to 1.47, p = 0.012). In conclusion, mitral TEER in patients with RHD is associated with higher rates of hospital complications, crossover to surgery, and readmissions but could be performed selectively in patients at high surgical risk who have favorable anatomy.

INVICTUS: Vitamin K antagonists remain the standard of care for rheumatic heart disease-associated atrial fibrillation

INTRODUCTION

Rheumatic heart disease (RHD) remains a major healthcare problem. Atrial fibrillation (AF) is the commonest sustained arrhythmia in RHD, leading to major complications and morbidity in a young population. Currently, anticoagulation with vitamin K antagonists (VKA) is the mainstay of therapy for the prevention of thromboembolic adverse events. However, effective use of VKA remains challenging, especially in developing countries, showing a need for alternatives. Novel oral anticoagulants (NOACs), including rivaroxaban, could form a safe and effective alternative to fulfil a major unmet need in RHD patients with AF. However, until recently, no data was available for the use rivaroxaban in patients with rheumatic heart disease associated AF. Study and Results: The INVICTUS trial was conducted to assess efficacy and safety of once-daily rivaroxaban compared with a dose-adjusted VKA for the prevention of cardiovascular events in patients with RHD-associated AF. A total of 4531 patients (age: 50.5 ± 14.6 years) were followed for 3.1 ± 1.2 years in which 560/2292 patients in the rivaroxaban group and 446/2273 in the VKA group had a primary-outcome adverse event. The restricted mean survival time was 1599 days in the rivaroxaban group and 1675 days in the VKA group (difference, -76 days; 95% confidence interval [CI], -121 to -31; P <0.001). A higher incidence of death occurred in the rivaroxaban group than in the VKA group (restricted mean survival time, 1608 days vs. 1680 days; difference, -72 days; 95% CI, -117 to -28). No significant between-group difference in the rate of major bleeding was noted.

LESSONS LEARNED

The INVICTUS trial shows that Rivaroxaban is inferior to Vitamin K-antagonists in patients with RHD associated AF as VKA therapy led to a lower rate of ischemic and lower mortality due to vascular causes, without significantly increasing the rate of major bleeding. The results support current guidelines, which recommend vitamin K antagonist therapy for the prevention of stroke in patients with RHD associated AF.

Management of atrial fibrillation in rheumatic heart disease

Rheumatic heart disease (RHD) is the underlying cause of a significant proportion of atrial fibrillation (AF) in the low- and middle-income countries, while nonvalvular AF is the most common cause of AF in high-income countries. RHD is also common among African Americans, migrants, and the indigenous population of high-income countries. The onset of AF in RHD patients is a clinical marker of worse outcomes and is associated with significant morbidity and mortality. Despite RHD being a major cause of morbidity and mortality in the young in many parts of the world, it is often neglected by policymakers, the media, and even the medical fraternity. Stroke risk assessment using various risk scores has not been systematically evaluated in rheumatic AF patients. Rate control may not be ideal for symptom control in rheumatic AF patients considering the young age and an active lifestyle. There is limited information regarding the nonpharmacological management of rheumatic AF. The current management guidelines based on nonvalvular AF do not apply to rheumatic AF patients who are often younger, are women, and have fewer comorbidities. This review critically looks at specific areas such as stroke prevention with reference to direct oral anticoagulants, cardioversion, rate and rhythm control strategies, and the role of nonpharmacological methods in rheumatic AF management. Future recommendations must be cognizant of local health care systems and resourcing considering the geographic distribution of the disease.

Comparison of in-hospital outcomes of patients undergoing catheter ablation for typical versus atypical atrial flutter

BACKGROUND

Catheter ablation (CA) is indicated as definitive therapy for patients with either typical or atypical atrial flutter (TAFlutter and AAFlutter, respectively) which is unresponsive to medical therapy. There is a paucity of data regarding in-hospital outcomes of patients undergoing CA.

METHODS

Retrospective study using the NIS to identify patients ≥18 years who underwent CA between 2015 and 2017. Individuals were identified using ICD-10-CM/PCS for TAFlutter, AAFlutter, and CA.

RESULTS

A total of 17,390 patients underwent CA for Aflutter (33% AAFlutter and 67% TAFlutter). The TAFlutter group was younger (mean 65.9 years vs. 67.2 years), with less females (30% vs. 43%, p ≤ 0.001 for both) compared to the AAFlutter group. The TAFlutter group had a higher rate of diabetes, tobacco use, obesity, and chronic obstructive pulmonary disease (p ≤ 0.001 for all). The AAFlutter cohort had increased prior strokes and atrial fibrillation (p ≤ 0.001 for both). The mean CHA₂DS₂-VASc score was found to be 2.3 in AAFlutter compared to 2.1 in TAFlutter (p ≤ 0.001). There were significantly higher proportions of thromboembolic events, transfusions, and longer length of stay in the TAFlutter group (p ≤ 0.001 for all) with the AAFlutter group having significantly higher rates of cardioversion, implantation of cardiac devices, and increased hospital charges (p ≤ 0.001 for all); no significant difference was found in mortality after controlling for comorbidities.

CONCLUSIONS

We found higher complication rates in CA for patients with TAFlutter, but no difference in in-hospital all-cause mortality. Variation in CA depending upon the mechanism of AFlutter may underlie these differences, and warrant further study.

Contemporary Diagnosis and Management of Rheumatic Heart Disease: Implications for Closing the Gap: A Scientific Statement From the American Heart Association

The global burden of rheumatic heart disease continues to be significant although it is largely limited to poor and marginalized populations. In most endemic regions, affected patients present with heart failure. This statement will seek to examine the current state-of-the-art recommendations and to identify gaps in diagnosis and treatment globally that can inform strategies for reducing disease burden. Echocardiography screening based on World Heart Federation echocardiographic criteria holds promise to identify patients earlier, when prophylaxis is more likely to be effective; however, several important questions need to be answered before this can translate into public policy. Population-based registries effectively enable optimal care and secondary penicillin prophylaxis within available resources. Benzathine penicillin injections remain the cornerstone of secondary prevention. Challenges with penicillin procurement and concern with adverse reactions in patients with advanced disease remain important issues. Heart failure management, prevention, early diagnosis and treatment of endocarditis, oral anticoagulation for atrial fibrillation, and prosthetic valves are vital therapeutic adjuncts. Management of health of women with unoperated and operated rheumatic heart disease before, during, and after pregnancy is a significant challenge that requires a multidisciplinary team effort. Patients with isolated mitral stenosis often benefit from percutaneous balloon mitral valvuloplasty. Timely heart valve surgery can mitigate the progression to heart failure, disability, and death. Valve repair is preferable over replacement for rheumatic mitral regurgitation but is not available to the vast majority of patients in endemic regions. This body of work forms a foundation on which a companion document on advocacy for rheumatic heart disease has been developed. Ultimately, the combination of expanded treatment options, research, and advocacy built on existing knowledge and science provides the best opportunity to address the burden of rheumatic heart disease.

Update on Prevention and Management of Rheumatic Heart Disease

Rheumatic heart disease (RHD) remains the most common cause of cardiovascular morbidity and mortality globally in children and young adults. This article focuses on prevention and management of RHD. Pregnancy can unmask previously undiagnosed RHD and poses high risk for mother and fetus. Management of anticoagulation is important. Definitive catheter and surgical intervention are the only treatments that can improve outcomes of patients with moderate or severe RHD. Access to intervention remains very limited in RHD endemic regions. There are ongoing global efforts to increase awareness, public policy adoption, and greater access to treatment.

Electrophysiologic evidence of epicardial connections between low right atrium and remote right atrial region or coronary sinus musculature: Relevance for catheter ablation of typical atrial flutter

BACKGROUND

The coronary sinus (CS) is surrounded by a myocardial coat with extensive connections to the left and right atria that contributes to the interatrial electrical connection. Whereas epicardial connections between CS musculature and the left atrium have largely been demonstrated, clinically relevant epicardial connections from the CS musculature toward the low right atrium (LRA) and epicardial connections between two regions of the right atrium remain questionable.

METHODS

Five patients underwent electrophysiology (EP) study for typical atrial flutter (AFl) using either conventional multipolar catheters (four patients) or three-dimensional high-density mapping system (one patient).

RESULTS

All five patients had a similar sequence of events during the EP studies. After several cavotricuspid isthmus (CTI) radiofrequency (RF) applications, double potentials were recorded along the ablation line while tachycardia persisted. The right atrial activation pattern strongly suggested the presence of a complete endocardial CTI line of the block. Based on the detailed conventional atrial mapping, RF applications at the middle cardiac vein/CS ostium allowed sinus rhythm restoration in four patients. High-density mapping showed an early breakthrough site at the septal side of the ablation line, close to the CS ostium during counterclockwise AFl, in the fifth patient. RF applications at this site resulted in tachycardia termination.

CONCLUSION

Our observations suggested the existence of epicardial fibers connecting the LRA with either the CS musculature or a remote right atrial region. When AFl ablation fails whereas evidence for the local endocardial block is observed, the operators should integrate this finding in the diagnosis and ablation strategy.

Clinical characteristics and rhythm outcome of catheter ablation of hemodynamically corrected valvular atrial fibrillation

BACKGROUND

Although the hemodynamic burden and structural substrate contribute to valvular atrial fibrillation (VAF) mechanisms, the role of catheter ablation has rarely been reported. We investigated the clinical characteristics, mapping findings, and long-term rhythm outcomes after catheter ablation of hemodynamically corrected VAF.

METHODS

We compared 77 patients with VAF (46.8% male, 52.7±8.8 years old, 46.8% paroxysmal AF, 24.7% with maze procedures) and 2244 patients with non-VAF (NVAF) who underwent catheter ablation. Among the VAF patients, 44 (57.1%) had mechanical valve AF (MV-AF) and 33 (42.9%) underwent a prior mitral valvuloplasty (MVP-AF). We analyzed the catheter ablation rhythm outcomes for MV-AF and MVP-AF.

RESULTS

The left atrial (LA) diameter was greater (p<0.001), LA voltage lower (p<0.001), and procedure-related complication rate higher (mainly sinus node dysfunction, p=0.004) for VAF than NVAF. During 70.2±1.8 months of follow-up, the rhythm outcome of VAF did not significantly differ from that of NVAF after catheter ablation (log rank p=0.399), even after excluding patients with maze procedures (log rank p=0.629). The clinical recurrence rates did not differ between the MV-AF and MVP-AF groups (log rank p=0.244), or between patients with prior maze procedures and those without (log rank p=0.651). The main conduction recovery sites of previous maze procedures were the perimitral (84.2%) and cavotricuspid isthmus (84.2%) areas, and recurrence mechanisms were macroreentry (63.2%) and focal/microreentry (26.3%) at scar border zones.

CONCLUSIONS

Although hemodynamically corrected VAF was associated with advanced LA remodeling, the rhythm outcome did not significantly differ from that of NVAF after catheter ablation.

Presence of increased inflammatory infiltrates accompanied by activated dendritic cells in the left atrium in rheumatic heart disease

Aims

Left atrial (LA) structural remodelling develops in rheumatic heart disease (RHD) according to the disease severity of the mitral valve and the presence of atrial fibrillation. Sustained active inflammation has been previously reported in the LA of patients with RHD, suggesting a direct role of cell-mediated immunity in the pathogenesis of LA remodelling. Dendritic cells (DCs) have a major antigen-presenting role, and are known as crucial modulators of innate and adaptive immunity. We investigated whether DCs are involved in the pathogenesis of LA remodelling in RHD.

Methods and results

Immunohistochemical analyses were performed using antibodies to CD11c, CD209 and CD80 as markers of myeloid DCs, migratory-active DCs, mature DCs and infiltrated inflammatory cells including T lymphocytes (CD3) and M1 (CD68; pro-inflammatory profile) and M2 (CD163; pro-resolution profile) macrophages. Furthermore, tenascin-C, an extracellular matrix (ECM) protein that appears during ECM remodelling and inflammatory response, was examined. Infiltrated myeloid DCs, migratory-active DCs, mature DCs and other inflammatory infiltrates including T lymphocytes and M1 and M2 macrophages, were significantly higher in the RHD group than the non-RHD group. The positive area fraction for tenascin-C was significantly higher in the RHD group than in the non-RHD group.

Conclusion

Our histological findings suggest that inflammation may persist long after a bout of rheumatic fever, ultimately leading to ECM remodelling. We identified and quantitatively assessed several subsets of DCs and other immunocompetent cells, and our results indicated that activation of DCs has some role in persistence of LA inflammation in patients with chronic RHD.

Is proximal coronary sinus involved in the circuit in some cases of ECG "typical" atrial flutter?

AIM

It is commonly conceived that coronary sinus (CS) participates in atrial flutter (AFL) circuit but limited to the fibers surrounding its ostium. We evaluated the involvement of proximal CS in typical AFL.

METHODS

Twenty AFL patients underwent entrainment mapping using postpacing interval minus AFL cycle length (PPI-AFL CL) including CS where a decapolar catheter was positioned with proximal bipole 1 cm from the ostium.

RESULTS

We compared patients with proximal CS within the circuit (group 1, PPI-AFL CL ≤ 20 ms + concealed entrainment) and those without (group 2, PPI-AFL CL > 20 ms). Group 1 patients were older, 77.5 ± 4 vs 71 ± 12 years (P < 0.05). No difference was found in AFL CL, PPI-AFL CL at cavotricuspid isthmus (CTI) entry, plateau, and septal site. Group 1 patients had shorter PPI-AFL CL at proximal CS (9 ± 3 vs 40 ± 15 ms; P < 0.001) and fragmented mesodiastolic CS atrial potentials (APs) (106 ± 27 vs 58.5 ± 22 ms; P < 0.001). A mid-septal unexcitable scar was found in five of eight group 1 patients vs one of 12 group 2 patients (P < 0.05). All were ablated at CTI. A patient had AFL recurrence and underwent a second attempt: PPI-AFL CL was 60 ms at CTI entry and less than or equal to 20 ms at septal CTI and proximal CS; AFL was terminated 1 cm inside CS, applying RF at a fragmented AP.

CONCLUSION

Proximal CS appears to be involved in a substantial subset of typical AFL patients, in whom advanced age, fragmented CS APs, and the presence of right atrial scar are prevalent. Proximal CS might be considered as an un-"innocent by-stander," but able, in rare cases, to generate a second AFL circuit.

Radiofrequency Ablation of Left Atrial Reentrant Tachycardias in Rheumatic Mitral Valve Disease: A Case Series

BACKGROUND

Left atrial (LA) reentrant tachycardias are not uncommon in regions where rheumatic heart disease is prevalent. Some of these arrhythmias may be curable by radiofrequency ablation (RFA). However, there are limited data pertaining to this in existing literature.

CASE REPORT

Three patients who had rheumatic mitral valve disease with past history of surgical-/catheter-based intervention and having no significant residual disease had symptomatic atrial flutter despite optimal medical management. An electrophysiological study confirmed an LA focal/micro-reentrant mechanism in all. There was patchy scarring of the LA, and successful RFA of these arrhythmias could be achieved.

CONCLUSION

The focal nature of the scar in these patients may suggest that the rheumatic involvement of the atrium or the hemodynamic consequence of the vulvar lesion causes nonuniform insult to the atrial tissue and limited scar. At least in some patients with limited scarring, early RFA may help in the maintenance of sinus rhythm.

Patient selection for ambulatory cardiac monitoring in the Indian healthcare environment

Cardiovascular disease (CVD) in India comprises the bulk of non-communicable diseases, resulting in 2 million deaths per year. The incidence of CVD in India is estimated to be up to four times higher than in other countries. Though the quantification of the prevalence of rhythm disorders in India is not available, it can be inferred to be proportionately high. Identification and treatment of arrhythmia is limited by several socioeconomic factors including low health insurance penetration, limited reimbursement and high out-of-pocket expenditures. Thus, there exists a need in India to (1) select an appropriate tool that is both high yielding and cost effective and (2) employ a suitable patient selection method. This paper focuses on these two aspects for cardiac arrhythmia diagnosis using ambulatory monitoring technology, while keeping in mind the dynamics of the Indian healthcare setting.

Prospective observations in the clinical and electrophysiological characteristics of intra-isthmus reentry

INTRODUCTION

Intra-isthmus reentry (IIR) is a circuit within the cavotricuspid isthmus (CTI). The purpose of this study is to prospectively define the electrogram and surface ECG characteristics of IIR, and its clinical implications.

METHODS AND RESULTS

Fourteen patients underwent electrophysiological studies and were found to have IIR. Detailed electrogram mapping of the CTI was available in all, electroanatomic mapping (EAM) in 8 of 14 (57%) patients. In all, entrainment mapping during tachycardia proved reentry, and showed that the anteroinferior CTI was out of the circuit and the septal CTI was in the circuit in 12 of 14 patients, whereas in 2, the circuit was confined within the mid and/or anteroinferior CTI. Fractionated potentials (FPs) spanning 34-71% of the tachycardia cycle length were recorded within the CTI in all, and double potentials were inscribed in 10 of 14 (71%). Analysis of the tricuspid annulus electrograms showed spontaneous shifts from a counterclockwise (CCW) to clockwise or fusion patterns. Surface ECGs showed either typical CCW pattern (12 patients) or atypical patterns (3 patients). The EAMs showed a focal pattern in 3, a CCW pattern in 5. The successful ablation site always occurred at the area with maximal FP duration. Over the same period, 33 of 384 (9%) patients who underwent ablation for CTI-dependent flutter had prior successful CTI ablation, 7 of 33 (21%) were found to have IIR during the redo procedure.

CONCLUSIONS

(1) Electrogram and ECG patterns of IIR frequently show atypical flutter. (2) IIR was successfully ablated in an area of the CTI associated with maximal duration of FPs. (3) IIR is a significant cause of "recurrent flutter" in patients with prior CTI ablation.

Results of radiofrequency ablation of permanent atrial fibrillation of >2 years duration and left atrial size >5 cm using 2-mm irrigated tip ablation catheter and targeting areas of complex fractionated atrial electrograms

Complex fractionated atrial electrograms (CFAEs) have shown promise as target sites for ablation of atrial fibrillation (AF); however, the data are limited with regard to patients with a large left atrium (LA) (>5 cm), and/or a permanent AF duration of >2 years. We tested the hypothesis that ablation of user-defined, computer-generated CFAE and pulmonary vein isolation, without additional lines would help long-term maintenance of sinus rhythm (SR). A total of 21 patients, 9 men and 12 women, aged 32 to 78 years (mean 44 +/- 3.3) were selected. All had chronic AF for >2 years (range 2 to 20; mean 3.8) and a LA of 5.3 to 11.3 cm (mean 6.4 cm). The underlying structural heart disease was rheumatic mitral valve disease in 18, aortic stenosis in 1, and hypertension in 2. Mapping and ablation was done using the NAVx Ensite system and a 2-mm-tip IBI Therapy Cool Path ablation catheter. The target included circumferential pulmonary vein ablation and elimination of areas in the LA and proximal coronary sinus showing CFAEs. During ablation, 3 patients converted to SR. In 15 others, significant organization of the atrial activity occurred. They then underwent successful electrical cardioversion. Three patients showed no change in atrial activity nor had electrical cardioversion. No procedural complications occurred. Patients took oral amiodarone for 3 months after the procedure. At 3 to 12 months (mean 9.8) of follow-up, 3 patients who were in AF at the end of the ablation procedure continued to be in AF. Of the rest, all but 3 were able to maintain SR without antiarrhythmic drugs. In conclusion, ablation using a 2-mm tip irrigation catheter, targeting user-defined CFAEs and pulmonary vein isolation facilitated maintenance of SR in most patients with a LA >5 cm and an AF duration of >2 years.

Electrical remodelling of the left and right atria due to rheumatic mitral stenosis

AIMS

To characterize the atrial remodelling in mitral stenosis (MS).

METHODS AND RESULTS

Twenty-four patients with severe MS undergoing commissurotomy and 24 controls were studied. Electrophysiological evaluation was performed in 12 patients in each group by positioning multi-electrode catheters in both atria to determine the following: effective refractory period (ERP) at 10 sites at 600 and 450 ms; conduction time; conduction delay at the crista terminalis (CT); and vulnerability for atrial fibrillation (AF). P-wave duration (PWD) was determined on the surface ECG. In the remaining 12 patients in each group, electroanatomic maps of both atria were created to determine conduction velocity and identify regions of low voltage and electrical silence. Patients with MS had larger left atria (LA) (P < 0.0001); prolonged PWD (P = 0.0007); prolonged ERP in both LA (P < 0.0001) and right atria (RA) (P < 0.0001); reduced conduction velocity in the LA (P = 0.009) and RA (P < 0.0001); greater number (P < 0.0001) and duration (P< 0.0001) of bipoles along the CT with delayed conduction; lower atrial voltage in the LA (P < 0.0001) and RA (P < 0.0001); and more frequent electrical scar (P = 0.001) compared with controls. Five of twelve with MS and none of the controls developed AF with extra-stimulus (P = 0.02).

CONCLUSION

Atrial remodelling in MS is characterized by LA enlargement, loss of myocardium, and scarring associated with widespread and site-specific conduction abnormalities and no change or an increase in ERP. These abnormalities were associated with a heightened inducibility of AF.

Tachycardia-induced cardiomyopathy: mechanisms of heart failure and clinical implications

The prognosis of dilated cardiomyopathy is generally poor. The cause of ventricular dysfunction often cannot be identified. In most cases, the clinical history of cardiomyopathy is irreversible but, in some cases, potentially curable causes may be identified. The development of cardiomyopathy may be correlated to atrial or to ventricular arrhythmias. In this scenario, atrial fibrillation is the most frequent cause of ventricular dysfunction, even if it may also be secondary to heart failure. The diagnosis of tachycardia-induced cardiomyopathy can be made only after the improvement of the left ventricular function once the cardiac frequency has slowed down.

Surgical treatment of atrial fibrillation : a systematic review

BACKGROUND

The recently published overwhelming number of publications on the surgical treatment of AF, using a wide variety of techniques, blurred any precise appreciation of the nowadays surgical treatment of AF. As a consequence, the "state of the art" of the surgical technique of AF is ill-defined.

OBJECTIVES

In this review the efficacy of the alternative sources of energy (radiofrequency-microwave and cryoablation; (group I) and the classical "cut and sew" Cox-Maze III (group II), which claims a 97-99% sinus rhythm (SR) success rate, were evaluated in the surgical treatment of atrial fibrillation (AF).

METHODS

A computerized search in the PubMed and Medline database was conducted. Only original, English written, clinical manuscripts on the surgical treatment of atrial fibrillation citing the clinical outcome, including the postoperative sinus rhythm, were included. The following data were registered: the absolute numbers and percentages of treated patients, gender (male versus female) distribution, the type of arrhythmia (permanent or paroxysmal AF), type of surgery (mitral or non-mitral valve or a lone AF surgical procedure), postoperative morbidity (bleeding, the use of an intra-aortic balloon pump, cerebral vascular accident), postoperative pacemaker implantations, 30-day mortality, survival and sinus rhythm conversion. The mean values for age (years), left atrial diameter (mm), preoperative duration of AF (years) and left ventricular ejection fraction (%) were also recorded.

RESULTS

Forty-eight studies were included comprising 3832 patients: 2279 in group I and 1553 in group II. The mean duration of AF, left atrial diameter and LVEF were 5.4 versus 5.5 years (p=0.90), 55.5 versus 57.8 mm (p=0.23) and 57 versus 58% (p=0.63). The postoperative SR rates for group I and II were 78.3 versus 84.9% (p=0.03). However, the "cut and sew" Cox-Maze III was conducted in younger patients (55.0 versus 61.2 years; p=0.005), more often to treat paroxysmal (22.9 versus 8.0%) and lone AF (19.3 versus 1.6%). Alternative sources of energy were predominantly used to treat permanent AF (92.0%), almost always as a concomitant surgical procedure (98.4%) and increasingly in combination with non-mitral valve surgery (18.5%). After correction for these variations, the postoperative SR conversion rates for group I and II did not differ significantly anymore.

CONCLUSIONS

We could not identify any significant difference in the postoperative SR conversion rates between the classical 'cut and sew' and the alternative sources of energy, which were used to treat atrial fibrillation.

Impact of Catheter Ablation of the Coronary Sinus on Paroxysmal or Persistent Atrial Fibrillation

OBJECTIVES

This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF).

BACKGROUND

The CS musculature and connections have been implicated in the genesis of atrial arrhythmias.

METHODS

Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage. RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF.

RESULTS

Endocardial ablation significantly prolonged CSCL by 17 +/- 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation); subsequent epicardial ablation further increased local CSCL by 32 +/- 27 msec (P < 0.001). AFCL prolonged significantly both during endocardial and epicardial ablation (median: 152 to 167 msec P = 0.03) and was associated with AF termination in 16 (35%) patients (46% of paroxysmal and 30% of persistent AF). AFCL prolongation > or =5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P < or = 0.04.

CONCLUSION

Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.

Left Atrial Ablation Versus Biatrial Ablation for Persistent and Permanent Atrial Fibrillation

OBJECTIVES

The aim of this study was to compare--in patients with persistent and permanent atrial fibrillation (AF)--the efficacy and safety of left atrial ablation with that of a biatrial approach.

BACKGROUND

Left atrium-based catheter ablation of AF, although very effective in the paroxysmal form of the arrhythmia, has an insufficient efficacy in patients with persistent and permanent AF.

METHODS

Eighty highly symptomatic patients (age, 58.6 +/- 8.9 years) with persistent (n = 43) and permanent AF (n = 37), refractory to antiarrhythmic drugs, were randomized to two different ablation approaches guided by electroanatomical mapping. A procedure including circumferential pulmonary vein, mitral isthmus, and cavotricuspid isthmus ablation was performed in 41 cases (left atrial ablation group). In the remaining 39 patients (biatrial ablation group), the aforementioned approach was integrated by the following lesions in the right atrium: intercaval posterior line, intercaval septal line, and electrical disconnection of the superior vena cava.

RESULTS

During follow-up (mean duration 14 +/- 5 months), AF recurred in 39% of patients in the left atrial ablation group and in 15% of patients in the biatrial ablation group (p = 0.022). Multivariable Cox regression analysis showed that ablation technique was an independent predictor of AF recurrence during follow-up.

CONCLUSIONS

In patients with persistent and permanent AF, circumferential pulmonary vein ablation, combined with linear lesions in the right atrium, is feasible, safe, and has a significantly higher success rate than left atrial and cavotricuspid ablation alone.

Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of subsequent arrhythmias

BACKGROUND

Catheter ablation of atrial fibrillation (AF) is challenging in patients with long-standing persistent AF. The clinical outcome and subsequent arrhythmia recurrence after using an ablation method targeting multiple left atrial sites with the aim of achieving acute AF termination has not been characterized.

METHODS

Sixty patients (mean age: 53 +/- 9 years) with persistent AF (mean duration: 17 +/- 27 months) were prospectively followed after catheter ablation. Catheter ablation targeting the following sites was performed in a random sequence: (i) electrical isolation of all pulmonary veins (PV); (ii) disconnection of other thoracic veins; (iii) atrial ablation at sites possessing complex electrical activity, activation gradients, or short cycle lengths. Finally, linear ablation of the LA roof and mitral isthmus was performed if sinus rhythm was not restored following energy delivery to the above sites. At 1, 3, 6, and 12 months after ablation, patients underwent clinical review and 24-hour ambulatory ECG monitoring to identify asymptomatic arrhythmia. Repeat mapping and catheter ablation was performed in any patient experiencing recurrent atrial tachycardia (AT). Clinical success was defined as the absence of any sustained atrial arrhythmia.

RESULTS

AF terminated during ablation in 52 patients (87%). The fluoroscopy and procedural durations were 84 +/- 30 minutes and 264 +/- 77 minutes, respectively. Three months after ablation, sustained ATs were documented in 24 patients (associated with AF in 2). Mapping in 23 patients showed a single AT in 7 while multiple ATs were observed in 16. Macroreentry was confirmed to be due to gaps in the ablation lines, while focal ATs originated from discrete sites or isthmuses near the left atrial appendage, coronary sinus, pulmonary veins, or fossa ovalis; these sites were similar to those at which the greatest impact was observed on the fibrillatory process during the initial ablation procedure. After repeat ablation, at 11 +/- 6 months of follow-up, 57 patients (95%) were in sinus rhythm and 3 developed recurrent AF or AT. All patients in sinus rhythm demonstrated improved exercise capacity and all but 2 had evidence of atrial transport as assessed by Doppler echocardiography (mitral A wave velocity 34 +/- 17 cm/sec) by 6 months.

CONCLUSION

Catheter ablation of long-lasting persistent AF associated with acute AF termination achieves medium to long-term restoration and maintenance of sinus rhythm in 95% of patients. Arrhythmia recurrence in the majority of patients is AT.

Management of atrial fibrillation in rheumatic valvular heart disease

PURPOSE OF REVIEW

Atrial fibrillation in patients with rheumatic valvular heart disease results in significant morbidity and possibly mortality.

RECENT DEVELOPMENTS

The recent advances in treatment options for non-rheumatic atrial fibrillation have widened its scope of management. These treatment modalities have not been extensively validated in rheumatic valvular heart disease.

SUMMARY

A review and comparison of the available data in atrial fibrillation and rheumatic valvular heart disease vis-à-vis non-rheumatic atrial fibrillation is presented.

Hybrid Therapy with Right Atrial Catheter Ablation and Previously Ineffective Antiarrhythmic Drugs for the Management of Atrial Fibrillation

BACKGROUND

Many patients with paroxysmal atrial fibrillation (AF) become refractory to antiarrhythmic drugs (AADs). Early studies suggested that linear catheter ablation in the right atrium may provide sufficient substrate modification to reestablish therapeutic efficacy of previously ineffective AADs.

METHODS

This prospective before-after multicenter trial evaluated the safety and effectiveness of hybrid therapy that included right atrial catheter ablation coupled with a regimen of previously ineffective AADs on AF episode frequency and symptoms in drug refractory patients with paroxysmal AF. A standard linear lesion set (lateral, septal, isthmus) was used in all subjects. AF episode frequency, clinical arrhythmia symptoms, condition-specific (AFSS) and global health-related quality of life (SF-36) were assessed prior to ablation and at 6 months.

RESULTS

Ninety-three subjects, refractory to an average 2.9 AADs at baseline, qualified for inclusion and underwent right atrial catheter ablation. Eighty-four subjects (90%) provided 6 month AF episode frequency data which demonstrated a significant decrease compared to baseline (3.4 vs. 9.5, p < 0.0001). Forty-nine subjects (58%) were considered a clinical success by virtue of achieving a pre-specified target level episode frequency reduction of 50% or greater. Substantial and statistically significant improvements were realized almost uniformly for all measured arrhythmia symptoms as well as for both quality of life measures. The incidence of major complications was 5.4%.

CONCLUSIONS

The addition of right atrial catheter ablation to a regimen of previously ineffective AADs is associated with a significant reduction in the frequency, duration and severity of AF episodes and symptoms.

Limited Benefit of Septal Pre-Excitation in Pace Prevention of Atrial Fibrillation

BACKGROUND

Pre-excitation of the intra-atrial septum (IAS) by pacing at the ostium of the coronary sinus (CSO) can prevent atrial fibrillation (AF) in case of single atrial premature beats (APBs). We investigated whether pre-excitation of IAS, either by pacing at CSO or at the right ventricle in the presence of retrograde conduction (RV), can prevent atrial tachyarrhythmia triggered by single and multiple APBs. AF vulnerability was compared to pacing at the right atrium (RA) and sinus rhythm (SR).

METHODS

Seventeen patients, age 52 +/- 21 years, who exhibited retrograde VA conduction and reproducible induction of atrial tachyarrhythmia during an electrophysiological procedure, were studied. Both during SR and pacing (S1-S1:600 ms) at RA, CSO, and right ventricle (RV), single (A1-S2:200 ms) and multiple premature stimuli (A1-S2-S3-S4:200-180-180 ms) were delivered at RA (4 x diastolic threshold).

RESULTS

During pacing at RA, single and multiple APBs invariably induced runs of atrial tachyarrhythmia (mean duration 34 +/- 67 sec and 37 +/- 69 sec, range 1 sec to 20 min). During preventive pacing at CSO and RV, single APBs (A1-S2:200 ms) did not induce atrial arrhythmia (0 +/- 0 sec, 0 +/- 0 sec, P < 0.05 vs pacing at RA). In contrast, when multiple APBs were applied, pacing at CSO or RV failed to prevent initiation of AF (mean duration 36 +/- 63 sec, 38 +/- 65 sec, NS). Also during SR, single APBs did not induce AF (0 +/- 0 sec, P < 0.05 vs pacing at RA) whereas multiple APBs invariably induced AF (39 +/- 74 sec, NS).

CONCLUSIONS

Compared to pacing at RA, pre-excitation of IAS either by pacing at CSO or at RV with retrograde conduction can prevent initiation of paroxysms of atrial tachyarrhythmia triggered by single but not by multiple right APBs. These findings imply that the potential benefit of choosing an optimal pacing site in patients requiring atrial-based pacing is limited. Moreover, in the absence of bradycardia, no specific pacing site offers incremental benefit over the natural "protective" effect of sinus rhythm.

Long-Term Follow-Up of Right Atrial Ablation in Patients with Atrial Fibrillation:

INTRODUCTION

The aim of this study was to evaluate the efficacy and the impact on quality of life of a new ablative approach to the right atrium in patients with atrial fibrillation (AF).

METHODS AND RESULTS

Seventy-four symptomatic patients with paroxysmal (n = 49) or permanent (n = 25) refractory AF underwent radiofrequency ablation. A nonfluoroscopic electroanatomic mapping system was used to perform the following lesions: (1) an isthmus line between the tricuspid annulus and the inferior vena cava; (2) a posterior intercaval line from the superior vena cava and the inferior vena cava; (3) a septal line from the superior vena cava to the fossa ovalis, proceeding to the coronary sinus ostium where a circumferential line around the ostium was performed, and then on to the inferior vena cava; and (4) a transversal lesion connecting the posterior intercaval and the septal lesions. In addition, electrical disconnection of the superior vena cava was performed. There were no complications. Postablation remapping showed the absence of discrete electrical activity inside and just around the ablation lines. Electrical disconnection of the superior vena cava was obtained in all patients. After 21 +/- 6 months, 49 patients (66%) had stable sinus rhythm with continuation of the previous antiarrhythmic drug therapy, 13 patients (18%) were considered improved, and 12 (16%) received no benefit (unsuccessful procedure). After ablation, quality of life was significantly improved, reaching the levels of the general Italian population. Ejection fraction and the extent of the low-voltage area were found by multivariate analysis to be independent predictors of AF recurrence.

CONCLUSION

The results of the present study suggest that this ablative approach in combination with antiarrhythmic drugs is safe and effective in treating AF, leading to a marked increase in quality of life in patients with refractory AF.

Role of the Coronary Sinus in Maintenance of Atrial Fibrillation

INTRODUCTION

Bursts of tachycardia arising in the pulmonary veins may play an important role in perpetuating atrial fibrillation (AF). However, the role of the coronary sinus (CS) in the perpetuation of AF has been unclear. The aim of this study was to determine whether the CS plays a role in perpetuation of AF.

METHODS AND RESULTS

Pulmonary vein isolation was performed by segmental ostial ablation with radiofrequency energy in 22 consecutive patients with paroxysmal AF. Bipolar and unipolar electrograms recorded in the left atrium and CS were analyzed during atrial pacing from the mitral annulus and during AF. There was a mean of 2.5 +/- 0.5 electrical connections between the CS and the left atrium. The electrical connections between the left atrium and CS were ablated with a mean of 6.2 +/- 2.7 minutes of radiofrequency energy applied along the atrial side of the inferior mitral annulus. During AF, episodes of intermittent tachycardia alternated between the left atrium and the CS. Among the 22 patients, sustained AF was still inducible in 9 after pulmonary vein isolation. After electrical disconnection of the CS from the left atrium, sustained AF was inducible in only 3 of these 9 patients.

CONCLUSION

The CS may be a source of rapid repetitive electrical activity during AF. The lower probability of inducible sustained AF after electrical disconnection of the CS from the left atrium suggests that the CS may play a role in perpetuating AF.

Atrial tachycardia successfully treated by electrical isolation of the superior vena cava

This case report describes a patient with an atrial tachycardia that was difficult to induce and that originated from the superior vena cava. Although the patient had frequent episodes of tachycardia, the tachycardia induced in the electrophysiological laboratory was nonsustained and could not be adequately localized for focal ablation. A circumferential mapping catheter was used to guide electrical isolation of the superior vena cava from the right atrium, curing the tachycardia. Electroanatomic mapping and intracardiac echocardiography were used to monitor the ablation and document patency of the superior vena cava throughout the ablation.

Electrophysiologic characteristics of the spontaneous onset and termination of atrial fibrillation

Electrophysiologic characterization of the onset and termination of atrial fibrillation (AF) is poorly defined. Our study population consisted of 21 consecutive patients (mean age 58 +/- 9 years, 6 women) with intermittent (10 patients) or persistent (11 patients) AF. Mapping of the left atrium (LA) and the right atrium (RA) during initiation and termination of AF was performed with a 64-electrode basket catheter. A total of 92 spontaneous AF onsets (in 16 patients) and 63 spontaneous AF terminations were analyzed. Irrespective of the origin of the triggering atrial premature complex (APC), the onset of AF was preceded by an intermediary rhythm that consisted of repetitive firing from the focus that generated the initial APC, reentry around the mitral annulus, or typical atrial flutter. The earliest fibrillatory activity was constantly produced by circumvented regions (generators) localized most frequently in the posterior wall of the LA. Generators of fibrillatory activity were not observed in the RA for any of the patients. In the RA, AF is maintained by a mixture of macro-reentry and driving wave fronts of left atrial origin. Four modes of AF termination were observed: a multifocal rhythm (19 episodes, 30%), left atrial tachycardia (17 episodes, 27%), direct conversion to sinus rhythm (15 episodes, 24%), and conversion to typical atrial flutter (12 episodes, 19%). A repetitive rapid rhythm initiated most often by APCs plays a crucial role in the initiation of AF via activation of the generators of fibrillatory activity. The LA plays a central role in the initiation of AF by serving as a substrate for generators of fibrillatory activity. Termination of AF consists of a heterogenous group of unstable rhythms.