Catheter Ablation for Atrial Fibrillation in Patients with Heart Failure: Current Evidence and Future Opportunities

Atrial fibrillation (AF) and heart failure (HF) are highly prevalent cardiac disorders worldwide, and both are associated with poor prognosis. The incidence of AF and HF has been increasing substantially in recent years, mainly due to the progressive aging of the population. These disorders often coexist, and may have a causal relationship, with one contributing to the development or progression of the other. AF is a significant risk factor for adverse outcomes in HF patients, including mortality, hospitalization, and stroke. Although the optimal treatment for AF with HF remains unclear, catheter ablation (CA) has emerged as a promising treatment option. This review provides a comprehensive overview of the current scientific evidence regarding the efficacy of CA for managing AF in HF patients. In addition, the potential benefits and risks associated with CA are also discussed. We will also explore the factors that may influence treatment outcomes and highlight the remaining gaps in knowledge in this field.

Pre-procedural predictors of left atrial low-voltage zones in patients undergoing catheter ablation of atrial fibrillation

Pulmonary vein isolation has become a cornerstone treatment for catheter ablation of atrial fibrillation (AF). Recent reports show that additional ablation targeting low-voltage zones reduces AF recurrence. However, the pre-procedural predictors of low-voltage zones remain elusive. We retrospectively enrolled 359 patients (mean age 63.7 ± 10.8 years; 73 females; and 149 had persistent atrial fibrillation) who underwent catheter ablation for AF and left atrial (LA) voltage mapping during sinus rhythm or atrial pacing. Low-voltage zones were defined as area of > 5 cm2 with a bipolar electrogram amplitude of < 0.50 mV. Overall, 51 (14.2%) patients had low-voltage zones. Patients with low-voltage zones were older (67.9 ± 9.9 vs. 63.0 ± 10.8 years; P = 0.003), predominantly female (33.3% vs. 18.2%; P = 0.013), had higher prevalence of dilated cardiomyopathy (DCM) (11.8% vs. 1.6%; P = 0.002) and hypertrophic cardiomyopathy (HCM) (9.8% vs. 2.6%; P = 0.025), and had larger LA volumes (153.6 ± 46.4 vs. 117.7 ± 67.8 mL; P < 0.001) than those without low-voltage zones. Multivariate logistic regression analysis revealed that age (OR 1.060; 95% CI 1.022–1.101, P = 0.002), female sex (OR 2.978; 95% CI 1.340–6.615, P = 0.007), DCM (OR 8.341; 95% CI 1.381–50.372, P = 0.021), HCM (OR 5.044; 95% CI 1.314–19.363, P = 0.018), persistent AF (OR 4.188; 95% CI 1.928–9.100, P < 0.001), and larger LA volume (OR 3.215; 95% CI 1.378–7.502, P = 0.007) were independently associated with the presence of low-voltage zones. Patient age, female sex, DCM, HCM, persistent AF and larger LA volume may predict the presence of low-voltage zones and could be useful in selecting the appropriate ablation strategy for AF.

Efficacy of isoproterenol in the evaluation of dormant conduction and arrhythmogenic foci identification in atrial fibrillation ablation

Background

Catheter ablation for atrial fibrillation (AF) is an established therapy. However, postoperative recurrence is a serious issue caused by the reconduction of the isolated pulmonary veins (PV) and the onset of non-PV foci. The objectives of this study were to elucidate dormant conduction, confirm PV arrhythmia substrate, induce non-PV foci after PV isolation, and assess the acute efficacy of high dose isoproterenol (ISP) when administered in addition to adenosine.

Methods

The study consisted of 100 patients with drug-refractory AF (paroxysmal and persistent) who underwent ablation therapy (either radio-frequency or cryoballoon ablation) as the first-line of therapy at our hospital. All patients first underwent PV isolation (PVI) and were administered adenosine followed by ISP (6 μg × 5 min). The effects were observed, and the therapeutic strategy was evaluated.

Results

Persistent dormant conduction due to ISP administration was observed in 13 patients. In over half of the patients, arrhythmia substrates were identified in the PV. Ten patients presented with persistent PV firing. The ablation of non-PV foci was additionally performed in 23 patients.

Conclusions

We found that dormant conduction, as a result of ISP administration, is persistent and ISP is useful when performing an ablation. In addition, ISP administration is useful for the identification of PV arrhythmia substrates and induction of non-PV foci. However, the effectiveness of ISP may be partially due to the complementary effect of adenosine, and, therefore, a combination of the two drugs seems preferable.

Right atrial volume is superior to left atrial volume for prediction of atrial fibrillation recurrence after direct current cardioversion

BACKGROUND

The value of right atrial volume as a predictor for recurrence of atrial fibrillation (AF) after direct current cardioversion (DCCV) is unknown.

METHODS

We sought to compare the performance of right atrial volume indexed to body surface area (RAVI), left atrial diameter, left atrial volume indexed to body surface area (LAVI), and biatrial volume index (BAVI) for the prediction of AF recurrence at 6 months after DCCV. This study included the first 95 consecutive patients from the AF Clinic at a large tertiary care hospital who underwent DCCV and who had an echocardiogram available within 6 months before DCCV. Maximal LAVI, RAVI, and BAVI were determined from the echocardiogram before DCCV. Electrocardiographic and clinical data were acquired at baseline, before cardioversion, and at each clinic visit.

RESULTS

Of the 95 patients (64 male; mean age, 63 ± 12 years), history of systemic hypertension, diabetes mellitus, heart failure, and transient ischemic attack/stroke was present in 60 (63%), 14 (15%), 27 (28%), and 5 (5%) patients, respectively. Mean duration from AF diagnosis to DCCV was 3.5 ± 5.0 years. At 6 months after DCCV, 53 (56%) had reverted to AF. RAVI had superior predictive ability (area under the receiver operator characteristic curve: RAVI, 0.77; left atrial diameter, 0.54; LAVI, 0.64; and BAVI, 0.70). RAVI ≥ 42 mL/m(2) provided the best accuracy for prediction of recurrence (76% accuracy, 71% sensitivity, 83% specificity, 90% positive predictive value, and 56% negative predictive value). Best accuracy for LAVI was ≥ 48 mL/m(2) (70% accuracy, 53% sensitivity, 79% specificity, 85% positive predictive value; 43% negative predictive value).

CONCLUSIONS

RAVI is superior to LAVI for the prediction of AF recurrence at 6 months after DCCV.

Curative ablation of atrial fibrillation: comparison between deep sedation and general anesthesia

OBJECTIVE

To compare deep sedation with general anesthesia for curative ablation of atrial fibrillation.

METHODS

We conducted a prospective, randomized study with 32 patients, aged between 18 and 65 years, ASA 2 and 3, BMI d" 30 kg/m2, divided into two groups: deep sedation (G1) and general anesthesia (G2). All patients received intravenous midazolam (0.5 mg / kg). G1 received propofol (1mg/kg) and O2 by facemask, followed by continuous infusion of propofol (25-50mg/kg/min) and remifentanil (0.01-0.05 mg / kg / min). G2 received propofol (2mg/kg) and laryngeal mask with built-in drain tube, followed by continuous infusion of propofol (60-100mg/kg/min) and remifentanil (0.06 to 0.1g/kg/min). We compared heart rate, invasive blood pressure, arterial blood gases, complications and recurrence (outcome) in three months.

RESULTS

G1 patients had arterial blood gas with higher PaCO2 levels and lower pH (p = 0.001) and higher incidence of cough. There was a decrease in Mean Arterial Pressure (MAP) and Heart Rate (HR) in G2. Except cough, complications and recurrence were similar in both groups.

CONCLUSION

Both techniques can be used for the curative ablation of atrial fibrillation. General anesthesia provided smaller respiratory changes and greater immobility of the patient.

Six-year follow-up of catheter ablation in paroxysmal atrial fibrillation

BACKGROUND

Although pulmonary vein (PV) antrum isolation is an established therapy for drug-resistant paroxysmal atrial fibrillation (PAF), long-term (>5 years) follow-up data are limited. This study investigated long-term clinical outcome of catheter ablation.

METHODS AND RESULTS

From September 2003 to August 2006, 161 patients (mean age, 60±9 years; 119 male) with symptomatic drug-refractory PAF who underwent extensive encircling PV isolation (EEPVI) with a double Lasso technique were included. Right-sided and left-sided circular lesions encircling the ipsilateral PVs were created. The procedure endpoint was electrical isolation of the PV antrum. Patients with recurrent atrial tachyarrhythmia (ATa) had their previous lesions assessed and consolidated. Trigger ablation was added if necessary. EEPVI was successfully performed at the initial procedure. During a median follow-up of 6.4 years (25th-75th percentile, 5.8-7.1 years), 86 patients (53.4%) had recurrent ATa. Among 78, 15 and 4 patients undergoing 2nd, 3rd and 4th procedures, PV reconnections were observed in 68, 10 and 2, respectively. During a median follow-up of 6.0 years (25th-75th percentile, 5.2-6.9 years) after a mean of 1.6±0.7 procedures per patient, 144 patients (89.4%) were free from ATa. No progression toward persistent AF was observed in any patients.

CONCLUSIONS

The vast majority of drug-resistant PAF could be controlled by EEPVI without an additional atrial substrate modification. No progression toward persistent AF was observed during a median follow-up of 6 years.

Left atrial expansion index predicts atrial fibrillation in dyspnea

BACKGROUND

The left atrial (LA) expansion index for predicting atrial fibrillation (AF) in a relatively low-risk cohort is not fully understood.

METHODS AND RESULTS

In this prospective study of 2,200 dypnea patients, the LA expansion index was calculated as (Volmax-Volmin)×100%/Volmin, where Volmax was defined as maximum LA volume and Volmin was defined as minimum volume. The endpoints were 2-year frequency of AF, including both paroxysmal and persistent. Of the 180 participants (8.2%) who had AF attacks over a median follow-up of 2.7 years, 90 (4.1%) had at least 1 episode of persistent AF. Compared to patients with paroxysmal AF, those with persistent AF had a much lower LA expansion index (100±59% vs. 44±24%). LA expansion index was associated exponentially with the incidence of persistent AF. Independent predictors of AF included age, renal function impairment, pulmonary artery systolic pressure, and LA expansion index. Persistent AF, however, had significant independent associations only with prior heart failure, renal function impairment, diastolic dysfunction, and LA expansion index (odds ratio, 0.970; 95% confidence interval: 0.959-0.981 per 1% increase, P<0.0001). Compared to other parameters, LA expansion index <61.4% was the best cut-off point to predict persistent AF.

CONCLUSIONS

The LA expansion index is associated with the presence of AF, and a reduced LA expansion index has a strong association with persistent AF.

Catheter ablation in combination with left atrial appendage closure for atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting millions of individuals worldwide. The rapid, irregular, and disordered electrical activity in the atria gives rise to palpitations, fatigue, dyspnea, chest pain and dizziness with or without syncope. Patients with AF have a five-fold higher risk of stroke. Oral anticoagulation (OAC) with warfarin is commonly used for stroke prevention in patients with AF and has been shown to reduce the risk of stroke by 64%. Warfarin therapy has several major disadvantages, however, including bleeding, non-tolerance, interactions with other medications and foods, non-compliance and a narrow therapeutic range. These issues, together with poor appreciation of the risk-benefit ratio, unawareness of guidelines, or absence of an OAC monitoring outpatient clinic may explain why only 30-60% of patients with AF are prescribed this drug. The problems associated with warfarin, combined with the limited efficacy and/or serious side effects associated with other medications used for AF, highlight the need for effective non-pharmacological approaches to treatment. One such approach is catheter ablation (CA), a procedure in which a radiofrequency electrical current is applied to regions of the heart to create small ablation lesions that electrically isolate potential AF triggers. CA is a well-established treatment for AF symptoms, that may also decrease the risk of stroke. Recent data showed a significant decrease in the relative risk of stroke and transient ischemic attack events among patients who underwent ablation compared with those undergoing antiarrhythmic drug therapy. Since the left atrial appendage (LAA) is the source of thrombi in more than 90% of patients with non-valvular atrial fibrillation, another approach to stroke prevention is to physically block clots from exiting the LAA. One method for occluding the LAA is via percutaneous placement of the WATCHMAN LAA closure device. The WATCHMAN device resembles a small parachute. It consists of a nitinol frame covered by fabric polyethyl terephthalate that prevents emboli, but not blood, from exiting during the healing process. Fixation anchors around the perimeter secure the device in the LAA (Figure 1). To date, the WATCHMAN is the only implanted percutaneous device for which a randomized clinical trial has been reported. In this study, implantation of the WATCHMAN was found to be at least as effective as warfarin in preventing stroke (all-causes) and death (all-causes). This device received the Conformité Européenne (CE) mark for use in the European Union for warfarin eligible patients and in those who have a contraindication to anticoagulation therapy. Given the proven effectiveness of CA to alleviate AF symptoms and the promising data with regard to reduction of thromboembolic events with both CA and WATCHMAN implantation, combining the two procedures is hoped to further reduce the incidence of stroke in high-risk patients while simultaneously relieving symptoms. The combined procedure may eventually enable patients to undergo implantation of the WATCHMAN device without subsequent warfarin treatment, since the CA procedure itself reduces thromboembolic events. This would present an avenue of treatment previously unavailable to patients ineligible for warfarin treatment because of recurrent bleeding or other warfarin-associated problems. The combined procedure is performed under general anesthesia with biplane fluoroscopy and TEE guidance. Catheter ablation is followed by implantation of the WATCHMAN LAA closure device. Data from a non-randomized trial with 10 patients demonstrates that this procedure can be safely performed in patients with a CHADS2 score of greater than 1. Further studies to examine the effectiveness of the combined procedure in reducing symptoms from AF and associated stroke are therefore warranted.

Patient preferences at ten years following initial diagnosis of atrial fibrillation: the Belgrade Atrial Fibrillation Study

BACKGROUND

Many atrial fibrillation (AF) patients have a poor understanding of the management of this condition. We investigated patient attitudes towards AF and a potential invasive treatment following an average 10-year period of prospective rhythm control in a cohort of newly diagnosed AF patients.

METHODS

This was a prospective registry-based study. At the regular annual visit in 2007, patients were asked at random to answer several AF-related questions.

RESULTS

Of 390 patients, 277 (71.0%) reported symptom reduction over time, but only 45 (11.5%) reported that they had "got used" to AF; 201 patients (51.5%) stated they would always prefer sinus rhythm, and 280 (71.2%) would accept an invasive AF treatment. Independent predictors for choosing an invasive procedure were younger age, impaired career/working capacity, and male gender (all P < 0.05).

CONCLUSION

Our findings suggest that most AF patients prefer sinus rhythm and would readily accept an invasive procedure if it offered the possibility of a cure for their AF.

An increase in right atrial magnetic strength is a novel predictor of recurrence of atrial fibrillation after radiofrequency catheter ablation

BACKGROUND

Differences in electrical properties between left and right atria (LA and RA) after pulmonary vein isolation (PVI) for atrial fibrillation (AF) are currently poorly understood. Magnetocardiograms were used to investigate the effect of PVI on bi-atrial magnetic field changes and their relationship to clinical outcomes.

METHODS AND RESULTS

This study included 71 patients undergoing PVI for paroxysmal AF. Magnetocardiograms were recorded at baseline and 1 day, 8 weeks, and 24 weeks after ablation. Peak magnitude of LA and RA segments on P waves was separately compared before and after PVI. During a 16-month post-ablation period, 53 (75%) patients were free from AF recurrences. LA magnetic strength in patients without recurrence persistently decreased for 24 weeks and was significantly lower at 8 weeks than that in patients with recurrence (1.28±0.69 vs. 1.74±0.71 pico-Tesla, P=0.02). RA magnetic strength in patients with recurrence persistently rose for 24 weeks and was significantly higher at 8 weeks than that in patients without recurrence (2.17±0.82 vs. 3.00±1.12 pico-Tesla, P=0.001). Multivariate analysis showed RA magnetic strength at 8 weeks to be the strongest predictor of AF recurrence (odds ratio=3.335; 95% confidence interval=1.181-9.416; P=0.02).

CONCLUSIONS

PVI resulted in distinct changes in magnetic strength in both the LA and the RA. A persistent rise in RA magnetic strength might be a robust predictor of AF recurrence after ablation.

Three-dimensional mapping of cardiac arrhythmias - string of pearls -

The evolution of 3-dimensional (D) mapping systems has contributed to improved procedures for ablation of complex tachyarrhythmia in terms of providing detailed anatomical information along with the ability to integrate with pre-acquired computed tomography/magnetic resonance imaging/intracardiac echocardiography images, reducing the radiation exposure, and producing activation and substrate maps. 3-D mapping systems are categorized as magnetic based vs. impedance based according to the catheter location technology, and are also classified as contact based vs. non-contact based according to the data collection technology. Contact-based mapping systems are used widely, in which a series of electrograms is taken sequentially in contact with the heart, thus requiring a relatively stable and sustained arrhythmia to create an activation map. Non-contact mapping systems, however, allow a beat-to-beat analysis of the activation even in non-sustained, polymorphic, or hemodynamically intolerant tachycardia. In this article, the clinical utility of 3-D mapping systems is discussed based on the literature and on experience, with particular emphasis on the non-contact mapping system.

Right atrial anatomical remodeling affects early outcomes of nonvalvular atrial fibrillation after radiofrequency ablation

BACKGROUND

The impact of the right atrial (RA) anatomical remodeling on outcomes of atrial fibrillation (AF) after radiofrequency ablation (RFA) is unclear.

METHODS AND RESULTS

Sixty-three patients (50 men, 57±10 years, 23 persistent AF [PeAF]) who underwent RFA for AF were enrolled. Both RA and left atrial (LA) volumes, measured with multidetector computed tomography, as well as echocardiographic parameters were compared between subjects with early (<3 months, n=13) or 1-year (n=19) recurrence after RFA and without recurrence. The RA volume index (RAVI) was larger (98±21 vs. 77±22 ml/m²) and PeAF was more common (62% vs. 30%) in the early recurrence group (P<0.05 for all), whereas the LA volume index (LAVI) was similar between the 2 groups (78±15 vs. 72±19 ml/m², P=0.23). Notably, RAVI was the only independent predictor of early recurrence (for each 10 ml/m² increase, OR: 1.650, 95%CI: 1.017-2.677, P=0.04). PeAF was the only independent predictor of 1-year recurrence after RFA (OR: 4.496, 95%CI: 1.110-18.211, P=0.04), whereas RAVI and LAVI were not.

CONCLUSIONS

RA anatomical remodeling might affect the early recurrence of AF after RFA. However, the chronicity of AF, rather than RA and LA anatomical remodeling, is a determinant of 1-year recurrence of AF after RFA.