Pulmonary-vein isolation for atrial fibrillation in patients with heart failure

BACKGROUND

Pulmonary-vein isolation is increasingly being used to treat atrial fibrillation in patients with heart failure.

METHODS

In this prospective, multicenter clinical trial, we randomly assigned patients with symptomatic, drug-resistant atrial fibrillation, an ejection fraction of 40% or less, and New York Heart Association class II or III heart failure to undergo either pulmonary-vein isolation or atrioventricular-node ablation with biventricular pacing. All patients completed the Minnesota Living with Heart Failure questionnaire (scores range from 0 to 105, with a higher score indicating a worse quality of life) and underwent echocardiography and a 6-minute walk test (the composite primary end point). Over a 6-month period, patients were monitored for both symptomatic and asymptomatic episodes of atrial fibrillation.

RESULTS

In all, 41 patients underwent pulmonary-vein isolation, and 40 underwent atrioventricular-node ablation with biventricular pacing; none were lost to follow-up at 6 months. The composite primary end point favored the group that underwent pulmonary-vein isolation, with an improved questionnaire score at 6 months (60, vs. 82 in the group that underwent atrioventricular-node ablation with biventricular pacing; P<0.001), a longer 6-minute-walk distance (340 m vs. 297 m, P<0.001), and a higher ejection fraction (35% vs. 28%, P<0.001). In the group that underwent pulmonary-vein isolation, 88% of patients receiving antiarrhythmic drugs and 71% of those not receiving such drugs were free of atrial fibrillation at 6 months. In the group that underwent pulmonary-vein isolation, pulmonary-vein stenosis developed in two patients, pericardial effusion in one, and pulmonary edema in another; in the group that underwent atrioventricular-node ablation with biventricular pacing, lead dislodgment was found in one patient and pneumothorax in another.

CONCLUSIONS

Pulmonary-vein isolation was superior to atrioventricular-node ablation with biventricular pacing in patients with heart failure who had drug-refractory atrial fibrillation. (ClinicalTrials.gov number, NCT00599976.)

Atrial Fibrillation Ablation in Patients With Therapeutic International Normalized Ratio

Background— The best approach to management of anticoagulation before and after atrial fibrillation ablation is not known.

Methods and Results— We compared outcomes in consecutive patients undergoing pulmonary vein antrum isolation for persistent atrial fibrillation. Early in our practice, warfarin was stopped 3 days before ablation, and a transesophageal echocardiogram was performed to rule out clot. Enoxaparin, initially 1 mg/kg twice daily (group 1) and then 0.5 mg/kg twice daily (group 2), was used to “bridge” patients after ablation. Subsequently, warfarin was continued to maintain the international normalized ratio between 2 and 3.5 (group 3). Minor bleeding was defined as hematoma that did not require intervention. Major bleeding was defined as either cardiac tamponade, hematoma that required intervention, or bleeding that required blood transfusion. Pulmonary vein ablation was performed in 355 patients (group 1=105, group 2=100, and group 3=150). More patients had spontaneous echocardiographic contrast in groups 1 and 2. One patient in group 1 had an ischemic stroke compared with 2 patients in group 2 and no patients in group 3. In group 1, 23 patients had minor bleeding, 9 had major bleeding, and 1 had pericardial effusion but no tamponade. In group 2, 19 patients had minor bleeding, and 2 patients developed symptomatic pericardial effusion with need for pericardiocentesis 1 week after discharge. In group 3, 8 patients developed minor bleeding, and 1 patient developed pericardial effusion with no tamponade.

Conclusions— Continuation of warfarin throughout pulmonary vein ablation without administration of enoxaparin is safe and efficacious. This strategy can be an alternative to bridging with enoxaparin or heparin in the periprocedural period.

Remote magnetic navigation: human experience in pulmonary vein ablation

OBJECTIVES

We aimed at assessing the feasibility and efficacy of remote magnetic navigation (MN) and ablation in patients with atrial fibrillation (AF).

BACKGROUND

This novel MN system could facilitate standardization of the procedures, reducing the importance of the operator skill.

METHODS

After becoming familiar with the system in 48 previous patients, 45 consecutive patients with AF were considered for ablation using the Niobe II remote magnetic system (Stereotaxis, St. Louis, Missouri) in a stepwise approach: circumferential pulmonary vein ablation (CPVA), pulmonary vein antrum isolation (PVAI), and, if failed, PVAI using the conventional approach. Remote navigation was done using the coordinate or the wand approach. Ablation end point was electrical disconnection of the pulmonary veins (PVs).

RESULTS

Using the coordinate approach, the target location was reached in only 60% of the sites, whereas by using the wand approach 100% of the sites could be reached. After step 2 ablation, only 1 PV in 4 patients (8%) could be electrically isolated. Charring on the ablation catheter tip was seen in 15 (33%) of the cases. In 23 patients, all PVs were isolated with the conventional thermocool catheter, and in 22 patients only the right PVs were isolated with the conventional catheter. After a mean follow-up period of 11 +/- 2 months, recurrence was seen in 5 patients (22%) with complete PVAI and in 20 patients (90%) with incomplete PVAI.

CONCLUSIONS

Remote navigation using a magnetic system is a feasible technique. With the present catheter technology, effective lesions cannot be achieved in most cases. This appears to impact the cure rate of AF patients.

Incidence of Atrial Arrhythmias Detected by Permanent Pacemakers (PPM) Post-Pulmonary Vein Antrum Isolation (PVAI) for Atrial Fibrillation (AF): Correlation with Symptomatic Recurrence

BACKGROUND

Studies examining AF recurrences post-PVAI base recurrence on patient reporting of symptoms. However, whether asymptomatic recurrences are common is not well known.

OBJECTIVE

To assess the incidence of atrial tachycardia/fibrillation post-PVAI as detected by a PPM and whether these recurrences correlate to symptomatic recurrence.

METHODS

Eighty-six consecutive patients with symptomatic AF and PPMs with programmable mode-switch capability underwent PVAI. Mode switching was programmed post-PVAI to occur at an atrial-sensed rate of >170 bpm. Patients were followed with clinic visits, ECG, and PPM interrogation at 1, 3, 6, and 9 months post-PVAI. The number and duration of mode-switching episodes (MSEs) were recorded at each visit and is presented as median (interquartile range).

RESULTS

The patients (age 57 +/- 8 years, EF 54 +/- 10%) had paroxysmal (65%) and persistent (35%) AF pre-PVAI. Sensing, pacing, and lead function were normal for all PPMs at follow-up. Of the 86 patients, 20 (23%) had AF recurrence based on symptoms. All 20 of these patients had appropriate MSEs detected. Of the 66 patients without symptomatic recurrence, 21 (32%) had MSEs detected. In 19 of these patients, MSEs were few in number, compared with patients with symptomatic recurrence (16 [4-256] vs 401 [151-2,470], P < 0.01). The durations were all <60 seconds. All of these nonsustained MSEs occurred within the first 3 months post-PVAI, gradually decreasing over time. The other 2 of 21 remaining patients had numerous (1,343 [857-1,390]) and sustained (18 +/- 12 minutes) MSEs that also persisted beyond 3 months (1 beyond 6 months). Therefore, the incidence of numerous, sustained MSEs in asymptomatic patients post-PVAI was 2 of 66 (3%).

CONCLUSIONS

Detection of atrial tachyarrhythmias by a PPM occurred in 30% of patients without symptomatic AF recurrence. Most of these episodes were <60 seconds and waned within 3 months. Sustained, asymptomatic episodes were uncommon.

Vagal responses induced by endocardial left atrial autonomic ganglion stimulation before and after pulmonary vein antrum isolation for atrial fibrillation

BACKGROUND

Elimination of vagal inputs into the left atrium (LA) may be necessary for successful catheter ablation of atrial fibrillation (AF). These vagal inputs are clustered in autonomic ganglia (AG) that are close to the pulmonary vein antrum (PVA) borders, but whether standard intracardiac echocardiography (ICE)-guided PVA isolation (PVAI) affects these inputs is unknown.

OBJECTIVE

The purpose of this study was to assess whether standard ICE-guided PVAI affects vagal responses induced by endocardial AG stimulation in the LA.

METHODS

Twenty consecutive patients undergoing first-time PVAI (group 1) and 20 consecutive patients undergoing repeat PVAI for AF recurrence (group 2) were enrolled in the study. Before ablation, electrical stimulation (20 Hz, pulse duration 10 ms, voltage range 12-20 V) was performed through an 8-mm-tip ablation catheter. Based on prior data, regions around all four PVA borders were carefully mapped and stimulated to localize AG inputs. A positive stimulated vagal response was defined as atrioventricular (AV) block, asystole, or increase in mean RR interval by >50%. Locations of positive vagal responses were recorded wth biplane fluoroscopy and CARTO. All patients then underwent standard ICE-guided PVAI by an operator blinded to the locations of vagal responses. Stimulation of the AG locations was then repeated postablation.

RESULTS

Patients (age 54 +/- 11 years, 30% female, ejection fraction 54% +/- 7%) had a history of paroxysmal (75%) and persistent (25%) AF. In group 1, vagal responses were induced in all 20 patients around a mean of 3.8 +/- 0.4 PVAs per patient. The most common response was asystole (53%), mean RR slowing >50% (28%), and AV block (20%). Postablation, vagal responses could no longer be induced in all 20 patients. A diminished response was induced (RR slowing <50%) in 2/20 patients around one PVA each. In group 2, vagal responses were not induced in any of the 20 repeat patients. Stimulation capture postablation was confirmed because transient, nonsustained (<30 seconds) AF or atrial flutter was induced in all 40 patients with stimulation, whether vagal responses were induced or not.

CONCLUSIONS

Standard ICE-guided PVAI eliminates vagal responses induced by AG stimulation. Responses are not seen in patients presenting for repeat PVAI, despite clinical recurrence of AF.

Pulmonary Vein Antral Isolation Using an Open Irrigation Ablation Catheter for the Treatment of Atrial Fibrillation

OBJECTIVES

We sought to test how catheter ablation using an open irrigation catheter (OIC) compares with standard catheters for pulmonary vein antrum isolation.

BACKGROUND

Open irrigation catheters have the advantage of delivering greater power without increasing the temperature of the catheter tip, which enables deeper and wider lesions without the formation of coagulum on catheters.

METHODS

Catheter ablation was performed using an 8-mm catheter (8MC) or an OIC. Patients were randomized to 3 groups: 8MC; OIC-1, OIC with a higher peak power (50 W); and OIC-2, OIC with lower peak power (35 W).

RESULTS

A total of 180 patients were randomized to the 3 treatment strategies. Isolation of pulmonary vein antra was achieved in all patients. The freedom from atrial fibrillation was significantly greater in the 8MC and OIC-1 groups compared with the OIC-2 group (78%, 82%, and 68%, respectively, p = 0.043). Fluoroscopy time was lower in OIC-1 compared with OIC-2 and 8MC (28 +/- 1 min, 53 +/- 2 min, and 46 +/- 2 min, respectively, p = 0.001). The mean left atrium instrumentation time was lower in the OIC-1 compared with the OIC-2 and 8MC groups (59 +/- 3 min, 90 +/- 5 min, and 88 +/- 4 min, respectively, p = 0.001). However, there was a greater incidence of "pops" in the OIC-1 (100%, 0%, 0%, p < 0.001) along with higher incidences of pericardial effusion (20%, 0%, 0%, p < 0.001) and gastrointestinal complaints (17% in OIC-1, 3% in 8MC, and 5% in OIC-2, p = 0.031).

CONCLUSIONS

Although there was a decrease in fluoroscopy and left atrium instrumentation time with the use of OIC at higher power, this setting was associated with increased cardiovascular and gastrointestinal complications.

Left atrial appendage exclusion and the risk of thromboembolic events following mitral valve surgery

OBJECTIVES

We aimed to evaluate left atrial appendage (LAA) exclusion in patients undergoing mitral valve surgery with respect to thromboembolic events.

BACKGROUND

LAA is the predominant source of emboli in patients with atrial fibrillation. Prophylactic LAA exclusion at the time of heart surgery has been recommended to reduce the risk of future thromboembolism.

METHODS

An observational cohort of 136 patients undergoing LAA exclusion during mitral valve surgery was identified between May 1993 and November 1998 at our institution.

RESULTS

During a mean follow-up of 3.6 +/- 1.3 years, there were 14 (12.3%) thromboembolic events. Compared with patients who received warfarin upon hospital discharge, there were more thromboembolic events in patients not prescribed warfarin upon hospital discharge (n = 7/67, 10% vs n = 6/40, 15%, respectively). The warfarin status was not known for one patient. The majority of thromboembolic events (n = 10/14, 71%) occurred in those who underwent mitral valve repair.

CONCLUSION

In this observational study, patients who undergo LAA exclusion during mitral valve surgery to reduce the risk of thromboembolism have a significant incidence of thromboembolic events, especially when warfarin therapy is not prescribed upon hospital discharge.

Efficacy of Adjuvant Anterior Left Atrial Ablation During Intracardiac Echocardiography-Guided Pulmonary Vein Antrum Isolation for Atrial Fibrillation

BACKGROUND

Recent data have shown that the septum and anterior left atrial (LA) wall may contain "rotor" sites required for AF maintenance. However, whether adding ablation of such sites to standard ICE-guided PVAI improves outcome is not well known.

OBJECTIVE

To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF.

METHODS

One hundred AF patients (60 paroxysmal, 40 persistent/permanent) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation (Group I). These patients were compared with 100 randomly selected, matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation (Group II). All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated. In group I, a decapolar lasso catheter was used to map the septum and anterior LA wall during AF (induced or spontaneous) for continuous high-frequency, fractionated electrograms (CFAE). Sites where CFAE were identified were ablated until the local EGM was eliminated. A complete anterior line of block was not a requisite endpoint. Patients were followed up for 12 months. Recurrence was assessed post-PVAI by symptoms, clinic visits, and Holter at 3, 6, and 12 months. Patients also wore rhythm transmitters for the first 3 months. Recurrence was any AF/AFL >1 min occurring >2 months post-PVAI.

RESULTS

Patients (age 56 +/- 11 years, 37% female, EF 53%+/- 11%) did not differ in baseline characteristics between group I and II by design. Group I patients had longer procedure time (188 +/- 45 min vs 162 +/- 37 min) and RF duration (57 +/- 12 min vs 44 +/- 20 min) than group II (P < 0.05 for both). Overall recurrence occurred in 15/100 (15%) in group I and 20/100 (20%) in group II (P = 0.054). Success rates did not differ for paroxysmal patients between group I and II (87% vs 85%, respectively). However, for persistent/permanent patients, group I had a higher success rate compared with group II (82% vs 72%, P = 0.047).

CONCLUSIONS

Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF.

Pacing Evaluation-Atrial SUpport Study in Cardiac Resynchronization Therapy (PEGASUS CRT): design and rationale

BACKGROUND

Cardiac resynchronization therapy (CRT) has been demonstrated to be an effective heart failure (HF) therapy. All pivotal trials of CRT to date have used atrial-synchronous biventricular pacing wherein there is no or minimal atrial pacing. In clinical practice, however, physicians often program CRT devices to have atrial rate support pacing, either by increasing the lower rate limit or by activating the rate sensor.

OBJECTIVE

The purpose of this study is to evaluate the effect of empiric atrial support pacing in patients with HF who have received a CRT defibrillator (CRT-D) device.

METHODS

PEGASUS CRT is a multicenter, 3-arm, randomized clinical trial of approximately 1200 patients receiving a CRT-D device. For the first 6 weeks after implant, devices are programmed to DDD with a lower rate limit of 40 beats/min. At 6 weeks, patients are randomized to DDD-40, DDD-70, or DDDR-40. All randomized patients are followed for 1 year, and at each visit, mortality, HF events, quality of life, New York Heart Association class, and atrial and ventricular arrhythmic episodes are evaluated. An exercise substudy will also be conducted, enrolling a minimum of 375 patients. Patients in this substudy will complete 2 cardiopulmonary exercise tests to evaluate the effect pacing mode has on exercise capacity. This randomized controlled trial will address whether empiric atrial support pacing is of clinical benefit to patients with HF who receive a CRT-D device.

Pulmonary vein total occlusion following catheter ablation for atrial fibrillation: clinical implications after long-term follow-up

OBJECTIVES

We present the clinical course and management outcomes of patients with total pulmonary vein occlusion (PVO).

BACKGROUND

Pulmonary vein occlusion is a rare complication that can develop after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The long term follow-up data of patients diagnosed with PVO are minimal.

METHODS

Data from 18 patients with complete occlusion of at least one pulmonary vein (PV) were prospectively collected. All patients underwent RFA for AF using different strategies between September 1999 and May 2004. Pulmonary vein occlusion was diagnosed using computed tomography (CT) and later confirmed by angiography when intervention was warranted. Lung perfusion scans were performed on all patients before and after intervention. The percent stenoses of the veins draining each independent lung were added together to yield an average cumulative stenosis of the vascular cross-sectional area draining the affected lung (cumulative stenosis index [CSI]).

RESULTS

The patients' symptoms had a positive correlation with the CSI (r = 0.843, p < 0.05) and a negative one with the lung perfusion (r = -0.667, p < 0.05). A CSI > or =75% correlated well with low lung perfusion (<25%; r = -0.854, p < 0.01). Patients with a CSI > or =75% appeared to improve mostly when early (r = -0.497) and repeat dilation/stenting (r = 0.0765) were performed.

CONCLUSIONS

Patients with single PVO are mostly asymptomatic and should undergo routine imaging. On the other hand, patients with concomitant ipsilateral PV stenosis/PVO and a CSI > or =75% require early and, when necessary, repeated pulmonary interventions for restoration of pulmonary flow and prevention of associated lung disease.

Atrial Arrhythmias After Surgical Maze

OBJECTIVES

We describe the clinical and electrophysiologic characteristics and management of post "cut and sew" Maze arrhythmias in symptomatic patients.

BACKGROUND

The Cox Maze procedure was developed as a surgical treatment of atrial fibrillation. Until recently, invasive electrophysiologic studies in patients with symptomatic post-operative arrhythmias in this patient population have not been described.

METHODS

The management and clinical course of consecutive patients with post-Maze arrhythmias refractory to antiarrhythmic drugs (AADs) between January 2000 and December 2003 are presented.

RESULTS

Twenty-three patients (15 men) presented 14 +/- 14 months after Maze surgery for treatment of atrial fibrillation (AF). Eight patients underwent "cut and sew" Maze for lone AF with no other surgical indication. Fifteen patients underwent the "cut and sew" Maze procedure in addition to another surgical procedure: mitral valve surgery (11 patients) and coronary artery bypass graft surgery (4 patients). Eight patients (35%) had recurrent AF secondary to recovered conduction around the lines encircling the pulmonary veins. Five patients were documented to have focal atrial tachycardia, which was mapped to the coronary sinus in 3 patients, to the posterolateral right atrium in 1 patient, and to the left atrial (LA) septum in 1 patient. Four patients had right atrium incisional atrial flutter (AFL), and 6 had LA incisional AFL, which was mapped around the mitral valve annulus in 4 patients and around the right pulmonary veins in 2 patients. Twenty-two of the 23 patients were treated successfully with radiofrequency ablation. At 1-year follow-up, 19 patients were arrhythmia-free and taking no AADs.

CONCLUSIONS

After surgical "cut and sew" Maze, approximately one-third of patients experiencing atrial arrhythmias have AF secondary to pulmonary vein-left atrium conduction recovery. Moreover, incisional AFL seems to be a common finding in this group of patients. Catheter-based mapping and ablation of these arrhythmias seems to be feasible and effective.

Incidence of Atrial Fibrillation in Heart Transplant Patients: Long-Term Follow-Up

BACKGROUND

The incidence of atrial fibrillation (AF) in heart transplant patients has not been well documented.

METHODS

To determine the incidence of AF in a cohort of patients undergoing cardiac transplantation, clinical data were obtained from a prospectively collected database for all consecutive orthotopic heart transplantation (OHT) patients and for all consecutive coronary artery bypass graft (CABG) surgery patients between January 1984 and March 2004 at our institution. A cohort of 1,714 OHT patients and low-risk CABG (normal ejection fraction [EF] and no left ventricular hypertrophy [LVH]) patients were age- and sex-matched.

RESULTS

The average age in the two groups was 56 +/- 7 years with 87% male and 81% white race and body mass index (BMI) of 26 +/- 4. There were 3 cases of AF (0.3%) in the OHT group and 757 cases of AF (21%) in the low-risk CABG group. The strongest independent predictor of freedom from postoperative AF was having had a transplant (odds ratio [OR] 96, 95% confidence interval [CI] 13-720). The incidence of AF, atrial flutter (AFL), and supraventricular tachycardia (SVT) in OHT was 0.33, 2.8%, and 1.3%, respectively. Given that incidence of AF, AFL, and SVT in historical post-CABG population is 25%, 17%, and 4.3%, transplanted patients appear to have lower incidence of AF, AFL, and SVT than the reference population. Consistent with this, transplanted patients underwent few ablation procedures for atrial arrhythmias. Additionally, the three patients with AF had bicaval anastomoses suggesting the possibility of PACs originating in the donor superior vena cava (SVC) or IVC (inferior vena cava) initiating AF in these patients.

CONCLUSIONS

In a cohort study of transplant and low-risk CABG patients, the strongest independent predictor of freedom from AF is having undergone transplant surgery. One potential explanation for the markedly lower incidence of AF may be effective isolation of thoracic veins with documented cases retaining the native SVC.

Extensive Ablation During Pulmonary Vein Antrum Isolation Has No Adverse Impact on Left Atrial Function: An Echocardiography and Cine Computed Tomography Analysis

BACKGROUND

Although pulmonary vein antrum isolation (PVAI) may cure atrial fibrillation (AF) and improve left atrial (LA) function, the effect of extensive LA ablation on LA function is not well known.

OBJECTIVE

To assess the impact of PVAI on LA function remotely postablation.

METHODS

Consecutive patients undergoing PVAI had either transthoracic (TTE) and transesophageal (TEE) echocardiography (n = 41) or cine EBCT (n = 26) performed preablation and 6 months postablation. Only patients with paroxysmal and persistent, but not permanent, AF were included. Imaging was done in sinus rhythm for all patients. LA diameter (LAD), LA systolic and diastolic areas, and left atrial fractional area change (LFAC) were assessed by TTE. Transmitral (TMF), left atrial appendage (LAA), and pulmonary venous (PVF) Doppler flows were measured by TEE. Peak A on TMF, LAA peak emptying velocity (LAAF), and peak A reversal (AR) on PVF were used as surrogates of LA contractile function. Peak S on PV flow was used as a surrogate of reservoir function. LA areas, volumes, and LA ejection fraction (LAEF) were measured from cine EBCT.

RESULTS

Mean radiofrequency ablation time was 45 +/- 21 minutes. All four PVs were isolated for all patients; there were no cases of PV stenosis. Echocardiography revealed a significant reduction in LAD and LA areas post-PVAI. Both peak A and peak AR were also higher post, while other variables showed strong trends toward improvement. In the subset of patients with persistent AF, post-PVAI improvements were seen in LA size, peak A, and even peak S (P = 0.04). Cine EBCT showed a significant decrease in both LA areas and volumes post-PVAI. There was also a significant improvement in LAEF post-PVAI from 17 +/- 6% to 22 +/- 5% (P = 0.01).

CONCLUSION

Extensive ablation during PVAI does not cause deterioration in LA function, and may cause long-term improvement, especially in patients with higher AF burden.

Transcranial Doppler Detection of Microembolic Signals During Pulmonary Vein Antrum Isolation: Implications for Titration of Radiofrequency Energy

BACKGROUND

Cerebrovascular events are an important complication during pulmonary vein antrum isolation (PVAI). Microembolic signals (MES) have been associated with stroke and neurological impairment. However, the incidence of MES during PVAI, and their relationship to microbubble formation and radiofrequency (RF) parameters are unknown.

OBJECTIVES

We sought to assess the relationship between MES, microbubble detection, and neurological outcome and the impact of RF titration strategy on these parameters.

METHODS

We studied 202 patients in two groups undergoing PVAI using an intracardiac echocardiography (ICE)-guided technique. MES were detected by transcranial Doppler (TCD) using insonation of the middle cerebral arteries. The number of microbubbles on ICE were qualitatively labeled as FEW, MODERATE, and SHOWER. In group I (n = 107), RF output was titrated to avoid microbubble formation and in group II (n = 95), standard power-limited RF output was used.

RESULTS

TCD detected MES in all 202 patients during PVAI with an average of 1,793 +/- 547 per patient; 90% were detected during left atrial ablation. Over 85% of MES occurred after microbubbles. Group I patients had significantly lower numbers of MES (1,015 +/- 438 per patient) compared to group II patients (2,250 +/- 864 per patient) (P < 0.05). Group II also had a 3.1% incidence of acute neurological complications versus 0.9% in group I (P = 0.10). Patients with clinical events had significantly higher numbers of MES. There were no significant correlations between RF power, temperature, or impedence and MES number.

CONCLUSIONS

MES directly correlate to the amount of microbubble formation on ICE, and may result in cerebroembolic complications. Titration of RF according to microbubble formation by ICE during PVAI may be important for minimizing the occurrence of MES and possibly acute neurological complications.

The effects of altering time delays of coupled pacing during acute atrial fibrillation

BACKGROUND

Coupled pacing (CP), which consists of delivering a premature electrical stimulation to the heart after the effective refractory period of ventricular activation, is a novel method for controlling ventricular rate during atrial fibrillation (AF). It also has been established that CP improves pump function by enhancing external cardiac work and myocardial efficiency.

OBJECTIVE

The purpose of the present study was to determine if two time delays for CP (short and long) would result in similar improvements in ventricular function.

METHODS

In a canine model, we applied CP at two time delays (CP-S and CP-L) during two stages: sinus rhythm (SR) and acute AF. The cardiac responses to CP during SR served as the nontachycardic and nondepressed control. During both rhythms, we shortened the coupling interval until we obtained maximal contractility, designated CP-S. Next, we increased the delay until we started to see a measurable secondary contraction (left ventricular pressure development of approximately 20 mmHg). These longer delays were designated CP-L.

RESULTS

Our results showed that the ventricular rate of intrinsic activation (VRIA) remained decreased despite prolongation of the time delay of CP during both AF and SR. Also, both delays of CP increased left ventricular systolic pressure (LVSP) and dLVP/dt, which are indices of myocardial contractility. In contrast, CP increased external cardiac work only during AF. Prolonging this time delay did not markedly decrease the improvement in external cardiac work. Myocardial O(2) consumption (MVO(2)) did not significantly change as the result of CP during either SR or AF. Finally, myocardial efficiency improved during AF as the result of CP at both time delays.

CONCLUSIONS

In conclusion, shorter time delays for CP increased contractile strength during both SR and AF. However, extending the time delay of CP had minimal effects on diminishing the improved ventricular pump function and energetics that resulted from CP during AF. Thus, the maximal enhancement of myocardial contractility via CP-S was not needed to maintain the improved ventricular function during acute AF when CP is applied.

Response of atrial fibrillation to pulmonary vein antrum isolation is directly related to resumption and delay of pulmonary vein conduction

BACKGROUND

The role of pulmonary vein (PV) isolation in ablative treatment of atrial fibrillation (AF) has been debated in conflicting reports. We sought to compare PV conduction in patients who had no AF recurrence (group I), patients who could maintain sinus rhythm on antiarrhythmic medication (group II), and patients who had recurrent AF despite antiarrhythmic medication (group III) after PV antrum isolation (PVAI).

METHODS AND RESULTS

PV conduction was examined in consecutive patients undergoing second PVAI for AF recurrence. We also recruited some patients cured of AF to undergo a repeat, limited electrophysiological study at >3 months after PVAI. All patients underwent PVAI with an intracardiac echocardiography (ICE)-guided approach with complete isolation of all 4 PV antra (PVA). The number of PVs with recurrent conduction and the shortest atrial to PV (A-PV) conduction delay was measured with the use of consistent Lasso positions defined by ICE. Late AF recurrence was defined as AF >2 months after PVAI with the patient off medications. Patients in groups I (n=26), II (n=37), and III (n=44) did not differ at baseline (38% permanent AF; ejection fraction 53+/-6%). Recurrence of PV-left atrial (LA) conduction was seen in 1.7+/-0.8 and 2.2+/-0.8 PVAs for groups II and III but only in 0.2+/-0.4 for group I (P=0.02). In patients with recurrent PV-LA conduction, the A-PV delay increased from the first to second procedure by 69+/-47% for group III, 267+/-110% for group II, and 473+/-71% for group I (P<0.001). When pacing was at a faster rate, A-PV block developed in all 5 of the group I patients with recurrent PV-LA conduction.

CONCLUSIONS

The majority of patients with drug-free cure show no PV-LA conduction recurrence. Substantial A-PV delay is seen in patients able to maintain sinus rhythm on antiarrhythmic medication or cured of AF compared with patients who fail PVAI.

Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of symptomatic atrial fibrillation: a randomized trial

CONTEXT

Treatment with antiarrhythmic drugs and anticoagulation is considered first-line therapy in patients with symptomatic atrial fibrillation (AF). Pulmonary vein isolation (PVI) with radiofrequency ablation may cure AF, obviating the need for antiarrhythmic drugs and anticoagulation.

OBJECTIVE

To determine whether PVI is feasible as first-line therapy for treating patients with symptomatic AF.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter prospective randomized study conducted from December 31, 2001, to July 1, 2002, of 70 patients aged 18 to 75 years who experienced monthly symptomatic AF episodes for at least 3 months and had not been treated with antiarrhythmic drugs.

INTERVENTION

Patients were randomized to receive either PVI using radiofrequency ablation (n=33) or antiarrhythmic drug treatment (n=37), with a 1-year follow-up.

MAIN OUTCOME MEASURES

Recurrence of AF, hospitalization, and quality of life assessment.

RESULTS

Two patients in the antiarrhythmic drug treatment group and 1 patient in the PVI group were lost to follow-up. At the end of 1-year follow-up, 22 (63%) of 35 patients who received antiarrhythmic drugs had at least 1 recurrence of symptomatic AF compared with 4 (13%) of 32 patients who received PVI (P<.001). Hospitalization during 1-year follow-up occurred in 19 (54%) of 35 patients in the antiarrhythmic drug group compared with 3 (9%) of 32 in the PVI group (P<.001). In the antiarrhythmic drug group, the mean (SD) number of AF episodes decreased from 12 (7) to 6 (4), after initiating therapy (P = .01). At 6-month follow-up, the improvement in quality of life of patients in the PVI group was significantly better than the improvement in the antiarrhythmic drug group in 5 subclasses of the Short-Form 36 health survey. There were no thromboembolic events in either group. Asymptomatic mild or moderate pulmonary vein stenosis was documented in 2 (6%) of 32 patients in the PVI group.

CONCLUSION

Pulmonary vein isolation appears to be a feasible first-line approach for treating patients with symptomatic AF. Larger studies are needed to confirm its safety and efficacy.