Short-term safety and efficacy of left atrial appendage closure with the WATCHMAN device in patients with small left atrial appendage ostia.

INTRODUCTION: Left atrial appendage (LAA) closure with the WATCHMAN device, according to FDA labelling, is recommended in patients with a maximal LAA ostial width between 17 and 31 mm. The safety and efficacy of LAA closure in patients with a maximal LAA ostial width < 17 mm has not been evaluated. The goal of this study was to determine the acute and short-term safety and efficacy of LAA closure with the WATCHMAN device in patients with a maximal LAA ostial width < 17 mm. METHODS AND RESULTS: Thirty-two consecutive patients with a maximal LAA ostial width < 17 mm as determined by a screening transesophageal echocardiogram (TEE) underwent LAA closure with the WATCHMAN device between March 2015 and November 2016 at five medical centers, and were included in this study. Mean age, body mass index (BMI), and CHA2 DS2 -VASC score were 70.8 ± 8.6 years, 29.3 ± 6.5 kg/m2 , and 3.9 ±1.2, respectively. At the screening TEE, mean maximal LAA ostial width and depth were 15.6 ± 0.6 mm (range 14-16) and 23.2 ± 4.5 mm (range 13-31), respectively. Successful LAA closure with the WATCHMAN device was achieved in 31 of 32 patients (97%), with no major complications. TEE performed 45 days after LAA closure demonstrated no peridevice leak > 5 mm and no device related thrombi. Warfarin was discontinued in all 31 patients 45 days after LAA closure. CONCLUSIONS: LAA closure with the WATCHMAN device can be successfully and safely achieved in patients with a maximal LAA ostial width < 17 mm.

Association of Antitachycardia Pacing or Shocks With Survival in 69,000 Patients With an Implantable Defibrillator.

AIMS: Antitachycardia pacing (ATP) is an effective treatment for ventricular tachycardia (VT) and can reduce the frequency of shocks in patients with an implantable cardioverter defibrillator (ICD). The association between survival and ATP, as compared to a shock, has not been confirmed in a large patient population. This study aims to determine if patients with an ICD receiving ATP have lower mortality, as compared to those receiving shock. METHODS: Sixty-nine thousand three hundred and sixty-eight patients underwent ICD implantation between October 2008 and May 2013 and were enrolled in the remote monitoring network Merlin.net™ (St. Jude Medical, St. Paul, MN, USA). Patients were categorized into three groups based on the type of ICD therapy received during follow-up: no therapy (N = 47,927), ATP (N = 8,049), and shock (N = 13,392) groups. Survival was determined by linking implant records to the Social Security Death Index. RESULTS: The no therapy (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.56-0.64, P < 0.001) and ATP (HR 0.70, 95% CI 0.64-0.77, P < 0.001) groups were associated with a lower mortality risk than the shock group. These results were unaffected by age, gender, device type, atrial fibrillation (AF) burden, or ventricular rate. ATP was effective in 85% of episodes and ATP effectiveness was dependent on the ventricular rate. CONCLUSIONS: Mortality rates were higher in ICD patients who received only ATP compared to no therapy, but ICD patients who received a shock had higher mortality compared to both groups. Furthermore, the data suggest that age, gender, device type, AF burden, and rate of arrhythmia do not change the trend of higher mortality in patients receiving ICD shock compared to ATP alone.

The role of ventricular tachycardia ablation in the reduction of implantable defibrillator shocks.

Frequent shocks from an implantable defibrillator (ICD) can have adverse cardiac affects and lead to increased pain, anxiety, and a decreased quality of life. Pharmacologic attempts and ICD reprogramming strategies aimed at reducing ICD shocks have modest results, with frequent discontinuation of medicines because of side effects. Ventricular tachycardia (VT) ablation is recommended in the treatment of patients with frequent ICD shocks caused by VT. VT ablation may also be considered in patients with an initial ICD shock and as prophylactic treatment in patients with a history of sustained VT who are undergoing ICD implant.

Does the risk-benefit analysis favor the extraction of failed, sterile pacemaker and defibrillator leads?

Transvenous pacemaker and defibrillator (PM-D) lead failure is an important clinical problem. Lead extraction is routinely performed in patients with transvenous pacemaker and defibrillator (PM-D) infections. The management of sterile PM-D leads that have failed or are no longer required is less uniform. While extraction of excess or failed sterile PM-D leads is often advocated, the risk of lead extraction must be weighed against the risk of abandoning these leads. There are no randomized trials comparing lead extraction with abandoning sterile leads in this setting. What then are the data that are used to advocate the extraction of excess or failed, sterile chronically implanted PM-D leads, and are the data adequate to make this recommendation?

Patient selection for cardiac resynchronization therapy: from the Council on Clinical Cardiology Subcommittee on Electrocardiography and Arrhythmias and the Quality of Care and Outcomes Research Interdisciplinary Working Group, in collaboration with the Heart Rhythm Society.

Cardiac resynchronization therapy (CRT) is a relatively new therapy for patients with symptomatic heart failure resulting from systolic dysfunction. CRT is achieved by simultaneously pacing both the left and right ventricles. Biventricular pacing resynchronizes the timing of global left ventricular depolarization and improves mechanical contractility and mitral regurgitation. Published clinical trials have demonstrated that CRT results in improved clinical status and lower mortality rate when selected patients with systolic ventricular dysfunction and heart failure are treated with CRT. This advisory identifies appropriate candidates for CRT on the basis of the inclusion criteria and results from the published clinical trials.

Role of permanent pacing to prevent atrial fibrillation: science advisory from the American Heart Association Council on Clinical Cardiology (Subcommittee on Electrocardiography and Arrhythmias) and the Quality of Care and Outcomes Research Interdisciplinary Working Group, in collaboration with the Heart Rhythm Society.

This advisory summarizes the current database on pacing modalities and algorithms used to prevent and terminate atrial fibrillation (AF). On the basis of the evidence indicating that ventricular pacing is associated with a higher incidence of AF in patients with sinus node dysfunction, a patient who has a history of AF and needs a pacemaker for bradycardia should receive a physiological pacemaker (dual chamber or atrial) rather than a single-chamber ventricular pacemaker. For patients who need a dual-chamber pacemaker, efforts should be made to program the device to minimize the amount of ventricular pacing when atrioventricular conduction is intact. Many pacemakers and implantable defibrillators have features designed to prevent AF and to terminate AF with rapid atrial pacing. The evidence to support their use is limited, although these algorithms appear to be safe and usually add little additional cost. For patients who have a bradycardia indication for pacing and also have AF, no consistent data from large randomized trials support the use of alternative single-site atrial pacing, multisite right atrial pacing, biatrial pacing, overdrive pacing, or antitachycardia atrial pacing. Even fewer data support the use of atrial pacing in the management of AF in patients without symptomatic bradycardia. At present, permanent pacing to prevent AF is not indicated; however, additional studies are ongoing, which will help to clarify the role of permanent pacing for AF.

Characterization of the coronary sinus ostium by cardiac magnetic resonance imaging.

The diameter and the angle of the coronary sinus (CS) ostium was analyzed in 101 patients who underwent cardiac magnetic resonance imaging and had left ventricular ejection fractions < or =0.35 (n = 40) or > or =0.65 (n = 61). The angle of the CS ostium in patients with LVEFs < or =0.35 was less acute than in patients with LVEFs > or =0.65 (73 degrees +/- 12 degrees vs 65 degrees +/- 10 degrees, p <0.01). There was no statistically significant difference in the diameter of the CS ostium in patients with LVEFs < or =0.35 compared with those with LVEFs > or =0.65 (8 +/- 3 vs 8 +/- 2 mm, p = 0.5). The diameter and the angle of the CS ostium were not different when analyzed on the basis of the duration of the QRS complex, left atrial dimension, or left ventricular end-diastolic dimension. In conclusion, on the basis of cardiac magnetic resonance imaging data, the angle of the CS is less acute in patients with LVEFs < or =0.35 than in those with LVEFs > or =0.65.

Right Ventricular Pacing for Assessment of Cavo-Tricuspid Isthmus Block.

Background: Cavo-tricuspid isthmus (CTI) dependent atrial flutter is typically treated with cardiac ablation. Standard techniques to assess CTI block after ablation can be technically challenging. Right ventricular (RV) pacing may allow for another technique to assess CTI block after ablation. Objective: The purpose of this study was to evaluate RV pacing as a method to assess CTI block after ablation of CTI dependent atrial flutter, and define endpoints of ablation using this technique. Methods: 28 patients undergoing ablation of CTI dependent atrial flutter with intact ventriculoatrial (VA) conduction were prospectively enrolled in this study and underwent the RV pacing protocol, as well as standard coronary sinus (CS) pacing techniques to assess CTI block. Results: The mean trans-isthmus conduction interval during CS pacing (TICICS) at 600 and 400ms after CTI ablation was 168 +/- 9ms and 175 +/- 18ms, respectively. The mean trans-isthmus conduction interval during RV pacing (TICIRV) at 600ms and 400ms after CTI ablation was 109 +/- 5ms and 111 +/- 5ms, respectively. A TICIRV >100ms was associated with a successful outcome after CTI ablation. Conclusions: RV pacing may add incremental value in the assessment of CTI block in patients undergoing ablation of CTI dependent atrial flutter.

Clinical assessment and management of patients with implanted cardioverter-defibrillators presenting to nonelectrophysiologists.

All physicians increasingly will encounter patients who have implanted cardioverter-defibrillators (ICDs) for protection from ventricular arrhythmias. This advisory provides a concise summary relevant to the assessment and management of patients with ICDs, including those who present to primary care or emergency department physicians with symptoms suggesting arrhythmia or ICD malfunction and those who require cardiac or surgical procedures.

Efficacy and temporal stability of reduced safety margins for ventricular defibrillation: primary results from the Low Energy Safety Study (LESS).

BACKGROUND: Traditionally, a safety margin of at least 10 J between the maximum output of the pulse generator and the energy needed for ventricular defibrillation has been used because lower safety margins were associated with unacceptably high rates of failed defibrillation and sudden cardiac death. The Low Energy Safety Study (LESS) was a prospective, randomized assessment of the safety margin requirements for modern implantable cardioverter-defibrillator (ICD) systems. METHODS AND RESULTS: A total of 636 patients undergoing initial ICD implantation with a dual-coil lead and active pulse generator were evaluated. The defibrillation threshold (DFT) and enhanced DFT (DFT+ and DFT++) were measured using a modified step-down protocol. Conversion testing of induced ventricular fibrillation before discharge, at 3 months, and at 12 months was performed, as was randomization to chronic programming at either 2 steps above DFT++ or maximal output. The induced ventricular fibrillation data had conversion success rates of 91.4%, 97.9%, 99.1%, 99.6%, and 99.8% for safety margins of 0, 1, 2, 3, and 4 steps above the DFT++, respectively. A margin of 4 to 6 J was adequate to maintain high conversion success over time (98.9% before discharge versus 99.2% at 12 months; P=NS). Over a mean follow-up of 24+/-13 months, conversion of spontaneously occurring ventricular tachyarrhythmias >200 bpm was identical (97.3%), despite a safety margin difference of 5.2+/-1.1 J for the 2-step group versus 20.8+/-4.2 J for maximal output. CONCLUSIONS: With a rigorous implantation algorithm, a safety margin of about 5 J is adequate for safe implantation of modern ICD systems.

Pulmonary vein isolation for paroxysmal and persistent atrial fibrillation.

BACKGROUND: The pulmonary veins (PVs) have been demonstrated to often play an important role in generating atrial fibrillation (AF). The purpose of this study was to determine the safety and efficacy of segmental PV isolation in patients with paroxysmal or persistent AF. METHODS AND RESULTS: In 70 consecutive patients (mean age, 53 +/- 11 years) with paroxysmal (58) or persistent (12) AF, segmental PV isolation guided by ostial PV potentials was performed. The left superior, left inferior, and right superior PVs were targeted for isolation in all patients, and the right inferior PV was isolated in 20 patients. Among the 230 targeted PVs, 217 (94%) were completely isolated, with a mean of 6.5 +/- 4.2 minutes of radiofrequency energy applied at a maximum power setting of 35 W. A second PV isolation procedure was performed in 6 patients (9%). At 5 months of follow-up, 70% of patients with paroxysmal and 22% of patients with persistent AF were free from recurrent AF (P<0.001), and 83% of patients with paroxysmal AF were either free of symptomatic AF or had significant improvement. Among various clinical characteristics, only paroxysmal AF was an independent predictor of freedom from recurrence of AF (P<0.05). One patient developed unilateral quadrantopsia after the procedure. There were no other complications. CONCLUSIONS: With a segmental isolation approach that targets at least 3 PVs, a clinically satisfactory result can be achieved in >80% of patients with paroxysmal AF. The clinical efficacy of pulmonary vein isolation is much lower when AF is persistent than when it is paroxysmal.

Segmental ostial ablation to isolate the pulmonary veins during atrial fibrillation: feasibility and mechanistic insights.

BACKGROUND: The purpose of this study was to determine the feasibility and mechanistic implications of segmental pulmonary vein (PV) ostial ablation during atrial fibrillation (AF). METHODS AND RESULTS: Forty consecutive patients underwent PV isolation for AF. Among 125 PVs targeted for isolation, ablation was performed during AF in 70 veins and during sinus rhythm in 55 veins. A decapolar Lasso catheter was positioned near the ostium. During AF, ostial ablation was performed near the Lasso catheter electrodes that recorded a tachycardia with a cycle length shorter than in the adjacent left atrium. During sinus rhythm, ostial ablation was guided by PV potentials. Complete PV isolation was achieved in 70 PVs (100%) ablated during AF and in 53 PVs (96%) ablated during sinus rhythm (P=0.4). The mean durations of radiofrequency energy needed for isolation were 7.4+/-4.4 and 5.2+/-3.9 minutes during AF and sinus rhythm, respectively (P<0.01). Before ablation, an immediate recurrence of AF (IRAF), occurred after cardioversion in 18 of 40 patients, and IRAF was consistently abolished by PV isolation. The probability of AF termination during isolation of a PV was directly related to the extent of tachycardia in that vein. As more PVs were isolated, induction of persistent AF by rapid pacing became less likely. CONCLUSIONS: Segmental ostial ablation guided by PV tachycardia during AF is feasible and as efficacious as during sinus rhythm. The responses to cardioversion, ablation, and rapid pacing observed in this study imply that IRAF is triggered by the PVs and that PV tachycardias may play an important role in the perpetuation of AF.

Is defibrillation testing required for defibrillator implantation?

The assessment of defibrillation (DFT) efficacy has long been the standard of care during defibrillator implantation. To ensure an acceptable DFT safety margin, early defibrillator systems frequently required that the shock polarity and the location, type, or number of electrodes had to be altered. Advances in defibrillator and lead technology have resulted in lower and more consistent DFT thresholds in the range of 10 J, with an infrequent requirement to modify the DFT system. Yet, one can make an argument for and against continuation of DFT testing at the time of defibrillator implantation. The goal of this paper is to address both the data that do support and the data that do not support continuation of DFT testing at the time of device implantation. Scientifically, DFT testing should be abandoned only when prospective evidence demonstrates that defibrillator implantation without testing is as safe and has the same mortality benefits as implantation with testing. The most attractive aspect of eliminating DFT efficacy testing is that more patients may have the opportunity to be treated with this life-saving therapy. Perhaps there are alternative strategies to improve accessibility to defibrillator therapy without possibly eroding its effectiveness. In the end, will lives be saved or lost if we discontinue DFT efficacy testing and lower the barriers to implantable defibrillator therapy?

Amiodarone versus implantable cardioverter-defibrillator:randomized trial in patients with nonischemic dilated cardiomyopathy and asymptomatic nonsustained ventricular tachycardia--AMIOVIRT.

OBJECTIVES: The purpose of this multicenter randomized trial was to compare total mortality during therapy with amiodarone or an implantable cardioverter-defibrillator (ICD) in patients with nonischemic dilated cardiomyopathy (NIDCM) and nonsustained ventricular tachycardia (NSVT). BACKGROUND: Whether an ICD reduces mortality more than amiodarone in patients with NIDCM and NSVT is unknown. METHODS: One hundred three patients with NIDCM, left ventricular ejection fraction < or =0.35, and asymptomatic NSVT were randomized to receive either amiodarone or an ICD. The primary end point was total mortality. Secondary end points included arrhythmia-free survival, quality of life, and costs. RESULTS: The study was stopped when the prospective stopping rule for futility was reached. The percent of patients surviving at one year (90% vs. 96%) and three years (88% vs. 87%) in the amiodarone and ICD groups, respectively, were not statistically different (p = 0.8). Quality of life was also similar with each therapy (p = NS). There was a trend with amiodarone, as compared to the ICD, towards improved arrhythmia-free survival (p = 0.1) and lower costs during the first year of therapy ($8,879 US dollars vs. $22,039 US dollars, p = 0.1). CONCLUSIONS: Mortality and quality of life in patients with NIDCM and NSVT treated with amiodarone or an ICD are not statistically different. There is a trend towards a more beneficial cost profile and improved arrhythmia-free survival with amiodarone therapy.

Rate-dependent effect of verapamil on atrial refractoriness.

OBJECTIVES: The purpose of this study was to determine whether verapamil has rate-dependent effects on the atrial effective refractory period (AERP). BACKGROUND: Block of calcium current (I(Ca)) and rapid component of the delayed rectifier potassium current (I(Kr)) by verapamil is frequency-dependent. This may result in variable effects of verapamil on the AERP, depending on the rate. METHODS: The subjects of this study were 30 adults with a mean age of 45 +/- 13 years who did not have structural heart disease. In 20 subjects, the AERP was measured at basic drive cycle lengths (BDCLs) of 650 to 250 ms, in 50 ms decrements, before and after infusion of 0.1 mg/kg verapamil. The effective refractory periods (ERPs) were measured in the setting of autonomic blockade in 10 subjects and without autonomic blockade in 10 subjects. Ten subjects served as a control group and received a saline infusion instead of verapamil. RESULTS: Verapamil significantly prolonged the AERP at BDCLs of 650 to 500 ms (p < 0.01 or p < 0.05) and significantly shortened the ERP at BDCLs of 300 and 250 ms (p < 0.01). In the control group, there were no significant differences between the baseline and post-saline measurements of ERP. CONCLUSIONS: Verapamil prolongs AERP at slow rates and shortens AERP at rapid rates. These findings are consistent with a predominant effect on I(Ca) at rapid rates and a predominant effect on I(Kr) at slow rates.

Clinical significance of early recurrences of atrial fibrillation after pulmonary vein isolation.

OBJECTIVES: The purposes of this study were to describe the prevalence of early recurrences of atrial fibrillation (ERAF) that occur within two weeks after pulmonary vein (PV) isolation, and to determine whether ERAF is predictive of long-term outcome after PV isolation. BACKGROUND: Atrial fibrillation (AF) sometimes recurs within days after PV isolation and may prompt an early repeat intervention. METHODS: Segmental PV isolation was performed using radiofrequency energy in 110 consecutive patients (mean age 53 +/- 11 years) with paroxysmal (93 patients) or persistent (17 patients) AF. Three to four PVs were targeted for isolation in all patients. Pulmonary vein isolation was complete in 338 of the 358 PVs that were targeted (94%). RESULTS: Early recurrences of AF occurred in 39 of 110 patients (35%) at a mean of 3.7 +/- 3.5 days after the procedure. The prevalence of ERAF was similar in patients with paroxysmal and persistent AF (33% and 47%, respectively, p = 0.4). Beyond the first two weeks, at 208 +/- 125 days of follow-up, 60 of the 71 patients without ERAF (85%) and 12 of the 39 patients with ERAF (31%) were free of recurrent AF in the absence of antiarrhythmic drug therapy (p < 0.001). CONCLUSIONS: Early recurrences of AF occur in approximately 35% of patients within two weeks after isolation of three to four PVs, and are associated with a lower long-term success rate than in patients without ERAF. However, approximately 30% of patients with ERAF have no further symptomatic AF during long-term follow-up. Therefore, temporary antiarrhythmic drug therapy may be more appropriate than early repeat ablation in patients with ERAF.

Relationship between atrial tachyarrhythmias and symptoms.

OBJECTIVES: The purpose of this study was to correlate patient-reported symptoms of atrial fibrillation with the underlying rhythm. BACKGROUND: The reliability of patient-reported symptoms as a marker of atrial fibrillation recurrence has not been well studied. METHODS: This prospective multicenter trial correlated the recurrence of atrial tachyarrhythmias with symptoms in patients with a history of atrial fibrillation and a standard indication for permanent pacing. Pacemaker-detected atrial tachyarrhythmia events were correlated with symptoms. Patients logged symptomatic events into the device's memory via an external manual activator. Patients were followed for 12 months and were contacted weekly to ensure compliance with activator usage. Episodes were classified as symptomatic atrial tachyarrhythmia, asymptomatic atrial tachyarrhythmia, or symptomatic nonatrial tachyarrhythmia depending on concordance between patient symptoms and the rhythm. RESULTS: Forty-eight patients underwent implantation of a DDDRP pacemaker and were followed for 12 +/- 2 months. A median of 25.0 (4.0-55.8) symptomatic events attributed to atrial fibrillation. A median of 1.0 (0.0-10.0) symptomatic atrial tachyarrhythmia episodes were documented during follow-up. Symptoms related to atrial fibrillation were reported in 6% of atrial tachyarrhythmia episodes identified by the pacemaker. The probability that symptoms were associated with an atrial tachyarrhythmia (positive predictive value) was 17%. The ventricular rate between symptomatic and asymptomatic atrial tachyarrhythmia events was not significantly different. CONCLUSIONS: Among patients with symptomatic bradycardia and a history of atrial fibrillation, symptoms of atrial fibrillation often were not associated with documented atrial tachyarrhythmias, and more than 90% of atrial tachyarrhythmias were clinically silent.

One conversion of ventricular fibrillation is adequate for implantable cardioverter-defibrillator implant: an analysis from the Low Energy Safety Study (LESS).

OBJECTIVES: The purpose of this study was to analyze defibrillation conversion data from the Low Energy Safety Study (LESS) to determine how implant criteria that use fewer inductions of ventricular fibrillation (VF) correlate with outcome and, in particular, to assess the reliability of using a single VF induction and test shock at 14 J. BACKGROUND: A safety margin of 10 J has become standard for implantation of an implantable cardioverter-defibrillator (ICD), but the specifics and rigor of the implant test sequence are not standardized. METHODS: In LESS, 611 ICD recipients completed a rigorous VF induction test scheme that began at 14 J and continued until the energy that succeeded three times without a failure was determined (DFT++). The data were analyzed to determine how well the outcome of the first 14-J shock and various other combinations of first and/or second shocks predicted a rigorous gold standard of DFT++ < or =21 J (i.e., three successes at < or =21 J). RESULTS: The positive predictive accuracy for the 91% of patients in whom the first 14-J shock succeeded was virtually identical to the positive predictive accuracy for the commonly used criteria of two successes at < or =17 J (99.1% vs 99.0%, P = .69), and slightly higher than the positive predictive accuracy for two successes at < or =21 J (98.8%, P = .51). A single success at 17 J or 21 J had a somewhat lower positive predictive accuracy of 98.2% (P = .17). Eliminating VF induction testing would have resulted in a significantly lower positive predictive accuracy of 97.1% (P = .01). CONCLUSIONS: A single conversion success at 14 J on the first VF induction provides similar positive predictive accuracy as two successes at 17 J or 21 J. Using this criterion, 91% of patients meet implant criteria with a single induction of ventricular fibrillation.

Cardiac resynchronization therapy for congestive heart failure.

Cardiac resynchronization represents a novel therapeutic strategy for the treatment of congestive heart failure due to systolic dysfunction. Since its modest beginnings in the 1990s, cardiac resynchronization therapy has gained widespread acceptance as a useful adjunct to pharmacologic therapy for congestive heart failure. Randomized trials have consistently shown functional improvement in patients with congestive heart failure due to systolic dysfunction, a wide QRS complex on electrocardiogram and sinus rhythm, that are treated with cardiac resynchronization therapy. This review article will address the rationale, mechanisms of action, limitations and appropriate selection of patients for cardiac resynchronization therapy.