Introduction: Surgical left atrial appendage exclusion (LAA-Ex) is often performed to eliminate the need for long-term anticoagulation either as a stand-alone or concomitant procedure during cardiac surgery. A modified MAZE procedure is also usually performed during surgical LAA-Ex. Residual arrhythmogenic foci within the LAAA and/or zones of slow conduction along the stump of the LAA may contribute to recurrent atrial tachycardias (AT) after LAA-Ex. The purpose of this study was to determine the role of the LAA in recurrent atrial tachycardias (ATs) after surgical LAA-Ex. Methods: Catheter ablation (CA) was performed to eliminate ATs in 21 patients with history of AF (persistent in 18/21, 86%) 25±26 months after surgical LAA-Ex. There were 3 women; mean age was 66±9 years; and the left atrial diameter was 54±8 mms. A concomitant MAZE procedure and CA was performed previously, in 16 and 9 patients, respectively. Two patients had neither maze nor catheter ablation. There was residual blood flow into the LAA in 1/21 patient. Results: A reentrant AT involving the stump of the LAA was identified in 5/21 (24%) patients. Focal ablation on a critical isthmus within a zone of slow conduction along the LAA stump terminated AT in 3/5 patients. In the remaining 2 patients a linear lesion set from the stump to an existing line of block (left atrial roof line and anterior mitral annulus) terminated the macroreentrant AT revolving around the LAA stump. During 16±13 months of follow-up 10/21 patients (48%) remained free from recurrent ATs without antiarrhythmic drug therapy. A repeat ablation was performed in 3 patients, the mechanism of the AT was epicardial, perimitral, and multifocal but did not involve the LAA. Conclusions: After surgical LAA-Ex recurrent ATs are not uncommon and can involve the LAA stump, Although these ATs can be successfully identified and ablated, other ATs may recur and prompt additional antiarrhythmic or ablative therapy.

BACKGROUND:Electrical isolation of the left atrial appendage (LAA) improves outcomes of patients with persistent atrial fibrillation (AF) but may increase the risk of thromboembolism. OBJECTIVE:The purpose of this study was to describe a method to map and ablate appendage drivers without complete electrical isolation. METHODS:One hundred thirteen patients underwent an ablation procedure for persistent AF. The procedure was performed during AF and consisted of pulmonary vein and posterior LA isolation as well as ablation of the LAA. The right atrium (RA) was targeted in patients with a right-to-left gradient in cycle length (CL). The end point of appendage ablation was CL slowing or AF termination but not complete isolation. RESULTS:Among the 113 patients (mean age 64.6 ± 8.6 years; ejection fraction 54% ± 13%; LA diameter 46 ± 6.5 mm), radiofrequency ablation terminated AF in 51 patients (45%). RA ablation was performed in 41 patients (36%) at the index or repeat procedure. The mean AF CL in the RA appendage (RAA) was shorter than that in the LAA (160 ± 32 ms vs 186 ± 29 ms; P < .01) in these patients. The most frequent target in the RA was the RAA (CLs approaching 50-60 ms). Discontinuing radiofrequency ablation upon AF termination or conduction slowing prevented LAA isolation. After a mean follow-up of 24 ± 15 months, 89 patients (78%) remained arrhythmia-free without antiarrhythmic medications. CONCLUSION:An ablation strategy guided by the AF CL addresses LAA drivers without complete electrical isolation and also helps identify the RAA as a source of persistent AF.

Background: Diabetes mellitus (DM) and glycemic control are risk factors for atrial fibrillation (AF). Metformin may have antifibrillatory properties by altering atrial metabolism. It is unknown whether metformin has favorable effects on the outcomes of catheter ablation (CA) for AF. Objective: To determine whether metformin use is associated with maintenance of sinus rhythm after CA for AF. Methods and Results: A 1 st CA was performed in 271 consecutive patients with DM and AF (age: 65±9 years, women: 34 %; and paroxysmal AF: 50%). A total of 182 (67%) patients were treated with metformin and 79/182 were also receiving other antidiabetics or insulin. HbA1c and preprocedural fasting blood glucose were similar among the patients treated with and without metformin (7.2±1.4% vs. 7.2±1.3%, P=0.95 and 162± 61 vs. 159±66 mg/dL, P=0.72). At a median of 10 months (IQR: 5-23, mean 15±13 months) after CA, 100/182 patients (55%) on metformin remained in sinus rhythm without concomitant antiarrhythmic drugs (AAD) compared to 36/89 patients (40%) not receiving metformin (P=0.03). On K-M analysis, patients on metformin were more likely to stay in sinus rhythm after CA, with or without AADs (P<0.001, log-rank, Figure). On Cox proportional hazards analysis, adjusted for age, gender, BMI, type of AF(paroxysmal vs. non-paroxysmal), fasting blood glucose, AAD use, obstructive sleep apnea, chronic kidney disease, and left atrial diameter, metformin use was associated with a ~35% lower probability of recurrent atrial arrhythmia(HR: 0.65, ±95% CI: 0.44-0.97, P=0.04). Increase in left atrial diameter (per mm, HR: 1.05, ±95% CI:1.01-1.08, P=0.001) and non-paroxysmal AF (HR: 1.9, ±95% CI: 1.3-2.9, P=0.001) were associated with a higher risk of recurrence after CA of AF. Conclusion: In patients with DM, the use of metformin was associated with a significant reduction in recurrent atrial arrhythmias after CA for AF independent of the other risk factors, including preprocedural glycemic control.

Background Implanted defibrillators are capable of recording activity data based on company-specific proprietary algorithms. This study aimed to determine the prognostic significance of baseline and decline in device-derived activity level across different device companies in the real world. Methods We performed a retrospective cohort study of patients (n = 280) who underwent a defibrillator implantation (Boston, Medtronic, St. Jude, and Biotronik) for primary prevention at the University of Michigan from 2014 to 2016. Graphical data obtained from device interrogations were retrospectively converted to numerical data. The activity level averaged over a month from a week postimplantation was used as baseline. Subsequent weekly average activity levels (SALs) were standardized to this baseline. SAL below 59.4% was used as a threshold to group patients. All-cause mortality and death/heart failure were the primary end-points of this study. Results Fifty-six patients died in this study. On average, they experienced a 50% decline in SAL prior to death. Patients (n = 129) who dropped their SAL below threshold were more likely to be older, male, diabetic, and have more symptomatic heart failure. They also had a significantly increased risk of heart failure/death (hazard ratio [HR] 3.6, 95% confidence interval [95% CI] 2.3-5.8,P < .0001) or death (HR 4.2, 95% CI 2.2-7.7,P < .0001) compared to those who had sustained activity levels. Lower baseline activity level was also associated with significantly increased risk of heart failure/death and death. Conclusion Significant decline in device-derived activity level and low baseline activity level are associated with increased mortality and heart failure in patients with an ICD for primary prevention.

It is not clear whether maintenance of sinus rhythm after catheter ablation (CA) of atrial fibrillation (AF) is associated with an improvement in activity levels and exercise tolerance and a subsequent decrease in body weight. We included 987 patients (mean age=61±10 years) with paroxysmal (n=605

BACKGROUND The role of cryoballoon ablation (CBA) for antral pulmonary vein isolation (APVI) has not been well established in persistent atrial fibrillation (PerAF). Isolation of the left atrial posterior wall (BOX) after APVI has been suggested to improve the efficacy of radiofrequency catheter ablation (RFA) in PerAF. OBJECTIVE The purpose of this study was to compare characteristics and clinical outcomes of APVI by CBA vs APVI 1 BOX by contact force-guided RFA (CF-RFA) in patients with PerAF. METHODS APVI was performed in 167 consecutive patients with PerAF (mean age 64 +/- 9 years; left atrial diameter 46 +/- 6 mm) using CBA (n = 90) or CF-RFA (n = 77). After APVI, a roofline was created in 33 of 90 patients (37%) in the CBA group and BOX was performed in all 77 patients in the CF-RFA group. RESULTS During 21 +/- 10 months of follow-up after a single ablation procedure, 37 of 90 patients (41%) in the CBA group (APVI) and 39 of 77 (51%) in the CF-RFA group (APVI + BOX) remained in sinus rhythm without antiarrhythmic drugs (AADs) (P = .22). During repeat ablation, APVI + BOX using CF-RFA was performed in 20 of 90 patients (22%) and in 18 of 77 patients (23%) who initially underwent CBA or CF-RFA, respectively. At 19 +/- 10 months after repeat ablation, sinus rhythm was maintained in 55 of 90 patients (61%) and 52 of 77 patients (68%) in the CBA and CF-RFA groups without AADs, respectively (P = .39). CONCLUSION In PerAF, an initial approach of APVI by CBA or APVI + BOX by CF-RFA has a similar efficacy of 40%-50% without AADs. After repeat ablation for APVI + BOX by CF-RFA in similar to 25%, sinus rhythm is maintained in 60%-70% of patients without AADs.

BACKGROUND The role of the ligament of Marshall (LOM) in patients with atrial fibrillation (AF) has not been well defined. OBJECTIVE The purpose of this study was to describe the role of the LOM in patients with AF and related arrhythmias. METHODS Fifty-six patients (mean age 63+/-11 years; persistent AF in 48 [86%]; ejection fraction 0.49 +/- 0.13; left atrial diameter 4.7 +/- 0.6 cm) with LOM-mediated arrhythmias were included. RESULTS A LOM-pulmonary vein (PV) connection was present in 18 patients (32%) and was eliminated with radiofrequency (RF) ablation at the left lateral ridge or crux (n=12), at the mitral annulus (n=3), or with alcohol/ethanol (EtOH) ablation of the vein of Marshall (VOM; n=3). A LOM-mediated atrial tachycardia (AT) was present in 13 patients (23%). Thirty-one patients with refractory mitral isthmus conduction were referred for potential EtOH ablation. In the+/-patients in whom VOM was injected during perimitral reentry, EtOH resulted in slowing in 3 patients and termination in 1 patient. In others, EtOH infusion resulted in complete isolation of the left-sided PVs and left atrial appendage. Repeat RF and adjunctive EtOH ablation of the VOM tended to be more effective in creating conduction block across the mitral isthmus than RF ablation alone (P = .057). CONCLUSION The LOM is responsible for a variety of arrhythmia mechanisms in patients with AF and atrial tachycardia. It may be ablated at any point along its course, at the mitral annulus, at the lateral ridge/PV antrum, and epicardially in the coronary sinus and the VOM itself. EtOH ablation of the VOM may be an adjunctive strategy in patients with refractory perimitral reentry.

### Learning objectives Atrial fibrillation (AF) is the most common cardiac arrhythmia and the incidence and prevalence of this disease are rising.1 2 It is estimated that by the year 2050 there will be over 7.5 million patients with AF in the USA alone.3 This disease carries a significant risk of morbidity and mortality driven in large part by the development of heart failure and thromboembolism.4 Oral anticoagulation therapy is effective in reducing risk of stroke and systemic embolism and is the standard of care for patients undergoing either a rhythm or rate control strategy. For years warfarin has been the mainstay of stroke prophylaxis. More recently, direct-acting oral anticoagulants (DOACs) have entered the marketplace.5 Their site of action within the coagulation cascade is outlined in figure 1.6 7 These newer agents have rapidly been incorporated into modern practice,8 though there remains a role for warfarin among various subgroups. Selecting an appropriate agent is a complex decision and must take account a patient’s comorbidities, preference for dosing and monitoring, concern over the lack of a specific antidote, and importantly, financial constraints. Figure 1 Overview of the coagulation system and sites of action of novel oral anticoagulants. The extrinsic pathway is activated by the exposure of tissue factor-expressing cells to blood through vascular injury. The intrinsic pathway is activated by the binding of factor IXa to factor VIIIA on anionic cell surfaces to form the intrinsic tenase complex. Activated platelets provide binding sites for this interaction. These processes then proceed through a common pathway ultimately resulting in activated …

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BACKGROUND:Adenosine can reveal dormant pulmonary vein (PV) conduction after PV isolation (PVI) in patients with paroxysmal atrial fibrillation (AF). However, the impact of elimination of adenosine-provoked dormant PV conduction after PVI has not been formally evaluated.OBJECTIVE:The purpose of this study was to determine whether ablation of PV reconnections unmasked by adenosine improves outcomes.METHODS:Patients with paroxysmal AF (n = 129) were randomized to receive either adenosine (n = 61) or no adenosine (n = 68) after PVI. Dormant conduction revealed by adenosine after PVI was ablated until all adenosine-mediated reconnections were eliminated. Thereafter, both groups received isoproterenol.RESULTS:Acute reconnection was seen in 23 patients (37%) in the adenosine group. There was a significant difference between the number of PVs reconnected if patients were given adenosine >60 minutes after initial PVI compared to those who received adenosine <60 minutes after initial PVI (3/32 [9.4%] vs 24/32 [75%], P <.0001). Patients who did not receive adenosine had more PV reconnections after isoproterenol infusion compared to patients in the adenosine group (17/68 [25.0%] vs 5/61 [8.2%], P = .018). There was no difference in the rate of AF recurrence in patients who received adenosine (24/61 [39%]) compared to control patients (23/68 [34%], log-rank P = .83).CONCLUSION:Adenosine can reveal dormant conduction in more than one-third of patients with paroxysmal AF undergoing PVI. However, adenosine administration, and additional ablation of the resultant connections, does not improve long-term outcomes compared to a protocol that includes isoproterenol infusion.

Atrial tachycardia (AT) may be encountered in a variety of settings in the electrophysiology laboratory. It constitutes a differential diagnosis in patients presenting for an electrophysiological evaluation and ablation for paroxysmal supraventricular tachycardia.1 These patients typically do not have any evidence of structural heart disease. Patients may also present with AT in setting of an atrial myopathic process, related to acquired (eg, rheumatic heart disease) or congenital heart disease,2 cardiac surgery, or an idiopathic process. Finally, patients with atrial fibrillation (AF), especially the persistent variety, often require repeat procedures for organized ATs.3 Although the prevalence of precise arrhythmia mechanism differs in these contexts, broadly speaking, there are 2 possibilities: focal activation and macroreentry. Focal arrhythmias may be further characterized as being caused by abnormal automaticity, triggered activity, or microreentry/localized reentry. See Article by Liu et al Defining the operative mechanism is important because it helps tailor the ablation approach. For example, targeting the site of origin of a focal AT should be sufficient in preventing recurrence. In contradistinction, the end point during a procedure for macroreentrant tachycardia includes not only arrhythmia termination during radiofrequency energy delivery, but also demonstration of linear block. Lerman et al have previously explored these various possibilities and found that adenosine infusion helped distinguish between the various mechanisms responsible for AT in patients.4,5 In this issue of the Journal, Dr Lerman and his colleagues present their experience with adenosine in delineating the mechanism of AT in a large series of patients.6 Among the 59 patients, approximately one third had undergone a prior procedure for either AF or AT. The criteria for macroreentry included accounting for >90% of the tachycardia cycle length (CL) and documenting intersection of early and late areas on 3-dimensional (3D) mapping. A focal mechanism was diagnosed …

Introduction: Home telemetry monitoring with accurate automated rhythm classification can have important clinical benefits in the timely diagnosis and appropriate management of patients with atrial fibrillation (AF). We clinically validated a novel personal e-Health device and algorithm developed to distinguish AF from sinus rhythm (SR). Methods: A handheld electrocardiogram (ECG) recording system (Maestro) and signal processing platform were developed. The Maestro provides an LCD interface that continuously shows an ECG, heart rate, and heart rhythm status. Twenty second ECG signals analogous to Lead I were acquired from 66 patients presenting to the arrhythmia clinic at the University of Michigan Hospital either in SR or AF. Electrograms were segmented into non-overlapping 6-second samples and one random segment per patient was selected for analysis by the Maestro system. Simultaneous 5 or 12 lead ECGs were obtained from these patients and 3 expert physicians blinded to the Maestro analysis identified the rhythm as SR or AF. The Maestro system applied several signal conditioning algorithms to each ECG sample. The dimensionless temporal R-R interval variability (VRR) index and spectral frequency dispersion metric (FDM) were computed. Results: The 2-dimensional scatter-gram of the samples demonstrated 2 distinct clusters of VRR and FDM for patients with SR and AF. The VRR index clusters for SR and AF patients were 0.018 ± 0.013 and 0.187 ± 0.073 (mean±std), respectively (p < 0.001). The FDM clusters for SR and AF patients occurred at 10.5 ± 5.916 and 15.892 ± 3.337, respectively (p < 0.001). We developed a Gaussian Mixed Model (GMM) classifier to distinguish between the AF and SR clusters. Only after the GMM classifier was obtained were the Maestro classifications compared to the physicians’ readings. The algorithm correctly categorized AF (N = 46) and SR (N = 20) for all Maestro segments analyzed with 100% specificity and sensitivity. Conclusion: The Maestro handheld telemetry unit utilizes a novel classification algorithm and was demonstrated to acquire and automatically analyze 6-second electrograms for rapid and accurate classification of patients in SR or AF in this initial clinical validation trial.

Background— Ventricular arrhythmias have been described to originate from intramural locations. Intramural scar can be assessed by delayed-enhanced MRI, but MRIs cannot be performed on every patient. The objective of this study was to assess the value of voltage mapping to detect MRI-defined intramural scar and to correlate the scar with ventricular arrhythmias. Methods and Results— In 15 consecutive patients (3 women; age 55±16 years; ejection fraction, 49±13%) with structural heart disease, intramural scar was detected by delayed-enhanced MRI. All patients underwent endocardial unipolar and bipolar voltage mapping guided by the registered intramural scar. Scar volume by MRI was 11.7±8 cm 3 with a scar thickness of 4.6±0.7 mm and a preserved endocardial/epicardial rim of 3.3±1.6 and 4.8±2.6 mm, respectively. Endocardial bipolar voltage was 1.6±1.73 mV at the scar, 2.12±2.15 mV in a 1 cm perimeter around the scar, and 2.83±3.39 mV in remote myocardium without scar. The corresponding unipolar voltage was 4.94±3.25, 6.59±3.81, and 8.32±3.39 mV, respectively ( P <0.0001). Using receiver–operator characteristic curves, a unipolar cut-off value of 6.78 mV (area under the curve, 0.78) and a bipolar cut-off value of 1.55 mV (area under the curve, 0.69) best separated endocardial measurements overlying scar as compared with areas not overlying a scar. At least 1 intramural ventricular arrhythmia was eliminated in all but 2 patients in this series. Conclusions— Intramural scar can be detected by unipolar and bipolar voltage, unipolar voltage being more useful. Mapping and ablation of intramural arrhythmias originating from an intramural focus can be accomplished.

BACKGROUND Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of cardiomyopathy. In this study, the determinants of PVC-induced left ventricular (LV) dysfunction were assessed.METHODS The subjects of this study were 241 consecutive patients (115 men [48%], mean age 48 +/- 14 years) referred for ablation of frequent PVCs. One hundred eighty patients (75%) experienced palpitations and 61 (25%) did not. The PVC burden was determined by 24-hour Holter monitoring, and echocardiograms were performed to assess LV function. An LV ejection fraction of <50% was considered abnormal.RESULTS LV ejection fraction (mean 0.36 +/- 0.09) was present in 76 of 241 patients (32%). There was a higher prevalence of males among the patients with PVC cardiomyopathy compared to patients with normal LV function (51/76 [67%] vs 64/165 [39%]; P <.0001). The mean PVC burden was significantly higher in patients with PVC cardiomyopathy than in patients with normal LV function (28% +/- 12% vs 15% +/- 13%; P < .0001). Among symptomatic patients, those with cardiomyopathy had a significantly longer duration of palpitations (135 +/- 118 months) compared with patients with normal LV function (35 +/- 52 months; P <.0001). The proportion of asymptomatic patients was significantly higher in the presence of cardiomyopathy (36/76, 47%) than in normal LV function (25/165, 15%; P <.0001). Symptom duration of 30 to 60 months, symptom duration >60 months, the absence of symptoms, and the PVC burden in asymptomatic patients were independent predictors of impaired LV function (adjusted odds ratio [95% confidence interval]: 4.0 [1.1-14.4], 20.1 [6.3-64.1], 13.1 [4.1-37.8], and 2.1 [1.2-3.6], respectively).CONCLUSIONS The duration of palpitations and the absence of symptoms are independently associated with PVC-induced cardiomyopathy.

A 58-year-old man underwent pulmonary vein isolation for paroxysmal atrial fibrillation. At the end of the procedure, the pulmonary veins were inspected for reconnection. The origin of a potential on the ring catheter placed in the right superior pulmonary vein is discussed.

A 56-year-old man with 3 prior left atrial ablations for atrial fibrillation was referred for ablation for recurrent paroxysmal atrial fibrillation. A spontaneous premature atrial depolarization occurred when the ring catheter was positioned in the left inferior pulmonary vein and a decapolar catheter was in the coronary sinus. Caution should be used with further ablation.