Erica S. Zado

Electroanatomic Substrate and Ablation Outcome for Suspected Epicardial Ventricular Tachycardia in Left Ventricular Nonischemic Cardiomyopathy

OBJECTIVES The aim of the study was to define the epicardial substrate and ablation outcome in patients with left ventricular nonischemic cardiomyopathy (NICM) and suspected epicardial ventricular tachycardia (VT). BACKGROUND Ventricular tachycardia in NICM often originates from the epicardium. METHODS Twenty-two patients with NICM underwent detailed endocardial and epicardial bipolar voltage maps and VT ablation for suspected epicardial VT. Eight patients with normal hearts and idiopathic VT served to define normal epicardial electrograms. Low-voltage regions were also assessed for wide (>80 ms), split, or late electrograms. RESULTS Normal epicardial bipolar voltage was identified as >1.0 mV on the basis of the reference population. Confluent low-voltage areas were present in 18 epicardial (82%) and 12 endocardial (54%) maps and were typically over basal lateral LV. In the 18 patients with epicardial VT on the basis of activation/pacemapping, the mean epicardial area was greater than the endocardial low-voltage area (55.3 +/- 33.5 cm(2) vs. 22.9 +/- 32.4 cm(2), p < 0.01). Epicardial low-voltage areas showed 49.7% wide (>80 ms), split, and/or late electrograms rarely seen in the reference patients (2.3%). During follow-up of 18 +/- 7 months, ablation resulted in VT elimination in 15 of 21 patients (71%) including 14 of 18 patients (78%) with epicardial VT. CONCLUSIONS In patients with NICM and VT of epicardial origin, the substrate is characterized by areas of basal LV epicardial > endocardial bipolar low voltage. The electrograms in these areas are not only small (<1.0 mV) but wide (>80 ms), split, and/or late, and help identify the substrate targeted for successful ablation.

Epicardial Substrate and Outcome With Epicardial Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

Background— Efficacy of endocardial ventricular tachycardia (VT) ablation in arrhythmogenic right ventricular cardiomyopathy/dysplasia may be limited by epicardial VT, right ventricular thickening, or both. We sought to characterize the endocardial versus epicardial substrate, measure right ventricular free wall thickness, and determine epicardial ablation efficacy in patients with right ventricular cardiomyopathy/dysplasia. Methods and Results— Thirteen consecutive patients (3 female; aged 43±15 years; range, 17 to 70 years) undergoing endocardial and epicardial sinus rhythm voltage mapping and epicardial VT ablation after failed endocardial VT ablation were included. In each patient, the low bipolar voltage area (<1.0 mV for epicardium and <1.5 mV for endocardium) was more extensive on the epicardium (95±47 versus 38±32 cm2; P<0.001) and was uniformly marked by multicomponent and late electrograms. The basal right ventricular thickness assessed by electroanatomic map was >10 mm in 6 of 13 patients compared with 5 to 10 mm in 4 reference patients without structural disease. Twenty-seven VTs were targeted on the epicardium with the use of activation, entrainment, or pace mapping with focal/linear ablation and targeting of late potentials. Epicardial VTs were targeted opposite normal endocardium in 10 patients (77%) and/or opposite ineffective endocardial ablation sites in 11 patients (85%). During 18±13 months, 10 of the 13 patients (77%) had no VT, with 2 patients having only a single VT at 2 and 38 months, respectively. Conclusions— Patients with right ventricular cardiomyopathy/dysplasia and VT after endocardial ablation have a more extensive epicardial area of electrogram abnormalities and frequently have basal right ventricular wall thickening. Epicardial substrate and VT mapping identifies targets, and ablation results in VT control.

Electroanatomic Substrate and Outcome of Catheter Ablative Therapy for Ventricular Tachycardia in Setting of Right Ventricular Cardiomyopathy

Background—To gain insight into the pathogenesis of right ventricular (RV) cardiomyopathy and ventricular tachycardia (VT), we determined the clinical and electroanatomic characteristics and outcome of ablative therapy in consecutive patients with (1) RV dilatation, (2) multiple left bundle-branch block (LBBB)–type VTs, and (3) an abnormal endocardial substrate defined by contiguous electrogram abnormalities. Methods and Results—All 21 patients had detailed RV bipolar electrogram voltage mapping. Eighteen patients had simultaneous left ventricular (LV) mapping, including all 4 patients with right bundle-branch block (RBBB) VT. VT was ablated in 19 patients by use of focal and/or linear lesions with irrigated-tip catheters in 10 of 19 patients. Eighteen patients were men, age 47±18 years, and none had a family history of RV dysplasia. RV volume was 223±89 cm3. Electrogram abnormalities extended from perivalvular tricuspid valves (5 patients), pulmonic valves (6 patients), or both valves (10 patients). Electrogram abnormalities always involved free wall, spared the apex, and included the septum in 15 patients (71%). The area of abnormality was 55±37 cm2 (range, 12 to 130 cm2) and represented 34±19% of the RV. In 52 of 66 LBBB VTs, the origin was from the RV perivalvular region. LV perivalvular low-voltage areas noted in 5 patients were associated with a RBBB VT origin. No VT recurred after ablation in 17 patients (89%) during 27±22 months. Conclusions—In patients with RV cardiomyopathy and VT, (1) perivalvular electrogram abnormalities represent the commonly identified substrate and source of most VT, (2) LV perivalvular endocardial electrogram abnormalities and VT can occasionally be identified, and (3) aggressive ablative therapy provides long-term VT control.

Efficacy of Repeat Pulmonary Vein Isolation Procedures in Patients with Recurrent Atrial Fibrillation

Introduction: Pulmonary vein (PV) isolation is effective in the treatment of most patients with atrial fibrillation (AF). Some advocate the addition of linear ablation techniques to improve efficacy; however, previous studies suggest recurrent PV conduction is responsible for AF recurrence. The aim of this study was to determine the effectiveness of repeat PV isolation in patients with recurrent AF after an initial ablation procedure and to determine if any patient characteristics predict failure of repeat PV isolation procedures.

The Risk of Thromboembolism and Need for Oral Anticoagulation After Successful Atrial Fibrillation Ablation

OBJECTIVES The aim of this multicenter study was to evaluate the safety of discontinuing oral anticoagulation therapy (OAT) after apparently successful pulmonary vein isolation. BACKGROUND Atrial fibrillation (AF) is associated with an increased risk of thromboembolic events (TE) and often requires OAT. Pulmonary vein isolation is considered an effective treatment for AF. METHODS We studied 3,355 patients, of whom 2,692 (79% male, mean age 57 +/- 11 years) discontinued OAT 3 to 6 months after ablation (Off-OAT group) and 663 (70% male, mean age 59 +/- 11 years) remained on OAT after this period (On-OAT group). CHADS(2) (congestive heart failure, hypertension, age [75 years and older], diabetes mellitus, and a history of stroke or transient ischemic attack) risk scores of 1 and > or =2 were recorded in 723 (27%) and 347 (13%) Off-OAT group patients and in 261 (39%) and 247 (37%) On-OAT group patients, respectively. RESULTS During follow-up (mean 28 +/- 13 months vs. 24 +/- 15 months), 2 (0.07%) Off-OAT group patients and 3 (0.45%) On-OAT group patients had an ischemic stroke (p = 0.06). No other thromboembolic events occurred. No Off-OAT group patient with a CHADS(2) risk score of > or =2 had an ischemic stroke. A major hemorrhage was observed in 1 (0.04%) Off-OAT group patient and 13 (2%) On-OAT group patients (p < 0.0001). CONCLUSIONS In this nonrandomized study, the risk-benefit ratio favored the suspension of OAT after successful AF ablation even in patients at moderate-high risk of TE. This conclusion needs to be confirmed by future large randomized trials.

Incidence and location of focal atrial fibrillation triggers in patients undergoing repeat pulmonary vein isolation: implications for ablation strategies.

Introduction: The etiology of atrial fibrillation (AF) recurrences after pulmonary vein (PV) isolation is not well described. The aim of this study was to examine the reason for recurrent AF in patients undergoing a repeat attempt at AF trigger ablation.

Long-Term Outcome After Successful Catheter Ablation of Atrial Fibrillation

Background—Pulmonary vein isolation (PVI) is increasingly used for treatment of atrial fibrillation (AF), but few reports exist regarding long-term success. We determined 5-year outcomes of PVI among patients with freedom from AF off antiarrhythmic drugs (AAD) for 1 year after PVI. Methods and Results—Consecutive patients with paroxysmal or persistent AF who underwent PVI at the University of Pennsylvania from 2000 to 2003 and were free from AF 1 year after ablation were included. Proximal isolation of PVs and non-PV triggers of AF was performed. Long-term ablation success, defined as freedom from AF off AAD after a single ablation procedure, was determined. All patients had transtelephonic monitoring at 3 to 6 months and 12 months and at least yearly contact thereafter. One hundred twenty-three patients were free of AF without AAD at 1 year. AF freedom off AAD was 85% at 3 years and 71% at 5 years, with an approximate 7% per year late recurrence rate after the first year. Patients with recurrent AF ≥5 years after index PVI were older, had larger left atrial size, more AF triggers and more likely had persistent AF. In multivariate analysis, persistent AF (odds ratio, 2.8; 95% confidence interval, 1.4 to 5.7, P=0.005) and age (odds ratio, 1.1; 95% confidence interval, 1.0 to 1.1, P=0.036) independently predicted long-term AF recurrence. Conclusions—Among patients with paroxysmal or persistent AF and AF freedom 1 year after segmental PVI, the majority (71%) remained free of AF for up to 5 years, with an approximate late recurrence rate of 7% per year. Continued vigilance for recurrent AF after PV isolation is warranted, particularly in patients with persistent AF.

Utility of Exit Block for Identifying Electrical Isolation of the Pulmonary Veins

Pulmonary Vein Exit Block. Introduction: Electrical isolation of the pulmonary veins (PVs) to treat paroxysmal atrial fibrillation (AF) has been described using “entry block” as an endpoint for PV isolation. We describe a new technique for guiding PV isolation, using “exit block” out of the PV after ablation as a criterion for successful isolation.

Endocardial unipolar voltage mapping to identify epicardial substrate in arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND The risk and success of epicardial substrate ablation for ventricular tachycardia (VT) support the value of techniques identifying the epicardial substrate with endocardial mapping. OBJECTIVE The purpose of this study was to test the hypothesis that endocardial unipolar voltage mapping in patients with right ventricular (RV) VT and preserved endocardial bipolar voltage abnormalities might identify the extent of epicardial bipolar voltage abnormality. METHODS Using a cutoff of < 5.5 mV for normal endocardial unipolar voltage derived from 8 control patients without structural heart disease, 10 patients with known ARVC/D (group 1, retrospective) and 13 patients with RV VT (group 2, prospective) with modest or no endocardial bipolar voltage abnormalities underwent detailed endocardial and epicardial mapping. RESULTS The area of epicardial unipolar voltage abnormality in all 10 group 1 patients with ARVC/D (62 ± 21 cm²) and in 9 of the 13 group 2 patients (8 with criteria for ARVC/D) (53 ± 21 cm²) was on average three times more extensive than the endocardial bipolar abnormality and correlated (r = 0.63, P <.05 and r = 0.81, P <.008, respectively) with the larger area epicardial bipolar abnormality with respect to size (group 1: 82 ± 22 cm²; group 2: 68 ± 41 cm²) and location. In the remaining 4 group 2 patients and 3 additional reference patients without structural heart disease, endocardial bipolar, endocardial unipolar, and, as predicted, epicardial bipolar voltage all were normal. CONCLUSION Endocardial unipolar mapping with cutoff of 5.5 mV identifies more extensive areas of epicardial bipolar signal abnormalities in patients with ARVC/D and limited endocardial VT substrate.

Long‐Term Clinical Efficacy and Risk of Catheter Ablation for Atrial Fibrillation in the Elderly

Introduction: The number of elderly patients with atrial fibrillation (AF) is increasing rapidly, and the safety and efficacy of catheter ablation in this demographic group has not been established.