Joshua M Cooper

Publications (56)382.4 Total impact

• Article: Assessing Arrhythmia Burden After Catheter Ablation of Atrial Fibrillation Using an Implantable Loop Recorder: The ABACUS Study.

  Suraj Kapa, Andrew E Epstein, David J Callans, Fermin C Garcia, David Lin, Rupa Bala, Michael P Riley, Mathew D Hutchinson, Edward P Gerstenfeld, Wendy Tzou, Francis E Marchlinski, David Frankel, Joshua M Cooper, Gregory Supple, Rajat Deo, Ralph J Verdino, Vickas V Patel, Sanjay Dixit
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  ABSTRACT: INTRODUCTION: Arrhythmia monitoring in patients undergoing atrial fibrillation (AF) ablation is challenging. Transtelephonic monitors (TTMs) are cumbersome to use and provide limited temporal assessment. Implantable loop recorders (ILRs) may overcome these limitations. We sought to evaluate the utility of ILRs versus conventional monitoring (CM) in patients undergoing AF ablation. METHODS AND RESULTS: Forty-four patients undergoing AF ablation received ILRs and CM (30-day TTM at discharge and months 5 and 11 postablation). Over the initial 6 months, clinical decisions were made based on CM. Subjects were then randomized for the remaining 6 months to arrhythmia assessment and management by ILR versus CM. The primary endpoint was arrhythmia recurrence. The secondary endpoint was actionable clinical events (change of antiarrhythmic drugs [AADs], anticoagulation, non-AF arrhythmia events, etc.) due to either monitoring strategy. Over the study period, 6 patients withdrew. In the first 6 months, AF recurred in 18 patients (7 noted by CM, 18 by ILR; P = 0.002). Five patients in the CM (28%) and 5 in the ILR arm (25%; P = NS) had AF recurrence during the latter 6 months. AF was falsely diagnosed frequently by ILR (730 of 1,421 episodes; 51%). In more patients in the ILR compared with the CM arm, rate control agents (60% vs 39%, P = 0.02) and AADs (71% vs 44%, P = 0.04) were discontinued. CONCLUSION: In AF ablation patients, ILR can detect more arrhythmias than CM. However, false detection remains a challenge. With adequate oversight, ILRs may be useful in monitoring these patients after ablation.
  Journal of Cardiovascular Electrophysiology 03/2013; · 3.06 Impact Factor
• Article: Sequential Dual Chamber Extrastimulation Provides Clue to Supraventricular Tachycardia Mechanism.

  David S Frankel, Joshua M Cooper
  Journal of Cardiovascular Electrophysiology 01/2013; · 3.06 Impact Factor
• Article: Apical Ventricular Tachycardia Morphology in Left Ventricular Non-Ischemic Cardiomyopathy Predicts Poor Transplant-Free Survival.

  David S Frankel, Cory M Tschabrunn, Joshua M Cooper, Sanjay Dixit, Edward P Gerstenfeld, Michael P Riley, David J Callans, Francis E Marchlinski
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  ABSTRACT: BACKGROUND: The scar of patients withleft ventricular (LV) non-ischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) typically originates at or near the mitral annulus and extends a variable distance towards the apex. OBJECTIVES: To determine whether electrocardiograms (ECG) of VT with LV apical exit sites would identify patients with larger scars, extending a greater distance from the base towards the apex and decreased heart transplant/left ventricular assist device (LVAD)-free survival. METHODS: Consecutive patients with LVNICM undergoing VT ablation between May 2008 and April 2011 were studied. All ECGs of spontaneous and induced VT were analyzed. Apical VT was defined as left bundle branch morphology with precordial transition ≥V5 or right bundle branch morphology with precordial transition ≤V3. Scar percentage was defined as the area of low voltage divided by total surface area. RESULTS: Thirty-twoof 76 total patients had one or more apical VTs. Those with apical VTs had larger percentage endocardial and epicardial bipolar scars (14.9% vs 8.1%, p=0.01 and 15.5% vs 5.5%, p=0.03, respectively), scar that although originating from the periannular region (94.7% of patients) was more likely to extend apically beyond the basal half (48.3% vs 24.4%, p=0.05 endocardial and 85.7% vs 25.9%, p=0.07 epicardial), and worse transplant/LVAD-free survival during 332 days mean follow-up (p=0.006). CONCLUSIONS: Patients with NICM and apical VTs have larger voltage abnormality extending as contiguous or patchy "scar" from the base further towards the apex, and worse transplant/LVAD-free survival. Particular attention should be paid to optimal heart failure management in these patients, with more guarded prognosis.
  Heart rhythm: the official journal of the Heart Rhythm Society 12/2012; · 4.56 Impact Factor
• Article: Efforts to Enhance Catheter Stability Improve Atrial Fibrillation Ablation Outcome.

  Mathew D Hutchinson, Fermin C Garcia, Jeff E Mandel, Nabil Elkassabany, Erica S Zado, Michael P Riley, Joshua M Cooper, Rupa Bala, David S Frankel, David Lin, Gregory E Supple, Sanjay Dixit, Edward P Gerstenfeld, David J Callans, Francis E Marchlinski
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  ABSTRACT: BACKGROUND: Contemporary techniques to enhance anatomical detail and catheter contact during atrial fibrillation ablation include: 1) the integration of pre-acquired tomographic reconstructions with electroanatomical mapping (I-EAM); 2) the use streerable introducers (SI); and 3) high frequency jet ventilation (HFJV). OBJECTIVE: We hypothesized that using these stabilizing techniques during AF ablation would improve 1-year procedural outcome. METHODS: We studied 300 patients undergoing AF ablation at our institution. Patients were assigned to three equal treatment groups (100 patients each) based upon the tools utilized: 1) Group 1- AF ablation performed without I-EAM, SI or HFJV; 2) Group 2- AF ablation performed using I-EAM and SI, but without HFJV; and 3) Group 3- AF ablation performed with I-EAM, SI, and HFJV. The primary outcome was freedom from AF 1-year after a single ablation procedure. The burden of both acute and chronic PV reconnection was also assessed. RESULTS: Patients from Groups 2 and 3 had significantly more non-paroxysmal AF (17% vs. 30% vs. 39%, p=0.002), larger left atria (4.2±0.8 vs. 4.4±0.7 vs. 4.5±0.8 cm, p<0.001), and higher BMI (28.5±5.8 vs. 29.1±4.8 vs. 31.2±5.4, p<0.001). Despite these differences, with adoption of I-EAM, SI, and HFJV we noted a significant improvement in 1-year freedom from AF (52% vs. 66% vs. 74%; p=0.006) as well as fewer acute (1.1±1.2 vs. 0.9±1.1 vs. 0.6±0.9, p=0.03) and chronic (3.5±0.9 vs. 3.2±0.9 vs. 2.4±1.0, p=0.02) PV reconnections. CONCLUSIONS: The incorporation of contemporary tools to enhance anatomical detail and ablation catheter stability significantly improved 1-year freedom from AF after ablation.
  Heart rhythm: the official journal of the Heart Rhythm Society 11/2012; · 4.56 Impact Factor
• Article: New Unipolar Electrogram Criteria to Identify Irreversibility of Nonischemic Left Ventricular Cardiomyopathy.

  Bieito Campos, Miguel E Jauregui, Kyoung-Min Park, Stavros E Mountantonakis, Edward P Gerstenfeld, Haris Haqqani, Fermin C Garcia, Mathew D Hutchinson, David J Callans, Sanjay Dixit, David Lin, Michael P Riley, Wendy Tzou, Joshua M Cooper, Rupa Bala, Erica S Zado, Francis E Marchlinski
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  ABSTRACT: OBJECTIVES: This study sought to assess the value of left ventricular (LV) endocardial unipolar electroanatomical mapping (EAM) in identifying irreversibility of LV systolic dysfunction in patients with left ventricular nonischemic cardiomyopathy (LVCM). BACKGROUND: Identifying irreversibility of LVCM would be helpful but cannot be reliably accomplished by bipolar EAM or cardiac magnetic resonance identification of macroscopic scar. METHODS: Detailed endocardial LV EAM was performed in 3 groups: 1) 24 patients with irreversible LVCM (I-LVCM) but with no or minimal macroscopic scar (<15% LV surface) evidenced on bipolar voltage EAM and/or cardiac magnetic resonance; 2) 14 patients with reversible ventricular premature depolarization-mediated LVCM (R-LVCM); and 3) 17 patients with structurally normal hearts. LV endocardial unipolar electrogram amplitude and area of unipolar amplitude abnormality were defined after excluding macroscopic scar. RESULTS: Unipolar amplitude differed in the 3 groups: median of 7.6 (interquartile range [IQR]: 5.5 to 9.7) mV in I-LVCM group, 13.2 (IQR: 10.4 to 16.2) mV in R-LVCM group, and 16.3 (IQR: 13.6 to 19.8) mV in structurally normal hearts group (p < 0.001). Areas of unipolar abnormality represented a large proportion of total LV surface in I-LVCM, 64.7% (IQR: 47.5% to 75.9%) compared with R-LVCM, 5.2% (IQR: 0.0% to 19.1%) and structurally normal hearts, 0.1% (IQR: 0.0% to 0.9%), groups (p < 0.001). A unipolar abnormality area cutoff of 32% of total LV surface was 96% sensitive and 100% specific in identifying irreversible cardiomyopathy among patients with LV dysfunction (I-LVCM and R-LVCM), p < 0.001. CONCLUSIONS: Detailed unipolar voltage mapping can identify irreversible myocardial dysfunction consistent with fibrosis, even in the absence of bipolar EAM or cardiac magnetic resonance abnormalities, and may serve as valuable prognostic tool in patients presenting with LVCM to facilitate clinical decision making.
  Journal of the American College of Cardiology 10/2012; · 14.16 Impact Factor
• Article: Percutaneous Epicardial Ventricular Tachycardia Ablation After Non-Coronary Cardiac Surgery or Pericarditis.

  Cory M Tschabrunn, Haris M Haqqani, Joshua M Cooper, Sanjay Dixit, Fermin C Garcia, Edward P Gerstenfeld, David J Callans, Erica S Zado, Francis E Marchlinski
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  ABSTRACT: BACKGROUND: Patients with previous non-coronary cardiac surgery or pericarditis may require epicardial access to facilitate successful VT ablation. Percutaneous pericardial access is known to be difficult in these patients due to the presence of pericardial adhesions. OBJECTIVE: To examine the success and safety of percutaneous pericardial access as well as the ability to map and ablate epicardial VT targets. METHODS: We studied ten consecutive patients with prior non-coronary cardiac surgery (8 patients) or prior pericarditis (2 patients) who required epicardial access for VT ablation. RESULTS: Percutaneous pericardial access was achieved by experienced operators and dense adhesions interfering with catheter mapping were encountered in all patients. Using blunt dissection with a deflected ablation catheter adhesions were divided over the course of 19-125 minutes (mean 57±38min, median 47min). This dissection allowed for sufficient epicardial mapping in 9/10 patients (90%). The clinical targeted VTs were rendered non-inducible in 8 (80%) patients. One patient had 70cc of bleeding with initial puncture. No other complications occurred. During long-term follow-up of 24±27 months (median 13 months), 5 patients have remained VT free. CONCLUSION: Percutaneous pericardial access for epicardial VT ablation in patients with previous non-coronary cardiac surgery or pericarditis can usually be obtained. However, dense pericardial adhesions are often encountered and may limit the ability to map the entire epicardial space. Typically, appropriate targets can be reached and ablated by disrupting the adhesions with the ablation catheter and/or deflectable sheath facilitating excellent long-term clinical outcome in half of the patients with no major complications.
  Heart rhythm: the official journal of the Heart Rhythm Society 10/2012; · 4.56 Impact Factor
• Article: Predictors of recovery of left ventricular dysfunction after ablation of frequent ventricular premature depolarizations.

  Marc W Deyell, Kyoung-Min Park, Yuchi Han, David S Frankel, Sanjay Dixit, Joshua M Cooper, Mathew D Hutchinson, David Lin, Fermin Garcia, Rupa Bala, Michael P Riley, Edward Gerstenfeld, David J Callans, Francis E Marchlinski
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  ABSTRACT: Frequent ventricular premature depolarizations (VPDs) can cause reversible left ventricular (LV) dysfunction. However, not all patients normalize their LV function after VPD elimination. To evaluate predictors of recovery of LV function following the elimination of frequent VPDs. We identified patients with ≥10% VPDs/24 h and an LV ejection fraction of <50% who underwent successful ablation between 2007 and 2011. Subjects were classified as having reversible (≥10% increase to a final LV ejection fraction of ≥50%) or irreversible (≤10% increase or final LV ejection fraction <50%) LV dysfunction on the basis of echocardiographic follow-up. A reference group with ≥10% VPDs but normal LV function was identified. One hundred fourteen patients with ≥10% VPDs were identified; 66 had preserved and 48 had impaired LV function. Over a median follow-up of 10.6 months, 24 of 48 were classified as reversible and 13 of 48 as irreversible and 11 of 44 were excluded. There was a gradient of VPD QRS duration between the control, reversible, and irreversible groups (mean VPD QRS 135, 158, and 173 ms, respectively; P < .001). This gradient persisted even for the same site of origin. In multivariate analysis, the only independent predictor of irreversible LV function was VPD QRS duration (odds ratio 5.07 [95% confidence interval 1.22-21.01] per 10-ms increase). In patients with LV dysfunction and frequent VPDs, we identified VPD QRS duration as the only independent predictor for the recovery of LV function after ablation. This suggests that VPD QRS duration may be a marker for the severity of underlying substrate abnormality.
  Heart rhythm: the official journal of the Heart Rhythm Society 05/2012; 9(9):1465-72. · 4.56 Impact Factor
• Article: Noninvasive programmed ventricular stimulation early after ventricular tachycardia ablation to predict risk of late recurrence.

  David S Frankel, Stavros E Mountantonakis, Erica S Zado, Elad Anter, Rupa Bala, Joshua M Cooper, Rajat Deo, Sanjay Dixit, Andrew E Epstein, Fermin C Garcia, Edward P Gerstenfeld, Mathew D Hutchinson, David Lin, Vickas V Patel, Michael P Riley, Melissa R Robinson, Wendy S Tzou, Ralph J Verdino, David J Callans, Francis E Marchlinski
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  ABSTRACT: The goal of this study was to evaluate the ability of noninvasive programmed stimulation (NIPS) after ventricular tachycardia (VT) ablation to identify patients at high risk of recurrence. Optimal endpoints for VT ablation are not well defined. Of 200 consecutive patients with VT and structural heart disease undergoing ablation, 11 had clinical VT inducible at the end of ablation and 11 recurred spontaneously. Of the remaining 178 patients, 132 underwent NIPS through their implantable cardioverter-defibrillator 3.1 ± 2.1 days after ablation. At 2 drive cycle lengths, single, double, and triple right ventricular extrastimuli were delivered to refractoriness. Clinical VT was defined by comparison with 12-lead electrocardiograms and stored implantable cardioverter-defibrillator electrograms from spontaneous VT episodes. Patients were followed for 1 year. Fifty-nine patients (44.7%) had no VT inducible at NIPS; 49 (37.1%) had inducible nonclinical VT only; and 24 (18.2%) had inducible clinical VT. Patients with inducible clinical VT at NIPS had markedly decreased 1-year VT-free survival compared to those in whom no VT was inducible (<30% vs. >80%; p = 0.001), including 33% recurring with VT storm. Patients with inducible nonclinical VT only, had intermediate 1-year VT-free survival (65%). When patients with VT and structural heart disease have no VT or nonclinical VT only inducible at the end of ablation or their condition is too unstable to undergo final programmed stimulation, NIPS should be considered in the following days to further define risk of recurrence. If clinical VT is inducible at NIPS, repeat ablation may be considered because recurrence over the following year is high.
  Journal of the American College of Cardiology 04/2012; 59(17):1529-35. · 14.16 Impact Factor
• Article: Long-term follow-up of patients with cardiac sarcoidosis and implantable cardioverter-defibrillators.

  Brian P Betensky, Cory M Tschabrunn, Erica S Zado, Lee R Goldberg, Francis E Marchlinski, Fermin C Garcia, Joshua M Cooper
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  ABSTRACT: Ventricular tachyarrhythmias are an important cause of morbidity and mortality in cardiac sarcoidosis. To date, the prevalence and incidence of ventricular tachycardia/ventricular fibrillation (VT/VF) in this population remain unknown. To determine the prevalence and incidence of ventricular tachyarrhythmias in patients with cardiac sarcoidosis and to identify the clinical attributes associated with appropriate implantable cardioverter-defibrillator (ICD) therapies. We studied 45 patients with ICDs, biopsy-proven systemic sarcoidosis, and cardiac involvement, as evidenced by histopathology, cardiac magnetic resonance imaging, and/or (18)F-fluoro-2-deoxyglucose-positron emission tomography imaging. Device logs and medical records were retrospectively reviewed. Appropriate ICD therapies for VT/VF were observed in 37.8% of the patients with an incidence of 15% per year. Inappropriate ICD therapies occurred in 13.3% of the patients. Longer ICD follow-up (4.5 ± 3.1 years vs 1.5 ± 1.5 years; P = .001), depressed left ventricular ejection fraction (35.5% ± 15.5% vs 50.9% ± 15.5%; P = .002), and complete heart block (47.1% vs 17.9%; P = .048) were associated with appropriate ICD therapy. While there was no significant difference in the total number of shocks/antitachycardia pacing-terminated events between primary (n = 29) and secondary (n = 16) prevention groups, there was a trend toward more events in the secondary prevention arm after 2 years. Ventricular tachyarrhythmias requiring ICD therapy were common in patients with cardiac sarcoidosis, with an estimated incidence rate of 15% per year. Longer follow-up, left ventricular systolic dysfunction, and complete heart block were associated with VT/VF. Patients with primary prevention ICDs had high rates of appropriate ICD therapy but not as high as did secondary prevention patients. In the absence of reliable risk stratification techniques, consideration should be given to prophylactic ICD implantation in patients with cardiac sarcoidosis.
  Heart rhythm: the official journal of the Heart Rhythm Society 02/2012; 9(6):884-91. · 4.56 Impact Factor
• Article: Ablation of ventricular arrhythmias arising near the anterior epicardial veins from the left sinus of Valsalva region: ECG features, anatomic distance, and outcome.

  Miguel E Jauregui Abularach, Bieito Campos, Kyoung-Min Park, Cory M Tschabrunn, David S Frankel, Robert E Park, Edward P Gerstenfeld, Stavros Mountantonakis, Fermin C Garcia, Sanjay Dixit, Wendy S Tzou, Mathew D Hutchinson, David Lin, Michael P Riley, Joshua M Cooper, Rupa Bala, David J Callans, Francis E Marchlinski
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  ABSTRACT: Left ventricular outflow tract tachycardia/premature depolarizations (VT/VPDs) arising near the anterior epicardial veins may be difficult to eliminate through the coronary venous system. To describe the characteristics of an alternative successful ablation strategy targeting the left sinus of Valsalva (LSV) and/or the adjacent left ventricular (LV) endocardium. Of 276 patients undergoing mapping/ablation for outflow tract VT/VPDs, 16 consecutive patients (8 men; mean age 52 ± 17 years) had an ablation attempt from the LSV and/or the adjacent LV endocardium for VT/VPDs mapped marginally closer to the distal great cardiac vein (GCV) or anterior interventricular vein (AIV). Successful ablation was achieved in 9 of the 16 patients (56%) targeting the LSV (5 patients), adjacent LV endocardium (2 patients), or both (2 patients). The R-wave amplitude ratio in lead III/II and the Q-wave amplitude ratio in aVL/aVR were smaller in the successful group (1.05 ± 0.13 vs 1.34 ± 0.37 and 1.24 ± 0.42 vs 2.15 ± 1.05, respectively; P = .043 for both). The anatomical distance from the earliest GCV/AIV site to the closest point in the LSV region was shorter for the successful group (11.0 ± 6.5 mm vs 20.4 ± 12.1 mm; P = .048). A Q-wave ratio of <1.45 in aVL/aVR and an anatomical distance of <13.5 mm had sensitivity and specificity of 89%, 75% and 78%, 64%, respectively, for the identification of successful ablation. VT/VPDs originating near the GCV/AIV can be ablated from the LSV/adjacent LV endocardium. A Q-wave ratio of <1.45 in aVL/aVR and a close anatomical distance of <13.5 mm help identify appropriate candidates.
  Heart rhythm: the official journal of the Heart Rhythm Society 02/2012; 9(6):865-73. · 4.56 Impact Factor
• Article: Randomized ablation strategies for the treatment of persistent atrial fibrillation: RASTA study.

  Sanjay Dixit, Francis E Marchlinski, David Lin, David J Callans, Rupa Bala, Michael P Riley, Fermin C Garcia, Mathew D Hutchinson, Sarah J Ratcliffe, Joshua M Cooper, Ralph J Verdino, Vickas V Patel, Erica S Zado, Nancy R Cash, Tony Killian, Todd T Tomson, Edward P Gerstenfeld
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  ABSTRACT: The single-procedure efficacy of pulmonary vein isolation (PVI) is less than optimal in patients with persistent atrial fibrillation (AF). Adjunctive techniques have been developed to enhance single-procedure efficacy in these patients. We conducted a study to compare 3 ablation strategies in patients with persistent AF. Subjects were randomized as follows: arm 1, PVI + ablation of non-PV triggers identified using a stimulation protocol (standard approach); arm 2, standard approach + empirical ablation at common non-PV AF trigger sites (mitral annulus, fossa ovalis, eustachian ridge, crista terminalis, and superior vena cava); or arm 3, standard approach + ablation of left atrial complex fractionated electrogram sites. Patients were seen at 6 weeks, 6 months, and 1 year; transtelephonic monitoring was performed at each visit. Antiarrhythmic drugs were discontinued at 3 to 6 months. The primary study end point was freedom from atrial arrhythmias off antiarrhythmic drugs at 1 year after a single-ablation procedure. A total of 156 patients (aged 59±9 years; 136 males; AF duration, 47±50 months) participated (arm 1, 55 patients; arm 2, 50 patients; arm 3, 51 patients). Procedural outcomes (procedure, fluoroscopy, and PVI times) were comparable between the 3 arms. More lesions were required to target non-PV trigger sites than a complex fractionated electrogram (33±9 versus 22±9; P<0.001). The primary end point was achieved in 71 patients and was worse in arm 3 (29%) compared with arm 1 (49%; P=0.04) and arm 2 (58%; P=0.004). These data suggest that additional substrate modification beyond PVI does not improve single-procedure efficacy in patients with persistent AF. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00379301.
  Circulation Arrhythmia and Electrophysiology 12/2011; 5(2):287-94. · 6.46 Impact Factor
• Article: Allergic reaction to suture material after an ICD procedure: device infection mimicry.

  Cory M Tschabrunn, Misha Rosenbach, Nimrod Lavi, Joshua M Cooper
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  ABSTRACT: When an implanted device is infected, complete explantation of the device system, including lead extraction, is usually required. Superficial problems with wound healing may be managed more conservatively, but distinguishing between a surface process and deeper infection can pose a clinical challenge. We present a case of poor wound healing after an ICD pocket revision procedure, and an allergic reaction to the suture material was found to be the cause. Diagnosis, management, and future implications of suture allergy are discussed.
  Journal of Cardiovascular Electrophysiology 11/2011; 23(3):330-2. · 3.06 Impact Factor
• Article: Single channel ICD noise without loss of conductor circuit integrity.

  Marc W Deyell, Rutuke K Patel, Joshua M Cooper
  Pacing and Clinical Electrophysiology 10/2011; 35(5):616-21. · 1.35 Impact Factor
• Article: Sinus rhythm ECG criteria associated with basal-lateral ventricular tachycardia substrate in patients with nonischemic cardiomyopathy.

  Wendy S Tzou, Erica S Zado, David Lin, David J Callans, Sanjay Dixit, Joshua M Cooper, Rupa Bala, Fermin Garcia, Mathew D Hutchinson, Michael P Riley, Rajat Deo, Edward P Gerstenfeld, Francis E Marchlinski
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  ABSTRACT: Patients with nonischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) usually have basal-lateral scar in the left ventricle (LV). We sought to determine electrocardiogram (ECG) characteristics that may help identify NICM patients with basal-lateral scar and VT. Phase I, study patients (n = 25) had NICM, VT, and endocardial/epicardial basal-lateral LV low voltage consistent with scar on detailed mapping. ECGs were compared to controls (n = 18) with NICM, and comparable age and gender without VT/known scar. All patients had either sinus or paced atrial rhythm ECGs without bundle-branch block or ventricular pacing. In phase II, criteria were evaluated prospectively, blinded to clinical data, using ECGs from 15 NICM patients, of which 7 patients had VT and endocardial/epicardial basal-lateral LV scar on detailed mapping. Of ECG characteristics studied, V1 R and R:S ratio, and V6 S and S:R ratio were univariately associated with basal-lateral-scar associated VT. Controlling for LVEF and multicollinearity in multivariate analyses, V1 R ≥ 0.15 mV (P = 0.001) and V6 S ≥ 0.15 mV (P < 0.001), or V6 S:R ≥ 0.2 mV (P < 0.001), best predicted presence of basal-lateral scar. In Phase II, the former criteria best identified those with NICM and VT because of basal-lateral scar, with sensitivity and specificity 0.86 and 0.88, respectively. Among patients with NICM, VT, and normal QRS duration, V1 R ≥ 0.15 mV and V6 S ≥ 0.15 mV predicted presence of basal-lateral LV areas of bipolar low voltage. This ECG information may have important value in defining presence of LV scar and possible risk for VT in NICM patients. 
  Journal of Cardiovascular Electrophysiology 07/2011; 22(12):1351-8. · 3.06 Impact Factor
• Article: The V(2) transition ratio: a new electrocardiographic criterion for distinguishing left from right ventricular outflow tract tachycardia origin.

  Brian P Betensky, Robert E Park, Francis E Marchlinski, Matthew D Hutchinson, Fermin C Garcia, Sanjay Dixit, David J Callans, Joshua M Cooper, Rupa Bala, David Lin, Michael P Riley, Edward P Gerstenfeld
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  ABSTRACT: We sought to develop electrocardiography (ECG) criteria for distinguishing left ventricular outflow tract (LVOT) from right ventricular outflow tract (RVOT) origin in patients with idiopathic outflow tract ventricular tachycardia (OTVT) and lead V(3) R/S transition. Several ECG criteria have been proposed for differentiating left from right OTVT origin; ventricular tachycardias (VTs) with left bundle branch block and V(3) transition remain a challenge. We analyzed the surface ECG pattern of patients with OTVT with a precordial transition in lead V(3) who underwent successful catheter ablation. Sinus and VT QRS morphologies were measured in limb and precordial leads with electronic calipers. The V(2) and V(3) transition ratios were calculated by computing the percentage R-wave during VT (R/R+S)(VT) divided by the percentage R-wave in sinus rhythm (R/R+S)(SR). We retrospectively analyzed ECGs from 40 patients (mean age 44 ± 14 years, 21 female) with outflow tract premature ventricular contractions (PVCs)/VT. Patients with structural heart disease, paced rhythms, and bundle branch block during sinus rhythm were excluded. The V(2) transition ratio was significantly greater for LVOT PVCs compared with RVOT PVCs (1.27 ± 0.60 vs. 0.23 ± 0.16; p < 0.001) and was the only independent predictor of LVOT origin. In 21 prospective cases, a V(2) transition ratio ≥0.60 predicted an LVOT origin with 91% accuracy. A PVC precordial transition occurring later than the sinus rhythm transition excluded an LVOT origin with 100% accuracy. The V(2) transition ratio is a novel electrocardiographic measure that reliably distinguishes LVOT from RVOT origin in patients with lead V(3) precordial transition. This measure might be useful for counseling patients and planning an ablation strategy.
  Journal of the American College of Cardiology 05/2011; 57(22):2255-62. · 14.16 Impact Factor
• Article: Isolated septal substrate for ventricular tachycardia in nonischemic dilated cardiomyopathy: incidence, characterization, and implications.

  Haris M Haqqani, Cory M Tschabrunn, Wendy S Tzou, Sanjay Dixit, Joshua M Cooper, Michael P Riley, David Lin, Mathew D Hutchinson, Fermin C Garcia, Rupa Bala, Ralph J Verdino, David J Callans, Edward P Gerstenfeld, Erica S Zado, Francis E Marchlinski
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  ABSTRACT: The substrate for ventricular tachycardia (VT) in nonischemic cardiomyopathy (NICM) has a predilection for the basolateral left ventricle with right bundle branch block VT morphology. The purpose of this study was to describe a unique group of NICM patients with septal VT substrate. Between 1999 and 2010, 31 (11.6%) of 266 patients with NICM undergoing VT ablation had septal substrate and no lateral involvement. Mean age was 59 ± 12 years, and ejection fraction was 30% ± 14%. Eight patients had heart block. Cardiac magnetic resonance showed septal delayed enhancement in 8 of 9 patients. Electroanatomic mapping demonstrated bipolar low voltage (<1.5 mV) extending from the basal septum in 22 of 31 patients. The remaining 9 patients had normal endocardial bipolar voltage but abnormal unipolar septal voltage (<8.3 mV) consistent with intramural abnormalities. Epicardial mapping in 14 patients showed no scar in 9 and patchy basal left ventricular summit scar in 5. VTs were mapped to the septal substrate, with 62% having right bundle branch block morphology and V(2) precordial transition pattern break in 17% suggesting periseptal exit. After substrate and targeted VT ablation, no VT was inducible in 66% and no "clinical targeted" VT in 86%. Over a mean follow-up of 20 ± 28 months, VT recurred in 10 (32%) patients. Isolated septal VT substrate is uncommon in NICM. Biventricular low-voltage zones extending from the basal septum are characteristic, but septal scarring can be entirely intramural as evidenced by unipolar/bipolar electrograms and imaging. Multiple unmappable morphologies are the rule, often requiring several procedures aggressively targeting the septal substrate to achieve moderate long-term VT control.
  Heart rhythm: the official journal of the Heart Rhythm Society 03/2011; 8(8):1169-76. · 4.56 Impact Factor
• Article: Endocardial unipolar voltage mapping to detect epicardial ventricular tachycardia substrate in patients with nonischemic left ventricular cardiomyopathy.

  Mathew D Hutchinson, Edward P Gerstenfeld, Benoit Desjardins, Rupa Bala, Michael P Riley, Fermin C Garcia, Sanjay Dixit, David Lin, Wendy S Tzou, Joshua M Cooper, Ralph J Verdino, David J Callans, Francis E Marchlinski
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  ABSTRACT: Patients with nonischemic left ventricular cardiomyopathy (LVCM) and ventricular tachycardia (Vt) have complex 3-dimensional substrate with variable involvement of the endocardium (ENDO) and epicardium (EPI). The purpose of this study was to determine whether ENDO unipolar (UNI) mapping with a larger electric field of view could identify EPI low bipolar (BIP) voltage regions in patients with LVCM undergoing Vt ablation. The reference value for normal ENDO unipolar voltage was determined from 6 patients without structural heart disease. Consecutive patients undergoing Vt ablation over an 8-year period with detailed (>100 points) LV ENDO and EPI mapping and normal LV ENDO BIP voltage were identified. From this cohort, we compared patients with structurally normal hearts and normal EPI BIP voltage (EPI-, group 1) with patients with LVCM and low LV EPI BIP voltage regions present (EPI+, group 2). Confluent regions of ENDO UNI and EPI BIP low voltage (>2 cm(2)) were measured. The normal signal amplitude was >8.27 mV for LV ENDO UNI electrograms. Detailed LV ENDO-EPI maps in 5 EPI- patients were compared with 11 EPI+ patients. Confluent ENDO UNI low-voltage regions were seen in 9 of 11 (82%) of the EPI+ (group 2) patients compared with none of 5 EPI- (group 1) patients (P<0.001). In all 9 patients with ENDO UNI low voltage, the ENDO UNI low-voltage regions were directly opposite to an area of EPI BIP low voltage (61% ENDO UNI-EPI BIP low-voltage area overlap). EPI arrhythmia substrate can be reliably identified in most patients with LVCM using ENDO UNI voltage mapping in the absence of ENDO BIP abnormalities.
  Circulation Arrhythmia and Electrophysiology 02/2011; 4(1):49-55. · 6.46 Impact Factor
• Article: Temporary external implantable cardioverter defibrillator in the pacemaker-dependent ventricular tachycardia patient.

  Joshua M Cooper, Nimrod Lavi, Glenn M Polin, Sanjay Dixit, Ralph J Verdino
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  ABSTRACT: A patient with ischaemic cardiomyopathy underwent implantable cardioverter defibrillator (ICD) extraction for a severe pocket infection and sepsis. During 5 weeks of critical medical care after device extraction, heart block and recurrent monomorphic ventricular tachycardia (VT) were managed with an 'externalized' active fixation pacemaker lead and a resterilized ICD generator. This case demonstrates how a permanent pacing lead and an external ICD generator can provide reliable temporary pacing and automatic anti-tachycardia pacing for recurrent VT until a new device can be implanted and more permanent VT treatment options are feasible.
  Europace 11/2010; 13(5):761-3. · 1.98 Impact Factor
• Article: Tissue-specific variability in human epicardial impedance.

  Jason T Jacobson, Mathew D Hutchinson, Joshua M Cooper, Y Joseph Woo, Richard S Shandler, David J Callans
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  ABSTRACT: Epicardial ablation can be employed to treat ventricular tachycardia. Voltage attenuation in regions of fat can mimic epicardial scar, limiting its specificity. Ablation over fat may not be as effective. Prior animal data have shown that infarcted myocardium has lower impedance than normal, and human bioimpedance studies suggest peripheral fat displays higher impedance. Therefore, we tested the hypothesis that human epicardial fat has higher impedance than myocardium when measured with standard ablation tools. Patients undergoing elective surgery for coronary artery or valve disease were enrolled. A reference patch was placed on the patients' back between the scapulae and connected to a standard RF generator (Stockert, GmBH, Germany). Impedance was measured by passing a 1 μA, 50 kHz current from the catheter tip to the patch. After sternotomy but before initiation of cardiopulmonary bypass, an ablation catheter (Celsius, Biosense Webster, Diamond Bar, CA, USA) was placed onto the epicardial surface in ventricular regions visually identified as fat or myocardium. At each site, impedance was recorded from the generator. A total of 37 (7 patients) points were sampled. Impedance was significantly higher in regions of fat versus normal muscle (697 Ω vs. 301 Ω; P = 0.01). Moreover, normal sites from the LV had higher impedance than from the RV (381 Ω vs. 271 Ω; P = 0.01). Human epicardial fat has higher tissue impedance than normal muscle. Using epicardial impedance and voltage mapping in conjunction may improve differentiation of arrhythmia substrate from epicardial fat and improve the efficacy of epicardial ablation.
  Journal of Cardiovascular Electrophysiology 10/2010; 22(4):436-9. · 3.06 Impact Factor
• Article: Removing the Twiddling stigma: spontaneous lead retraction without patient manipulation.

  Joshua M Cooper, Stavros Mountantonakis, Melissa R Robinson
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  ABSTRACT: After pacemaker or implantable cardioverter-defibrillator (ICD) implantation, it takes weeks for the leads to scar in place. Occasionally, newly implanted leads dislodge by retracting towards the device pocket. This phenomenon is generally called 'Twiddler's Syndrome,' with the invoked mechanism being patient manipulation of the device pocket. We present a case of a 27-year-old man who had complete retraction of the atrial lead, but not the ventricular lead, after a submuscular dual-chamber ICD implantation. The specifics of this case demonstrate that leads can spontaneously retract during normal arm movement, without any conscious or unconscious device manipulation by the patient. Leads must be firmly secured in the device pocket via their suture sleeves in order to minimize the risk of retraction, regardless of mechanism.
  Europace 09/2010; 12(9):1347-8. · 1.98 Impact Factor