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ABSTRACT: AIMS: The prognostic significance of ventricular tachycardia (VT) induced by three extrastimuli (ES) is similar to that of VT induced by one or two ES in patients with coronary disease and abnormal left ventricular (LV) function. The significance of VT inducible with four ES is unclear. To examine the prognostic significance of VT inducible with the fourth ES in patients with post-myocardial infarct (MI) LV dysfunction.METHODS AND RESULTS: Consecutive patients (n= 432) with post-MI LV ejection fraction ≤40% underwent electrophysiological (EP) studies for risk stratification. Inducible VT ≥ 200 ms cycle length (CL) with one to four ES was considered inducible. The primary endpoint of arrhythmia (sudden death or spontaneous VT/ventricular fibrillation) was compared among patients with VT inducible with less than or equal to two, three, and four ES. The incidence of inducible VT was 37.9% (n= 164). In patients with inducible VT, inducibility was with less than or equal to two, three, and four ES in 24% (n= 39), 46% (n= 75), and 30% (n= 50). Compared to VT induced with less than or equal to three ES, VT induced with the fourth ES was of shorter CL (218 vs. 256 ms, P = 0.01) and more likely to be haemodynamically unstable requiring cardioversion (77 vs. 55%, P = 0.05). After 3 years the primary endpoint occurred in 28 ± 8, 28 ± 6, and 18 ± 6% in patients with VT induced with less than or equal to two, three, and four ES, respectively (P= 0.31) and in 5 ± 2% of EP-negative patients (P< 0.01).CONCLUSION: In patients with post-MI LV dysfunction, VT can be induced in a significant proportion of patients with the fourth ES. These patients are at comparable risk of arrhythmia to patients with inducible VT with less than or equal to three ES.
Europace 06/2012; · 1.98 Impact Factor
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Gopal Sivagangabalan,
Danna Spears,
Stephane Masse,
Bruce Urch,
Robert D Brook,
Frances Silverman,
Diane R Gold,
Karl Z Lukic,
Mary Speck,
Marjan Kusha,
Talha Farid,
Kwaku Poku,
Evelyn Shi,
John Floras,
Kumaraswamy Nanthakumar
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ABSTRACT: We tested the hypothesis that exposure to concentrated ambient particles (CAP) and/or ozone (O(3)) would increase dispersion of ventricular repolarization.
Elevated levels of air pollution are associated with cardiac arrhythmias through mechanisms yet to be elucidated.
Each of 25 volunteers (18 to 50 years of age) had four 2-h exposures to 150 μg/m(3) CAP; 120 parts per billion O(3); CAP + O(3); and filtered air (FA). Exposure-induced changes (Δ = 5-min epochs at end-start) in spatial dispersion of repolarization were determined from continuous 12-lead electrocardiographic recording.
Spatial dispersion of repolarization assessed by corrected ΔT-wave peak to T-wave end interval increased significantly for CAP + O(3) (0.17 ± 0.03, p < 0.0001) exposure only, remaining significant when factoring FA (CAP + O(3) - FA) as control (0.11 ± 0.04, p = 0.013). The influence on repolarization was further verified by a significant increase in ΔQT dispersion (for CAP + O(3) compared with FA (5.7 ± 1.4, p = 0.0002). When the low-frequency to high-frequency ratio of heart rate variability (a conventional representation of sympathetic-parasympathetic balances) was included as a covariate, the effect estimate was positive for both corrected ΔT-wave peak to T-wave end interval (p = 0.002) and ΔQT dispersion (p = 0.038). When the high-frequency component (parasympathetic heart rate modulation) was included as a covariate with corrected ΔT-wave peak to T-wave end interval, the effect estimate for high frequency was inverse (p = 0.02).
CAP + O(3) exposure alters dispersion of ventricular repolarization in part by increasing sympathetic and decreasing parasympathetic heart rate modulation. Detection of changes in repolarization parameters, even in this small cohort of healthy individuals, suggests an underappreciated role for air pollutants in urban arrhythmogenesis.
Journal of the American College of Cardiology 01/2011; 57(2):198-206. · 14.16 Impact Factor
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ABSTRACT: Effective chest compressions during prolonged ventricular fibrillation (VF) have been shown to increase the chances of successful defibrillation to a rhythm associated with a sustainable cardiac output. There is currently no effective method of recording the degree of antegrade coronary artery flow during chest compression in VF.
This study sought to quantify the relationship between the antegrade coronary flow and the characteristics of human VF using near real-time wavelet-based electrocardiographic markers.
VF experiments were conducted in 8 isolated human hearts. The Langendorff perfusion enabled different flow rates (perfusion) during VF, which allowed for the simulation of chest compression with different efficacies. After the initiation of VF, the hearts were maintained in ischemia (no flow) for 3 minutes, followed by a 2-minute reperfusion and defibrillation. The experiments were repeated at flows of 0%, 30%, and 100% of baseline perfusion, and volume-conducted surface electrograms were recorded and analyzed using continuous wavelet transform in 5-second frames.
Near real-time wavelet features were derived that demonstrated significant differences in the multicomponent nature of VF signals and predicted perfusion rate characteristics for different flow rates (i.e., 0%, 30%, and 100%; P < .0006). A pattern classifier was trained using the feature values from 5 hearts, and the flow rates for 3 additional hearts were predicted with an accuracy of 90%.
VF electrogram characteristics as measured by wavelet analysis relate to antegrade coronary flow rate during VF. These findings suggest that chest compression efficacy of physiological importance could be monitored using near real-time wavelet analysis.
Heart rhythm: the official journal of the Heart Rhythm Society 12/2010; 8(5):740-9. · 4.56 Impact Factor
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ABSTRACT: Prompt thrombolytic reperfusion reduces postinfarct ventricular electrical instability after ST elevation myocardial infarction (STEMI).
The purpose of this study was to examine the relationship between reperfusion time and inducible ventricular tachycardia (VT) early and spontaneous ventricular arrhythmias (VAs) late after primary percutaneous coronary intervention (PCI) for STEMI.
Consecutive patients were recruited if they (1) had no prior coronary disease, (2) had been reperfused with primary PCI, (3) had postinfarct ejection fraction ≤40%, and (4) had undergone cardiac electrophysiologic study (n = 128). Three groups were compared according to reperfusion time: early (≤3 hours, n = 26), intermediate (>3-5 hours, n = 45), or delayed reperfusion (>5 hours, n = 57). Spontaneous VA was a composite endpoint of sudden death or defibrillator-treated VA.
Mean ejection fraction (33% ± 5%, 31% ± 6%, and 31% ± 7%, P = .41) and peak creatinine kinase (P = .37) were similar between groups. VT was inducible in 11.5%, 17.8%, and 36.8% of patients in the early, intermediate, and delayed reperfusion groups, respectively (P = .003). At 2 years, the incidence of spontaneous VA was 0%, 8.9%, and 14% in the early, intermediate, and delayed reperfusion groups, respectively (P = .025). By multivariable analysis, delayed reperfusion conferred a sixfold increase in the odds of inducible VT (P = .01). Although inducible VT was the strongest predictor of spontaneous VA (hazard ratio 14.31, P = .001), delayed reperfusion conferred a threefold increase in risk when inducible VT was excluded from the multivariable model (P = .035).
Reperfusion time is a critical determinant of postinfarct ventricular electrical instability early and late after STEMI treated with primary PCI.
Heart rhythm: the official journal of the Heart Rhythm Society 11/2010; 8(4):493-9. · 4.56 Impact Factor
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ABSTRACT: Sudden death risk is highest early after myocardial infarction (MI). Inducible ventricular tachycardia (VT) confers increased risk of spontaneous ventricular arrhythmias.
The purpose of this study was to evaluate outcomes of electrophysiology (EP)-guided defibrillator implantation early after ST-elevation MI in patients with ejection fraction ≤40%.
EP study was performed 9 days after MI (n = 360). Predischarge defibrillator was recommended if VT with cycle length ≥200 ms was induced with ≤4 extrastimuli (EP-positive [EP(pos)], n = 142). EP-negative (EP(neg)) patients were discharged without a defibrillator (n = 218). Primary endpoint was either sudden death or spontaneous ventricular arrhythmia.
Defibrillator was implanted in 71% of EP(pos) patients (median 21 days post-MI) and withheld in 94% of EP(neg) patients. At 2 years, primary endpoint was 4.3% in the EP(neg) group and 22% in the EP(pos) group (adjusted hazard ratio 0.46, P = .035, EP(neg) vs EP(pos)). Lack of a defibrillator in EP(pos) patients conferred a fourfold increased risk of sudden death (P = .014). EP(neg) patients without a defibrillator were at significantly lower risk for the primary endpoint than were EP(pos) patients without a defibrillator (adjusted HR 0.34, P = .011). Short inducible VT cycle length (200-230 ms) and use of the fourth extrastimulus identified patients at significant arrhythmic risk.
EP study performed early after MI identified patients at significant long-term arrhythmic risk at a critical time after MI in whom defibrillator implantation was protective. A large majority of patients (EP(neg); two thirds) were at significantly lower risk of arrhythmic events without a defibrillator in the long term.
Heart rhythm: the official journal of the Heart Rhythm Society 11/2010; 7(11):1589-97. · 4.56 Impact Factor
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Heart rhythm: the official journal of the Heart Rhythm Society 10/2010; · 4.56 Impact Factor
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Journal of the American College of Cardiology 05/2010; 55(21):2409-11. · 14.16 Impact Factor
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ABSTRACT: Identification of arrhythmogenic scar using non-contact (NC) sinus rhythm (SR) mapping is limited. Dynamic substrate mapping (DSM) overcomes these limitations but is less accurate than plunge needle electrode mapping. We developed a revised method for calculating DSM which was validated using detailed histological analysis and compared with conventional mapping modalities.
Mapping was performed in eight sheep, >9 weeks post-myocardial infarction. Twenty multielectrode needles were deployed at thoracotomy in the left ventricle within and surrounding scar, and located using Ensite. Simultaneous catheter, needle, and NC electrograms were recorded during SR and multisite pacing. Dynamic substrate mapping maps were calculated as the maximum local peak negative voltage (PNV). Absolute mean DSM (AMDSM) maps, based on peak-peak voltage (P-PV), were calculated to minimize local pacing effects and take into account anisotropic influence. Dynamic substrate mapping and AMDSM maps were normalized based on global maximum voltages attained. Histologically quantified scar and mapping criteria were compared using Spearman's correlation and receiver operator curves (area under the curve, AUC) using 50% scar cut-off. For unipolar mapping, needles had greatest sensitivity at identifying scar which was better for P-PV (AUC; needle = 0.90, catheter = 0.70, NC = 0.66) than for PNV (AUC; needle = 0.79, NC = 0.38). AMDSM (AUC = 0.75) had superior scar discrimination than either catheter (AUC; unipolar = 0.70, bipolar = 0.71) or DSM (AUC = 0.67). Absolute mean DSM accuracy was improved when valvular geometries were excluded (AUC = 0.77).
Absolute mean DSM was comparably accurate in identifying scarred myocardium as PNV needle mapping but was superior to conventional catheter and NC mapping.
Europace 04/2010; 12(6):881-9. · 1.98 Impact Factor
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ABSTRACT: ST segment resolution (STR) predicts epicardial and microvascular reperfusion after primary percutaneous coronary intervention (PPCI) or thrombolysis for ST-elevation myocardial infarction. Immediate restoration of epicardial coronary flow, with improved microvascular perfusion, is much more likely with PPCI. However, the predictive value of immediate STR compared to 90 minutes after PPCI remains unknown. In 622 consecutive patients with ST-elevation myocardial infarction (mean age 59 +/- 13 years), 217 had complete STR immediately after PPCI (group A), 188 had complete STR only at 90 minutes (group B), and 217 had incomplete STR at either point (group C). The primary end point was mortality and adverse cardiovascular events ([MACE] death, nonfatal repeat myocardial infarction, and heart failure). Group A had a greater left ventricular ejection fraction (53%, 47%, and 46%, p <0.001) and lower all-cause mortality (1.8%, 3.2%, and 6%, p = 0.07), lower heart failure (1.8%, 4.3%, and 7.8%, p <0.001), and MACE (5.1%, 9.6%, and 16.1%, p = 0.001) at 30 days compared to groups B and C, respectively. The rate of MACE at 1 year was 7.6%, 17.1%, and 20.2% in groups A, B, and C, respectively (p <0.001). Immediate STR independently predicted MACE (adjusted hazard ratio 0.36, 95% confidence interval 0.21 to 0.61, p = 0.001, group A vs C), and STR at 90 minutes did not. In conclusion, STR analysis performed immediately after PPCI provided superior differentiation for adverse cardiovascular events compared to STR at 90 minutes. Immediate STR should be the contemporary goal of reperfusion with PPCI.
The American journal of cardiology 02/2010; 105(4):467-74. · 3.58 Impact Factor
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ABSTRACT: Post infarct ventricular tachycardia (VT) often involves the interventricular septum (IVS) and requires transmural septal ablation. The purpose of this study was to compare the efficacy of bipolar ablation (BIA) versus sequential unipolar ablation (SUA) in creating a transmural ablation line along the IVS scar border.
Both ablation strategies were compared in a phantom agar model first and then in 10 post infarct sheep. In the phantom agar model BIA lesions were larger, transmural, and less dependent on catheter alignment and contact compared with SUA. Noncontact mapping was used in the animals to identify the septal scar border and create a 30-mm ablation line. In five animals BIA (50 W) was performed between two irrigated catheters on either side of the IVS, and in five control animals SUA (50 W) was performed, first on the left ventricle (LV) septal scar border and then on the opposing right ventricle (RV) septal surface. Electrical block along ablation lines was confirmed with noncontact mapping. BIA required significantly less ablations (12 + or - 1 vs 29 + or - 7, P = 0.001), ablation time (22 + or - 3 vs 48 + or - 6 minutes, P < 0.001), and energy (58 + or - 7 vs 124 + or - 21 kJ, P < 0.001). At pathological examination all ablation lines in both groups were transmural at the IVS border. BIA endocardial ablation lines (LV + RV) were significantly longer than SUA lines (76 + or - 10 vs 49 + or - 11 mm, P = 0.003).
BIA of the IVS is highly effective at creating a transmural ablation line, requiring less ablation and creating longer lesions than SUA. BIA ablation may have a role for post infarct VT involving the IVS.
Pacing and Clinical Electrophysiology 01/2010; 33(1):16-26. · 1.35 Impact Factor
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ABSTRACT: The long-term outcomes of patients with inducible very fast ventricular tachycardia (VFVT) of cycle length (CL) 200 to 250 ms have not been well studied.
Consecutive patients with ischemic cardiomyopathy with a left ventricular ejection fraction (LVEF) of <or=40% (n = 300) underwent programmed ventricular stimulation (PVS) and were divided into 4 groups based on results of the study. Group A were noninducible, had induced ventricular fibrillation (VF), or polymorphic VT (CL < 200 ms); group B had inducible VFVT (200-250 ms); group C had inducible fast ventricular tachycardia (FVT; CL 251-320 ms); and group D had inducible slow VT (CL >320 ms). The primary endpoint was spontaneous ventricular arrhythmia or sudden death.
The mean age was 63 +/- 12 years and mean LVEF was 29 +/- 7%. At mean follow-up of 38 +/- 25 months (median 30 months), the primary endpoint rate was 6.6%, 34%, 44%, and 71% in groups A, B C, and D, respectively (P < 0.001). Neither mode of induction of VT nor LVEF altered the observed pattern in the primary endpoint. There was no significant difference in the primary endpoint among implanted cardioverter defibrillator recipients in groups B and C (38% vs 45%, P = 0.43). Adjusted hazard ratios for the primary endpoint compared to group A were 3.2, 3.5, and 7.0 in groups B, C, and D, respectively (P < 0.05).
Inducible VFVT (200-250 ms) is a clinically significant arrhythmia with adverse long-term outcomes and should not be considered a nonspecific finding of PVS.
Journal of Cardiovascular Electrophysiology 10/2009; 21(3):262-9. · 3.06 Impact Factor
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ABSTRACT: Q waves can develop early in infarction and indicate infarct progression better than symptom duration. ST resolution (STR) is a predictor of reperfusion success. Our aim was to assess the prognostic impact of Q waves on presentation and STR after primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction. The combined end point was of mortality and adverse cardiovascular events (MACE; death, repeat myocardial infarction, or heart failure). Q waves on presentation (Q wave, n = 332; no Q wave, n = 337) was associated with significantly less mean STR, greater incidence of akinetic, dyskinetic, or aneurysmal regional wall motion, lower left ventricular ejection fraction, and worse in-hospital and 1-year MACEs (1 year 24% vs 8.2%, p <0.001). In addition, Q waves on presentation compared to no Q waves were associated with worse 1-year MACE regardless of infarct presentation in < or =3 hours, infarct location, and adequate STR (> or =70%). Q waves on presentation and inadequate STR (<70%), but not symptom duration, were independent predictors of MACE by multivariable analysis (adjusted hazard ratios of 2.7 and 2.4 for Q waves and STR, respectively). Compared to group A (no Q waves on presentation with STR), patients in group B (no Q waves with inadequate STR), group C (Q waves with STR), and group D (Q waves with inadequate STR) had hazard ratios of 3.0, 3.6, and 7.7, respectively (p <0.05) for the occurrence of MACE. In conclusion, assessment of Q-wave status on presentation and STR immediately after PPCI provides a simple and early clinical predictor of outcomes in ST-elevation myocardial infarction.
The American journal of cardiology 10/2009; 104(6):780-5. · 3.58 Impact Factor
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ABSTRACT: Methods to identify high-risk patients and timing of implantable cardioverter-defibrillator (ICD) therapy after ST-elevation myocardial infarction need further optimization.
We evaluated outcomes of early ICD implantation in patients with inducible ventricular tachycardia. Consecutive patients treated with primary percutaneous coronary intervention for acute ST-elevation myocardial infarction underwent early left ventricular ejection fraction (LVEF) assessment. Patients with LVEF >40% were discharged (group 1); patients with LVEF < or =40% underwent risk stratification with electrophysiological study. If no ventricular tachycardia was induced, patients were discharged without an ICD (group 2). If sustained monomorphic ventricular tachycardia (> or =200-ms cycle length) was induced, an ICD was implanted before discharge (group 3). Follow-up was obtained up to 30 months in all patients and up to 48 months in a subgroup of patients with LVEF < or =30% without an ICD. The primary end point was total mortality. Group 1 (n=574) had a mean LVEF of 54+/-8%; group 2 (n=83), 32+/-6%; and group 3 (n=32), 29+/-7%. At a median follow-up of 12 months, there was no significant difference in survival between the 3 groups (P=0.879), with mortality rates of 3%, 3%, and 6% for groups 1 through 3, respectively. In the subgroup of group 2 patients with LVEF < or =30% and no ICD (n=25), there was 9% mortality at a median follow-up of 25 months. In group 3, 19% had spontaneous ICD activation resulting from ventricular tachycardia.
Early ICD implantation limited to patients with inducible ventricular tachycardia enables a low overall mortality in patients with impaired LVEF after primary percutaneous coronary intervention for ST-elevation myocardial infarction.
Circulation 08/2009; 120(3):194-200. · 14.74 Impact Factor
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ABSTRACT: We assessed a novel simultaneous biventricular mapping and ablation approach for septal ventricular tachycardia (VT) in a chronic ovine infarct model.
In 8 sheep with inducible VT, mapping and ablation were performed 9+/-3 months after percutaneously induced myocardial infarction, with left ventricular ejection fraction 23+/-8%. Scar was identified by EnSite Dynamic Substrate Mapping plus CARTO voltage mapping. Thirty VT episodes (cycle length, 235+/-42 ms) were mapped with simultaneous analyses using EnSite arrays deployed in both the left ventricle and the right ventricle. Short ablation lines were created perpendicular to the breakout pathway along the scar border in the ventricle with earliest activity. If septal VT was still inducible, this line was extended before ablation in the second chamber. The end point of noninducibility of VT was achieved in all animals. The mean difference in delay in noncontact breakout timing between the ventricles was shorter for VT with (n=18) than without (n=12) septal breakout (32+/-7.8 ms, P<0.001). In 5 of 6 animals, after ablation in one ventricle, septal VT was still inducible with a common breakout site in the second ventricle. After septal ablation in the second ventricle, VT was no longer inducible. In the 6 animals in which septal VT had been ablated, transmural septal ablation was identified at the scar border, with overlapping left ventricular and right ventricular ablation lesions present in 5 of 6 (septal thickness 8 to 17 mm) and left ventricular endocardial ablation being transmural in 1 of 6 (6 mm).
Biventricular scar and VT activation mapping correctly localizes septal VT pathways, directing ablation from one or both septal endocardial aspects. Creation of a transmural septal lesion at the scar border interrupting VT exit points is highly effective at ablating septal VT.
Circulation Arrhythmia and Electrophysiology 08/2009; 2(4):441-9. · 6.46 Impact Factor
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ABSTRACT: Shorter reperfusion times lead to better outcomes in patients with ST-elevation myocardial infarction (STEMI). We assessed the efficacy of prehospital triage with bypass of community hospitals and early activation of the cardiac catheterization team on revascularization times, left ventricular (LV) ejection fraction, and survival. Patients with STEMI (624) were divided into 3 groups determined by site of triage: ambulance field triage (163), interventional center emergency department (202), and 3 community hospital emergency departments (259). Compared with community hospital and interventional center triages, ambulance field triage resulted in a significant median decrease in door-to-balloon times of 68 and 27 minutes, respectively (p <0.001). LV ejection fraction was highest in the field triage group (52 +/- 13%) compared with the interventional center (49 +/- 12%) and community hospital (48 +/- 12%, p = 0.017) groups. Thirty-day mortality was lowest in the ambulance field group (3%) compared with the interventional facility (11%) and community hospital (4%, p = 0.007) groups. There was a significant difference in long-term survival with up to 30-month follow-up among the 3 triage groups (p = 0.041). With time-dependent Cox regression modeling the difference in survival was significant only during the first week after STEMI (p = 0.020). Every extra minute of symptom onset to reperfusion time was associated with a relative risk of long-term mortality of 1.003 (95% confidence interval 1.000 to 1.006, p = 0.027). In conclusion, field triage of patient with STEMI decreased revascularization times, which preserved LV function, and improved early survival.
The American journal of cardiology 05/2009; 103(7):907-12. · 3.58 Impact Factor
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ABSTRACT: Substrate-based ablation is useful for nonhemodynamically tolerated postinfarct ventricular tachycardia. We assessed the accuracy of the CARTO contact and EnSite noncontact systems at identifying scar in a chronic ovine model with intramural plunge needle electrode recording and histological validation.
Scar mapping was performed on 8 male sheep with previous percutaneous-induced myocardial infarction. Up to 20 plunge needles were inserted into the left ventricle of each animal in areas of dense scar, scar border, and normal myocardium. A simultaneous CARTO map and EnSite geometry were acquired using a single catheter, and needle electrode locations were registered. A dynamic substrate map was constructed using ratiometric 50% peak negative voltage. The scar percentage around each needle location was quantified histologically. Analysis was performed on 152 plunge needles and corresponding histological blocks. Spearman correlation with histology was 0.690 (P<0.001) for needle electrode peak-to-peak voltage (PPV), 0.362 (P<0.001) and 0.492 (P<0.001) for CARTO bipolar and unipolar PPV, and 0.381 (P<0.001) for EnSite dynamic substrate map (< or =40 mm from array). The area under the receiver operator characteristics curve (<50% and > or =50% scar) was 0.896 for needle electrode PPV, 0.726 and 0.697 for CARTO bipolar and unipolar PPV, and 0.703 for EnSite dynamic substrate map (< or=40 mm from array).
Both the CARTO contact and EnSite noncontact systems were moderately accurate in identifying postinfarct scar when compared with intramural electrodes and confirmed with histology. The EnSite dynamic substrate map was comparable to the CARTO contact bipolar PPV when points >40 mm from the array were excluded.
Circulation Arrhythmia and Electrophysiology 12/2008; 1(5):363-9. · 6.46 Impact Factor
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ABSTRACT: We assessed the efficacy of antitachycardia pacing (ATP) and low-energy (5J) shock for very fast ventricular tachycardia (VFVT), cycle length 200-250 ms, in patients with implantable cardioverter defibrillators (ICDs).
One hundred and fifty-two consecutive patients with standard indications for ICD therapy were enrolled. Before discharge from the hospital each patient had an electrophysiological study (EPS) performed through the device, to assess the efficacy of ATP and low-joule shock at terminating VFVT. Initial therapy for VFVT consisted of three bursts of ATP followed by low-energy shock, and high-energy shocks as required. The mean age of enrolled patients was 63 +/- 13 years, and the mean left ventricular ejection fraction (LVEF) was 31 +/- 13%. During the predischarge EPS, a total of 125 VT episodes were induced in 64 patients. In patients with VFVT, the success rate of ATP was 30% (14/46), the acceleration rate was 26% (12/46), and the success rate of low-energy shock was 86% (25/29). In patients with fast ventricular tachycardia (FVT), cycle lengths 251-320 ms, the success rate of ATP was 62% (24/39), the acceleration rate was 18% (7/39), and the success rate of low-energy shock was 94% (17/18).
This study has demonstrated for the first time that ATP and low-energy shock are effective, as an alternative to high-energy shock, to revert induced VFVT. Low-energy shock has a very high success rate for VT slower than VFVT. Clinical studies are required prior to consideration for empiric programming.
Pacing and Clinical Electrophysiology 10/2008; 31(9):1095-9. · 1.35 Impact Factor
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The Canadian journal of cardiology 27(2):263.e25-7. · 3.36 Impact Factor
