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Adequate real-world safety and efficacy of leadless pacemakers (LPs) have been demonstrated up to 3 years after implantation. Longer-term data are warranted to assess the net clinical benefit of leadless pacing. The purpose of this study was to evaluate the long-term safety and efficacy of LP therapy in a real-world cohort. In this retrospective cohort study, all consecutive patients with a first LP implantation from December 21, 2012, to December 13, 2016, in 6 Dutch high-volume centers were included. The primary safety endpoint was the rate of major procedure- or device-related complications (ie, requiring surgery) at 5-year follow-up. Analyses were performed with and without Nanostim battery advisory-related complications. The primary efficacy endpoint was the percentage of patients with a pacing capture threshold ≤2.0 V at implantation and without ≥1.5-V increase at the last follow-up visit. A total of 179 patients were included (mean age 79 ± 9 years), 93 (52%) with a Nanostim and 86 (48%) with a Micra VR LP. Mean follow-up duration was 44 ± 26 months. Forty-one major complications occurred, of which 7 were not advisory related. The 5-year major complication rate was 4% without advisory-related complications and 27% including advisory-related complications. No advisory-related major complications occurred a median 10 days (range 0–88 days) postimplantation. The pacing capture threshold was low in 163 of 167 patients (98%) and stable in 157 of 160 (98%). The long-term major complication rate without advisory-related complications was low with LPs. No complications occurred after the acute phase and no infections occurred, which may be a specific benefit of LPs. The performance was adequate with a stable pacing capture threshold. [ABSTRACT FROM AUTHOR]

Background: The Shockless IMPLant Evaluation (SIMPLE) trial showed that defibrillation testing (DT) at the time of implantable cardioverter-defibrillator (ICD) implant did not improve shock efficacy or reduce mortality. There are no data regarding the risk of complications, including stroke, among patients with atrial fibrillation (AF) who undergo DT.Objective: The purpose of this prospectively planned substudy of SIMPLE was to evaluate the effect of DT vs no DT on clinical outcomes among patients with AF.Methods: We compared efficacy (failed appropriate shock/arrhythmic death) and safety between patients who had AF on their immediate preprocedural ECG to the rest of the study patients. Then among patients with AF we compared these outcomes between patients randomized to DT vs no DT.Results: Of the 2500 patients enrolled in SIMPLE, 251 (10%) were in AF immediately before ICD implant. AF patients had an increased risk of failed appropriate shock/arrhythmic death (adjusted hazard ratio [HR] 1.64; 95% confidence interval [CI] 1.13-2.39; P = .009) and higher all-cause mortality (adjusted HR 1.58; 95% CI 1.2-2.08; P = .001). Among AF patients, perioperative complications and stroke did not significantly differ between DT vs no-DT groups (9.2% vs 5.4%; P = .2; and 1.7% vs 1.5%; P >.999, respectively). Failed appropriate shock or arrhythmic death occurred in 35 of 251 AF patients (14%), and the no-DT group proved not inferior to the DT group (HR 0.58; 95% CI 0.30-1.15; Pnoninferiority = .006).Conclusion: ICD recipients with AF are at increased risk for adverse outcomes; however, DT does not improve arrhythmic survival or shock efficacy. There is no evidence that DT increased the occurrence of perioperative stroke. [ABSTRACT FROM AUTHOR]

Background: Patients with hypertrophic cardiomyopathy (HCM) are considered to be at high risk for elevated defibrillation thresholds, periprocedural complications, and failed appropriate shocks.Objective: The purpose of this study was to determine the value of defibrillation testing (DT) in HCM patients undergoing implantable cardioverter-defibrillator (ICD) insertion.Methods: Defibrillation thresholds, perioperative complications, and long-term outcomes were compared between patients with HCM and those with ischemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM) enrolled in the SIMPLE (Shockless IMPLant Evaluation) trial (Clinialtrials.gov Identifier: NCT00800384). In patients with HCM, outcomes were also compared between those randomized to DT vs no DT.Results: Adequate defibrillation safety margin without system change was achieved in 46 of 52 (88.5%) HCM and 948 of 1047 (90.5%) ICM/DCM patients (P = .63). Perioperative complications occurred in 1 of 52 (1.9%) HCM patients with DT compared to 67 of 1047 (6.4%) ICM/DCM patients with DT (P = .37) or 3 of 42 (7.1%) HCM patients without DT (P = .32). During follow-up, there was no significant difference between HCM vs ICM/DCM patients in terms of all-cause mortality (adjusted hazard ratio [HR] 1.02, 95% confidence interval [CI] 0.45-2.34), composite of arrhythmic death or failed appropriate shock (adjusted HR 0.33, 95% CI 0.04-2.42), inappropriate shocks (adjusted HR 1.64, 95% CI 0.69-3.89), or system complications (adjusted HR 1.93, 95% CI 0.88-4.27). All-cause mortality (HR 0.26, 95% CI 0.03-2.20), appropriate (HR 0.24, 95% CI 0.03-2.05), and inappropriate shocks (HR 2.13, 95% CI 0.51-8.94) were similar in HCM patients without or those with DT.Conclusion: We did not find any difference in intraoperative defibrillation efficacy, perioperative complications, and long-term outcomes between patients with HCM and those with ICM/DCM. DT did not improve intraoperative or clinical shock efficacy in HCM patients. [ABSTRACT FROM AUTHOR]

Background: The Shockless IMPLant Evaluation trial randomized 2500 patients receiving a first implantable cardioverter-defibrillator (ICD)/cardiac resynchronization therapy-defibrillator device to have either defibrillation testing (DT) or no DT. It demonstrated that DT did not improve shock efficacy or reduce mortality.Objective: This prospective substudy evaluated the effect of DT on postoperative troponin levels and their predictive value for total and arrhythmic mortality.Methods: Troponin levels were measured between 6 and 24 hours after ICD implantation in 2200 of 2500 patients.Results: A postoperative serum troponin level above the upper limit of normal (ULN) was more common in patients undergoing DT (n = 509 [46.4%]) than in those not subjected to DT (n = 456 [41.3%]; P = .02). After excluding patients with known preoperative troponin levels above the ULN, consistent findings were observed (42.1% vs 37.5%; P = .04). During a mean follow-up of 3.1 ± 1.0 years, the annual mortality rate was increased in patients with postoperative troponin levels above the ULN (adjusted hazard ratio [HR] 1.43; 95% confidence interval [CI] 1.15-1.76; P = .001) irrespective of DT or no DT. Likewise, patients with elevated troponin levels had a significantly higher risk of arrhythmic death (adjusted HR 1.80; 95% CI 1.23-2.63; P = .002). The rate of first appropriate ICD shock (adjusted HR 0.89; 95% CI 0.71-1.12; P = .32) or failed appropriate shock (adjusted HR 1.02; 95% CI 0.59-1.76; P = .95) was similar in patients with or without troponin elevation.Conclusion: DT at the time of ICD implantation is associated with increased troponin levels, indicating subclinical myocardial injury caused by the procedure. Elevated troponin levels but not DT seem to predict clinical outcomes in ICD recipients. [ABSTRACT FROM AUTHOR]

Background Large randomized trials demonstrated the beneficial effect of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy–defibrillator (CRT-D) treatments in selected patients. Data on long-term follow-up of patients outside the setting of clinical trials are scarce. Objective The aim of this study was to evaluate the long-term outcome of ICD and CRT-D recipients. Methods All patients who underwent ICD (n = 1729 [57%]) or CRT-D (n = 1326 [43%]) implantation at the Leiden University Medical Center since 1996 were evaluated. Follow-up visits were performed every 3–6 months, and events were registered. Cumulative incidence curves of device therapy and device-related complications were adjusted for the competing risk of all-cause mortality. Results After a median follow-up of 5.1 years (25th–75th percentile 3.1–7.8 years), 842 patients (28%) died. The cumulative incidence of all-cause mortality was 49% (95% confidence interval [CI] 45%–54%) in ICD recipients after 12 years of follow-up and 55% (95% CI 52%–58%) in CRT-D recipients after 8 years of follow-up. A total of 1081 patients (35%) received appropriate defibrillator therapy. The cumulative incidence of appropriate therapy in ICD patients was 58% (95% CI 54%–62%) after 12 years of follow-up and 39% (95% CI 35%–43%) in CRT-D patients after 8 years of follow-up. Twelve-year cumulative incidences of adverse events were 20% (95% CI 18%–22%) for inappropriate shock, 6% (95% CI 5%–8%) for device-related infection, and 17% (95% CI 14%–21%) for lead failure. Conclusion After long-term follow-up of ICD (12 years) and CRT-D (8 years) recipients, 49% of ICD recipients and 55% of CRT-D recipients had died. Appropriate ICD therapy was received by the majority (58%) of ICD recipients and by almost 40% of CRT-D recipients. [ABSTRACT FROM AUTHOR]

Background Transvenous left ventricular (LV) lead placement for cardiac resynchronization therapy–defibrillator (CRT-D) delivery is unsuccessful in 8% to 10% of cases. These patients might benefit from an epicardial lead. However, data on long-term epicardial lead performance are scarce. Furthermore, extracting an epicardial lead requires a rethoracotomy. Objective The purpose of this study was to determine data on almost a decade of experience with epicardial leads and investigate the safety of partially leaving this lead in place after device infection. Methods All adult patients receiving an epicardial lead (Medtronic CapSure Epi, model 4968) for CRT-D in the Leiden University Medical Center were included. Leads were implanted during a standalone procedure or in combination with other cardiothoracic procedures. Electrical lead parameters were assessed at implantation and every 6 months thereafter. In case of device infection the epicardial lead was cut off parasternal, just outside the thoracic cavity, leaving the distal part of the lead in place. Results Two-hundred sixteen patients were included with a median follow-up of 3 years (25th–75th percentile 1.0–5.5). LV pacing threshold decreased within 6 months after implantation [1.1 V (95% confidence interval [CI] 0.9–1.2) vs 0.8 V (95% CI 0.7–0.9), P = .01] and stabilized thereafter. Mean LV electrogram was 15.2 ± 7.5mV, and average lead impedance was 633.5 ± 174.0 Ω. Five-year cumulative incidence was 1.6% for lead failure and 9.6% for device infection. The retained epicardial lead caused skin erosion in 3 patients and fistula formation in 1. Conclusion This study demonstrates that epicardial LV leads have an excellent long-term performance. Partially retaining the lead after device infection was associated with a risk of reinfection with limited long-term clinical implications for the patient. [ABSTRACT FROM AUTHOR]

The article studies the prevalence of externalized conductors and electrical abnormalities in Riata implantable cardioverter-defibrillator (ICD) leads using fluoroscopic screening and standard ICD assessment. The authors conducted fluoroscopic screening of the Riata ICD leads of patients identified by ICD implantation centers contacted by the Netherlands Heart Rhythm Association Device Advisory Committee. The study reveals externalized conductors in Riata leads have a high level of prevalence.

Background: Although data on the mode of death of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with defibrillator (CRT-D) patients have been examined in randomized clinical trials, in routine clinical practice data are scarce. To provide reasonable expectations and prognosis for patients and physicians, this study assessed the mode of death in routine clinical practice. Objective: To assess the mode of death in ICD/CRT-D recipients in routine clinical practice. Methods: All patients who underwent an ICD or CRT-D implantation at the Leiden University Medical Center, the Netherlands, between 1996 and 2010 were included. Patients were divided into primary prevention ICD, secondary prevention ICD, and CRT-D patients. For patients who died during follow-up, the mode of death was retrieved from hospital and general practitioner records and categorized according to a predetermined classification: heart failure death, other cardiac death, sudden death, noncardiac death, and unknown death. Results: A total of 2859 patients were included in the analysis. During a median follow-up of 3.4 years (interquartile range 1.7–5.7 years), 107 (14%) primary prevention ICD, 253 (28%) secondary prevention ICD, and 302 (25%) CRT-D recipients died. The 8-year cumulative incidence of all-cause mortality was 39.9% (95% confidence interval 37.0%–42.9%). Heart failure death and noncardiac death were the most common modes of death for all groups. Sudden death accounted for approximately 7%–8% of all deaths. Conclusion: For all patients, heart failure and noncardiac death are the most common modes of death. The proportion of patients who died suddenly was low and comparable for primary and secondary ICD and CRT-D patients. [Copyright &y& Elsevier]

Background: One of the major drawbacks of implantable cardioverter-defibrillator (ICD) treatment is the limited device service life. Thus far, data concerning ICD longevity under clinical circumstances are scarce. In this study, the ICD service life was assessed in a large cohort of ICD recipients. Objective: To assess the battery longevity of ICDs under clinical circumstances. Methods: All patients receiving an ICD in the Leiden University Medical Center were included in the analysis. During prospectively recorded follow-up visits, reasons for ICD replacement were assessed and categorized as battery depletion and non–battery depletion. Device longevity and battery longevity were calculated. The impact of device type, generation, manufacturer, the percentage of pacing, the pacing output, and the number of shocks on the battery longevity was assessed. Results: Since 1996, 4673 ICDs were implanted, of which 1479 ICDs (33%) were replaced. Mean device longevity was 5.0 ± 0.1 years. A total of 1072 (72%) ICDs were replaced because of battery depletion. Mean battery longevity of an ICD was 5.5 ± 0.1 years. When divided into different types, mean battery longevity was 5.5 ± 0.2 years for single-chamber ICDs, 5.8 ± 0.1 for dual-chamber ICDs, and 4.7 ± 0.1 years for cardiac resynchronization therapy–defibrillators (P <.001). Devices implanted after 2002 had a significantly better battery longevity as compared with devices implanted before 2002 (5.6 ± 0.1 years vs 4.9 ± 0.2 years; P <.001). In addition, large differences in battery longevity between manufacturers were noted (overall log-rank test, P <.001). Conclusions: The majority of ICDs were replaced because of battery depletion. Large differences in longevity exist between different ICD types and manufacturers. Modern ICD generations demonstrated improved longevity. [Copyright &y& Elsevier]

Background: Cardiac device infections (CDIs) are a serious complication associated with the implantation of cardiac rhythm devices. However, the effect of CDI on the subsequent risk of mortality is unknown. Objective: To assess the prognostic importance of CDI in recipients of implantable cardioverter-defibrillator and cardiac resynchronization therapy – defibrillator. Methods: All patients who received their initial implantable cardioverter-defibrillator/cardiac resynchronization therapy – defibrillator between January 2000 and September 2009 were included. During follow-up, the occurrence of CDI and all-cause mortality were noted. The prognostic importance of the first CDI on mortality was assessed by modeling CDI as a time-dependent covariate in the Cox proportional hazards model. Results: A total of 2476 patients (79% men; mean age 62 ± 13 years) were included in this analysis. During follow-up, CDI occurred in 64 (2.6%) patients. The 1-year mortality following first CDI was 16.9% (95% confidence interval 6.7%–27.1%). Experiencing the first CDI was associated with a 1.9-fold (hazard ratio 1.87; 95% confidence interval 1.07–3.26) increased risk of mortality compared to patients who did not experience CDI. After controlling for possible confounders, this increased to a 2.4-fold (hazard ratio 2.40; 95% confidence interval 1.35–4.28) increased risk of mortality. Conclusions: In a large cohort of patients who receive implantable cardioverter-defibrillator/cardiac resynchronization therapy – defibrillator after their initial implant, the 3-year incidence of CDI was 2.6%. The occurrence of CDI was associated with substantial 1-year mortality, and patients experiencing CDI had a more than 2-fold increased risk of mortality compared with patients who remained free from CDI. [Copyright &y& Elsevier]

The article examines the outcome of 136 adults with congenital heart disease in the Netherlands and Belgium after the implantable cardioverter defibrillator (ICD) therapy. Secondary prevention indication, symptomatic nonsustained ventricular tachycardia and coronary artery disease were linked with appropriate ICD shocks. The eight-year survival rates for low-, intermediate- and high-risk patients are also mentioned. About 29% of the patients had 45 complications associated with ICD.

Abstract: Background and purpose: Left ventricular ejection fraction lacks specificity to predict sudden cardiac death in heart failure. T-wave alternans (TWA; beat-to-beat T-wave instability, often measured during exercise) is deemed a promising noninvasive predictor of major cardiac arrhythmic event. Recently, it was demonstrated that TWA during recovery from exercise has additional predictive value. Another mechanism that potentially contributes to arrhythmogeneity is exercise-recovery hysteresis in action potential morphology distribution, which becomes apparent in the spatial ventricular gradient (SVG). In the current study, we investigated the performance of TWA amplitude (TWAA) during a complete exercise test and of exercise-recovery SVG hysteresis (SVGH) as predictors for lethal arrhythmias in a population of heart failure patients with cardioverter-defibrillators (ICDs) implanted for primary prevention. Methods: We performed a case-control study with 34 primary prevention ICD patients, wherein 17 patients (cases) and 17 patients (controls) had no ventricular arrhythmia during follow-up. We computed, in electrocardiograms recorded during exercise tests, TWAA (maximum over the complete test) and the exercise-recovery hysteresis in the SVG. Statistical analyses were done by using the Student t test, Spearman rank correlation analysis, receiver operating characteristics analysis, and Kaplan-Meier analysis. Significant level was set at 5%. Results: Both SVGH and TWAA differed significantly (P < .05) between cases (mean ± SD, SVGH: −18% ± 26%, TWAA: 80 ± 46 μV) and controls (SVGH: 5% ± 26%, TWAA: 49 ± 20 μV). Values of TWAA and SVGH showed no significant correlation in cases (r = −0.16, P = .56) and in controls (r = −0.28, P = .27). Receiver operating characteristics of SVGH (area under the curve = 0.734, P = .020) revealed that SVGH less than 14.8% discriminated cases and controls with 94.1% sensitivity and 41.2% specificity; hazard ratio was 3.34 (1.17-9.55). Receiver operating characteristics of TWA (area under the curve = 0.699, P = .048) revealed that TWAA greater than 32.5 μV discriminated cases and controls with 93.8% sensitivity and 23.5% specificity; hazard ratio was 2.07 (0.54-7.91). Discussion and conclusion: Spatial ventricular gradient hysteresis bears predictive potential for arrhythmias in heart failure patients with an ICD for primary prevention, whereas TWA analysis seems to have lesser predictive value in our pilot group. Spatial ventricular gradient hysteresis is relatively robust for noise, and, as it rests on different electrophysiologic properties than TWA, it may convey additional information. Hence, joint analysis of TWA and SVGH may, possibly, improve the noninvasive identification of high-risk patients. Further research, in a large group of patients, is required and currently carried out by our group. [Copyright &y& Elsevier]

Abstract: Background and Purpose: Several studies have demonstrated that the spatial mean QRS-T angle (SA) predicts cardiac events and mortality. Spatial mean QRS-T angle is a vectorcardiographic variable. Because in clinical practice, 12-lead standard electrocardiograms (ECGs) are recorded rather than vectorcardiograms (VCGs) according to Frank, VCGs are commonly obtained by synthesizing them from 12-lead ECGs, by using a VCG synthesis matrix. Hence, the thus computed SA is an estimate of the real SA measured in the Frank VCG. Recent studies have shown that Kors VCG synthesis matrix yields better estimates of SA than the inverse Dower VCG synthesis matrix. Our current study aims to compare the predictive power of these SA variants for the occurrence of potentially lethal arrhythmias. Methods: The study group consisted of patients with ischemic heart disease and left ventricular systolic dysfunction who received an implantable cardioverter-defibrillator (ICD) for primary prevention. During follow-up, the occurrence of appropriate device therapy (occurrence of ventricular arrhythmia) was noted. Alternative SAs were computed in VCGs synthesized from standard 12-lead ECGs by using either the inverse Dower matrix (SA-Dower) or the Kors matrix (SA-Kors). Comparison of the predictive power of SA-Dower and SA- Kors was performed by receiver operating characteristic analysis, by Kaplan-Meier analysis, and by univariate and multivariate Cox regression analysis, using every 10th percentile of SA as a cutoff value. Results: The study group consisted of 412 patients (361 men; mean ± SD age 63 ± 11 years), in which 56 patients had appropriate ICD therapy during follow-up. Receiver operating characteristic analysis revealed that the area under the curve of SA-Kors was significantly larger than area under the curve of SA-Dower (0.646 vs 0.607, P = .043). The discriminative power of SA-Kors for the absence/presence of appropriate ICD therapy in patients during follow-up was generally superior to SA-Dower over a wide range of cutoff values in the Kaplan-Meier analysis and generally yielded stronger hazard ratios in the univariate and multivariate Cox regression analyses. Conclusion: If there is no specific reason to use the inverse Dower matrix, VCG synthesis from standard 12-lead ECGs should preferably be done by using the Kors matrix. It is likely to assume that already published studies in which the predictive value of SA-Dower was demonstrated would yield stronger results if the SA-Dower angles were substituted by SA-Kors angles. [Copyright &y& Elsevier]

The article presents a research study about the value of the QRS-T angle for the prediction of mortality and implantable cardioverter-defibrillator (ICD) therapy for primary patients with coronary heart disease. The study revealed that the strong predictor of proper device therapy was the QRS-T angle. Furthermore, the analysis has indicated the appropriate value in the identification of patients.

The article presents a study depicting the long-term lead failure rate in a large single-center cohort. According to the article, the overall incidence of lead failure was 1.3 per 100 lead-years. By comparing different groups of leads, it depicts that there is a major differences in the event rates. It notes that the small-diameter defibrillation leads of a specific manufacturer may have higher risk of early lead failure.

Background: Data on the occurrence and implications of new-onset atrial fibrillation (AF) following cardiac resynchronization therapy (CRT) are scarce. We studied the incidence of new onset AF in CRT-defibrillator (CRT-D) recipients. The influence of new-onset AF on echocardiographic response to CRT and the rate of adverse events also were evaluated. Objective: The purpose of this study was to assess the incidence and implications of new-onset AF following CRT. Methods: The study population consisted of 223 consecutive patients with no history of AF. New-onset AF was defined as atrial high-rate episodes >180 bpm for more than 10 minutes/day as detected by the device. Echocardiography was performed at baseline and after 6 months of biventricular pacing. Long-term events included implantable cardioverter-defibrillator therapy for ventricular arrhythmias, hospitalization for heart failure, and all-cause mortality. Results: Fifty-five (25%) patients developed new-onset AF during mean follow-up of 32 ± 16 months. When compared to the patients who maintained sinus rhythm during follow-up, patients who developed AF showed less left ventricular (LV) reverse remodeling (ΔLV end-systolic volume 37 ± 53 vs >19 ± 37 mL, P <.05) and less improvement in LV function (ΔLV ejection fraction 6.7% ± 8.9% vs 3.5% ± 10.3%, P <.05) . Importantly, patients who developed AF experienced more appropriate ICD shocks for ventricular arrhythmias, more inappropriate shocks, and more hospitalizations for heart failure. Conclusion: Recipients of CRT-D who develop new-onset AF show less echocardiographic response to CRT and more cardiac adverse events during long-term follow-up. [Copyright &y& Elsevier]

Background: Right ventricular (RV) pacing in implantable cardioverter-defibrillator (ICD) patients may have detrimental effects on morbidity and mortality, in particular by inducing heart failure (HF). Objective: We investigated whether RV pacing increases the risk of HF in an asymptomatic ICD population. Methods: We evaluated all patients without symptomatic HF who received an ICD. The primary endpoint was the occurrence of HF, which was defined as new HF, hospitalization for HF, or death due to HF. The secondary endpoint was appropriate shocks. Results: The study population consisted of 456 patients with mean left ventricular ejection fraction (LVEF) 40% ± 13%. Mean follow-up was 31 ± 22 months. Because of the bimodal distribution of pacing, patients were divided into two groups: paced ≤50% (median 0%; n = 313) and paced >50% (median 96%; n = 143). HF occurred more often in the paced >50% group (20% versus 9%; P <.001). Multivariate analysis identified RV pacing >50% (adjusted hazard ratio [HR] 1.85; 95% confidence interval [CI] 1.08–3.15; P = .03), baseline LVEF <26% (adjusted HR 3.15; 95% CI 1.77–5.59; P <.001), angina pectoris, history of atrial fibrillation, and baseline diuretic use as independent predictors of HF. RV pacing caused more HF events in patients with LVEF <26% (n = 64; 55% of paced >50% patients versus 20% of paced ≤50% patients; P = .006). RV pacing >50% also independently predicted appropriate shocks (adjusted HR 1.50; 95% CI 1.02–2.20; P = .04). Conclusion: RV pacing was associated with an increased risk of HF in asymptomatic ICD patients, particularly in those with preexistent left ventricular dysfunction. [Copyright &y& Elsevier]

Background: Proarrhythmic effects of cardiac resynchronization therapy (CRT) as a result of increased transmural dispersion of repolarization (TDR) induced by left ventricular (LV) epicardial pacing in a subset of vulnerable patients have been reported. The possibility of identifying these patients by ECG repolarization indices has been suggested.Objectives: The purpose of this study was to test whether repolarization indices on the ECG can be used to measure dispersion of repolarization during pacing.Methods: CRT devices of 28 heart failure patients were switched among biventricular, LV, and right ventricular (RV) pacing. ECG indices proposed to measure dispersion of repolarization were calculated. The effects of CRT on repolarization were simulated in ECGSIM, a mathematical model of electrocardiogram genesis. TDR was calculated as the difference in repolarization time between the epicardial and endocardial nodes of the heart model.Results: Patients: The interval from the apex to the end of the T wave was shorter during biventricular pacing (102 +/- 18 ms) and LV pacing (106 +/- 21 ms) than during RV pacing (117 +/- 22 ms, P < or =.005). T-wave amplitude and area were low during biventricular pacing (287 +/- 125 microV and 56 +/- 22 microV.s, respectively, P = .0006 vs RV pacing). T-wave complexity was high during biventricular pacing (0.42 +/- 0.26, P = .004 vs RV pacing). Simulations: Repolarization patterns were highly similar to the preceding depolarization patterns. The repolarization patterns of different pacing modes explained the observed magnitudes of the ECG repolarization indices. Average and local TDR were not different between pacing modes.Conclusion: In patients treated with CRT, ECG repolarization indices are related to pacing-induced activation sequences rather than transmural dispersion. TDR during biventricular and LV pacing is not larger than TDR during conventional RV endocardial pacing. [ABSTRACT FROM AUTHOR]

Background: Zones of slow conduction facilitate reentry, the major mechanism of ventricular tachycardia (VT) after myocardial infarction (MI). Identification of these zones during sinus rhythm (SR) is desirable for radiofrequency (RF) catheter ablation of VT. Local conduction velocity may correlate with electrogram duration.Objectives: The purpose of this study was to revise the definition of normal electrogram characteristics and to reevaluate the significance of low-amplitude, long-duration electrograms recorded during SR to select RF catheter ablation sites in patients with VT.Methods: Electroanatomic mapping was performed during SR in 10 control patients with normal left ventricles (LVs) and in 10 patients with stable VT after MI. From the controls, reference values for electrogram amplitude, duration (first peak to last peak distance), and fragmentation (positive deflection) were derived. In patients after MI, areas with signals exceeding these values were annotated and related to successful ablation sites.Results: Ninety-five percent of normal LV electrograms were > or =1.0 mV and < or =28 ms (range 5-39 ms) and all had < or =4 deflections. Based on these results, cutoff values were set at 1 mV, four deflections, and 40 ms. In infarcted hearts, 653 electrograms (44%) were <1.0 mV and of these, 303 were > or =40 ms with >4 deflections and restricted to circumscribed areas. Twenty-seven of 28 targeted VTs remained noninducible after RF catheter ablation within these areas, resulting in 86% sensitivity and 94% specificity for low-amplitude, long-duration electrograms predicting successful ablation sites.Conclusion: Identification of successful RF target areas during SR in patients with VT is feasible with high sensitivity and specificity using a mapping strategy based on voltage and duration criteria. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the effect of a systematic screening/treatment protocol on outcome in patients after aborted sudden death.Background: Patients after aborted sudden death are at high risk for recurrent events. In this regard, systematic screening is mandatory to reveal the underlying etiology, to detect and subsequently treat reversible causes, and to establish patient-tailored antiarrhythmic treatment.Methods: A total of 417 consecutive patients after aborted sudden death due to ventricular arrhythmias underwent echocardiography and coronary angiography. In the presence of coronary artery disease and myocardial ischemia, using stress-rest myocardial perfusion imaging/exercise testing, subsequent revascularization was performed. Patients without ischemic heart disease were further evaluated with magnetic resonance imaging, contrast echocardiography, right ventricular angiography and/or flecainide/ergonovine testing. After these diagnostic steps, final antiarrhythmic therapy was based on the outcome of electrophysiologic testing.Results: The majority of patients had ischemic heart disease (n = 300, 72%). After screening, 78 (78 of 300, 26%) patients underwent revascularization. In 69% of patients, ventricular arrhythmias were inducible during electrophysiologic testing. Therapy consisted of implantable defibrillators in 301 (72%) patients, antiarrhythmic drugs in 239 (57%) patients, and catheter ablation in 58 (14%) patients. During 5-year follow-up, only 3 (<1%) patients died suddenly. The 5-year survival rate was 82%; of 39 deaths, 10 (26%) patients died due to non-cardiac disease and 26 (67%) due to heart failure.Conclusions: Screening and treatment of patients after aborted sudden death according to a standardized protocol resulted in <1% arrhythmic deaths during 5-year follow-up. The majority of patients died of heart failure, stressing the importance of optimizing medical and surgical therapy and screening. [Copyright &y& Elsevier]