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A 53-year-old man with a subcutaneous implantable cardioverter-defibrillator (S-ICD) presented with inappropriate shocks. He underwent device extraction, and the lead was freed using a rotating mechanical dilator sheath. As patients with S-ICDs get older, extractions will become more complicated and more common. We have described a novel method of S-ICD lead extraction. (Level of Difficulty: Advanced.), Central Illustration

Objectives A prospective, multicenter study was performed to assess the safety and efficacy of the Durata and Optisure HV leads and the Ellipse VR implantable cardioverter-defibrillator (ICD) (St. Jude Medical, Sylmar, California) in a 1.5-T magnetic resonance imaging (MRI) environment. The primary safety objective was >90% freedom from MRI scan-related complications. The primary efficacy objectives were absence of change in capture threshold and absence of decrease of sensing amplitude from pre-MRI examination to 1 month after MRI. Background MRI scanning of patients has been shown to be safe in patients with magnetic resonance-conditional implantable cardioverter-defibrillators (ICD) systems. Methods Patients with a previously implanted magnetic resonance-conditional system underwent a nondiagnostic MRI scan. After the scan, a questionnaire was given to investigators and patients who returned for 1-month follow-up examination. A subset of patients underwent ventricular tachyarrhythmia or ventricular fibrillation (VT/VF) induction testing after the MRI to evaluate defibrillation function. Results There were 220 patients (81% male; 62.1 ± 11.2 years of age) enrolled who received an MRI scans from 29 centers. All primary safety and efficacy endpoints were met (p Conclusions The MRI Ready MRI-conditional ICD system is safe, and electrical performance was not affected in patients receiving a 1.5-T whole-body MRI scan. Investigators reported favorable collaboration between cardiologists and radiologists in the MRI Ready IDE clinical trial. (A Clinical Evaluation of the Durata or Optisure High Voltage Leads and Ellipse VR ICD Undergoing MRI, an IDE Study [MRI Ready IDE]; NCT02787291)

Clinical Case Download : Download full-size image A 44-year-old female presented after a resuscitated out-of-hospital cardiac arrest and was diagnosed with a nonischemic cardiomyopathy, as her coronary angiogram showed clean coronary arteries and her echocardiogram showed a left ventricular ejection fraction (LVEF) of 40%, LV end-diastolic dimension (LVEDD) 58 mm, and moderate mitral regurgitation. A right ventricular biopsy did not show evidence of myocarditis. She had a left bundle branch block (LBBB) with a QRS duration of 138 ms. She had no family history of premature sudden death, cardiomyopathy, or heart failure symptoms. She underwent placement of a single ventricular lead implantable cardioverter defibrillator. Ten years later, she subsequently had shocks for ventricular fibrillation (VF) with syncope. She was then initiated on mexiletine 200 mg orally twice daily, in addition to sotalol 80 mg orally twice daily. Her LVEF gradually diminished. Despite optimal medical therapy, her LVEF declined to 21%, LVEDD 59 mm and she developed moderate mitral regurgitation. She also experienced progressive decline of her exercise tolerance. She used to be able to go up three flights of stairs to her office without problems. Now, her office was moved to the first floor and even after one flight of stairs she had a lot of shortness of breath. She also noticed a significant loss of energy, especially since the last VF episode. She required intermittent use of Lasix for the treatment of pedal edema. She denied any orthopnea or paroxysmal nocturnal dyspnea or significant weight loss. She continued to have a baseline LBBB with a QRS of 138–142 ms at different recordings. How would you manage this patient going forward? Abstract Implantable cardioverter defibrillators (ICD) and cardiac resynchronization therapy (CRT) devices have been proven to improve survival in patients with heart failure (HF) and reduced ejection fraction (EF). Sex-specific differences in the incidence and etiology of sudden cardiac death (SCD) and HF exist, but the indications for ICD and CRT implants are universal for both sexes. However, the studies from which the indications were obtained include a much smaller percentage of women than men, and they were not powered to examine sex-specific differences in outcome. This is a systematic review of the epidemiology and incidence of SCD, pivotal ICD and CRT trials, and exploration of the sex-specific differences in outcomes and utilization of these devices. Efforts should be made in the future for a higher enrollment of women in such trials, ultimately resulting in a decrease in sex-based disparities in the utilization of these devices.

Introduction: The most common complication of alcohol septal ablation (ASA) is periprocedural high grade AV block (HGAVB). No long-term follow-up of cardiovascular implantable electronic device (CIED) utilization after ASA has been reported. Hypothesis: Pacemaker dependence on long-term follow up can be predicted by ECG or procedural characteristics. Methods: We analyzed all patients with hypertrophic cardiomyopathy who underwent ASA from December 1998 to December 2019 at our institution and received their first CIED within 30 days after ASA for HGAVB. All available follow-up interrogations were reviewed. CIED dependence was defined as ventricular pacing of ≥5%. CIED programming was determined by the patients’ cardiologists' discretion. Results: A total of 103 patients with hypertrophic cardiomyopathy underwent ASA. The average follow up duration was 10.1 years. Within 30 days after ASA, a total 25 patients received a CIED for HGAVB. On long term follow-up 16 patients (64%) were found to be CIED-dependent. Baseline characteristics, including pre and post-ASA ECG, were not significantly different between dependent and non-dependent patients (Table). The only predictor for CIED dependence was >1 ml of alcohol injected during ASA (OR 6.0, p Conclusions: CIED implantation after ASA is common. Almost two thirds of patients who received CIED for postprocedural HGAVB were CIED-dependent on long term follow up. CIED dependence can be predicted by amount of injected alcohol >1 ml during ASA.

Background Interrupted inferior vena cava (IVC) is a rare venous anomaly that complicates the treatment of patients who require electrophysiology (EP) procedures. Methods We describe five consecutive cases of patients with interrupted IVC who presented to the EP laboratory requiring interventional procedures including catheter ablation for atrial fibrillation and supraventricular tachycardia and left atrial appendage closure. All cases were successfully completed utilizing a variety of approaches to vascular access including transseptal puncture via transhepatic and internal jugular approaches. Conclusion Procedures in the EP lab can be performed successfully in patients with interrupted IVC.

Infections after placement of cardiac implantable electronic devices (CIEDs) are associated with substantial morbidity and mortality. There is limited evidence on prophylactic strategies, other than the use of preoperative antibiotics, to prevent such infections.We conducted a randomized, controlled clinical trial to assess the safety and efficacy of an absorbable, antibiotic-eluting envelope in reducing the incidence of infection associated with CIED implantations. Patients who were undergoing a CIED pocket revision, generator replacement, or system upgrade or an initial implantation of a cardiac resynchronization therapy defibrillator were randomly assigned, in a 1:1 ratio, to receive the envelope or not. Standard-of-care strategies to prevent infection were used in all patients. The primary end point was infection resulting in system extraction or revision, long-term antibiotic therapy with infection recurrence, or death, within 12 months after the CIED implantation procedure. The secondary end point for safety was procedure-related or system-related complications within 12 months.A total of 6983 patients underwent randomization: 3495 to the envelope group and 3488 to the control group. The primary end point occurred in 25 patients in the envelope group and 42 patients in the control group (12-month Kaplan-Meier estimated event rate, 0.7% and 1.2%, respectively; hazard ratio, 0.60; 95% confidence interval [CI], 0.36 to 0.98; P = 0.04). The safety end point occurred in 201 patients in the envelope group and 236 patients in the control group (12-month Kaplan-Meier estimated event rate, 6.0% and 6.9%, respectively; hazard ratio, 0.87; 95% CI, 0.72 to 1.06; P0.001 for noninferiority). The mean (±SD) duration of follow-up was 20.7±8.5 months. Major CIED-related infections through the entire follow-up period occurred in 32 patients in the envelope group and 51 patients in the control group (hazard ratio, 0.63; 95% CI, 0.40 to 0.98).Adjunctive use of an antibacterial envelope resulted in a significantly lower incidence of major CIED infections than standard-of-care infection-prevention strategies alone, without a higher incidence of complications. (Funded by Medtronic; WRAP-IT ClinicalTrials.gov number, NCT02277990.).

Cardiac resynchronization therapy (CRT) has become the gold standard for patients with systolic left ventricular function, left ventricular ejection fraction less than or equal to 35%, wide complex QRS, and symptomatic heart failure. Annual implantation volume has steadily increased because of expanding indications for CRT. Improved survival resulted in many of these patients having their CRT devices for many years and eventually requiring an increased number of device-related procedures, including coronary sinus lead revisions and replacements following a coronary sinus lead extraction.

Aims Lead perforation is a rare, well-known complication of cardiac implantable electronic device (CIED) implants, whose management is mostly not evidence-based. Main management strategies include conservative approach based on clinical and lead function follow-up vs. routine invasive lead revision approach. This study compared the complications of both strategies by composite endpoint, including recurrent perforation-related symptoms, recurrent pericardial effusion (PEf), lead dysfunction, and device infection during 12 month follow-up. Methods and results Multicentre retrospective analysis, inquiring data from imaging studies, device interrogation, pericardiocentesis, and clinical charts of patients with suspected perforating leads between 2007 and 2014 in five hospitals. All cases were reviewed by electrophysiologist and defined as definite perforations by suggestive symptoms along with lead perforation on imaging, bloody PEf on pericardiocentesis shortly after implant, or right ventricular (RV) lead non-capture along with diaphragmatic stimulation upon bipolar pacing. Clinical outcomes associated with both management approaches were compared, with respect to the composite endpoint. The study included 48 definitive perforation cases: 22 managed conservatively and 26 via lead revision. Conservative management was associated with an increased composite endpoint compared with lead revision (8/22 vs. 1/26; P = 0.007). The dominant complication among the conservative cohort was appearance of cardiac tamponade during follow-up; 5/6 occurring in cases which presented with no or only mild PEf and were treated by antiplatelets/coagulants during or shortly after CIED implantation. Conclusion A conservative management of CIED lead perforation is associated with increased complications compared with early lead revision. Lead revision may be the preferred management particularly in patients receiving antiplatelets/coagulants.

Background Prolongation of the baseline ECG PR interval is frequently encountered among cardiac resynchronization therapy (CRT) recipients. There are conflicting data regarding the association of a prolonged PR interval with long-term clinical outcome in this patient group. Objective The purpose of this study was to compare clinical outcomes and response to CRT in patients with normal ( Methods In this study, 283 patients (normal PR interval: n=158; prolonged PR interval: n=125) with documented baseline intrinsic PR interval were followed for 3 years after CRT implantation. The study population consisted of 24.7% women (mean age 66 ± 13 years, left ventricular ejection fraction 24% ± 7%). Results A Cox proportional hazard model identified baseline PR interval as a predictor of the composite end-point (all-cause mortality, heart failure hospitalization, left ventricular assist device implantation, and heart transplantation) in univariate analysis (hazard ratio [HR] 1.49, 95% confidence interval [CI] 1.02–2.17, P = .04) but not in multivariate analysis. It also predicted heart failure hospitalization in univariate (HR 1.6, 95% CI 1.1–2.4, P = .02) and multivariate analysis (HR 1.6, 95% CI 1.0–2.3, P = .03). A prolonged PR interval was associated with lower probability of reverse remodeling defined as ≥10% improvement in ejection fraction (64% vs 77%, P = .057), especially in patients with non–left bundle branch block ECG morphology (41% vs 68%, P = .03). Conclusion Among patients with CRT, a prolonged baseline PR interval is an independent predictor of worse prognosis and lower probability of reverse remodeling, especially for patients with non–left bundle branch block morphology on ECG.

Background Chronic anticoagulation is recommended for atrial fibrillation (AF) patients with thromboembolic risk factors regardless of AF duration/frequency. Continuous rhythm assessment with pacemakers (PMs)/implantable cardioverter-defibrillators (ICDs) and use of direct-acting oral anticoagulants (DOACs) may allow anticoagulation only around AF episodes, reducing bleeding without increasing thromboembolic risk. Objective The purpose of this study was to evaluate the feasibility/safety of intermittent DOAC use guided by continuous remote AF monitoring via dual-chamber PMs or ICDs. Methods Patients with nonpermanent AF, current DOAC use, CHADS2 score ≤3, a St. Jude Medical dual-chamber PM or ICD, and rare AF episodes were followed with biweekly and AF-alert based remote transmissions. Patients free of AF episodes lasting ≥6 minutes with a total AF burden Results Among 48 patients (mean age 71.3 years; 65% male; 79% paroxysmal AF; 87% CHADS2 score 1–2), 14,826 days of monitoring were completed. Patients used DOACs for 3763 days, representing a 74.6% reduction in anticoagulation time compared to chronic administration. Adverse events included 2 gastrointestinal bleeds (both on DOAC), 1 fatal intracerebral bleed (off DOAC), and no thromboembolic/stroke events. Conclusion Among patients with rare AF episodes and low-to-moderate stroke risk, PM/ICD-guided DOAC administration is feasible and decreased anticoagulation utilization by 75%. Few adverse events occurred, although the study was not powered to assess these outcomes. PM/ICD-guided DOAC administration may prove a viable alternative to chronic anticoagulation. Future studies are warranted.

Chronic kidney disease (CKD) severity is associated with increased morbidity and mortality in congestive heart failure (CHF). There is a paucity of data regarding renal improvement after cardiac resynchronization therapy (CRT) and its potential impact on clinical outcomes, especially in patients with severe CKD.

Background Magnetic resonance imaging (MRI) has been considered contraindicated in patients with cardiac pacemakers (PPMs). Recently, Medtronic (MDT) MRI SureScan PPM (Medtronic Inc., Minneapolis, MN, USA) and leads were introduced into clinical practice in the United States of America. Objective To compare MDT CapSureFix 5086 MRI SureScan lead-associated perforation and dislodgement rates with MDT non-MRI SureScan active fixation leads. Methods We retrospectively analyzed the records of all patients implanted with MDT CapSureFix 5086 MRI SureScan leads as well as all patients implanted with MDT 4076 and 5076 leads at our institution from April 2011 to April 2014. Results Four of 72 patients implanted with MDT CapSureFix 5086 MRI SureScan leads (5.5%) had evidence of lead perforation, necessitating pericardiocentesis in three cases and lead revision in one case. Three of the four perforations were delayed perforations, presenting more than 3 weeks postimplant. Two patients implanted with MDT CapSureFix 5086 MRI SureScan leads (2.8%) had lead dislodgement. Of 420 patients implanted with MDT non-MRI SureScan leads, there were two perforations (0.47%) and four dislodgements (0.9%). There were significantly increased lead perforations associated with MDT CapSureFix 5086 MRI SureScan leads (P = 0.005) and a nonsignificant trend toward increased dislodgements (P = 0.18) when compared with MDT non-MRI SureScan leads. Conclusion In contradiction to prior studies, this retrospective study suggests an increased perforation rate with MDT CapSureFix 5086 MRI SureScan leads. Most perforations were delayed perforations, presenting more than 3 weeks postimplant. Higher volume prospective studies with longer follow-up are needed to confirm our findings.

Cardiac resynchronization therapy has emerged as the gold standard for heart failure patients with left ventricular systolic dysfunction and electrical dyssynchrony from an intrinsic intraventricular conduction delay or right ventricular pacing. However, the limits imposed by the coronary sinus venous anatomy restrict the applicability of the technology for many potential recipients. Furthermore, conventional resynchronization, by virtue of utilizing a single site of epicardial origin for left ventricular activation, is non-physiological. Several technologies on the horizon, including multisite pacing, left ventricular endocardial, and leadless devices, and direct His-bundle pacing are aimed at improving the response rate of cardiac resynchronization and extending candidacy to patients ineligible for conventional therapy. In this review, we discuss the limitations of the present technology and the role for these new therapies.

Impact of Prior Valve Surgery in CRT Patients. Aims: Cardiac valve surgery (CVS) has been implicatedasapotentialbarriertooptimalresponseaftercardiacresynchronization therapy(CRT)though prospective data regarding outcome remains limited. We sought to determine CRT response in patients with a prior history of CVS. Methods and Results: We performed a retrospective analysis of a prospectively acquired cohort of CRT patients with history of CVS. Echocardiographic response was evaluated at baseline and 6 months. The coprimary endpoints were time to first heart failure (HF) hospitalization and a composite of all-cause mortality, transplantation and left ventricular assist device (LVAD) assessed over a 3-year follow-up period. The study group consisted of 569 patients undergoing CRT. Of these, 86 patients had a history of CVS (46.5% aortic, 37.2% mitral, 16.3% combined, and tricuspid), and were compared to 483 patients with no history of CVS. Baseline clinical and echocardiographic characteristics were not significantly different between the groups except for a higher incidence of atrial fibrillation (AF; 74.4% vs. 55.3%; P = 0.001), coronary artery bypass surgery (CABG; 58.1% vs. 38.7%; P = 0.001), and longer QRS duration (167.6 ± 29.3 milliseconds vs. 159.4 ± 27.5 milliseconds; P = 0.01) in those with prior CVS. Survival with respect to HF hospitalization and composite outcome was comparable in both groups. Echocardiographic response (improvement in left ventricular ejection fraction of 10%) was similar. No difference in clinical or echocardiographic outcome was found by type of valve surgery performed. Conclusion: Despite a higher incidence of AF, CABG, and longer QRS duration, history of CVS is not associated with worse clinical or echocardiographic outcome after CRT. (J Cardiovasc Electrophysiol, Vol.

This editorial refers to ‘Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study’, by P. Ritter et al ., doi:10.1093/eurheartj/ehv214. If at first the idea is not absurd, then there will be no hope for it.A. Einstein Since the first permanent pacemaker implant, almost 60 years ago, there has been continued progress and evolution of these devices. The technology has advanced on many fronts, with longer battery lives, smaller sized generators, with an intelligent ‘adaptive functionality’ closely mimicking the human physiology. However, contemporary implant technology has been disadvantaged by the need for a subcutaneous implantable device (with a risk for infection or erosion) and an attached pacing electrode system within the cardiac vasculature that itself is at risk for fracture and infection. The additional hazard of extracting malfunctioning or infected leads poses further challenges. Notably, almost 10% of the ∼700 000 pacemakers implanted annually worldwide are associated with lead-related problems.1,2 This, in turn, has created the need for a leadless pacemaker system. Although Spickler et al . first reported the theory of a totally self-contained leadless intracardiac pacemaker in 1970,3 it is only through recent technological advancements in battery energy, endocardial fixation, and delivery systems that this concept has become a reality. The leadless device not only has improved the aesthetics of an implant through eliminating the visible lump and scar of a conventional pectoral pacemaker implant but also has potentially reduced the risk of complications, related to infections and lead …

Background— T-wave alternans (TWA) has been implicated in the pathogenesis of ventricular arrhythmias and sudden cardiac death. However, to estimate and suppress TWA effectively, the phase of TWA must be accurately determined. Methods and Results— We developed a method that computes the beat-by-beat integral of the T-wave morphology, over time points within the T-wave with positive alternans. Then, we estimated the signed derivative of the T-wave integral sequence, which allows the classification of each beat to a binary phase index. In animal studies, we found that this method was able to accurately identify the T-wave phase in artificially induced alternans ( P P P P score ), to suppress TWA. Finally, we demonstrated that using the phase of TWA we can suppress spontaneous TWA during acute ischemia; 77.6% for alternans voltage ( P score ( P Conclusions— We developed a method to quantify the temporal variability of the TWA phase. This method is expected to enhance the utility of TWA in predicting ventricular arrhythmias and sudden cardiac death and raises the possibility of using upstream therapies to abort a ventricular tachyarrhythmia before its onset.

A 32-year-old woman was seen in the neurology clinic because of episodes of altered consciousness — staring, aphasia, and occasional sudden loss of postural tone and collapse. EEG revealed left-temporal-lobe seizures; brain imaging revealed a left-temporal-lobe mass.

Background Repolarization alternans (RA), a pattern of ventricular repolarization that repeats on an every other beat basis, has been closely linked with the substrate associated with ventricular tachycardia/ventricular fibrillation. Objective To evaluate a novel method to suppress RA. Methods We have developed a novel method to dynamically (on R-wave detection) trigger pacing pulses during the absolute refractory period. We have tested the ability of this method to control RA in a structurally normal swine heart in vivo. Results RA induced by triggered pacing can be measured from both intracardiac and body surface leads and the amplitude of R-wave triggered pacing-induced alternans can be locally modulated by varying the amplitude and width of the pacing pulse. We have estimated that to induce a 1 μV change in alternans voltage on the body surface, coronary sinus, and left ventricle leads, a triggered pacing pulse delivered in the right ventricle of 0.04±0.02, 0.05±0.025, and 0.06±0.033 μC, respectively, is required. Similarly, to induce a 1 unit change in K score (ratio of alternans peak to noise), a pacing stimulus of 0.93±0.73, 0.32±0.29, and 0.33±0.37 μC, respectively, is required. We have been able to demonstrate that RA can be suppressed by R-wave triggered pacing from a site that is within or across ventricles. Lastly, we have demonstrated that the proposed method can be used to suppress spontaneously occurring alternans in the diseased heart. Conclusion We have developed a novel method to suppress RA in vivo.

Implicated in up to half of all cardiovascular mortality among developed nations worldwide,w1 w2 sudden cardiac death (SCD) is associated with approximately 450 000 deaths annually in the USA and >700 000 deaths in Europe.w3 w4 In 23% of out-of-hospital and 17% of inhospital cardiac arrests, the initial observed rhythm was ventricular tachycardia (VT) or ventricular fibrillation (VF), both potentially treatable with defibrillation.w5 w6 Large scale trials have also demonstrated that implantable cardioverter defibrillators (ICDs) can improve survival through terminating malignant ventricular arrhythmias, particularly among SCD survivorsw7 and heart failure patients with systolic dysfunction.w8–w12 Based on these data, there has been a dramatic surge in the utilisation of ICDs over the past two decades, with 116 000 ICD device implantations in the USA in 2009 alone, of which 53 000 (46%) were implanted in patients younger than the age of 65 years.w6 With increasing use of ICDs, there has also been heightened awareness of device-related complications and associated risk–benefit trade-offs. Specifically, although it is clear that appropriate ICD therapies extend survival, inappropriate ICD shocks are common and occur in a similar magnitude of patients.w12 w13 Frequent ICD shocks are associated with diminished quality of life,w14 w15 and significant anxiety, depression and post-traumatic stress in a minority of patients.w16 w17 In addition, inappropriate ICD shocks have been linked to the possibility of proarryhthmiaw18–w20 and are associated with increased mortality in some patients, although any causal relationship remains controversial.1–3 w21–w23 Conversely, interventions to prevent inappropriate ICD shocks reduce morbidity,4 and also have been shown to reduce heart failure hospitalisation.5 As the use of ICDs continues to expand further into primary prevention and younger patient populations, identifying at-risk patients and devising a treatment plan for patients suffering from inappropriate shocks are critical. Strategies to avoid inappropriate …

The likelihood of success of conservative management of obstructive hypertrophic cardiomyopathy (HC) and the predictors of failure of conservative therapy are not known. We therefore evaluated the efficacy of an algorithm for the management of symptoms and predictors of failed conservative therapy in 249 consecutive symptomatic patients with obstructive HC referred to a dedicated HC program for management in general or for septal reduction therapy (SRT) in particular. There was considerable practice variation in the extent to which conservative therapy was optimized before referral for SRT. Over 3.7 ± 2.9-year follow-up, symptoms resolved with addition of or increase in dosage of a β blocker, calcium channel blocker, or disopyramide in 16%, 10%, and 10% of patients, respectively. Pacing with short atrioventricular delay controlled symptoms in 4 of 9 patients. In 63% of patients, conservative measures failed to control symptoms. Multivariate predictors of failure of conservative therapy were presence of New York Heart Association class III or IV symptoms (hazard ratio 2.0, 95% confidence interval 1.4 to 2.9, p = 0.001) and greater septal wall thickness (hazard ratio 1.06, 95% confidence interval 1.02 to 1.10, p = 0.003) at presentation. At time of presentation, 93 patients (37%) were already on optimal therapy and were referred for SRT. Of the remaining 156 patients who did not require immediate SRT, 93 (60%) were free from a recommendation for SRT at the end of the follow-up period. In conclusion, in symptomatic patients with obstructive HC, conservative therapy is successful in >1/3 of referred patients at 3.7-year follow-up, obviating SRT in these patients. Clinicians in programs offering SRT should optimize conservative therapy before recommending SRT.

Electrical Delay in Apically Positioned LV Leads. Introduction: In recent studies, an anatomical apical left ventricular (LV) lead pacing location has been associated with deleterious outcome after cardiac resynchronization therapy (CRT). The differential impact of the LV lead electrical location in these patients remains unknown. Methods and Results: Thirty-one consecutive CRT patients (mean age 71.7 ± 12.7 years, 55% left bundle-branch block [LBBB] morphology) with an apical LV lead and LV lead electrical delay (LVLED) were studied. Anatomical LV lead location was determined via review of coronary venography and chest radiographs. Electrical location was assessed through intraprocedural LVLED measurement. Patients were dichotomized into either “long” LVLED (LVLED ≥ 50% of QRS) or “short” LVLED groups (LVLED < 50%). Patients in the long LVLED group demonstrated significantly greater freedom from a primary composite endpoint of all-cause death, heart failure hospitalization, and cardiac transplantation at 2 years (81% vs 30%, P = 0.007 vs short LVLED patients). Longer LVLED was also associated with more favorable LV remodeling (LV end-systolic volume –41.9 ± 10.3 mL vs –4.3 ± 17.2 mL; P = 0.05), and greater improvement in LV ejection fraction (+9.4 ± 2.9% vs +2.3 ± 7.5%; P = 0.04). Even after multivariate adjustment, LVLED remained an independent predictor of the primary composite endpoint (HR 0.47, P = 0.031). Conclusions: Electrical lead localization, as estimated by LVLED ≥ 50%, is associated with improved long-term clinical outcome and measures of LV remodeling in patients with apical LV leads. Intraprocedural LVLED assessment may provide incremental utility in targeting lead placement even in conventionally unfavorable anatomical segments. (J Cardiovasc Electrophysiol, Vol. 24, pp. 182-187, February 2013)

Implicated in up to half of all cardiovascular mortality among developed nations worldwide,w1 w2 sudden cardiac death (SCD) is associated with approximately 450 000 deaths annually in the USA and >700 000 deaths in Europe.w3 w4 In 23% of out-of-hospital and 17% of inhospital cardiac arrests, the initial observed rhythm was ventricular tachycardia (VT) or ventricular fibrillation (VF), both potentially treatable with defibrillation.w5 w6 Large scale trials have also demonstrated that implantable cardioverter defibrillators (ICDs) can improve survival through terminating malignant ventricular arrhythmias, particularly among SCD survivorsw7 and heart failure patients with systolic dysfunction.w8–w12 Based on these data, there has been a dramatic surge in the utilisation of ICDs over the past two decades, with 116 000 ICD device implantations in the USA in 2009 alone, of which 53 000 (46%) were implanted in patients younger than the age of 65 years.w6 With increasing use of ICDs, there has also been heightened awareness of device-related complications and associated risk–benefit trade-offs. Specifically, although it is clear that appropriate ICD therapies extend survival, inappropriate ICD shocks are common and occur in a similar magnitude of patients.w12 w13 Frequent ICD shocks are associated with diminished quality of life,w14 w15 and significant anxiety, depression and post-traumatic stress in a minority of patients.w16 w17 In addition, inappropriate ICD shocks have been linked to the possibility of proarryhthmiaw18–w20 and are associated with increased mortality in some patients, although any causal relationship remains controversial.1–3 w21–w23 Conversely, interventions to prevent inappropriate ICD shocks reduce morbidity,4 and also have been shown to reduce heart failure hospitalisation.5 As the use of ICDs continues to expand further into primary prevention and younger patient populations, identifying at-risk patients and devising a treatment plan for patients suffering from inappropriate shocks are critical. Strategies to avoid inappropriate …

Background Predictable progression to battery depletion is necessary for device management in patients with pacemakers or implantable cardioverter-defibrillators, particularly in patients who either are pacemaker dependent or have required implantable cardioverter-defibrillator therapies. Objective To determine the incidence and characteristics of unexpected battery depletion in patients implanted with a cardiac resynchronization therapy – defibrillator (CRT-D) device. Methods All patients with a St Jude Atlas+ HF or Atlas II HF CRT-D device implanted between 2004 and 2007 at the Massachusetts General Hospital and the Nashville VA Medical Center (Vanderbilt University) were studied. All patients with early generator depletion (transition of generator voltage above specified elective replacement indicator [ERI] to end of life [EOL] in less than 90 days) were evaluated further. Results Eight cases (mean age 69.6 ± 9 years) with abrupt battery depletion were identified among 191 patients (4.2%) implanted with a St Jude Atlas CRT-D device. The longevity of 8 premature depletion devices was 46.4 ± 10 months (median 45 months). The battery voltage in these 8 devices decreased from a mean of 2.48 ± 0.03 V (above ERI) to 2.3 ± 0.08 V (below ERI) over 33.3 ± 23 days (range 1–59 days; median 38.5 days). One device reached EOL status within 1 day of having battery voltage above ERI and another device within 12 days. Conclusion The incidence of abrupt battery depletion was 4.2% in patients implanted with a St Jude Atlas CRT-D device. No common mechanism has been identified for this failure. Close monitoring of battery voltage and timely generator replacement are required in patients with these devices.

The incidence of spontaneous coronary artery dissection (SCAD), defined as nontraumatic, noniatrogenic, and nonatherosclerotic separation of the coronary artery wall, is rising with increasing awareness and advances in diagnostics. Optimal management of SCAD patients remains unclear because

Background: Infection following cardiovascular implantable electronic device (CIED) replacement is a serious complication, and rates of infection have increased. Analysis of procedural and clinical data from device replacement procedures collected by the REPLACE Registry may provide insights into infection prevention strategies and outcomes. Methods: We prospectively evaluated procedural complications in patients undergoing CIED replacement over 6 months from 72 U.S. sites. Major and minor infections were predefined and adjudicated by an independent blinded clinical events committee. Data regarding infection prevention strategies and infectious outcomes were analyzed for their potential relationships. Results: A total of 1,744 patients were included in REPLACE. All patients received preoperative intravenous antibiotics and 68.7% received postoperative systemic antibiotic therapy. CIED infection developed in 22 patients (1.3%), of which 14 cases were major (0.8%, 95% confidence interval [CI] 0.4%–1.3%) and eight were minor (0.5%, 95% CI 0.2%–0.9%). Patients with infections were more likely to have had postoperative hematomas (five of 22 [22.7%] vs 17 of 1,722 [0.98%], P = 0.002). Participating sites experiencing infection rates >5% were more likely to use povidone-iodine for topical antisepsis, had lower implantation volume, and had patients with higher Charlson Comorbidity Index (2.79 vs 2.32, 95% CI for difference 0.08–0.86, P = 0.019). Conclusions: In this multicenter prospective study with 6 months of follow-up, infections associated with CIED replacements were surprisingly infrequent, possibly due to the use of preoperative antibiotics. Patients with infections were more likely to have had a postoperative hematoma, and sites with higher infection rates had sicker patients and lower overall procedural volume. (PACE 2012; 35:81–87)

Background— Electric alternans is a pattern of variation in the shape of ECG waveform that occurs every other beat. In humans, alternation in ventricular repolarization, known as repolarization alternans (RA), has been associated with increased vulnerability to ventricular tachycardia/fibrillation and sudden cardiac death. Methods and Results— This study investigates the spatio-temporal variability of intracardiac RA and its relationship to body surface RA in an acute myocardial ischemia model in swine. We developed a real-time multichannel repolarization signal acquisition, display, and analysis system to record ECG signals from catheters in the right ventricle, coronary sinus, left ventricle, and epicardial surface before and after circumflex coronary artery balloon occlusion. We found that RA is detectable within 4 minutes after the onset ischemia and is most prominently seen during the first half of the repolarization interval. Ischemia-induced RA was detectable on unipolar and bipolar leads (both in near- and far-field configurations) and on body surface leads. Far-field bipolar intracardiac leads were more sensitive for RA detection than body surface leads, with the probability of body surface RA detection increasing as the number of intracardiac leads detecting RA increased, approaching 100% when at least three intracardiac leads detected RA. We developed a novel, clinically applicable intracardiac lead system based on a triangular arrangement of leads spanning the right ventricular and coronary sinus catheters, which provided the highest sensitivity for intracardiac RA detection when compared with any other far-field bipolar sensing configurations. Conclusions— In conclusion, intracardiac alternans, a complex spatio-temporal phenomenon associated with arrhythmia susceptibility and sudden cardiac death, can be reliably detected through a novel triangular right ventricular–coronary sinus lead configuration.

The optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricle (LV) lateral or posterolateral wall. However, little is known about the impact of segmental pacing site on outcomes.We assessed the impact of segmental LV lead position on CRT outcomes.Patients (n = 115) undergoing CRT were followed prospectively. Segmental LV lead position along the longitudinal axis (apical, midventricle, or basal) was determined retrospectively by examining coronary sinus (CS) venograms and chest X-rays. The primary outcome was a combined endpoint of heart failure hospitalization, cardiac transplantation, or all-cause mortality. Secondary outcomes included change in New York Heart Association (NYHA) functional class and degree of LV reverse remodeling.Patients were divided into two groups based on LV lead position: apical (n = 25) and basal/midventricle (n = 90). The apical group was older (72.9 +/- 8.9 vs. 66.5 +/- 13.3 years; P = .010) and more likely to have ischemic cardiomyopathy (77% vs. 52%, P.001). During a mean follow-up of 15.1 +/- 9.0 months, event-free survival was significantly lower in the apical group: 52% vs. 79%, hazard ratio [HR] 2.7 (95% confidence interval [CI] 1.5-5.5, P = .006). The adverse impact of apical lead placement remained significant after adjusting for clinical covariates: HR 2.3 (95% CI 1.1-4.8, P = .03). The apical group also experienced less improvement in NYHA functional class and less LV reverse remodeling.Apical LV lead placement is associated with worse CRT outcomes. Preferential positioning of LV leads in the basal/midventricle segments may improve outcomes.

Indications for catheter ablation of atrial fibrillation (AF) have expanded to include increasingly complex cases, such as long-standing persistent AF and structural heart disease. Although pulmonary vein isolation remains essential for most ablation procedures, the role of substrate modification has taken on increasing importance. Despite the various ablation strategies available, single-procedure efficacy remains suboptimal among patients with structural heart disease or long-standing persistent AF, where recurrence rates may exceed 50% after a single procedure. These high rates of AF recurrence support the notion that currently available procedural end points are ineffective in identifying which patients are most likely to benefit from substrate modification and defining when that substrate has been sufficiently modified such that additional ablation is unnecessary. In order to improve outcomes, the next generation of procedural end points should seek to define specific properties of the underlying atrial electrical substrate and characterize the impact of catheter ablation on those electrophysiologic properties. The use of substrate-driven end points would be a major step in the process of moving from empiric ablation lesions to a customized ablation strategy based on atrial physiology. In this article, we review current approaches to catheter ablation of AF and discuss specific procedural end points as they pertain to each ablation strategy. We also provide a paradigm for the future development of novel substrate-driven procedural end points.

The Sprint Fidelis lead has an increased incidence of lead fracture. The manufacturer has recommended programming alerts to preempt lead malfunction due to fracture. The current trigger for an alert is an increase in the right ventricular pacing impedance to greater than 1,000 Omega. Our patient suffered multiple inappropriate implantable cardioverter defibrillator therapies with stable impedance less than 1,000 Omega. This case of lead fracture would not have been detected with these programming alerts. Additional programming measures may detect lead fractures, including changing the lower detection for impedances, arranging for a percentage change in the impedance trend to trigger an alarm, or programming the device to warn if there is an increase in nonphysiologic short R-R interval counts.

Background— It is common practice to empirically limit the radiofrequency (RF) power when ablating the posterior left atrium during atrial fibrillation ablation to avoid thermal injury to the esophagus. The objective of this study was to determine whether RF energy delivery limited by luminal esophageal temperature (LET) monitoring is associated with a reduction in esophageal injury compared with a strategy of RF power limitation alone. Methods and Results— Eighty-one consecutive patients who underwent atrial fibrillation ablation followed by esophageal endoscopy were included in this observational study. All patients underwent extraostial electric pulmonary vein isolation by using an electroanatomic mapping system and irrigated RF ablation. All RF applications on the posterior left atrium were limited to 35 W. A commercially available, single-thermocouple esophageal probe was used to monitor LET in a subset of patients (n=67). In these cases, applications were promptly interrupted when LET was ≥38.5�C; further applications were performed at reduced power to obtain a LET P Conclusions— These data suggest that LET monitoring may be associated with a reduction in esophageal injury compared with power limitation alone.

Background— Atrial tachycardia (AT) that develops after ablation of atrial fibrillation often poses a more difficult clinical situation than the index arrhythmia. This study details the use of an impedance-based electroanatomic mapping system (Ensite NavX) in concert with a specialized multielectrode mapping catheter for rapid, high-density atrial mapping. In this study, this activation mapping was combined with entrainment mapping to eliminate ATs developing late after atrial fibrillation ablation. Methods and Results— All study patients developed AT after ablation for atrial fibrillation. The approach to AT ablation consisted of 4 steps: use of a 20-pole penta-array catheter to map the chamber rapidly during the rhythm of interest, analysis of the patterns of atrial activation to identify wave fronts of electric propagation, targeted entrainment at putative channels, and catheter ablation at these “isthmuses.” All ablations were performed with irrigated radiofrequency ablation catheters. Forty-one ATs were identified in 17 patients (2.4�1.6 ATs per patient). Using the multielectrode catheter in conjunction with the Ensite NavX system, we created activation maps of 33 of 41 ATs (81%) (mean cycle length, 284�71 seconds) with a mean of 365�108 points per map and an average mapping time of 8�3 minutes. Of the 33 mapped ATs, 7 terminated either spontaneously or during entrainment maneuvers. Radiofrequency energy was used to attempt ablation of 26 ATs; 25 of 26 of the ATs (96%) were terminated successfully by ablation or catheter pressure. Conclusions— This study demonstrates a strategy for rapidly defining and eliminating the scar-related ATs typically encountered after ablation of atrial fibrillation.

Background:Cardiac resynchronization therapy (CRT) outcome varies significantly among patients. We aimed to determine the impact of age, gender, and heart failure etiology on the long-term outcome of patients receiving CRT. Methods:A total of 117 patients with drug-refractory heart failure, New York Heart Association (NYHA) Class III or IV, and a wide QRS complex, who received CRT, were followed for one year. Long-term outcome was measured as a combined end point of hospitalization for heart failure and/or all cause mortality. Efficacy of CRT was compared between men and women, between older and younger patients, and between patients with ischemic and nonischemic heart disease. Time to the primary end point was estimated by the Kaplan-Meier method and comparisons were made using the Breslow-Wilcoxon test. Results:Baseline clinical characteristics were comparable between gender, age, and heart failure etiology subgroups. There was no significant difference in the combined end point between older versus younger (age >70, (n = 71), versus age < 70, (n = 46), P = 0.52); both genders (men, n = 91 vs women, n = 26, P = 0.46) and etiology of the cardiomyopathy (ischemic (n = 79) vs nonischemic (n = 38), P = 0.12). Substratification of the genders by the etiology of the cardiomyopathy, showed that women with ischemic cardiomyopathy (IW, n = 10) had a trend to a worse outcome compared to the other groups i.e., nonischemic women (NIW, n = 16), ischemic men (IM, n = 69), and nonischemic men (NIM, n = 22), P = 0.04. After adjusting for potential covariates, a Cox regression analysis showed no significant difference between the groups (P = 0.61). Conclusions:CRT outcome appears independent of age, gender, and heart failure etiology in this single institution study.

With the increasing use of pre-procedural imaging techniques such as magnetic resonance imaging (MRI) and their integration with electroanatomic mapping systems in catheter ablation for atrial fibrillation (AF), atypical anatomy of the pulmonary veins (PV), left atrium (LA) and their relationship to the thoracic aorta is increasingly recognized. To characterize atypical LA-PV anatomies revealed by pre-procedural MRI and their impact on the safety and efficacy of AF ablation procedures. We reported four patients who underwent AF ablation in our electrophysiology laboratory within the last year who had atypical LA-PV anatomy due to aorta compression recognized by pre-procedural three-dimensional (3D) MRI and anatomic segmentation. Twelve matched control cases without aorta compression were selected for comparison of LA-PV measurements. All four patients in this study had a normal-sized descending thoracic aorta that compressed the left atrium, and all patients had evidence of left inferior PV narrowing secondary to external compression. Two patients also had anterior LA compression leading to posteriorly displaced interatrial septum. Isolation was not achieved in some PVs due to anatomic restraints, concern regarding risks of aortic injury and worsening pulmonary vein stenosis. There were no immediate or short-term complications. Extrinsic compression by the descending aorta on the LA and PV leading to LA compression and/or preexisting PV stenosis is uncommon but has potentially important implications on the overall safety and efficacy of AF ablation procedures. Pre-procedural imaging plays an important role in assessing such anatomic variations and planning of the procedures in order to minimize the risk of PV stenosis and aortic injury.

Background— The present study examines the safety and feasibility of using a remote magnetic navigation system to perform endocardial and epicardial substrate-based mapping and radiofrequency ablation in patients with scar-related ventricular tachycardia (VT). Methods and Results— Using the magnetic navigation system, we performed 27 procedures on 24 consecutive patients with a history of VT related to myocardial infarction, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, or sarcoidosis. Electroanatomic mapping of the left ventricular, right ventricular, and ventricular epicardial surfaces was constructed in 24, 10, and 12 patients, respectively. Complete-chamber VT activation maps were created in 4 patients. A total of 77 VTs were inducible, of which 21 were targeted during VT with the remotely navigated radiofrequency ablation catheter alone. With a combination of entrainment and activation mapping, 17 of 21 VTs (81%) were successfully terminated in a mean of 8.4±8.2 seconds; for the remainder, irrigated radiofrequency ablation was necessary. The mean fluoroscopy times for endocardial and epicardial mapping were 27±23 seconds (range, 0 to 105 seconds) and 18±18 seconds (range, 0 to 49 seconds), respectively. In concert with a manually navigated irrigated ablation catheter, 75 of 77 VTs (97%) were ultimately ablated. Four patients underwent a second procedure for recurrent VT, 3 with the magnetic navigation system. After 1.2 procedures per patient, VT did not recur during a mean follow-up of 7±3 months (range, 2 to 12 months). Conclusions— The present study demonstrates the safety and feasibility of remote catheter navigation to perform substrate mapping of scar-related VT in a wide range of disease states with a minimal amount of fluoroscopy exposure.

Integration of 3-D electroanatomic mapping with Computed Tomographic (CT) and Magnetic Resonance (MR) imaging is gaining acceptance to facilitate catheter ablation of atrial fibrillation. This is critically dependent on accurate integration of electroanatomic maps with CT or MR images. We sought to examine the effect of patient- and technique-related factors on integration accuracy of electroanatomic mapping with CT and MR imaging of the left atrium.Sixty-one patients undergoing catheter-based atrial fibrillation (AF) ablation procedures were included. All patients underwent cardiac CT (n = 11) or MR (n = 50) imaging, and image integration with real-time electroanatomic mapping of the aorta and left atrium (LA). CARTO-Merge software (Biosense-Webster) was used to calculate the overall average accuracy of integration of electroanatomic points with the CT and MR-derived reconstructions of the LA and aorta.There was a significant correlation between LA size assessed by electroanatomic mapping (112 +/- 31 ml) and average integration error (1.9 +/- 0.6 mm) (r = 0.46, p = 0.0003). There was also greater integration error for patients with LA volume/= 110 ml (n = 31) versus110 ml (n = 30) (p = 0.004). In contrast, there was no significant association between average integration error and paroxysmal versus persistent AF, left ventricular ejection fraction, days from imaging to electroanatomic mapping, or images derived from CT versus MR.Patients with larger LA volume may be prone to greater error during integration of electroanatomic mapping with CT and MR imaging. Strategies to reduce integration error may therefore be especially useful in patients with large LA volume.

Permanent cardiac pacemakers have historically been considered a contraindication to magnetic resonance imaging (MRI).The purpose of the ProMRI Phase B Study, a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI pacemaker system in patients undergoing thoracic spine and cardiac MRI.The ProMRI Phase B study enrolled 245 patients with stable baseline pacing indices implanted with an Entovis pacemaker (DR-T or SR-T) and Setrox 53-cm and/or 60-cm lead(s). Device interrogation was performed at enrollment, pre- and post-MRI scan, and 1 and 3 months post-MRI. End-points were (1) freedom from MRI- and pacing system-related serious adverse device effects through 1 month post-MRI; (2) freedom from atrial and ventricular MRI-induced pacing threshold increase (0.5 V); and (3) freedom from P- and R-wave amplitude attenuation (50%), or P wave1.5 mV, or R wave5.0 mV at 1 month post-MRI.In total, 216 patients completed the MRI and 1-month post-MRI follow-up. One adverse event possibly related to the implanted system and the MRI procedure occurred, resulting in a serious adverse device effect-free rate of 99.6% (220/221; P.0001. Freedom from atrial and ventricular pacing threshold increase was 100% (194/194, P.001) and 100% (206/206, P.001) respectively. Freedom from P- and R-wave amplitude attenuation was 98.2% (167/170, P.001) and 100% (188/188, P.001) respectively.The results of the ProMRI Phase B study demonstrate the clinical safety and efficacy of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac MRI conditions.

The ProMRI Study is a multicenter prospective, single arm, non-randomized study to evaluate the clinical safety of the Biotronik ProMRI Pacemaker System in patients (Pts) undergoing cardiac or thoracic spine 1.5T MRI scanning. Pts with an Entovis (DR-T or SR-T) and Setrox 53cm or 60cm lead(s) were

International audience; AIMS: For patients undergoing cardiac resynchronization therapy (CRT) with implantable cardioverter-defibrillator (ICD; CRT-D), the effect of an improvement in left ventricular ejection fraction (LVEF) on appropriate ICD therapy may have significant implications regarding management at the time of ICD generator replacement. METHODS AND RESULTS: We conducted a meta-analysis to determine the effect of LVEF recovery following CRT on the incidence of appropriate ICD therapy. A search of multiple electronic databases identified 709 reports, of which 6 retrospective cohort studies were included (n = 1740). In patients with post-CRT LVEF ≥35% (study n = 4), the pooled estimated rate of ICD therapy (5.5/100 person-years) was significantly lower than patients with post-CRT LVEF \textless35% [incidence rate difference (IRD): -6.5/100 person-years, 95% confidence interval (95% CI): -8.8 to -4.2, P \textless 0.001]. Similarly, patients with post-CRT LVEF ≥45% (study n = 4) demonstrated lower estimated rates of ICD therapy (2.3/100 person-years) compared with patients without such recovery (IRD: -5.8/100 person-years, 95% CI: -7.6 to -4.0, P \textless 0.001). Restricting analysis to studies discounting ICD therapies during LVEF recovery (study n = 3), patients with LVEF recovery (≥35 or ≥45%) had significantly lower rates of ICD therapy compared with patients without such recovery (P for both \textless0.001). Patients with primary prevention indication for ICD, regardless of LVEF recovery definition, had very low rates of ICD therapy (0.4 to 0.8/100-person years). CONCLUSION: Recovery of LVEF post-CRT is associated with significantly reduced appropriate ICD therapy. Patients with improvement of LVEF ≥45% and those with primary prevention indication for ICD appear to be at lowest risk

Intracardiac electrograms can be used to guide left ventricular (LV) lead placement during implantation of cardiac resynchronization therapy (CRT) devices. Although attempts often are made to ensure that the LV lead is positioned at a site of maximal electrical delay, information on whether this is useful in predicting the acute hemodynamic response and long-term clinical outcome to CRT is limited.The purpose of this study was to assess the ability of intracardiac (electrogram) measurements made during LV lead placement in patients undergoing CRT for predicting acute hemodynamic response and long-term clinical outcome to CRT.Seventy-one subjects with standard indications for CRT underwent electrogram measurements and echocardiograms performed in the acute phase of this study. The LV lead electrical delay was measured intraoperatively from the onset of the surface ECG QRS complex to the onset of the sensed electrogram on the LV lead, as a percentage of the baseline QRS interval. Echocardiographic assessment of the hemodynamic response to CRT was measured as an intra-individual percentage change in dP/dt over baseline (DeltadP/dt, derived from the mitral regurgitation Doppler profile) with CRT on and off. dP/dt was measurable in 48 subjects, and acute responders to CRT were defined as those with DeltadP/dtor=25%. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to the primary endpoint was estimated by the Kaplan-Meier method, with comparisons made using the log rank test.LV lead electrical delay correlated weakly with DeltadP/dt of the combined group (n = 48, r = 0.311, P = .029) but was strongly correlated with DeltadP/dt in the nonischemic subgroup (n = 20, r = 0.48, P = .027). LV lead electrical delay (%) was significantly longer in acute responders (69.6 +/- 23.9 vs 31.95 +/- 11.57, P = .002) among patients with nonischemic cardiomyopathy. A reduced LV lead electrical delay (50% of the QRS duration) was associated with worse clinical outcome within the entire cohort (hazard ratio: 2.7, 95% confidence interval: 1.17-6.68, P = .032) as well as when stratified into ischemic and nonischemic subgroups.Measuring LV lead electrical delay is useful during CRT device implantation because it may help predict hemodynamic response and long-term clinical outcome.

CRT and LV Lead Proximity to an Akinetic Segment. Background: Previous studies report that the optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricular (LV) lateral and postero-lateral (PL) wall. However, little is known regarding whether pacing over an akinetic site impacts the contractile response and long-term outcome from CRT. Methods and Results: A total of 38 patients with ischemic cardiomyopathy were studied for their acute hemodynamic and 12-month clinical response to CRT. The intraindividual percentage change in dP/dt (%ΔdP/dt), over baseline, was derived from the mitral regurgitation (MR) Doppler profile with CRT on versus off. Two-dimensional echocardiography was used for myocardial segmentation and determinination of akinetic sites. LV lead implant site was determined using angiographic and radiographic data and categorized as being "on" (group 1) or "off" (group 2) an akinetic site. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to primary endpoint was estimated by the Kaplan-Meier method. Clinical characteristics and acute hemodynamic response was similar in both (group 1 [n = 14]; %AdP/dt 48.8 ± 67.4% vs group 2 [n = 24]; %ΔdP/dt 32.2 ± 40.1%, P = 0.92). No difference in long-term outcome was observed (P = 0.59). In contrast, lead placement in PL or mid-lateral (ML) positions was associated with a better acute hemodynamic response when compared to antero-lateral (AL) positions (PL, %ΔdP/dt 45.7 ± 50.7% and ML, %ΔdP/dt 45.1 ± 58.8% vs AL, %AdP/dt 2.9 ± 30.9%, respectively, P = 0.014). Conclusion: LV lead proximity to an akinetic segment does not impact acute hemodynamic or 12-month clinical response to CRT.

Electrical alternans is a pattern of variation in the shape of the ECG waveform that appears on an every-other-beat basis. In humans, alternation in ventricular repolarization, namely, repolarization alternans, has been associated with increased vulnerability to ventricular tachycardia/ventricular fibrillation and sudden cardiac death. This study investigates the utility of implantable cardioverter defibrillator electrograms to estimate repolarization alternans preceding a tachyarrhythmic event. It is demonstrated that microvolt-level repolarization alternans is present prior to an arrhythmic event, and one can record low-amplitude-noise signals that can be used to obtain reliable estimates of repolarization alternans. This study eventually may lead to new methods that would prevent the onset of malignant tachyarrhythmias.

OBJECTIVES We sought to explore the relative contributions of ventricular remodeling and myocardial dysfunction to heart failure in pressure overload hypertrophy (POH). BACKGROUND The mechanism that underlies heart failure in POH is adverse left ventricular (LV) chamber remodeling or decreased myocardial function, or a combination of these. METHODS Twenty weeks after suprarenal aortic banding in rats, animals with POH were classified as those with heart failure (POH-HF) or those with no heart failure (POH-NHF). The LV chamber and myocardial systolic and diastolic functions were determined from in vivo and ex vivo experiments. RESULTS The LV mass was similar in both POH groups. Chamber remodeling in the POH-HF group was characterized by marked LV enlargement with a normal relative wall thickness (eccentric remodeling), whereas remodeling in the POH-NHF group was characterized by a normal chamber size and increased relative wall thickness (concentric remodeling). The LV systolic function, as determined in vivo from the end-systolic pressure-diameter relationship and ex vivo from the pressure-volume relationship, was lower in the POH-HF group than in the POH-NHF and sham-operated control groups. In contrast, myocardial function was similar in both POH groups, as determined in vivo from the stress-midwall fractional shortening relationship and myocardial systolic stiffness, and ex vivo from the slope of the LV systolic stress-strain relationship. The diastolic chamber stiffness constant was lower in the POH-HF group than in the POH-NHF group, but the myocardial stiffness constant was similar in the two POH groups. CONCLUSIONS The two POH groups differed primarily in their remodeling process, which led to a chronically compensated state in one group and to heart failure in the other. Hence, heart failure in POH is more closely related to deleterious LV remodeling than to depressed myocardial function.

Summary Background The importance of risk stratification for sudden cardiac death (SCD) after septal myectomy for hypertrophic obstructive cardiomyopathy (HOCM) has not been emphasized previously. Methods and results We report 2 patients with SCD or ventricular tachycardia (VT) after septal myectomy for HOCM in whom risk factors for SCD were identified following surgical myectomy. One received an implantable cardioverter-defibrillator (ICD), which subsequently provided appropriate discharges for VT. The other delayed ICD implantation and suffered SCD. Conclusion These cases emphasize the importance of risk stratification for SCD after septal myectomy for HOCM.

Electrocardiographic alternans, a phenomenon of beat-to-beat alternation in cardiac electrical waveforms, has been implicated in the pathogenesis of ventricular arrhythmias and sudden cardiac (SCD). However, rather than merely being associated with an increased risk for SCD, several lines of pre-clinical and clinical evidence suggest that cardiac alternans may play a causative role in generating the electrophysiologic substrate necessary for the onset of ventricular arrhythmias. In the clinical setting, a positive microvolt T-wave alternans (MTWA) test has been associated with a heightened risk of arrhythmic mortality and SCD during medium- and long-term follow-up. Although deficiencies in Ca2+ transport processes have been implicated in the genesis of alternans at the sub-cellular and cellular level, the specific underlying mechanisms have not been fully elucidated. In this chapter we propose a framework of conditions necessary to give rise to alternans from the myocyte to the whole heart level. It supports the idea that alternans results from a synergistic interaction between a vulnerable substrate and an inciting trigger event. Lastly, the potential clinical utility of modulating repolarization alternans via electrical or pharmacologic therapies to prevent life threatening arrhythmias is explored.

Background This study investigates the hypothesis that morphologic analysis of intracardiac electrograms provides a sensitive approach to detect acute myocardial infarction or myocardial infarction‐ induced arrhythmia susceptibility. Large proportions of irreversible myocardial injury and fatal ventricular tachyarrhythmias occur in the first hour after coronary occlusion; therefore, early detection of acute myocardial infarction may improve clinical outcomes. Methods and Results We developed a method that uses the wavelet transform to delineate electrocardiographic signals, and we have devised an index to quantify the ischemia‐induced changes in these signals. We recorded body‐surface and intracardiac electrograms at baseline and following myocardial infarction in 24 swine. Statistically significant ischemia‐induced changes after the initiation of occlusion compared with baseline were detectable within 30 seconds in intracardiac left ventricle ( P P P P P P ECG recordings showed that the ischemic index is statistically significantly increased compared with baseline in lead I, aVR, and all precordial leads ( P P Conclusions We present a novel method that is capable of detecting ischemia‐induced changes in intracardiac electrograms as early as 30 seconds following myocardial infarction or as early as 12 minutes preceding tachyarrhythmic events.

Background— Identifying factors predictive of mortality may be important to decrease risk associated with cardiac implantable electrical device (CIED) replacement procedures. This study aimed to determine whether clinical factors and complications independently associate with death and to develop a mortality risk prediction tool after CIED replacement. Methods and Results— The prospective REPLACE Registry determined 6-month complication and mortality rates after CIED replacement with or without planned lead addition or revision. Vital status was collected. Kaplan-Meier survival and multivariable Cox proportional hazards regression analyses were performed to identify patient, procedural, or complication variables predictive of death. The REPLACE DARE (Death After Replacement Evaluation) Score was constructed using hazard ratios, reflecting relative risk contributions of each variable, combined into an additive mortality risk score equation. At 6 months, 70 of 1744 (4.0%) patients had died. Cox regression analysis found no significant association between major complications and death. However, recent heart failure admission, New York Heart Association class III/IV, antiarrhythmic drug use, cerebrovascular disease, and chronic kidney disease stage were independently associated with 6-month mortality. The REPLACE DARE Score was 2.0±1.4 in survivors versus 3.5±1.8 in nonsurvivors ( P P Conclusions— Comorbidities, but not complications, were significantly associated with mortality after CIED replacement. The REPLACE DARE Score is a novel tool that can identify patients with substantial mortality risk. Such patients should have the relative risk and benefit of their procedure considered carefully. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00395447.

This editorial refers to ‘Worldwide experience with a totally subcutaneous ICD: early results from the EFFORTLESS S-ICD registry’[†][1], by P.D. Lambiase et al. , on page 1657 While the clinical significance of the implantable cardioverter defibrillator (ICD) in the reduction of sudden cardiac arrest remains unequivocal, the quest for the best implantable system continues. The first successful, yet experimental ICD system involved two electrodes between the pectoralis muscle and the rib cage, two sensing electrodes in the chest wall musculature, with a pulse generator and capacitor implanted intra-abdominally in animals.1 The first ICD implanted in a human in 1980 consisted of epicardial patches and sensing leads.2 Subsequently, the advent of transvenous ICD leads significantly reduced the morbidity of the procedure and complication rates, while improving clinical outcomes. The transvenous leads, however, came with the cost of a spectrum of vascular complications as well as design faults. Therefore, the quest for a better implantable system has continued. The totally subcutaneous ICD (S-ICD), an innovative strategy obviating the need for vascular access, has come on as a contender to fill this void.3 Evidence favouring the clinical use of the S-ICD came from the feasibility studies and European registries that preceded the Food and Drug Administation (FDA) approval of the device.3–5 Most of these studies have comprised smaller numbers with limited follow-up, calling into question the applicability of these results in real-world practice. The study now presented by Lambiase et al. ,6 reporting on early data from the multicentre EFFORTLESS S-ICD registry, provides valuable information on system performance and inappropriate shock rates. This registry is a laudable effort and comprises an observational, non-randomized, standard of care evaluation of S-ICD in countries outside the USA. The term ‘worldwide experience’ in the title, however, may be a misnomer, as … [1]: #fn-2

Infection is an uncommon (0% to 6.7%) but serious complication after implantable cardioverter-defibrillator (ICD) implantation. All ICD primary implants, replacements, or revisions performed at the Massachusetts General Hospital between April 1983 and May 1999 were reviewed. A total of 21 ICD-related infections (1.2%) were identified among 1,700 procedures affecting 1.8% of the 1,170 patients who underwent a primary implant, a generator change, or a revision of their systems. The mean follow-up time was 35 ± 33 months. Of the 959 patients with long-term follow-up, 19 of the 584 patients (3.2%) with abdominal and 2 of the 375 patients (0.5%) with pectoral systems developed ICD-related infections (p = 0.03). There was no significant difference between the infection rate among the 959 primary ICD implants and the 447 replacements or system revisions. Only 5 of the patients (24%) had systemic signs of infection, including fever (T>100.5) and elevated white blood count >12,000. Cultures from the wound revealed staphylococcal species in 16 patients (76%). Nineteen patients were treated with removal of the entire ICD system in addition to intravenous antibiotics for 2 to 4 weeks. A decrease in the incidence of ICD-related infection has occurred since the advent of transvenous pectoral systems. The main organism responsible for ICD infection is Staphylococcus . The mainstay of ICD infection management consists of complete removal of the entire implanted system.