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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.

Aims Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker. Methods and results Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and

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

Chronic kidney disease (CKD) severity is associated with increased morbidity and mortality in congestive heart failure. 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.This was a retrospective analysis of a prospectively collected cohort of 260 patients with CKD undergoing CRT at a single center. Renal function was compared before and after CRT. The primary end point was a composite of death, heart transplant, and left ventricular assist device (LVAD), assessed at 5 years.Patients with more severe CKD demonstrated increased risk of death, transplant, or LVAD following CRT (P = 0.015). Renal response (estimated glomerular filtration rate improvement ≥10 mL/min/1.73 m(2) ) was observed in 14% of all patients and 28% of patients with stage IV CKD. Independent predictors of renal response included left ventricular ejection fraction improvement (odds ratio [OR] 1.06, confidence interval [CI] 1.01-1.10), angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use (OR 4.31, CI 1.08-17.23), and advanced CKD stage (OR 2.19, CI 1.14-4.23). Renal response independently decreased hazard of the primary outcome (HR 0.24, CI 0.08-0.73, P = 0.01). Renal responders with stage IV CKD had 80% 5-year event-free survival, compared to 0% for nonrenal responders in stage IV (P = 0.03).Although severity of CKD is associated with poorer outcome after CRT, improvement in renal function can occur in patients across all CKD stages. Renal responders, including those with stage IV CKD, demonstrate favorable 5-year outcomes. Assessment of renal response may help better prognostic outcomes following CRT.

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.

Background In 2008, the United States spent $2.2 trillion for healthcare, which was 15.5% of its GDP. 31% of this expenditure is attributed to hospital care. Evidently, even modest reductions in hospital care costs matter. A 2009 study showed that nearly $30.8 billion in hospital care cost during 2006 was potentially preventable, with heart diseases being responsible for about 31% of that amount. Methods Our goal is to accurately and efficiently predict heart-related hospitalizations based on the available patient-specific medical history. To the best of our knowledge, the approaches we introduce are novel for this problem. The prediction of hospitalization is formulated as a supervised classification problem. We use de-identified Electronic Health Record ( EHR ) data from a large urban hospital in Boston to identify patients with heart diseases. Patients are labeled and randomly partitioned into a training and a test set. We apply five machine learning algorithms, namely Support Vector Machines (SVM), AdaBoost using trees as the weak learner, logistic regression, a naive Bayes event classifier, and a variation of a Likelihood Ratio Test adapted to the specific problem. Each model is trained on the training set and then tested on the test set. Results All five models show consistent results, which could, to some extent, indicate the limit of the achievable prediction accuracy. Our results show that with under 30% false alarm rate, the detection rate could be as high as 82%. These accuracy rates translate to a considerable amount of potential savings, if used in practice.

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.

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.To compare MDT CapSureFix 5086 MRI SureScan lead-associated perforation and dislodgement rates with MDT non-MRI SureScan active fixation leads.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.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.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.

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

Cardiac valve surgery (CVS) has been implicated as a potential barrier to optimal response after cardiac resynchronization therapy (CRT) though prospective data regarding outcome remains limited. We sought to determine CRT response in patients with a prior history of CVS.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.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.

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.

Background —The transition from compensated left ventricular hypertrophy (LVH) to heart failure is associated with alterations in the myocardial interstitium. We hypothesized that LV dilatation is associated with modifications in collagen cross-linking. Methods and Results —We studied 2 rat models of LV dilatation: (1) pressure-overload hypertrophy with heart failure (POH-F) induced by suprarenal abdominal aortic banding and (2) LVH induced by 7 months of isoproterenol (ISO, 0.04 mg · kg −1 · d −1 ) administration. In POH-F rats and in rats receiving ISO, LV dilatation and a reduced systolic chamber performance were noted. Myocardial hydroxyproline concentrations ([HPRO]) were increased in the POH-F rats, whereas in rats receiving ISO, [HPRO] was decreased. In POH-F rats, the ratio of myocardial collagen type I to type III was increased, but in rats receiving ISO, myocardial collagen I/III was unchanged. In contrast to the diverse changes in myocardial collagen concentrations and phenotypes observed in the 2 models of LV dilatation, the ratio of myocardial insoluble to soluble (relationship between cross-linked and non–cross-linked) collagen was decreased in both the POH-F and ISO groups. Moreover, administration of captopril (0.22 mmol · kg −1 · d −1 ), which inhibited the ISO-induced reduction in myocardial insoluble/soluble collagen but not the reduction in [HPRO], prevented the ISO-induced alterations in LV dimensions and performance. Conclusions —Because decreases in the ratio of myocardial insoluble to soluble collagen parallel LV dilatation in rats, reductions in myocardial collagen cross-linking may be an important mechanism contributing to LV dilatation in heart disease.

We were pleased to see the results of the validation work done by Barra et al1 in examining the performance of the REPLACE (Death After Replacement Evaluation) DARE score2 in their patient population. The DARE score results in their implantable cardioverter-defibrillator (ICD) replacement group of 228 patients yielded findings that were consistent, and, for some metrics, nearly identical, to those found in the REPLACE population of 1744 patients, despite a longer follow-up period (33 months versus 6 months in REPLACE). We also appreciated the additional efforts by Barra et al1 to compare the DARE score performance to the predictive model proposed by Bilchick et al,3 which was developed on a larger population of Medicare patients (n=17 991) receiving de novo ICD implantation for primary prevention. Although the final risk model of Bilchick et al3 was based on 7 predictor variables in a related but somewhat different patient population with a longer average follow-up (4.4 years), the concordance with 5 of the 6 predictor variables used …

Aims Several studies have reported a poor outcome with cardiac resynchronization therapy (CRT) in non-left bundle branch block (LBBB) patients. Although the left ventricular (LV) lead location is an important determinant of the clinical outcome, there is scant information regarding its role in non-LBBB patients. This study sought to examine the impact of electrical and anatomical location of the LV lead in relation to baseline QRS morphology on the CRT outcome. Methods and results A left ventricular lead electrical delay (LVLED) was measured intra-procedurally as an interval between QRS onset on the surface electrocardiogram (ECG) to the peak of sensed electrogram on LV lead and corrected for QRS width. The impact of the LVLED on time to first heart failure hospitalization (HFH), and composite outcome of all-cause mortality, HFH, LVAD implantation, and cardiac transplantation at 3 years was assessed. Among 144 patients (age 67 ± 12 years, QRS duration 156 ± 28 ms, non-LBBB 43%), HFH was higher in non-LBBB compared with LBBB (43.5 vs. 24%, P = 0.015). Within LBBB, patients with the long LVLED (≥50%) had 17% HFH vs. 53% in the short LVLED (

Both anatomic and electrical locations of the left ventricular (LV) lead have been identified as important predictors of clinical outcomes in cardiac resynchronization therapy (CRT). The impact of LV lead location on incident device-treated ventricular arrhythmia (VA), however, is not well understood.To assess the relationship between electrical and anatomic LV lead location and device treated VAs in CRT.Sixty-nine patients undergoing CRT implantation for standard indications were evaluated. Anatomic LV lead location was assessed by means of coronary venography and chest radiography and categorized as apical or nonapical. Electrical LV lead location was assessed by LV electrical delay (LVLED) and was calculated as the time between the onset of the native QRS on the surface electrocardiogram and sensed signal on the LV lead during implantation and corrected for native QRS. Incident appropriate device-treated VA was assessed via device interrogation.Apical lead placement was an independent predictor of VAs (hazard ratio 5.29; 95% confidence interval 1.69-16.5; P = .004). Among patients with a nonapical lead, LVLED50% native QRS was an independent predictor of VAs (hazard ratio 6.90; 95% confidence interval 1.53-31.1; P = .012). Those with a nonapical lead and LVLED ≥ 50% native QRS were at substantially lower risk for first incident and recurrent VAs when compared to all other patients.The apical lead position is associated with an increased risk of VAs in CRT patients. Among patients with a nonapical lead position, an LVLED of50% of the native QRS is associated with an increased risk of VAs.

Electrical Alternans and ICD Undersensing. A 71-year-old patient underwent routine single-chamber implantable cardioverter defibrillator (ICD) generator replacement. During defibrillation threshold testing, ventricular tachycardia was induced but the ICD failed twice to properly detect the tachycardia due to endocardial R wave alternans and sensing of every other beat. The problem was resolved by inserting a separate sensing/pacing lead positioned further away from the existing ICD lead.

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.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.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 rates5% 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).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.

Background Pulmonary vein isolation (PVI) is recognized as a potentially curative treatment for atrial fibrillation (AF). Ablation of complex fractionated atrial electrograms (CFAEs) in addition to PVI has been advocated as a means to improve procedural outcomes, but the benefit remains unclear. Objective This study sought t synthesize the available data testing the incremental benefit of adding CFAE ablation to PVI. Methods We performed a meta-analysis of controlled studies comparing the effect of PVI with CFAE ablation vs. PVI alone in patients with paroxysmal and nonparoxysmal AF. Results Of the 481 reports identified, 8 studies met our inclusion criteria. There was a statistically significant increase in freedom from atrial tachyarrhythmia (AT) with the addition of CFAE ablation (relative risk [RR] 1.15, P = .03). In the 5 reports of nonparoxysmal AF (3 randomized controlled trials, 1 controlled clinical trial, and 1 trial using matched historical controls), addition of CFAE ablation resulted in a statistically significant increase in freedom from AT (n = 112 of 181 [62%] for PVI+CFAE vs. n=84 of 179 [47%] for PVI alone; RR 1.32, P = .02). In trials of paroxysmal AF (3 randomized controlled trials and 1 trial using matched historical controls), addition of CFAE ablation did not result in a statistically significant increase in freedom from AT (n = 131 of 166 [79%] for PVI+CFAE vs. n=122 of 164 [74%] for PVI alone; RR 1.04, P = .52). Conclusion In these studies of patients with nonparoxysmal AF, addition of CFAE ablation to PVI results in greater improvement in freedom from AF. No additional benefit of this combined approach was observed in patients with paroxysmal AF.

H1N1 Influenza A Virus Induced Atrioventricular Block. We report a case of an 18-year-old female who presented with respiratory failure secondary to H1N1 infection, and who subsequently developed high-degree atrioventricular (AV) block. The conduction abnormalities persisted over 2 weeks following complete resolution of respiratory symptoms. A permanent pacemaker was implanted for safety and subsequent pacemaker follow-up suggested reversibility of the conduction abnormality. This case highlights the potential impact of the H1N1 influenza virus on the cardiac conduction system. (J Cardiovasc Electrophysiol, Vol. 22, pp. 711-713, June 2011)

Background— Prospective studies defining the risk associated with pacemaker or implantable cardioverter-defibrillator replacement surgeries do not exist. These procedures are generally considered low risk despite results from recent retrospective series reporting higher rates. Methods and Results— We prospectively assessed predefined procedure-related complication rates associated with elective pacemaker or implantable cardioverter-defibrillator generator replacements over 6 months of follow-up. Two groups were studied: those without (cohort 1) and those with (cohort 2) a planned transvenous lead addition for replacement or upgrade to a device capable of additional therapies. Complications were adjudicated by an independent events committee. Seventy-two US academic and private practice centers participated. Major complications occurred in 4.0% (95% confidence interval, 2.9 to 5.4) of 1031 cohort 1 patients and 15.3% (95% confidence interval, 12.7 to 18.1) of 713 cohort 2 patients. In both cohorts, major complications were higher with implantable cardioverter-defibrillator compared with pacemaker generator replacements. Complications were highest in patients who had an upgrade to or a revised cardiac resynchronization therapy device (18.7%; 95% confidence interval, 15.1 to 22.6). No periprocedural deaths occurred in either cohort, although 8 later procedure-related deaths occurred in cohort 2. The 6-month infection rates were 1.4% (95% confidence interval, 0.7 to 2.3) and 1.1% (95% confidence interval, 0.5 to 2.2) for cohorts 1 and 2, respectively. Conclusions— Pacemaker and implantable cardioverter-defibrillator generator replacements are associated with a notable complication risk, particularly those with lead additions. These data support careful decision making before device replacement, when managing device advisories, and when considering upgrades to more complex systems. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00395447.

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.

Coronary Venous Geometry in Patients Undergoing CRT. Introduction: The coronary sinus (CS) is often distorted in patients with advanced cardiomyopathy, making CS cannulation difficult. The objective of this study was to examine the impact of the underlying cardiac pathology on the variability of the CS anatomy, using rotational coronary venous angiography (RCVA). Methods and Results: Seventy-nine patients undergoing RCVA for cardiac resynchronization therapy (CRT) were evaluated: age 63 ± 15 years, 43% with prior coronary artery bypass grafting (CABG). Aspects of the CS anatomy which could impact cannulation were examined: the CS ostial angle, the posterior displacement of the CS away from the atrioventricular groove, a measure of CS curvature, and the presence of stenoses and aneurysmal dilatations. The CS ostial angle was variable (65–151°, mean 119 ± 19°

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.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 wasor =38.5 degrees C; further applications were performed at reduced power to obtain a LET38.5 degrees C. Esophageal endoscopy was performed 1 to 3 days after the procedure. Ablation-related esophageal ulcerations were identified in 9 of 81 (11%) patients. All patients were asymptomatic. Of these 81 patients, LET monitoring during ablation occurred in 67 (83%) of patients. Esophageal injury was observed more frequently (36% versus 6%, P0.006) in the group without LET monitoring.These data suggest that LET monitoring may be associated with a reduction in esophageal injury compared with power limitation alone.

We sought to assess the risk of sudden cardiac death (SCD) and ventricular arrhythmia after alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy. ASA is a nonsurgical alternative to septal myectomy for treatment of symptomatic, drug-refractory, obstructive hypertrophic cardiomyopathy. The effect of ASA on ventricular arrhythmia risk is not well established. We examined the rates of SCD among 89 patients treated with ASA. The secondary end point was ventricular tachycardia/ventricular fibrillation (VT/VF), appropriate implantable cardioverter defibrillator (ICD) therapy, or cardiac arrest after ASA among those with implanted ICDs or permanent pacemakers (n = 42). Patients were classified as either high-risk or low-risk on the basis of established clinical indications for ICD implantation. No mortality was attributable to SCD at a mean follow-up of 5.0 +/- 2.3 years in the entire cohort. Among the 42 patients with an ICD or permanent pacemaker, 9 had documented VT/VF, cardiac arrest, or appropriate ICD therapy, resulting in an annual event rate of 4.9%/year. The annual event rate for VT/VF, cardiac arrest, or appropriate ICD therapy was 2.8%/year (4 of 29 patients) in low-risk patients and 13.4% in high-risk patients (5 of 13 patients). A 10-mm Hg increase in the immediate post-ASA gradient was associated with a hazard ratio of 2.66 for arrhythmic events (95% confidence interval 1.55 to 4.56, p0.001). In conclusion, ASA was performed in patients with highly symptomatic, drug-refractory hypertrophic cardiomyopathy with no mortality attributable to SCD and an annual rate of VT/VF, cardiac arrest, or appropriate ICD therapy of 4.9%/year.

Alcohol septal ablation (ASA) is a non-surgical alternative to septal myectomy for treatment of symptomatic, drug refractory hypertrophic obstructive cardiomyopathy (HOCM). The effect of ASA on the risk of ventricular arrhythmia (VA) is unknown. There is a theoretic concern for pro-arrhythmia at the site of myocardial injury. We examined the rates of sudden cardiac death (SCD) and VA (defined as VA requiring ICD therapy or documented VT/VF) among all 88 patients treated with ASA at Massachusetts General Hospital between 1998 and 2004. Of these patients, 37 had either an ICD or a permanent pacemaker in situ that enabled surveillance for VA events. Patients were classified as either high-risk (one of the following: VA or positive EP study, syncope due to suspected VA, family history of SCD, septal thickness ≥30mm by echocardiography, or failure to augment sBP >20mmHg on stress testing), or low-risk (no high-risk features). There was no mortality attributable to sudden cardiac death (mean follow up 35±21mo). The event rate for VA in low-risk patients was 3.0% per year (2/18 patients), and 6.3% annually among high-risk patients (4/16 patients). Device data were not available on three patients. In a stepwise Cox proportional hazards multivariate analysis that included pre-ASA arrhythmia, peri-ASA arrhythmia, pre-ASA gradient, change in gradient after ASA, peak CK-MB, and post-ASA gradient, only post-ASA gradient predicted future VA (HR 1.06, 95% CI 1.03–1.10, p

Background: Intracardiac echocardiography (ICE) can be integrated with pre-procedural CT or MR imaging to direct catheter ablation of atrial fibrillation (AF). Prior work has described ICE imaging of the left atrium (LA) with the ICE probe in the RA, but it is feasible to image the LA from an ICE probe placed directly into the LA via a trans-septal puncture performed for the mapping/ablation procedure. The purpose of this study was to determine whether direct LA imaging with ICE results in improved image integration during AF ablation compared with LA imaging indirectly from the RA. Methods: Twenty-five consecutive patients undergoing an AF ablation procedure with the CARTO-Sound system were studied. A 10 French phased array catheter with an embedded CARTO navigation sensor was employed to provide 2D echocardiogram images of the LA - 13 patients underwent imaging from the RA alone and 12 patients from the LA. The accuracy of the image integration was assessed by the average integration error after surface registration and the requirement to take supplementary electroanatomic mapping points to obtain acceptable image integration. Results: Twenty-five patients (56% paroxysmal AF, average LA size = 42±8 mm, average EF = 63±10 %) were examined. There was no difference in the time or number of ultrasound contours required to create a LA anatomic map with ICE imaging from the RA versus the LA (24±17min vs. 24±25min, P=1.0, 24±16 contours vs. 29±18 contours, P=0.5). The average integration error for all patients was 2.19±0.59mm. Direct LA imaging was associated with improved integration error compared to indirect LA imaging from the RA (1.85±0.33mm versus 2.51±0.62mm, P=0.004). Image integration using RA acquired LA images had a tendency to be less accurate resulting in the primary operator acquiring additional registration points to supplement the registration process (patients requiring additional registration points for registration: 3/12 for LA imaging versus 9/13 for RA imaging of the LA, P=0.05). Conclusion: Direct ICE imaging from within the LA is feasible and associated with improved accuracy of image integration during AF ablation.

Background Three-dimensional (3D) reconstruction of the left atrium (LA) can be performed using real-time intracardiac echocardiography (ICE) to facilitate image integration during atrial fibrillation (AF) ablation. Current users of this technology generally image the LA indirectly from the right atrium (RA). Objective The purpose of this study was to assess the feasibility and accuracy of image integration with placement of the ICE catheter directly in the LA to visualize the LA. Methods Thirty consecutive patients undergoing an AF ablation with the CARTO-Sound system were enrolled. A 10-Fr phased-array ICE catheter was used to obtain two-dimensional echocardiographic images of the LA; in 15 patients the ICE probe was placed in the LA, and in 15 patients it was placed only in the RA. Sequential images were obtained and merged with a preacquired computed tomography/magnetic resonance image. The accuracy of image integration was assessed by the value of the average image integration error after surface registration. Results Thirty patients (60% paroxysmal AF, LA size=42 ± 7 mm, ejection fraction=62% ± 10%) were studied. There was no difference in the time required to create the LA anatomic map and perform image integration with imaging from the LA versus the RA (22 ± 22 vs. 24 ± 16 minutes; P = .8). The number of ultrasound contours obtained was also similar (LA = 26 ± 17 vs. RA=24 ± 16; P = .7). The average integration error was less with direct LA imaging (LA = 1.83 ± 0.32 vs. RA=2.52 ± 0.58 mm; P = .0004). Conclusion Direct LA imaging with ICE is feasible and results in improved LA visualization and image integration.

Background Recent studies have reported a possible increased risk of delayed perforation with the St. Jude Riata defibrillator lead. Objective The purpose of this study was to determine the incidence and time of occurrence of this complication in a large number of patients who underwent implantationm at a single center. Methods We reviewed the data and clinical course on all patients who underwent implantation of the St. Jude Riata (1580/1581, 1590/1591, and the 7000/7001 ST series) right ventricular defibrillator lead at the Massachusetts General Hospital between June 2001 and October 2007. Data were compared with all Medtronic Sprint Fidelis leads implanted during the same time period. Results Of a total of 416 implanted Riata leads, follow-up data at 6 weeks and 3 months was available for 87% and 75% of patients, respectively. There were 6 cases of lead perforation (6 of 233, 2.6%) with the 1580/1581 series, no cases of lead perforation (0 of 92) with the 1590/1591 series, and 2 cases of perforation (2 of 92, 2.2%) with the 7000/7001 ST series. Interrogation the day after implantation did not reveal any abnormalities. Patients with perforation developed symptoms of chest pain or shortness of breath within 3 weeks post-implantation; interrogation revealed pacing thresholds of >5 V at 0.5 ms within the first follow-up period of 6 weeks. Conclusion All cases of perforation with the St. Jude Riata lead occurred within 6 weeks post-implantation and showed pacing thresholds >5 V at 0.5 ms. There were no cases of delayed perforation after 6 weeks in 307 patients with at least 3 months of follow-up.

Magnetic resonance (MR) imaging of the left atrium (LA) can be integrated with electroanatomic mapping systems to guide catheter ablation of atrial fibrillation (AF). The usefulness of this technique is dependent on the accuracy of image integration.The aim of this study is to determine the effect of heart rhythm at the time of pre-procedure MR imaging and heart rhythm at the time of ablation on integration error.Fifty-two consecutive patients who underwent catheter ablation for AF were included. All patients underwent MR imaging of LA and pulmonary veins and image integration with real-time electroanatomic mapping. The rhythm at the time of MR imaging and on the day of ablation was recorded. CARTO-Merge software (Biosense-Webster) was used to calculate the average accuracy of integration of electroanatomic points with MR-derived reconstructions.There was no significant difference in integration error between patients who were in AF at the time of their MR vs. those who were in sinus rhythm at the time of their MR (1.76 +/- 0.26 vs. 1.88 +/- 0.31 mm, p = 0.15). There was also no significant difference in integration error between patients who were in concordant vs. discordant rhythms at the time of MR vs. day of ablation (1.81 +/- 0.23 vs. 1.89 +/- 0.32 mm, p = 0.40). There was a trend toward less integration error between patients who were in AF on the day of ablation vs. those in sinus rhythm (1.74 +/- 0.26 vs. 1.89 +/- 0.31 mm, p = 0.07).Image integration can be performed to direct catheter ablation of AF regardless of the rhythm at the time of imaging and ablation.

T-wave alternans and QT dispersion were compared as predictors of the outcome of electrophysiologic study and arrhythmia-free survival in patients undergoing electrophysiologic evaluation. T-wave alternans was a highly significant predictor of these 2 outcome variables, whereas QT dispersion was not.

Introduction: Atrial tachycardias (AT) originating from the anteroseptal region of the aortic root, near the atrioventricular node can be challenging to eliminate safely by catheter ablation. In this study, we examine the characteristics of anteroseptal ATs in a cohort of patients at our centers, and demonstrate the long-term efficacy and safety of targeting the arrhythmias from within the base of the noncoronary aortic valve cusp (NCC). Methods & Results: From among a cohort of 54 patients with symptomatic focal AT undergoing invasive electrophysiological evaluation, the point of earliest right atrial (RA) activation was at the peri-AV nodal region in 10 patients, just postero-superior to the His-bundle. Before further mapping, RA lesions placed in two patients were unsuccessful in eliminating the arrhythmia. Because of its proximity to the interatrial septum, the base of the NCC was mapped using a retrograde aortic approach, and revealed a point of early activation without the presence of a His potential. The arrhythmia terminated with

Background : Patients who are anti-coagulated following pulse generator implantation have a 20% risk of hematoma development in the pre-pectoral pocket. In general, hematomas are correlated with patient discomfort & pain, lead to increased risk of infections, & may require surgical drainage leading to longer hospitalization. Objectives : This investigation was conducted to evaluate safety & effectiveness associated with use of D-Stat ® Flowable Hemostat following implantation of a pulse generator compared to standard of care. Safety endpoint evaluated the incidence of major study-related adverse events & effectiveness endpoint evaluated the incidence rate of clinically significant hematomas. Clinically relevant hematoma was defined as alteration in the standard of care. Methods : Two hundred sixty nine anticoagulated patients were enrolled at ten sites & followed through 8 weeks post-procedure. Patients undergoing implantation were randomized to either D-Stat Flowable Hemostat or standard of care. Results : No statistical differences were observed in the baseline demographics between treatment groups. The D-Stat Flowable group presented with 65.4% males compared to 71.4% in the control group. Mean age was 73.3 years in the D-Stat Flowable group vs 72.2 years in the control group. Pulse generator distribution between the study groups was 54.4% pacemakers & 45.5% ICDs in the D-Stat Flowable group vs 54.9% pacemakers & 45.1% ICDs in the control group. The safety of the D-Stat Flowable was successfully demonstrated as the incidence rate of major complications experienced in both groups (D-Stat Flowable: 21.3%; Control: 27.8%) was equivalent (p value 0.0008). The effectiveness of D-Stat Flowable was successfully demonstrated as the overall rate of clinically relevant hematomas experienced in the D-Stat Flowable group (11.8%) was significantly less than that of the control group (22.6%) (p-value 0.0231). Conclusions : The findings from this investigation demonstrate the use of D-Stat Flowable within the pre-pectoral pocket in anti-coagulated patient population undergoing placement of a pulse generator is safe and effective. Use of D-Stat Flowable resulted in a 48% reduction in the rate of clinically relevant hematomas in the target population.

Background: Alcohol septal ablation (ASA) is a promising treatment option for patients with hypertrophic obstructive cardiomyopathy (HOCM), but the creation of myocardial infarct during the procedure has raised concern about the proarrhythmic risk of ASA. We analyzed the incidence of clinically significant ventricular tachycardia (VT) and sudden cardiac death (SCD) following ASA at our center. Methods: A total of 97 ASAs in 88 patients were performed between 1998 and 2007 at MGH. 34 of these patients had an implantable cardiac defibrillator (ICD) or pacemaker (PPM) implanted prior to or immediately following ASA. 8 of 34 patients had prior ICD implants for either secondary (n=4) or primary (n=4) prevention for SCD. 8 patients had prior PPMs. 3 patients had implantation of ICD post-ASA and 15 patients had PPM implanted following ASA due to atrioventricular block (AVB). Clinical records as well as device data were analyzed to determine incidence of VT or SCD following ASA. Results: There were no deaths attributable to SCD in our cohort of 88 patients (mean follow-up 35 +/− 21 months, range 4 to 70 months). 1 patient with a previous ICD for primary prevention had VT storm 6 days following ASA. 1 patient who had a cardiac arrest 11 days following the ASA (thought to be a bradycardic arrest, since he had intermittent high grade AVB post-ASA) received an ICD. Neither of these patients had subsequent detections or therapies for VT. 1 patient was upgraded to an ICD following ASA due to NSVT, and 2 patients had ICD implants for NSVT or high risk of SCD. The former had subsequent detection of NSVT 24 months after implant, and therapy for VT 3 years later. 2 patients had upgrades of their PPM to an ICD > 12 months after ASA (for positive electrophysiology studies at other centers), but had no detection or therapies during the follow-up period. No other patients had therapies for tachyrrhythmias. Conclusion: In our experience of 97 procedures, we observed 1 episode of VT storm in the first week following ASA, 1 cardiac arrest, likely bradycardic, in the first 2 weeks after ASA, and only 1 patient with clinically significant VT years after ASA. Our data suggest that close follow-up is warranted in the 2 weeks after ASA, but that ASA does not seem to have a long-term proarrhythmic effect in patients with HOCM.

Aims Although acute haemodynamic improvement in response to cardiac resynchronization therapy (CRT) is reflective of a favourable cardiac contractile response, there is limited information regarding not only its ability to predict long-term clinical outcome but also cardiac-substrate-specific differences in the prognostic value of this measure. Methods and results Fifty-three heart failure patients (69 ± 11 years) with low left ventricle ejection fraction (LVEF) (22 ± 6%), wide QRS (169 ± 31 ms), and indications for CRT were included. There were no significant differences in age, New York Heart Association (NYHA) class, medications, QRS width, or LVEF between ischaemic ( n = 37) and non-ischaemic ( n = 16) groups. Echocardiograms were performed within 24 h of implantation with device OFF and ON. Acute haemodynamic response was measured as LV d P /d t derived from the CW Doppler of mitral regurgitation. Percentage change in d P /d t was used to classify patients: high- (HR: Δd P /d t > 25%) or poor-responders (PR: Δd P /d t ≤ 25%). Clinical response to CRT was defined by a combined endpoint of hospitalizations and all-cause mortality at 12 months. HR group had a significantly better outcome compared to the PR group ( P -value = 0.004) irrespective of the aetiology of the cardiomyopathy. Conclusion Echocardiographic assessment of the acute haemodynamic response to CRT predicts long-term clinical outcome in both ischaemic and non-ischaemic cardiomyopathy.

3D Anatomy of the Left Atrium. Background: Pulmonary vein isolation (PVI) has become one of the primary treatments for symptomatic drug-refractory atrial fibrillation (AF). During this procedure, delivery of ablation lesions to certain regions of the left atrium can be technically challenging. Among the most challenging regions are the ridges separating the left pulmonary veins (LPV) from the left atrial appendage (LAA), and the right middle pulmonary vein (RMPV) from the right superior (RSPV) and right inferior (RIPV) pulmonary veins. A detailed anatomical characterization of these regions has not been previously reported. Methods: Magnetic resonance angiography (MRA) was performed in patients prior to undergoing PVI. Fifty consecutive patients with a RMPV identified by MRA were included in this study. Ridges associated with the left pulmonary veins were examined in an additional 30 patients who did not have a RMPV. Endoluminal views were reconstructed from the gadolinium-enhanced, breath-hold three-dimensional MRA data sets. Measurements were performed using electronic calipers. Results: The width of the ridge separating the LPV from the LAA was found to be 3.7 ± 1.1 mm at its narrowest point. The segment of this ridge with a width of 5 mm or less was 16.6 ± 6.4 mm long. The width of the ridges separating the RMPV from the RSPV and the RIPV was found to be 3.0±1.5 mm and 3.1 ±1.8 mm, respectively. There were no significant differences between LPV ridges for patients with versus without a RMPV. Conclusion: The width of the ridges of atrial tissue separating LPV from the LAA and the RMPV from its neighboring veins may explain the technical challenge in obtaining stable catheter positions in these areas. A detailed assessment of the anatomy of these regions may improve the safety and efficacy of catheter ablation at these sites.

Background With the increasing use of implantable cardioverter-defibrillators (ICDs), device complications are becoming more common. Fungal-related ICD infections have rarely been reported, and little is known about the presentation, prevalence, and treatment options for these morbid infections. Objectives The purpose of this study was to characterize the clinical features, treatment, and outcomes of patients with fungal ICD infections. Methods We performed a retrospective review of ICD procedures performed at a single academic center and identified all ICD-related infections managed between 1983 and 2005. Results Among a total of 3,648 ICD-related procedures performed between 1983 and 2005, we identified 47 (1.3%) cases of ICD infections, of which 5 (0.1%) were due to a fungal pathogen. Fungal infections were more likely to be associated with abdominal devices, to have a local rather than systemic infection, and to have a longer duration from the original implant to presentation. All patients were treated with ICD system explantation and antifungal therapy. Conclusion Fungal infection of ICDs is a rare but serious complication of device implantation that must be treated aggressively with complete hardware explantation and prolonged antifungal therapy. Because most infections are late complications and have indolent onsets, a high level of clinical suspicion is required for early diagnosis.

Cardiac resynchronization therapy (CRT) is an important treatment for patients with congestive heart failure and ventricular dyssynchrony, but response to CRT is highly variable. We assessed whether a scoring system that encompasses a combination of patient selection and procedural variables would improve prediction of CRT response. Thirty-nine patients who underwent CRT with echocardiographic assessment of baseline contractility and left ventricular (LV) dyssynchrony, intraprocedural assessment of LV lead electrical delay, and postprocedural chest radiography were included. Baseline LV dyssynchrony was measured by Doppler tissue velocity imaging as the maximum time difference between peak systolic velocity of anterior, lateral, posterior, and septal walls. The hemodynamic effect of CRT was measured by Doppler analysis of mitral regurgitation as percent change in maximal +dP/dt (DeltadP/dt) with CRT on versus off. Acute responders to CRT were defined as Deltadp/dtor=25%. Clinical response was measured as a combined end point of hospitalization for heart failure and all-cause mortality. A 4-point response score was generated using variables associated with DeltadP/dt and assigning 1 point for a dorsoventral LV/right ventricular interlead distance10 cm, 1 point for a LV lead electrical delayor=50%, 1 point for a baseline maximum +dP/dt600 mm Hg/s, and 1 point for a maximum time difference100 ms. In conclusion, there was a significant association between response score (0 to 4 points) and acute hemodynamic response to CRT (p0.0001). Kaplan-Meier analysis associated a higher response score with improved 12-month event-free survival after CRT implantation (p=0.0019).

Acute and subacute complete heart block (CHB) are sequelae of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy. Temporary pacemakers are routinely placed at the time of ASA, but there are no widely accepted guidelines for their management. This study examined acute predictors of subacute CHB in 52 consecutive ASA procedures in 48 patients without preexisting permanent pacemakers. Acute CHB occurred during 32 ASA procedures (62%), with the return of atrioventricular conduction on the day of ASA in all cases. New intraventricular conduction defects (IVCDs) were noted after 32 procedures (62%); in 9 of these, there was new first-degree atrioventricular block as well. CHB recurred subacutely 36 +/- 22 hours after 13 ASA procedures (25%). In 5 of these cases, there was absent or inconsistent ventricular escape rhythm. Subacute CHB did not occur in 9 cases without acute CHB during ASA or new IVCDs after ASA. Acute CHB during ASA, new IVCDs after ASA, and new first-degree atrioventricular block after ASA incrementally increased the risk for subacute CHB. In conclusion, patients with acute CHB during ASA or new IVCDs after ASA are at high risk for developing subacute CHB, sometimes without a reliable escape rhythm; these patients should therefore have temporary pacing support foror = 48 hours after ASA or the last occurrence of CHB. Patients without acute CHB during ASA or new IVCDs after ASA are at low risk for subacute CHB.