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Introduction: Dual‐coil leads (DC‐leads) were the standard of choice since the first nonthoracotomy implantable cardioverter/defibrillator (ICD). We used contemporary data to determine if DC‐leads offer any advantage over single‐coil leads (SC‐leads), in terms of defibrillation efficacy, safety, clinical outcome, and complication rates. Methods and Results: In the Shockless IMPLant Evaluation study, 2500 patients received a first implanted ICD and were randomized to implantation with or without defibrillation testing. Two thousand and four hundred seventy‐five patients received SC‐coil or DC‐coil leads (SC‐leads in 1025/2475 patients; 41.4%). In patients who underwent defibrillation testing (n = 1204), patients with both lead types were equally likely to achieve an adequate defibrillation safety margin (88.8% vs 91.2%; P = 0.16). There was no overall effect of lead type on the primary study endpoint of "failed appropriate shock or arrhythmic death" (adjusted HR 1.18; 95% CI, 0.86‐1.62; P = 0.300), and on all‐cause mortality (SC‐leads: 5.34%/year; DC‐leads: 5.48%/year; adjusted HR 1.16; 95% CI, 0.94‐1.43; P = 0.168). However, among patients without prior heart failure (HF), and SC‐leads had a significantly higher risk of failed appropriate shock or arrhythmic death (adjusted HR 7.02; 95% CI, 2.41‐20.5). There were no differences in complication rates. Conclusion: In this nonrandomized evaluation, there was no overall difference in defibrillation efficacy, safety, outcome, and complication rates between SC‐leads and DC‐leads. However, DC‐leads were associated with a reduction in the composite of failed appropriate shock or arrhythmic death in the subgroup of non‐HF patients. Considering riskier future lead extraction with DC‐leads, SC‐leads appears to be preferable in the majority of patients. [ABSTRACT FROM AUTHOR]

Background Primary prophylactic implantable cardioverter defibrillator ( ICD) therapy is indicated for patients with reduced left ventricular ejection fraction ( LVEF). We aimed to determine if preoperative clinical risk profiling can predict long-term benefit, and if clinical risk scores can be applied and improved in a patient cohort outside the clinical trial setting. Methods Using registry data, 789 patients with reduced LVEF who received ICDs for primary prevention during 2006-2011 were identified (age 64 ± 11 years, 82% men, 63% ischemic etiology, 52% cardiac resynchronization therapy with defibrillator). The patients were divided into three risk groups, based on the presence of baseline clinical risk factors (age >70, QRS duration >120 ms, New York Heart Association class III- IV, atrial fibrillation history, or creatinine >106 μmol/L). Endpoints were all-cause mortality and survival free of adequate ICD therapy. Results Mean follow-up was 39 ± 18 months. Annual mortality was 7.6%, and increased with risk group ( p < .001). Rates of appropriate antitachycardia pacing and shock therapy were not statistically different between the groups, and ranged from 11%-16% and 6%-14%, respectively. By combining the previous risk score with data on diabetes, a better independent prediction of mortality was achieved; mortality rates then ranged from 11% (low-risk) to 46% (high-risk) ( p < .0001). Conclusions Implantable cardioverter defibrillator therapies occur across the spectrum of comorbidities in a population with systolic heart failure. However, all-cause mortality is considerably higher in the group of patients with accumulated risk factors, and using the proposed scoring system can be helpful for the evaluation and risk stratification of the patient prior to making a decision for a primary prophylactic ICD implantation. [ABSTRACT FROM AUTHOR]

ICD Lead Position and Outcome Introduction We aim to compare the acute and long-term success of defibrillation between non-apical and apical ICD lead position. Methods and Results The position of the ventricular lead was recorded by the implanting physician for 2,475 of 2,500 subjects in the Shockless IMPLant Evaluation (SIMPLE) trial, and subjects were grouped accordingly as non-apical or apical. The success of intra-operative defibrillation testing and of subsequent clinical shocks were compared. Propensity scoring was used to adjust for the impact of differences in baseline variables between these groups. There were 541 leads that were implanted at a non-apical position (21.9%). Patients implanted with a non-apical lead had a higher rate of secondary prevention indication. Non-apical location resulted in a lower mean R-wave amplitude (14.0 vs. 15.2, P < 0.001), lower mean pacing impedance (662 ohm vs. 728 ohm, P < 0.001), and higher mean pacing threshold (0.70 V vs. 0.66 V, P = 0.01). Single-coil leads and cardiac resynchronization devices were used more often in non-apical implants. The success of intra-operative defibrillation was similar between propensity score matched groups (89%). Over a mean follow-up of 3 years, there were no significant differences in the yearly rates of appropriate shock (5.5% vs. 5.4%, P = 0.98), failed appropriate first shock (0.9% vs. 1.0%, P = 0.66), or the composite of failed shock or arrhythmic death (2.8% vs. 2.3% P = 0.35) according to lead location. Conclusion We did not detect any reduction in the ICD efficacy at the time of implant or during follow-up in patients receiving a non-apical RV lead. [ABSTRACT FROM AUTHOR]

Background Risk stratification of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is mainly based on evaluations from patients at highly specialized centers. Aim To evaluate risk markers for appropriate implantable cardioverter defibrillator (ICD) therapy in an unselected, nationwide cohort of HCM. Methods Patients with an ICD due to HCM were identified from the Swedish ICD Registry since its start in 1995, merged with Patient Register data, and medical records were retrieved. Risk markers for ventricular arrhythmias leading to appropriate ICD therapy were analyzed using Cox proportional hazard ratio (HR). Results Of 321 patients (70.1% males), at least one appropriate therapy occurred in 77 (24.0%) during a mean follow-up of 5.4 years (5.3% per year; primary prevention 4.5%, secondary prevention 7.0%). Cumulative incidences at 1 year, 3 years, and 5 years were 8.1%, 15.3%, and 21.3%, respectively. Cardioversion effectively restored rhythm in 52% of the first episode and antitachycardia pacing was sufficient in the remaining. For the whole cohort, ejection fraction (EF) <50% (HR 2.63; P < 0.001) was associated with appropriate ICD therapy. In primary prevention, patients with established risk markers experienced appropriate therapy; atrial fibrillation (AF; HR 2.54; P = 0.010), EF < 50% (HR 2.78; P = 0.004), and nonsustained ventricular tachycardia (HR 1.80; P = 0.109) had the highest HR, and wall thickness ≥30 mm, syncope, exercise blood pressure response, or family history of SCD had weaker associations. Conclusion ICD therapy successfully terminates ventricular arrhythmias in HCM. In addition to conventional risk markers, a history of AF or EF < 50% may be considered in risk stratification. [ABSTRACT FROM AUTHOR]

Inappropriate ICD Shocks and Complications in HCM Introduction The expanded use of implantable cardioverter-defibrillators (ICDs) to prevent sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) based on risk stratification in individuals without known previous ventricular arrhythmia is justified by an acceptable risk of device-related adverse events. Such complications, leading to surgical procedures or inappropriate electrical shocks, may impact mortality, morbidity, quality of life, and cost-effectiveness. Methods and Results From the Swedish ICD Registry, implants due to HCM since 1995 until November 2012 in patients aged ≥18 years were identified and medical records reviewed. Inappropriate ICD shock occurred in 14.3% (46 of 321 patients; mean follow-up 5.4 years) with a recurrent episode in 28.2% of them. In multivariable analysis, hazard ratio (HR) for atrial fibrillation was 3.5 (95% confidence interval 1.8-6.8; P < 0.001) but showed no significant association to male sex (HR = 0.77), age (HR = 0.99), secondary indication (HR = 1.02) or device, ICD-DR/CRTD vs. ICD-VR (HR 1.07). Inappropriate shocks were triggered by atrial fibrillation/flutter or ectopic tachycardia (56.5%), sinus tachycardia (14.5%), lead dysfunction (14.5%), and T-wave oversensing (13.0%). A reintervention, besides elective device replacement, occurred in 92 patients (totally 150 procedures). The majority were lead-related (70.0%) procedures, especially of the ICD lead. Reintervention was associated with female sex (HR = 1.6 P = 0.04). Conclusion Inappropriate ICD shock triggered by atrial arrhythmias, lead dysfunction, or complications requiring surgical interventions, is a concern in HCM patients who will be eligible for long-term prevention of sudden death. Efforts to avoid adverse events and provide balanced risk-benefit information are important, especially in primary prevention. [ABSTRACT FROM AUTHOR]

Relatively few data have been reported on prospective changes in global longitudinal strain ( GLS) following cardiac resynchronization therapy ( CRT), and none are available on GLS during physical exercise. We investigated the effects of CRT on GLS, assessed by speckle tracking two-dimensional (2 D) echocardiography, at rest and during exercise after a mid-term follow-up. Twenty consecutive CRT patients (45% ischaemic) were assessed prospectively by speckle tracking 2 D echocardiography before implant (at rest) and at mid-term follow-up (during rest and bicycle exercise). GLS, septum and lateral wall longitudinal strain, left ventricular ejection fraction ( LVEF), and conventional functional variables were evaluated at baseline and follow-up. All patients completed the study protocol at rest. Exercise images were available in 90% of the patients. At follow-up, GLS improved at rest from −7·1 ± 2·6% to −9·1 ± 4·5% ( P<0·01), with a further increase to −11 ± 5·1% during exercise ( P<0·001). Longitudinal strain increased at rest both in the septum and in the lateral wall, with an additional increase during exercise in the lateral wall ( P<0·05). GLS correlated with LVEF both at rest ( r = −0·55 and r = −0·91 at baseline and 3 months, respectively; P<0·05) and during exercise ( r = −0·89, P<0·05). Improvement in GLS during rest and exercise can be observed in CRT patients at mid-term follow-up and seems to correlate with changes in LVEF. GLS may be a valuable method to assess left ventricular function during rest and exercise. [ABSTRACT FROM AUTHOR]

Aims The European CRT Survey is a joint initiative of the Heart Failure Association (HFA) and the European Heart Rhythm Association (EHRA) of the European Society of Cardiology evaluating the contemporary implantation practice of cardiac resynchronization therapy (CRT) in Europe. Methods and results Patients who had a successful CRT implantation were enrolled from 141 centres in 13 countries between November 2008 and June 2009. Baseline demographics, clinical and implantation data were collected, with a follow-up of ∼1 year (9–15 months). The current report describes clinical outcomes including symptom severity, cardiovascular (CV) hospitalization, and survival. A total of 2438 patients were enrolled, and follow-up data were acquired from 2111 patients (87%). The population included important groups of patients poorly represented in randomized controlled trials, including very elderly patients and those with prior device implantation, atrial fibrillation, and/or QRS duration <120 ms. Investigators reported substantial improvement in New York Heart Association (NYHA) functional class at follow-up. Patient self-assessment indicated that 81% of the patients felt improved, 16% reported no change, and 4% reported deterioration. During follow-up, 207 (10%) patients died, 346 (16%) had a CV hospitalization, and 501 (24%) died or had CV hospitalization. Worse NYHA functional class, atrial fibrillation, ischaemic aetiology, and device type (CRT-P, i.e. CRT alone) were associated with poorer survival. Women had a better outcome, as did patients who had a CRT-D (with an implantable cardioverter defibrillator function) device. Conclusions Outcomes including death and hospitalization in this European CRT survey were consistent with results from clinical trials of CRT. At 1 year follow-up, most patients who received a CRT device considered their symptoms improved compared with their pre-implant assessment. Although prospective, this is an observational study of successful CRT implantations, and outcomes in subgroup analyses must be interpreted with appropriate conservatism. [ABSTRACT FROM AUTHOR]

Objective: To establish the diagnostic accuracy of the transesophageal ventriculo-atrial (VA) interval in patients with paroxysmal supraventricular tachycardia (PSVT) and normal baseline electrocardiogram (ECG). Methods: The transesophageal VA interval during tachycardia was recorded in 318 patients (age 45 ± 17 years, 58% female) with PSVT and a normal surface ECG between attacks. Subsequently, all patients underwent an ablation procedure establishing the correct tachycardia diagnosis. Results: AV nodal reentrant tachycardia (AVNRT), AV reentrant tachycardia through a concealed accessory pathway (AVRT), and ectopic atrial tachycardia (EAT) were found in 213, 95, and 10 cases, respectively. Receiver operating characteristic curve analysis identified an optimal cutoff for a binary categorization of AVNRT versus AVRT/EAT at ≤80 ms (area under the curve 0.891). Owing to a biphasic distribution, AVNRT was very likely at VA intervals ≤90 ms with a sensitivity, specificity, and positive predictive value (PPV) of 87%, 91%, and 95%. In the range 91-160 ms the corresponding values for AVRT were 88%, 95%, and 88% (90%, 99%, and 98% in male patients). In the small group with VA intervals >160 ms (n = 29), the diagnosis was less clear (PPV of 67% for AVNRT). Conclusions: In patients with sudden onset regular tachycardia and a normal ECG during sinus rhythm, a transesophageal VA interval of ≤80 ms has the highest diagnostic accuracy to diagnose AVNRT versus AVRT/EAT. Overall, the biphasic distribution of VA intervals suggests considering AVNRT at 90 ms and below and AVRT between 91 and 160 ms (in particular in male patients) while the diagnosis is vague at VA intervals above 160 ms. Ann Noninvasive Electrocardiol 2011;16(4):327-335 [ABSTRACT FROM AUTHOR]

Aims Cardiac resynchronization therapy (CRT) is an effective treatment for a subset of patients with chronic heart failure. Data on the benefit of CRT in heart failure patients with previous right ventricular pacemakers or standard defibrillators are sparse. Methods and results The European (HFA, Heart Failure Association/EHRA, European Heart Rhythm Association) CRT Survey enrolled patients from 141 centres in 13 countries in Europe collecting baseline demographic, echocardiographic, clinical, and implant data, with follow-up at ∼1 year. The present analysis reports implantation data and 1 year outcomes regarding New York Heart Association (NYHA) class, global patient assessment, hospitalizations, complications, and mortality in patients undergoing de novo CRT implantations compared with those receiving an upgrade of a previously implanted device (pacemaker or implantable cardioverter–defibrillators). This analysis includes 2367 CRT implant procedures of which 692 (28%) were upgrades to CRT. Distribution of NYHA functional class and left ventricular function were similar between the groups. Procedural duration was also similar, although fluoroscopy time was shorter in the ‘upgrades’. There was no difference in the frequency of peri-procedural complications. There were similar improvements in NYHA functional class and similar reduction in QRS duration, but more patients reported unchanged global assessment status in the upgraded group. Total and cause-specific mortality at 1 year was low and the same in both groups. Conclusions More than one quarter of all CRT procedures are upgrades from existing systems, although this group has not been subject to randomized clinical trials. Our data suggest that there are no significant differences in clinical outcomes or complication rates between upgrades and de novo procedures. Clinical study no NCT 01185392 [ABSTRACT FROM AUTHOR]

Aims Myocardial contractile reserve (MCR) is a marker of myocardial viability. The impact of cardiac resynchronization therapy (CRT) on MCR during exercise has been little studied. Our aim was to investigate the effects of CRT on global and regional MCR by exercise echocardiography. Methods and results Twenty-seven CRT responders (56% ischaemic) were assessed by echocardiography during rest and bicycle exercise. Images were acquired during spontaneous rhythm (‘off') and active CRT (‘on'). Global MCR was expressed as the change (Δ) in left ventricular ejection fraction (LVEF) and aortic velocity-time integral (VTI) from rest to exercise. Regional MCR was expressed as the change in peak systolic tissue velocity (Sm) of the septum and lateral wall. Left ventricular ejection fraction and aortic VTI increased at ‘on' during rest and exercise, and the increase in global MCR during exercise was higher during ‘on' than ‘off' (Δ LVEF 6 ± 6 vs. 3 ± 3%; P= 0.009). Septum Sm increased during ‘on' at rest, and it was still higher during exercise (P≤ 0.01), although the absolute change from rest to exercise was similar during ‘on' and ‘off'. Lateral wall Sm did not change at rest during ‘on', but basal lateral wall MCR during exercise was higher at ‘on' than ‘off' (P= 0.036). Conclusion In CRT responders, there is a pacing-dependent increase in global MCR during exercise. The changes in regional MCR of the septum and lateral wall show different patterns. These factors may help to understand the determinants of improved exercise tolerance in CRT responders. [ABSTRACT FROM PUBLISHER]

Background: Intracardiac impedance (ICZ) has been known to reflect contractile capacity of the heart, and a strong relationship has been documented between stroke volume and ICZ. In this pilot study, conducted in heart failure patients during implantation of a biventricular device, we investigated acute changes in multiple vector ICZ signals during different pacing modes, and whether ICZ can be used to monitor hemodynamic variations. Methods: Z1 and Z2 impedance signals were recorded in the right ventricle (RV), and between the left ventricle (LV) and RV, respectively, in 12 patients during four programming modes. ICZ signals were analyzed with respect to average and peak-to-peak (p2p) amplitude and systolic slope, and correlated with noninvasive hemodynamic and echocardiographic variables. Results: ICZ p2p amplitude decreased during LV stimulation both in Z1 and in Z2 configuration (P = 0.021 and P = 0.022 vs intrinsic conduction, respectively). No significant variations in average amplitude or systolic slope were observed. ICZ variables correlated directly with hemodynamic measures (r = 0.48, P < 0.05, between Z2 p2p amplitude and pulse pressure), LV ejection fraction (r = 0.32, P < 0.05, for Z1 average amplitude), RV ejection fraction (r = 0.75, P < 0.05, for Z1 p2p amplitude), and inversely with ventricular volumes. Conclusions: Variations in ICZ may be observed during different pacing modes and seem to correlate with hemodynamic and echocardiographic variables. Multiple vector ICZ measurement may be a feasible tool for hemodynamic assessment in patients treated with biventricular pacing. [ABSTRACT FROM AUTHOR]

Abstract: Background: Relatively limited and conflicting data are available on the effects of cardiac resynchronization therapy (CRT) on coronary blood flow (CBF). Aims: To investigate changes in the left anterior descending coronary artery (LAD) flow under different CRT pacing modes by means of transthoracic Doppler echocardiography (TTE). Methods: Twenty-two responders to CRT (67±11 years) with idiopathic dilated cardiomyopathy underwent TTE assessment of LAD flow and Tissue Velocity Imaging during 4 programming modes: intrinsic conduction (IC), right ventricular pacing (RV), simultaneous biventricular pacing (BVP), BVP with left ventricular (LV) pre-activation. Results: Mean coronary flow velocity (CFV) was increased by simultaneous BVP (p =0.0063 vs. IC) and BVP with LV pre-activation (p <0.0001 vs. IC; p =0.027 vs. simultaneous BVP). Peak CFV and LAD flow velocity/time integral were highest during BVP with LV pre-activation. A reduction in septal-to-lateral delay and an increase in peak systolic velocity in the basal septum were observed during simultaneous BVP and BVP with LV pre-activation. Conclusions: In CRT responders with idiopathic dilated cardiomyopathy, an increase in LAD flow, assessed by TTE, was observed during simultaneous BVP and BVP with LV pre-activation. This was associated with an improvement in regional myocardial contraction and a decrease in intraventricular dyssynchrony. [Copyright &y& Elsevier]

Abstract: Background: Haemodynamic and functional effects of cardiac resynchronization therapy (CRT) have been studied mostly at rest. CRT effects on left ventricular (LV) dyssynchrony and function during stress have not been evaluated in detail. Aims: We studied the electromechanical effects of CRT at rest and during Dobutamine stress echocardiography (DSE), during active and withheld CRT. Methods: Twenty-one responders to CRT (62±12 yr) were assessed by walking test, quality of life, and BNP with active CRT (“on”) and 2 weeks after pacing withdrawal (“off”). DSE (10 μg/kg/min) was performed both at “on” and “off” to evaluate dyssynchrony parameters, systolic and diastolic function. Results: At rest, CRT withdrawal was associated with an increased interventricular mechanical delay (IVMD, from 21±18 ms to 49±24 ms, p <0.001) and impaired intraventricular synchrony. There was a significant decrease in LV systolic function and LV filling time. Dobutamine infusion had no impact on inter- and intraventricular synchrony. During stress, there was an improvement in LV performance both at “on” and “off”. However, LV dp/dt, aortic VTI, cardiac output, mean systolic peak velocities and LV filling time during dobutamine stress were significantly greater with CRT “on”. Conclusion: In long-term responders, CRT improves LV performance both at rest and during dobutamine stress. This is attributable to an improvement in LV synchrony, which is maintained during stress. [Copyright &y& Elsevier]

Aims: To evaluate the long-term clinical outcome and device performance of cardiac resynchronization therapy in a consecutive sample of patients with moderate to severe heart failure. Methods and Results: Between 1998 and 2000, forty consecutive patients with drug-refractory heart failure due to ischemic or idiopathic dilated cardiomyopathy were selected for cardiac resynchronization therapy (CRT). After successful implantation of the coronary sinus lead (n = 35, 88%), patients were followed every sixth month by New York Heart Association (NYHA) functional class, the 6-minute walking test (6´ walk), quality of life (QoL, Minnesota), and pacemaker control. NYHA-class and 6´ walk were significantly improved after 6 months and continued to improve gradually until 36 months of follow-up. The QoL improvement at 6 months was sustained over 3 years. After 3 years, the β-blocker dose could be increased in 10/23 patients as compared to baseline. Nine patients had to be re-operated. Coronary sinus lead thresholds were stable over time. Conclusion: The clinical improvements by CRT are sustained over 3 years of follow-up. In the setting of a University Medical Center, CRT can be applied in clinical routine with excellent clinical outcome, acceptable implantation success, and stable device performance over time. [ABSTRACT FROM AUTHOR]

STEINHAUS, D., et. al.: Implant Experience with an Implantable Hemodynamic Monitor for the Management of Symptomatic Heart Failure. Introduction: Management of congestive heart failure is a serious public health problem. The use of implantable hemodynamic monitors (IHMs) may assist in this management by providing continuous ambulatory filling pressure status for optimal volume management. Methods and Results: The Chronicle® system includes an implanted monitor, a pressure sensor lead with passive fixation, an external pressure reference (EPR), and data retrieval and viewing components. The tip of the lead is placed near the right ventricular outflow tract to minimize risk of sensor tissue encapsulation. Implant technique and lead placement is similar to that of a permanent pacemaker. After the system had been successfully implanted in 148 patients, the type and frequency of implant-related adverse events were similar to a single-chamber pacemaker implant. R-wave amplitude was 15.2 ± 6.7 mV and the pressure waveform signal was acceptable in all but two patients in whom presence of artifacts required lead repositioning. Implant procedure time was not influenced by experience, remaining constant throughout the study. Conclusion: Based on this evaluation, permanent placement of an IHM in symptomatic heart failure patients is technically feasible. Further investigation is warranted to evaluate the use of the continuous hemodynamic data in management of heart failure patients. (PACE 2005; 28:747–753) [ABSTRACT FROM AUTHOR]

NOWINSKI, K.,et al.: Pacing-Induced Electrophysiological Remodeling in Hypertrophic Obstructive Cardiomyopathy—Observations on Cardiac Memory. Background:Hypertrophic cardiomyopathy carries an increased risk for sudden cardiac death. While pacing therapy reduces the left ventricular outflow tract gradient and improves symptoms in a subgroup of hypertrophic obstructive cardiomyopathy (HOCM) patients, its electrophysiological consequences are unknown and were therefore assessed in this prospective study.Methods and Results:Fifteen consecutive HOCM patients were studied and compared with 14 patients without HOCM paced because of sinus bradycardia. ECG intervals were measured before pacemaker implantation and after≥3 months of DDD pacing in HOCM patients and≥5 weeks in controls. Both groups showed similar ECG signs of cardiac memory development. In HOCM patients, with baseline QTc 447± 33 ms, cardiac memory development was not associated with any significant changes in ECG intervals. In contrast, baseline repolarization in control patients was significantly prolonged by 6% (QTc 429± 33 vs 454± 46 ms; P<0.05). Furthermore, in HOCM patients repolarization was 7% shorter during DDD pacing compared to sinus rhythm (JTc 329± 25 vs 353± 21 ms; P<0.05), despite a significantly prolonged ventricular activation time (QRS duration 155± 16 vs 91± 9 ms; P<0.01).Conclusions:Importantly, the development of cardiac memory-induced different repolarization responses depending on baseline structure and electrophysiology. In HOCM patients repolarization was shorter during right ventricular apical pacing than during normal activation despite prolonged activation time.(PACE 2005; 28:561–567) [ABSTRACT FROM AUTHOR]

KENNERGREN C., et al.: Clinical Experience with an Automatic Threshold Tracking Algorithm Study. The automatic threshold tracking pacing system algorithm developed by St. Jude Medical, verifies ventricular capture beat by beat by recognizing the evoked response (ER) following each pacemaker stimulus. The present automatic threshold tracking function requires a bipolar ventricular lead with low polarization. The aim of this study was to evaluate a new algorithm developed to use with unipolar leads with different levels of polarization. An external pacemaker with the ability to sense intrinsic R waves and measure ER signals, as well as deliver stimulus, was used. An algorithm for detecting the true ER in a unipolar sensing configuration (tip-case) was developed. Based on the assumption that the true evoked R wave amplitude is independent of the stimulation amplitude, the algorithm calculates and subtracts the polarization present at any pacing stimulus from the measured ER. The resulting signal is analyzed to verify capture. This study comprises 35 patients of which 26 were new implants and 9 had chronic leads. The automatic threshold-tracking algorithm was calibrated for each patient and pacing was performed at different pulse amplitudes and pulse duration. Capture was verified for each paced beat. The recordings were stored for later comparison with the tape-recorded intracardiac heart signals. The new algorithm correctly verified capture or loss of capture for every single analyzed beat at the different pacing outputs in every individual patient. The results from this initial study suggests that the new ER detection principle will allow automatic threshold tracking to be used not only with low polarization bipolar leads but with most leads. (PACE 2003; 26:2219–2224) [ABSTRACT FROM AUTHOR]

This study was designed to prospectively assess ventricular de- and repolarization by the QRS, QT, and JT intervals, and their dispersion in the 12-lead ECG during right ventricular pacing at 60. 70, and 80 beats/min during the first month after AV junctional RE ablation. Previous reports have found early polymorphic ventricular arrhythmia after RF AV junctional ablation. Our hypothesis was that there is a proarrhythmic state following this procedure, which depends on the paced rate and time after ablation. The analysis of the immediate changes was based on 17 patients (10 men) with a mean age of 64 years (SD 14) (range 38-82 years). A 12-lead ECC was recorded during right ventricular pacing at 60, 70, and 80 beats/min within 24 hours (day 1), between 24 and 48 hours (day 2), and 1 week after ablation (day 7). For analysis of changes beyond 1 week, 13 additional patients with a mean age of 73 years (SD 8) (range 62-90 years) were analyzed on days 1, 7, and 30. All intervals were measured with a digitizing table. The mean QRS duration shortened by 2.4% at 60 beats/min (P < 0.01), and the mean QT and JT intervals shortened by 5-7% between days 1 and 7 (P < 0.001), The mean QT was 9% shorter and the mean QT interval was 13% shorter at 80 compared to 60 beats/min on day 1 (P < 0.001). QT dispersion was reduced by 13% when the stimulation rate was increased from 60 to 80 beats/min on day 1 (P < 0.05). There were no significant changes beyond the first week. The study results point to the induction of a proarrhythmic state immediately after AV junctional RE ablation resolving during the first week, Repolarization shortened gradually between 80 and 60 beats/min to an extent that is suggestive of a clinically important antiarrhythmic effect at the higher rate, which was supported also by clinical experience. [ABSTRACT FROM AUTHOR]

The health care costs for heart failure are substantial. Studies indicate that hospital treatment constitutes 65–75% of these. The aim of this study was to assess total and heart failure related hospital days as well as safety and efficacy of biventricular pacing in 16 patients with severe heart failure and delayed intraventricular conduction (QRS duration <150 ms). They were implanted with a biventricular pacemaker and followed by NYHA class, 6-min walk test and quality of life for a mean of 291±76 days. Total number of hospital days and the need for hospitalisations were monitored. Thirteen responders improved by at least one functional class. After 6 months of pacing the 6-min walk test improved from 375±83 m to 437±73 m (P<0.001) and Minnesota Living with Heart Failure quality of life score from 41±19 to 24±17 (P<0.001) compared to baseline. The need for hospital care decreased significantly after biventricular pacing. The total number of hospital days in all patients was 253 the year before compared to 45 the year after biventricular pacing (P<0.01). For heart failure related hospital days the corresponding figures were 183 and 39 days, respectively (P<0.01). Biventricular pacing improved 13/16 patients with severe heart failure and wide QRS complexes in this open study. The improvement resulted in a reduced need for hospital care. [ABSTRACT FROM PUBLISHER]

Cardiac Resynchronization Therapy. We report the case of a 55-year-old male patient with severe congestive heart failure in whom both a hemodynamic monitor and a biventricular pacemaker were implanted. The potential usefulness of the monitor to optimize AV delay and heart rate was prospectively evaluated. The AV delay associated with the lowest filling pressures recorded by the monitor was similar to the optimal AV delay as determined by standard echocardiography. Heart rates >70 beats/min acutely improved hemodynamics but were not tolerated when programmed chronically. This case illustrates that continuous hemodynamic monitoring may offer a useful tool for device tuning and treatment monitoring in cardiac resynchronization therapy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 94-96, January 2004) [ABSTRACT FROM AUTHOR]

Background: Primary prophylactic implantable cardioverter defibrillator (ICD) therapy is indicated for patients with reduced left ventricular ejection fraction (LVEF). We aimed to determine if preoperative clinical risk profiling can predict long-term benefit, and if clinical risk scores can be applied and improved in a patient cohort outside the clinical trial setting.Methods: Using registry data, 789 patients with reduced LVEF who received ICDs for primary prevention during 2006-2011 were identified (age 64 ± 11 years, 82% men, 63% ischemic etiology, 52% cardiac resynchronization therapy with defibrillator). The patients were divided into three risk groups, based on the presence of baseline clinical risk factors (age >70, QRS duration >120 ms, New York Heart Association class III-IV, atrial fibrillation history, or creatinine >106 μmol/L). Endpoints were all-cause mortality and survival free of adequate ICD therapy.Results: Mean follow-up was 39 ± 18 months. Annual mortality was 7.6%, and increased with risk group (p < .001). Rates of appropriate antitachycardia pacing and shock therapy were not statistically different between the groups, and ranged from 11%-16% and 6%-14%, respectively. By combining the previous risk score with data on diabetes, a better independent prediction of mortality was achieved; mortality rates then ranged from 11% (low-risk) to 46% (high-risk) (p < .0001).Conclusions: Implantable cardioverter defibrillator therapies occur across the spectrum of comorbidities in a population with systolic heart failure. However, all-cause mortality is considerably higher in the group of patients with accumulated risk factors, and using the proposed scoring system can be helpful for the evaluation and risk stratification of the patient prior to making a decision for a primary prophylactic ICD implantation. [ABSTRACT FROM AUTHOR]