Cost-effective analysis of automated programming optimization in cardiac resynchronization therapy: Holistic Markov modelling.

BACKGROUND: Automated optimization algorithm (AdaptivCRT; Medtronic, Mounds View, MN, USA) allowing automated optimization of cardiac resynchronization therapy (CRT), has been introduced. However, little is known concerning its cost-effectiveness. This study aims to evaluate the potential economic benefits of AdaptivCRT of CRT. METHODS: Markov modelling was informed by empirical data sourced from the AdaptivCRT Clinical Trial. Published meta-analyses were used to derive the impact of increasing response to hospitalization and mortality risks. Response was assessed via the clinical composite score. RESULTS: Deterministic results suggested a mean survival of 10.97 years with adaptive algorithms against 10.5 years without (+0.47 in favour of novel algorithms). Heart failure hospitalization costs were modelled to ¥1,382,753 (US $12,686) with novel devices against ¥1,524,747 (US $13,989) with previous technology models. Sensitivity analyses show CRT with Adaptive algorithm was projected to provide cost savings in all scenarios. CONCLUSIONS: The use of AdaptivCRT was projected to improve average patient survival and avoid costs in a Japanese healthcare setting.

Electroanatomic voltage mapping for tissue characterization beyond arrhythmia definition: A systematic review.

Three-dimensional (3D) reconstruction by means of electroanatomic mapping (EAM) systems, allows for the understanding of the mechanism of focal or re-entrant arrhythmic circuits, which can be identified by means of dynamic (activation and propagation) and static (voltage) color-coded maps. However, besides this conventional use, EAM may offer helpful anatomical and functional information for tissue characterisation in several clinical settings. Today, data regarding electromechanical myocardial viability, scar detection in ischaemic and nonischaemic cardiomyopathy and arrhythmogenic right ventricle dysplasia (ARVC/D) definition are mostly consolidated, while emerging results are becoming available in contexts such as Brugada syndrome and cardiac resynchronisation therapy (CRT) implant procedures. As part of an invasive procedure, EAM has not yet been widely adopted as a stand-alone tool in the diagnostic path. We aim to review the data in the current literature regarding the use of 3D EAM systems beyond the definition of arrhythmia.

His bundle pacing shows similar ventricular electrical activation as sinus: selective and nonselective His pacing indistinguishable.

His bundle pacing utilizes the His-Purkinje system to produce more physiological activation compared with traditional pacing therapies, but differences in electrical activation between pacing techniques are not yet quantified in terms of activation pattern. Furthermore, clinicians distinguish between selective and nonselective His pacing, but measurable differences in electrical activation remain to be seen. Hearts isolated from seven dogs were perfused using the Langendorff method. Electrograms were recorded using two 64-electrode basket catheters in the ventricles and a 128-electrode sock situated around the ventricles during sinus rhythm (right atrial pacing), right ventricular (RV) pacing, biventricular cardiac resynchronization therapy (biV-CRT), selective His pacing (selective capture of the His bundle), and nonselective His pacing (capture of nearby myocardium and His bundle). Activation maps were generated from these electrograms. Total activation time (TAT) was measured from the activation maps, and QRS duration was measured from a one-lead pseudo-ECG. Results showed that TAT, QRS duration, and activation sequence were most similar between sinus, selective, and nonselective His pacing. Bland-Altman analyses showed highest levels of similarity between all combinations of sinus, selective, and nonselective His pacing. RV and biV-CRT activation patterns were distinct from sinus and had significantly longer TAT and QRS duration. Cumulative activation graphs were most similar between sinus, selective, and nonselective His pacing. In conclusion, selective pacing and nonselective His bundle pacing are more similar to sinus compared with RV and biV-CRT pacing. Furthermore, selective pacing and nonselective His bundle pacing are not significantly different electrically.NEW & NOTEWORTHY Our high-density epicardial and endocardial electrical mapping study demonstrated that selective pacing and nonselective His bundle pacing are more electrically similar to sinus rhythm compared with right ventricular and biventricular cardiac resynchronization therapy pacing. Furthermore, small differences between selective and nonselective His bundle pacing, specifically a wider QRS in nonselective His pacing, do not translate into significant differences in the global activation pattern.

Trends of Acute Kidney Injury Requiring Dialysis Among Hospitalized Patients Undergoing Invasive Electrophysiology Procedures.

Electrophysiology (EP) procedures carry the risk of kidney injury due to contrast/hemodynamic fluctuations. We aim to evaluate the national epidemiology of acute kidney injury requiring dialysis (AKI-D) in patients undergoing EP procedures. Using the National Inpatient Sample, we included 2,747,605 adult hospitalizations undergoing invasive diagnostic EP procedures, ablation and implantable device placement from 2006 to 2014. We examined the temporal trend of AKI-D and outcomes associated with AKI-D. The rate of AKI-D increased significantly in both diagnostic/ablation group (8-21/10,000 hospitalizations from 2006 to 2014, P = 0.02) and implanted device group (19-44/10,000 hospitalizations from 2006 to 2014, P < 0.01), but it was explained by temporal changes in demographics and comorbidities. Cardiac resynchronization therapy and pacemaker placement had higher risk of AKI-D compared to implantable cardioverter-defibrillator placement (23 vs. 31 vs. 14/10,000 hospitalizations in cardiac resynchronization therapy, pacemaker placement, and implantable cardioverter-defibrillator group, respectively). Development of AKI-D was associated with significant increase in in-hospital mortality (adjusted odds ratio, 9.6 in diagnostic/ablation group, P < 0.01; adjusted odds ratio, 5.1 in device implantation group, P < 0.01) and with longer length of stay (22.5 vs. 4.5 days in diagnostic/ablation group, 21.1 vs. 5.7 days in implanted device group) and higher cost (282,775 vs. 94,076 USD in diagnostic/ablation group, 295,660 vs. 102,007 USD in implanted device group). The incidence of AKI-D after EP procedures increased over time but largely explained by the change of demographics and comorbidities. This increasing trend, however, was associated with significant increase in resource utilization and in-hospital mortality in these patients.

Reappraisal on pharmacological and mechanical treatments of heart failure.

Heart failure (HF) is a highly frequent disorder with considerable morbidity, hospitalization, and mortality; thus, it invariably places pressure on clinical and public health systems in the modern world. There have been notable advances in the definition, diagnosis, and treatment of HF, and newly developed agents and devices have been widely adopted in clinical practice. Here, this review first summarizes the current emerging therapeutic agents, including pharmacotherapy, device-based therapy, and the treatment of some common comorbidities, to improve the prognosis of HF patients. Then, we discuss and point out the commonalities and areas for improvement in current clinical studies of HF. Finally, we highlight the gaps in HF research. We are looking forward to a bright future with reduced morbidity and mortality from HF.

Wireless, battery-free, fully implantable multimodal and multisite pacemakers for applications in small animal models.

Small animals support a wide range of pathological phenotypes and genotypes as versatile, affordable models for pathogenesis of cardiovascular diseases and for exploration of strategies in electrotherapy, gene therapy, and optogenetics. Pacing tools in such contexts are currently limited to tethered embodiments that constrain animal behaviors and experimental designs. Here, we introduce a highly miniaturized wireless energy-harvesting and digital communication electronics for thin, miniaturized pacing platforms weighing 110 mg with capabilities for subdermal implantation and tolerance to over 200,000 multiaxial cycles of strain without degradation in electrical or optical performance. Multimodal and multisite pacing in ex vivo and in vivo studies over many days demonstrate chronic stability and excellent biocompatibility. Optogenetic stimulation of cardiac cycles with in-animal control and induction of heart failure through chronic pacing serve as examples of modes of operation relevant to fundamental and applied cardiovascular research and biomedical technology.

The effect of posture, exercise, and atrial pacing on atrioventricular conduction in systolic heart failure.

BACKGROUND: Optimization of atrioventricular (AV) intervals for cardiac resynchronization therapy (CRT) programming is typically performed in supine patients at rest, which may not reflect AV timing in other conditions. OBJECTIVE: To evaluate the effects of posture, exercise, and atrial pacing on intrinsic AV intervals in patients with CRT devices. METHODS: Rate-dependent A-V delay by exercise was a multicenter, prospective trial of patients in sinus rhythm following CRT implantation. Intracardiac electrograms were recorded to analyze atrial to right ventricular (ARV), atrial to left ventricular (ALV), and RV to LV (VV) time intervals. Heart rate was increased with incremental atrial pacing in different postures, followed by an exercise treadmill test. RESULTS: This study included 36 patients. At rest, AV intervals changed minimally with posture. With atrial pacing, AV interval immediately increased compared with sinus rhythm, with ARV slopes being 8.1 ± 7.7, 8.8 ± 13.4, and 6.8 ± 6.5 milliseconds per beat per minute (ms/bpm) and ALV slopes being 8.2 ± 7.7, 9.1 ± 12.8, and 7.0 ± 6.5 ms/bpm for supine, standing and sitting positions, respectively. As the paced heart rate increased, ARV and ALV intervals increased more gradually with similar trends. Interventricular conduction times changed less than 0.2 ms/bpm with atrial pacing. During exercise, the direction of change of intrinsic ARV intervals, as heart rate increased, was variable between patients with relatively small overall group changes (0.1 ± 1.4 and 0.2 ± 1.2 ms/bpm for ARV and ALV, respectively). CONCLUSION: Posture and exercise have a smaller effect on AV timing compared with atrial pacing. However, individualized optimization and dynamic rate related changes may be needed to maintain optimal fusion with left ventricular (LV) stimulation.

Fluoroscopy reduction during device implantation by using three-dimensional navigation. A single-center experience.

BACKGROUND AND OBJECTIVES: The use of nonfluoroscopic three-dimensional electroanatomic mapping (3DM) systems reduces radiation exposure during ablation procedures. In this study, we sought to determine the value of 3DM during routine device implant procedures. METHODS: Seventy nonselected patients underwent implantation of a single chamber, dual chamber, or biventricular device guided by Ensite (Abbott Laboratories) to limit fluoroscopy use and compared with 70 consecutive patients, who underwent matching procedures with standard fluoroscopy use (FL) in the period immediately preceding the use of 3DM. The venous anatomy, right atrium, and ventricle and coronary sinus were mapped with 0.035 inch J-wire, quadripolar catheter, and/or angioplasty wire. The leads were advanced under real-time visualization in Ensite. RESULTS: 3DM reduced both fluoroscopy time and dose. Median fluoroscopy time for FL vs 3DM was 5.5 minutes (interquartile range [IQR]: 3.8-8.1) vs 0.9 minutes (IQR: 0.6-1.9) (P < .001) for single chamber devices, 6.3 minutes (IQR: 5.1-7.9) vs 3.3 minutes (IQR: 1.9-4) (P < .001) for dual-chamber devices, and 28.6 minutes (IQR: 19.6-36.2) to 14.7 minutes (IQR: 10.4-22.3) (P = .009) for biventricular devices, respectively. The median air kerma for FL vs 3DM was 15.4 mGy (IQR: 8.1-30.2) vs 4 mGy (IQR: 1.8-8) (P < .001) for single chamber devices, 16 mGy (IQR: 12-18.5) to 9.4 mGy (IQR: 7.5-11.3) (P = .001) for dual-chamber devices, and 324 mGy (IQR: 143-668.7) to 115 mGy (IQR:77-204) (P = .014) for biventricular devices, respectively. There were no procedural complications. At 3-month follow-up, there was no difference in voltage threshold measurements between the groups. CONCLUSION: The use of 3DM leads to significantly reduced fluoroscopy time and fluoroscopy dose during routine device implantation.

Pain During "Noncomplex" Electrophysiological Studies and Cardiac Rhythm Device Surgery.

BACKGROUND: There are only limited data about peri-interventional pain during cardiac electrophysiological procedures without analgosedation. In this study, peri-interventional pain and recollection of it after the intervention were evaluated. METHODS: A total of 101 patients (43 electrophysiological/ablation procedures and 58 device surgeries) reported pain on a numerical rating scale (NRS; 0-10) before (pre), during (peri), and after (post) the intervention. Maximum pain (maxNRS) and the average of pain (meanNRS) were used for statistical analysis. Peri-interventional pain was compared with postinterventional data of the recollection of peri-interventional pain (peri-post). Patients were allocated into 2 groups (with 51 and 50 patients, respectively) to evaluate the mode of patient-staff interaction on pain recollection. Depressive, anxiety, and somatic symptom scales (Patient Health Questionnaire-15, Generalized Anxiety Disorder-7, and Patient Health Questionnaire-15) were used to analyze their influence on pain recollection. RESULTS: In total, 49.6% of patients (n = 50) complained of moderate to severe pain (maxNRS) at least once during the procedure. The comparison between peri and peri-post data revealed the following (median (range)-maxNRS, peri: 3 (0-10) versus peri-post: 4 (0-9) (ns), and meanNRS, peri: 1.4 (0-7) versus peri-post: 2.0 (0-6) (ns). The mode of patient-staff interaction had no influence on pain. No effect was found for psychosocial factor concerning pain and the recollection of pain. The results of the linear regression showed no influence of low-dose midazolam on recollection of pain. CONCLUSION: Half of the patients reported moderate to severe pain at least once during cardiac electrophysiological procedures without analgosedation. However, on average, patients reported only low pain levels. Postinterventional derived data on discomfort reflect the peri-interventional situation.

Electrically vs. imaging-guided left ventricular lead placement in cardiac resynchronization therapy: a randomized controlled trial.

AIMS: To test in a double-blinded, randomized trial whether the combination of electrically guided left ventricular (LV) lead placement and post-implant interventricular pacing delay (VVd) optimization results in superior increase in LV ejection fraction (LVEF) in cardiac resynchronization therapy (CRT) recipients. METHODS AND RESULTS: Stratified according to presence of ischaemic heart disease, 122 patients were randomized 1:1 to LV lead placement targeted towards the latest electrically activated segment identified by systematic mapping of the coronary sinus tributaries during CRT implantation combined with post-implant VVd optimization (intervention group) or imaging-guided LV lead implantation by cardiac computed tomography venography, 82Rubidium myocardial perfusion imaging and speckle tracking echocardiography targeting the LV lead towards the latest mechanically activated non-scarred myocardial segment (control group). Follow-up was 6 months. Primary endpoint was absolute increase in LVEF. Additional outcome measures were changes in New York Heart Association class, 6-minute walk test, and quality of life, LV reverse remodelling, and device related complications. Analysis was intention-to-treat. A larger increase in LVEF was observed in the intervention group (11 ± 10 vs. 7 ± 11%; 95% confidence interval 0.4-7.9%, P = 0.03); when adjusting for pre-specified baseline covariates this difference did not maintain statistical significance (P = 0.09). Clinical response, LV reverse remodelling, and complication rates did not differ between treatment groups. CONCLUSION: Electrically guided CRT implantation appeared non-inferior to an imaging-guided strategy considering the outcomes of change in LVEF, LV reverse remodelling and clinical response. Larger long-term studies are warranted to investigate the effect of an electrically guided CRT strategy.

Conceptual Intra-Cardiac Electrode Configurations That Facilitate Directional Cardiac Stimulation for Optimal Electrotherapy.

OBJECTIVE: Electrotherapy remains the most effective direct therapy against lethal cardiac arrhythmias. When an arrhythmic event is sensed, either strong electric shocks or controlled rapid pacing is automatically applied directly to the heart via an implanted cardioverter defibrillator (ICDs). Despite their success, ICDs remain a highly non-optimal therapy: the strong shocks required for defibrillation cause significant extra-cardiac stimulation, resulting in pain and long-term tissue damage, and can also limit battery life. When used in anti-tachycardia pacing mode, ICDs are also often ineffective, as the pacing electrode can be far away from the centre of the arrhythmia, making it hard for the paced wave to interrupt and terminate it. METHODS: In this paper, we present two conceptual intra-cardiac directional electrode configurations in silico based on novel arrangements of pairs of positive-negative electrodes. Both configurations have the potential to cause preferential excitation on specific regions of the heart. RESULTS: We demonstrate how the properties of the induced field varies spatially around the electrodes and how it depends upon the specific arrangements of dipole electrode pairs. The results show that when tested within anatomically-realistic rabbit ventricular models, both electrode configurations produce strong virtual electrodes on the targeted endocardial surfaces, with weaker virtual electrodes produced elsewhere. CONCLUSIONS: The proposed electrode configurations may facilitate targeted far-field anti-tachycardia pacing and/or defibrillation, which may be useful in cases where conventional anti-tachycardia pacing fails. In addition, the conceptual electrode designs intrinsically confine the electric field to the immediate vicinity of the electrodes, and may, thus, minimize pain due to unnecessary extra-cardiac stimulation.

Sudden-onset severe presyncope in a 67-year-old man.

A 67-year-old man presented to the emergency department with sudden onset of severe presyncope. He reported that he had a permanent pacemaker implanted in 2006 following atrioventricular node ablation for persistent atrial fibrillation (AF). After suffering increasing shortness of breath, he underwent upgrade to cardiac resynchronisation therapy (CRT) in 2016. He denied any recent falls, interventions or changes in medication. ECG monitoring showed AF with a broad ventricular escape rhythm at around 25 bpm with pauses of up to 3 s. Placement of a magnet over the device resulted in pacing (figure 1A). The implanted device (Medtronic Syncra C2TR01) was interrogated (figure 1B), and a chest radiograph was obtained (figure 2). heartjnl;105/8/657/F1F1F1Figure 1(A) Twelve-lead ECG demonstrating intrinsic rhythm and pacing after application of magnet. (B) Device interrogation with right ventricular threshold test. heartjnl;105/8/657/F2F2F2Figure 2(C) Anteroposterior chest radiograph demonstrating lead position on admission. QUESTION: What was the cause of this presentation?Noise oversensing on the right ventricular (RV) lead due to lead fracture.The RV septal lead has displaced into the right atrial (RA).RA and RV leads were switched in the can during the CRT upgrade.Increase in threshold of RV and left ventricular (LV) leads resulting in loss of capture.

Ventricular electrical delay as a predictor of arrhythmias in patients with cardiac resynchronization implantable cardioverter defibrillator.

BACKGROUND: Left ventricular (LV) remodeling and clinical response to cardiac resynchronization therapy (CRT) is inversely related to electrical dyssynchrony, measured as LV lead electrical delay (QLV). Presence of atrial or ventricular arrhythmia is correlated with worsening heart failure and LV remodeling. OBJECTIVE: We sought to assess the association of QLV with arrhythmic events in CRT recipients. METHODS: We identified patients implanted with a CRT device at our center. QLV interval was measured and corrected for baseline QRS (cQLV). We performed multivariable Logistic regression to assess the effect of cQLV on the occurrence of atrial/ventricular arrhythmic events. RESULTS: Sixty-nine patients were included in analyses. The cQLV was significantly shorter in patients with atria tachycardia/supraventricular tachycardia (AT/SVT) events compared to patients without AT/SVT events (43.4 ± 22% vs. 60.3 ± 26.7%, p = .006). In contrast, no significant difference in cQLV was observed between patients with and without ventricular tachycardia/fibrillation (VT/VF) events (46.2 ± 25.4% vs. 56 ± 25.7%, p = .13). cQLV was significantly shorter in patients with new onset AT/SVT events compared to those without (38.3 ± 22.2% vs. 55.7 ± 25.7%, p = .028). In contrast, no significant difference in cQLV was observed between patients with and without new onset VT/VF events (44.2 ± 25.2% vs. 56.3 ± 25.5%, p = .069). Following adjusted analyses, cQLV was a significant predictor of AT/SVT, but not for VT/VF. CONCLUSION: cQLV is a simple measure that can identify a vulnerable cohort of CRT patients at increased risk for atrial tachyarrhythmias, and hence can predict reverse remodeling and clinical response to CRT treatment.

Inhibition and restoration of CRT pacing - What is the mechanism?

The electrocardiogram (ECG) interpretation in patients with cardiac resynchronization therapy (CRT) may be challenging. The difficulty increases if not well-known pacemaker algorithm is turned on. We show a T-wave protection algorithm (LVTP) in a patient with CRT. Accelerated sinus rhythm and intermittent oversensing in left ventricular channel resulted in loss of CRT pacing. The restoration of biventricular pacing occurred when atrial rate decreased. We provide detailed descriptions of the electrocardiogram and intracardiac electrogram. LVTP may confuse ECG examination interpretation, especially in patients with accelerated atrial rhythm and oversensing in left ventricular channel.

Dispositivos implantables en la insuficiencia cardíaca con fracción de eyección reducida. Más de 30 años de demostrada eficacia terapéutica / Implantable devices in reduced ejection fraction heart failure. More than 30 years of proven therapeutic efficacy

En el presente artículo se analiza el rol de los dispositivos implantables en la mejoría de síntomas y en prevención primaria de muerte súbita en pacientes con insuficiencia cardíaca con fracción de eyección reducida. No se considera la prevención secundaria, es decir, la de aquellos pacientes que ya han presentado un evento arrítmico mayor, que puede ser motivo de otro artículo. Se destaca el análisis de las recomendaciones de las Guías Europeas 2016, tanto para la resincronización cardíaca como para el implante de cardiodesfibrilador, complementado con una descripción pormenorizada de los diferentes ensayos clínicos que pretende contribuir a una correcta toma de decisiones en la práctica clínica. Al final del capítulo el lector encontrará un resumen conceptual con mensajes clave para la puesta al día del conocimiento de estas terapias complementarias del tratamiento médico óptimo.

In this article, the role of implantable devices in improvement of symptoms and primary prevention of sudden death in patients with reduced ejection fraction heart failure, is analyzed. Secondary prevention is not considered, that is, of those patients who have already presented a major arrhythmic event, which may be the reason for another article. The analysis of the recommendations of the 2016 European Guidelines is highlighted, both for cardiac resynchronization and for the implantation of cardio-defibrillators, complemented with a detailed description of the different clinical trials, which aim to correct decision-making in clinical practice. At the end of the chapter, the reader will find a conceptual summary in which key messages are considered for updating the knowledge of these complementary therapies of optimal medical treatment.

Cardiac implantable electronic device and vascular access: Strategies to overcome problems.

For arrhythmia treatment or sudden cardiac death prevention in hemodialysis patients, there is a frequent need for placement of a cardiac implantable electronic device (pacemaker, implantable cardioverter defibrillator, or cardiac resynchronization device). Leads from a cardiac implantable electronic device can cause central vein stenosis and carry the risk of tricuspid regurgitation or contribute to infective endocarditis. In patients with end-stage kidney disease requiring vascular access and cardiac implantable electronic device, the best strategy is to create an arteriovenous fistula on the contralateral upper limb for a cardiac implantable electronic device and avoidance of central vein catheter. Fortunately, cardiac electrotherapy is moving toward miniaturization and less transvenous wires. Whenever feasible, one should avoid transvenous leads and choose alternative options such as subcutaneous implantable cardioverter defibrillator, epicardial leads, and leadless pacemaker. Based on recent reports on the leadless pacemaker/implantable cardioverter defibrillator effectiveness, in patients with rapid progression of chronic kidney disease (high risk of renal failure) or glomerular filtration rate <20 mL/min/1.73 m2, this option should be considered by the implanting cardiologist for future access protection.

Physician decision making in anticoagulating atrial fibrillation: a prospective survey of a physician notification system for atrial fibrillation detected on cardiac implantable electronic devices of patients at increased risk of stroke.

OBJECTIVES: The objectives of this study were to evaluate the effectiveness of a physician notification system for atrial fibrillation (AF) detected on cardiac devices, and to assess predictors of anticoagulation in patients with device-detected AF. METHODS: In 2013, a physician notification system for AF detected on a patient's CIED [including pacemakers, implantable cardioverter defibrillators (ICD) or cardiac resynchronization therapy (CRT) devices] was implemented, with a recommendation to consider oral anticoagulation in high-risk patients. We prospectively investigated the effectiveness of this system, and evaluated both patient and physician predictors of anticoagulation, as well as factors influencing physician decision making in prescribing anticoagulation. Both uni- and multivariable analysis as well as descriptive statistics were used in the analysis. RESULTS: We identified 177 patients with device-detected AF, 126 with a CHADS2 ⩾2. Only 41% were prescribed anticoagulation at any point within 12 months. On multivariable analysis, stroke risk as predicted by CHADS2 was not a predictor of anticoagulation. ASA use predicted a lower rate of anticoagulation (OR 0.39, 95% CI 0.16-0.97, p = 0.04); physicians in practice for <20 years were more likely to prescribe anticoagulation (OR 3.39, 95% CI 1.28-8.93, p = 0.01); and physicians who believed both cardiologist and family doctor should be involved in managing anticoagulation were more likely to prescribe anticoagulation (OR 3.28, 95% CI 1.02-10.5, p = 0.05). CONCLUSIONS: Patients on aspirin were less likely to be anticoagulated. Physicians in practice for <20 years and who believed that both the general practitioner and cardiologist should be involved in managing anticoagulants were more likely to prescribe anticoagulation.

Longer inter-lead electrical delay is associated with response to cardiac resynchronization therapy in patients with presumed optimal left ventricular lead position.

Aims: In a randomized trial of cardiac resynchronization therapy (CRT), a presumed optimal left ventricular (LV) lead position close to the latest mechanically activated non-scarred myocardium was achieved in 98% of patients by standard implantation. We evaluated whether inter-lead electrical delay (IED) was associated with response to CRT in these patients. Methods and results: We prospectively included 160 consecutive patients undergoing CRT. Pre-implant speckle-tracking echocardiography radial strain and 99mTc myocardial perfusion imaging determined the latest mechanically activated non-scarred myocardial segment. We measured procedural IED as the time interval between sensed signals in right ventricular and LV lead electrograms. All patients had LV pacing site concordant or adjacent to the latest mechanically activated non-scarred segment verified by cardiac computed tomography. Response to CRT was defined as ≥15% reduction in LV end-systolic volume at 6 months follow-up. Selecting a practical IED cut-off value of 100 ms, more patients with long IED than patients with short IED responded to CRT (87 vs. 68%; P = 0.004). In multivariate logistic regression analysis, IED ≥100 ms remained associated with CRT response after adjusting for baseline characteristics, including QRS duration and scar burden [odds ratio 3.19 (1.24-8.17); P = 0.01]. Categorizing IED by tertiles, CRT response improved with longer IED (P = 0.03). Comparable response rates were observed in patients with a concordant and adjacent LV lead position. Conclusion: A longer IED was associated with more pronounced LV reverse remodelling response in CRT recipients with a presumed optimal LV lead position concordant or adjacent to the latest mechanically activated non-scarred segment.