Assessing cardiac resynchronization therapy response in heart failure patients: a comparative analysis of efficacy and outcomes between transvenous and epicardial leads

Cardiac resynchronization therapy (CRT) is an effective treatment for selected heart failure (HF) patients. Although transvenous implantation is the standard method, it is not feasible in some patients, so the epicardial lead emerges as an alternative. We aim to compare CRT response, procedure-related complications, and the occurrence of clinical outcomes between patients with transvenous and epicardial leads. In a single-center retrospective study, we enrolled consecutive HF patients submitted to CRT implantation with a defibrillator between 2013 and 2022. Clinical response was defined as an improvement of at least one of the New York Heart Association classes with no occurrence of cardiovascular death or HF hospitalization in the first year of follow-up. Echocardiographic response was attained with an increase in left ventricular ejection fraction 10% or a reduction of left ventricular end-diastolic volume >15% at 6-12 months after CRT implantation. Major adverse cardiovascular events (MACE) (cardiovascular mortality and HF hospitalization) and all-cause mortality were evaluated. From a total of 149 patients, 38% (n=57) received an epicardial lead. Clinical (63% versus 60%, p=0.679) and echocardiographic (63% versus 60%, p=0.679) responses were similar between the transvenous and epicardial groups. Patients in the transvenous group had a shorter hospital stay (2 versus 7 days, p<0.001). Procedure-related complications were comparable between groups (24% versus 28%, p=0.572), but left ventricular lead-related complications were more frequent in the transvenous group (14% versus 2%). During a median follow-up of 4.7 years, the rate of MACE was 30% (n=44), with no differences in both groups (p=0.591), neither regarding HF hospitalization (p=0.917) nor cardiovascular mortality (p=0.060). Nevertheless, the epicardial group had a higher rate of all-cause mortality (35% versus 20%, p=0.005), the majority occurring during long-term follow-up (>12 months), with no deaths in the postoperative period. Considering the comparable rates of CRT response, procedure-related complications, and MACE between groups, we conclude that epicardial lead is a feasible alternative for CRT when transvenous lead implantation is not possible. The occurrence of a higher number of all-cause deaths in epicardial patients in the long-term follow-up was mainly due to infectious complications (unrelated to the lead) and the progression of oncological/chronic diseases.

Ventricular tachyarrhythmia treatment and prevention by subthreshold stimulation with stretchable epicardial multichannel electrode array

The implantable cardioverter-defibrillator (ICD) is an effective method to prevent sudden cardiac death in high-risk patients. However, the transvenous lead is incompatible with large-area electrophysiological mapping and cannot accommodate selective multichannel precision stimulations. Moreover, it involves high-energy shocks, resulting in pain, myocardial damage, and recurrences of ventricular tachyarrhythmia (VTA). We present a method for VTA treatment based on subthreshold electrical stimulations using a stretchable epicardial multichannel electrode array, which does not disturb the normal contraction or electrical propagation of the ventricle. In rabbit models with myocardial infarction, the infarction was detected by mapping intracardiac electrograms with the stretchable epicardial multichannel electrode array. Then, VTAs could be terminated by sequential electrical stimuli from the epicardial multichannel electrode array beginning with low-energy subthreshold stimulations. Last, we used these subthreshold stimulations to prevent the occurrence of additional VTAs. The proposed protocol using the stretchable epicardial multichannel electrode array provides opportunities toward the development of innovative methods for painless ICD therapy.

A Novel Approach for Repetitive Dislocation of Transvenous Left Ventricular Leads During Cardiac Resynchronization Therapy Implantation by the Loop Technique

Cardiac resynchronization therapy (CRT) for heart failure requires transvenous insertion of a left ventricular pacing lead through the coronary sinus. However, repeated intraoperative dislocations often occur. Therefore, we describe a novel technique that uses the loop technique to treat patients with repeated intraoperative dislocations during transvenous left ventricular lead implantation to stabilize the lead in its final position. In five patients with repeated intraoperative dislocation during transvenous left ventricular lead implantation, the loop technique was successfully used to stabilize the lead in its final position. The pacing and sensing parameters were satisfactory in all patients at implantation and 12 months post-operatively. Compared with the pre-operative values, the 12-month post-operative values for the left ventricular ejection fraction were significantly increased and the left ventricular end systolic dimension and left ventricular end diastolic dimension were significantly decreased (P < 0.05). The left ventricular ejection fraction of these 5 patients increased by more than 15%. CRT significantly improved the left ventricular structure and function of these 5 patients. During the 1-, 3-, 6-, and 12-month follow-ups, no left ventricular lead dislocations were observed. This loop technique is safe and effective and can be considered for repeated intraoperative dislocation during transvenous left ventricular lead implantation through the coronary sinus of a CRT device.

A new method to recommend left ventricular lead positions for improved CRT volumetric response and long-term prognosis

OBJECTIVES

Using ECG-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), we sought to develop and validate a new method to recommend left ventricular (LV) lead positions in order to improve volumetric response and long-term prognosis after cardiac resynchronization therapy (CRT).

METHODS

Seventy-nine patients received gated SPECT MPI at baseline, and echocardiography at baseline and follow-up. The volumetric response referred to a reduction of ≥ 15% in LV end-systolic volume 6 months after CRT. After excluding apical, septal, and scarred segments, there were three levels of recommended segments: (1) the optimal recommendation: the latest contracting viable segment; (2) the 2nd recommendation: the late contracting viable segments whose contraction delays were within 10° of the optimal recommendation; and (3) the 3rd recommendation: the viable segments adjacent to the optimal recommendation when there was no late contracting viable segment.

RESULTS

After excluding 11 patients whose LV lead was placed in apical or scarred segments, 75.6% of the patients concordant to recommended LV segments (n = 41) responded to CRT while 51.9% of those with non-recommended LV lead locations (n = 27) were responders (P = .043). Response rates were 76.9%, 76.9% , and 73.3% (P = .967), respectively, when LV lead was implanted in the optimal recommendation (n = 13), the 2nd recommendation (n = 13), and the 3rd recommendation (n = 15). LV leads placed at recommended segments reduced composite events of all-cause mortality or heart failure (HF) rehospitalization compared with pacing at non-recommended segments (log-rank χ2 = 5.623, P = .018).

CONCLUSIONS

Pacing in the recommended LV lead segments identified on gated SPECT MPI was associated with improved volumetric response to CRT and long-term prognosis.

A rule-based method for predicting the electrical activation of the heart with cardiac resynchronization therapy from non-invasive clinical data

Background

Cardiac Resynchronization Therapy (CRT) is one of the few effective treatments for heart failure patients with ventricular dyssynchrony. The pacing location of the left ventricle is indicated as a determinant of CRT outcome.

Objective

Patient specific computational models allow the activation pattern following CRT implant to be predicted and this may be used to optimize CRT lead placement.

Methods

In this study, the effects of heterogeneous cardiac substrate (scar, fast endocardial conduction, slow septal conduction, functional block) on accurately predicting the electrical activation of the LV epicardium were tested to determine the minimal detail required to create a rule based model of cardiac electrophysiology. Non-invasive clinical data (CT or CMR images and 12 lead ECG) from eighteen patients from two centers were used to investigate the models.

Results

Validation with invasive electro-anatomical mapping data identified that computer models with fast endocardial conduction were able to predict the electrical activation with a mean distance errors of 9.2 ± 0.5 mm (CMR data) or (CT data) 7.5 ± 0.7 mm.

Conclusion

This study identified a simple rule-based fast endocardial conduction model, built using non-invasive clinical data that can be used to rapidly and robustly predict the electrical activation of the heart. Pre-procedural prediction of the latest electrically activating region to identify the optimal LV pacing site could potentially be a useful clinical planning tool for CRT procedures.

It’s not ageing, stupid: why population ageing won’t bankrupt health systems

An ageing population is often viewed as a factor that will increase healthcare expenditures (HCE) to unsustainable levels. With nearly half the disease burden in high-income countries arising in older people, there are concerns that caring for a burgeoning older population that is sick and dependent on support will not be possible. The aim of this narrative review is to examine how population ageing is likely to affect future HCE growth. We find that despite the increasing share of older people over the next few decades, the changing age-mix will not be a significant driver of HCE growth. While older people, on average, incur higher per person healthcare spending than younger people, the proportions of the population at the oldest and most costly age groups increase very slowly over time. In the European Union, we estimate the changing age-mix to result in the increase of the average annual growth in per person health spending by no more than 0.6 additional percentage points per year between 2015 and 2050. Therefore, price growth and technological advancements, independent of population ageing, will be the main contributors to future HCE growth.

Alternative left ventricular pacing approaches for optimal cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) improves mortality, morbidity, and quality of life in selected heart failure patients with severe left ventricular (LV) ejection fraction impairment. However, between 20% and 40% of device recipients do not benefit clinically from CRT. Indeed, some anatomic and technical difficulties are related to the coronary venous implantation site via the coronary sinus (CS). Additionally, electrical constraints have been described, and CS does not always correspond to the optimal LV lead position. In the last decade, engineers and physicians have worked together to overcome the challenging LV lead implantation, and various biventricular pacing alternatives have been developed to improve CRT response. In this review, we discuss the evolution from CS pacing to wireless LV stimulation and His-bundle pacing.

Permanent His bundle pacing in heart failure patients: A systematic review and meta-analysis

BACKGROUND

Cardiac resynchronization therapy (CRT) is the standard-of-care therapy for the patients with heart failure and left ventricular (LV) dyssynchrony. However, approximately 30% of the patients show no response. Recent studies have shown that His bundle pacing (HBP) could be an alternative for the patients with CRT indications. The purpose of this study was to evaluate the efficacy of HBP in patients with heart failure.

METHODS

We searched PubMed and Embase databases for studies evaluating HBP in patients with heart failure and LV dyssynchrony. The successful rate of implantation, QRS duration, pacing threshold, LV function at baseline and follow-up, and mortality rates were extracted and summarized.

RESULTS

Eleven studies including 494 patients were included in this analysis. The overall successful rate for implantation was 82.4%. The main indications for HBP were CRT candidates and cardiomyopathy with atrial fibrillation undergoing atrioventricular node ablation. Permanent HBP resulted in narrow QRS duration of 116.3 ± 13.9 ms after implantation. LV functions, including echocardiographic parameters and clinical outcomes, significantly improved at follow-up (P < 0.001). However, there was a trend of increased capture and bundle branch block correction thresholds at follow-up compared to baseline (P = 0.01 and 0.02, respectively). During a mean follow-up of 23.7 months, 5.9% of the patients experienced heart failure-related hospitalization and the mortality rate was 9.1%.

CONCLUSION

Permanent HBP has shown promising results for heart failure patients in small observational studies. Randomized controlled trials are needed to assess the efficacy of HBP in these patients.

Development and validation of an automatic method to detect the latest contracting viable left ventricular segments to assist guide CRT therapy from gated SPECT myocardial perfusion imaging

OBJECTIVES

The purpose of this study is to use ECG-gated SPECT MPI to detect the latest contracting viable left ventricular (LV) segments to help guide the LV probe placement used in CRT therapy and to validate segment selection against the visual integration method by experts.

METHODS

For each patient, the resting ECG-gated SPECT MPI short-axis images were sampled in 3D to generate a polar map of the perfusion distribution used to determine LV myocardial viability, and to measure LV synchronicity using our phase analysis tool. In the visual integration method, two experts visually interpreted the LV viability and mechanical dyssynchrony from the short-axis images and polar maps of viability and phase, to determine the latest contracting viable segments using the 17-segment model. In the automatic method, the apical segments, septal segments, and segments with more than 50% scar were excluded as these are not candidates for CRT LV probe placement. Amongst the remaining viable segments, the segments, whose phase angles were within 10° of the latest phase angle (the most delayed contracting segment), were identified for potential CRT LV probe placement and ranked based on the phase angles of the segments. Both methods were tested in 36 pre-CRT patients who underwent ECG-gated SPECT MPI. The accuracy was determined as the percent agreement between the visual integration and automatic methods. The automatic method was performed by a second independent operator to evaluate the inter-operator processing reproducibility.

RESULTS

In all the 36 patients, the LV lead positions of the 1st choices recommended by the automatic and visual integration methods were in the same segments in 35 patients, which achieved an agreement rate of 97.2%. In the inter-operator reproducibility test, the LV lead positions of the 1st choices recommended by the two operators were in the same segments in 25 patients, and were in the adjacent segments in 7 patients, which achieved an overall agreement of 88.8%.

CONCLUSIONS

An automatic method has been developed to detect the latest contracting viable LV segments to help guide the LV probe placement used in CRT therapy. The retrospective clinical study with 36 patients suggests that this method has high agreement against the visual integration method by experts and good inter-operator reproducibility. Consequently, this method is promising to be a clinical tool to recommend the CRT LV lead positions.

Current role of echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established treatment for patients with heart failure and left ventricular systolic dysfunction. Patients are usually assessed by echocardiography, which provides a number of anatomical and functional information used for cardiac dyssynchrony assessment, prognostic stratification, identification of the optimal site of pacing in the left ventricle, optimization of the CRT device, and patient follow-up. Compared to other cardiac imaging techniques, echocardiography has the advantage to be non-invasive, repeatable, and safe, without exposure to ionizing radiation or nefrotoxic contrast. In this article, we review current evidence about the role of echocardiography before, during, and after the implantation of a CRT device.

Wideband LGE MRI permits unobstructed viewing of myocardial scarring in a patient with an MR-conditional subcutaneous implantable cardioverter-defibrillator

A subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative device for prevention of sudden cardiac death, without any leads within the heart. Patients implanted with any type of ICD may need catheter ablation of ventricular tachycardia (VT) to reduce the overall arrhythmia burden (e.g., recurrent monomorphic VT) and lower the incidence of painful shocks induced by the device. Late gadolinium enhancement (LGE) MRI is a useful pre-test for guiding VT ablation, because it can be used to map myocardial scar and produce better outcomes. Growing evidence suggests that MRI can be performed with manageable risks on patients with a cardiac implantable electronic device (CIED). Nonetheless, the diagnostic yield of cardiac MRI is still low because of severe image artifacts, regardless of MR-conditional or non-MR conditional labeling. Image artifacts in the heart induced by an S-ICD is expected to be larger than the artifacts induced by a transvenous ICD, because the former is twice as large in size and implanted closer to the heart. This is the first reported case of successful wideband LGE MRI in a patient implanted with an MR-conditional S-ICD. A 37-year-old man with ischemic cardiomyopathy was referred for a cardiac MRI at 1.5 T ten months after S-ICD implantation, in order to rule out constrictive pericarditis. Clinical standard LGE MRI produced severe image artifacts, rendering it useless. In contrast, wideband LGE MRI provided unobstructed viewing of myocardial scarring. This case illustrates the usefulness of wideband LGE MRI for assessment of myocardial scarring in a patient with an MR-conditional S-ICD.

Biophysical Modeling to Determine the Optimization of Left Ventricular Pacing Site and AV/VV Delays in the Acute and Chronic Phase of Cardiac Resynchronization Therapy

BACKGROUND

Cardiac anatomy and function adapt in response to chronic cardiac resynchronization therapy (CRT). The effects of these changes on the optimal left ventricle (LV) lead location and timing delay settings have yet to be fully explored.

OBJECTIVE

To predict the effects of chronic CRT on the optimal LV lead location and device timing settings over time.

METHODS

Biophysical computational cardiac models were generated for 3 patients, immediately post-implant (ACUTE) and after at least 6 months of CRT (CHRONIC). Optimal LV pacing area and device settings were predicted by pacing the ACUTE and CHRONIC models across the LV epicardium (49 sites each) with a range of 9 pacing settings and simulating the acute hemodynamic response (AHR) of the heart.

RESULTS

There were statistically significant differences between the distribution of the AHR in the ACUTE and CHRONIC models (P < 0.0005 in all cases). The site delivering the maximal AHR shifted location between the ACUTE and CHRONIC models but provided a negligible improvement (<2%). The majority of the acute optimal LV pacing regions (76-100%) and device settings (76-91%) remained optimal chronically.

CONCLUSION

Optimization of the LV pacing location and device settings were important at the time of implant, with a reduced benefit over time, where the majority of the acute optimal LV pacing region and device settings remained optimal with chronic CRT.

A Review of Image-guided Approaches for Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is a standard treatment for patients with heart failure; however, the low response rate significantly reduces its cost-effectiveness. A favourable CRT response primarily depends on whether implanters can identify the optimal left ventricular (LV) lead position and accurately place the lead at the recommended site. Myocardial imaging techniques, including echocardiography, cardiac magnetic resonance imaging and nuclear imaging, have been used to assess LV myocardial viability and mechanical dyssynchrony, and deduce the optimal LV lead position. The optimal position, presented as a segment of the myocardial wall, is then overlaid with images of the coronary veins from fluoroscopy to aid navigation of the LV lead to the target venous site. Once validated by large clinical trials, these image-guided techniques for CRT lead placement may have an impact on current clinical practice.

Zero x-ray cardiac resynchronization therapy device implantation guided by a nonfluoroscopic mapping system: A pilot study

BACKGROUND

Fluoroscopic guidance is the standard tool used in device implantation. This means that both the patient and the operator are exposed to radiation, which may sometimes be high. The possibility of single-lead permanent pacemaker implantation without fluoroscopy has already been demonstrated.

OBJECTIVE

The aim of our study was to investigate the feasibility and reliability of biventricular device implantation guided only by an electroanatomic navigation system.

METHODS

Sixty-one patients with heart failure underwent implantation of a cardiac resynchronization therapy (CRT) device with or without defibrillator (CRT-D; CRT-P). The procedure was performed with or without fluoroscopy guidance (Rx+; Rx0). In the latter case, the EnSite Velocity system was used; this system is able to reconstruct the anatomy and activation of the cardiac chambers by simultaneously collecting a "cloud" of anatomical points from multiple electrodes.

RESULTS

Lead positioning was achieved in 24 of 26 patients undergoing CRT implantation without fluoroscopy (92% success). No complications were observed during the procedure and no catheter dislodgment occurred the day after the implantation or during 1-month follow-up. Procedure time progressively decreased from 136 minutes in the first case to 59 minutes in the last one, suggesting that operators gradually gained confidence while using the new technique.

CONCLUSION

Our study demonstrates the feasibility, efficacy, and safety of lead positioning guided only by the nonfluoroscopic EnSite Velocity mapping system without the use of fluoroscopy in CRT-P or CRT-D implantation. The benefits in terms of significantly reduced fluoroscopy exposure are associated with technical and clinical advantages.

Nuclear Image-Guided Approaches for Cardiac Resynchronization Therapy (CRT)

Cardiac resynchronization therapy (CRT) is a standard treatment for patients with heart failure. However, 30-40 % of the patients having CRT do not respond to CRT with improved clinical symptom and cardiac functions. It is important for CRT response that left ventricular (LV) lead is placed away from scar and at or near the site of the latest mechanical activation. Nuclear image-guided approaches for CRT have shown significant clinical value to assess LV myocardial viability and mechanical dyssynchrony, recommend the optimal LV lead position, and navigate the LV lead to the target coronary venous site. All these techniques, once validated and implemented, should impact the current clinical practice.

3D fusion of LV venous anatomy on fluoroscopy venograms with epicardial surface on SPECT myocardial perfusion images for guiding CRT LV lead placement

OBJECTIVES

The aim of this study was to develop a 3-dimensional (3D) fusion tool kit to integrate left ventricular (LV) venous anatomy on fluoroscopy venograms with LV epicardial surface on single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for guiding cardiac resynchronization therapy (CRT) LV lead placement.

BACKGROUND

LV lead position is important for CRT response. For LV lead placement into viable regions with late activation, it is important to visualize both LV venous anatomy and myocardium.

METHODS

Major LV veins were manually identified on fluoroscopic venograms and automatically reconstructed into a 3D anatomy. 3D LV epicardial surface was extracted from SPECT MPI. SPECT-vein fusion that consisted of geometric alignment, landmark-based registration, and vessel-surface overlay was developed to fuse the 3D venous anatomy with the epicardial surface. The accuracy of this tool was evaluated using computed tomography (CT) venograms. LV epicardial surfaces and veins were manually identified on the CT images and registered with the SPECT image by an independent operator. The locations of the fluoroscopic and CT veins on the SPECT epicardial surfaces were compared using absolute distances on SPECT short-axis slice and the 17-segment model.

RESULTS

Ten CRT patients were enrolled. The distance between the corresponding fluoroscopic and CT veins on the short-axis epicardial surfaces was 4.6 ± 3.6 mm (range 0 to 16.9 mm). The presence of the corresponding fluoroscopic and CT veins in the 17-segment model agreed well with a kappa value of 0.87 (95% confidence interval: 0.82 to 0.93). The tool kit was used to guide LV lead placement in a catheter laboratory and showed clinical feasibility and benefit to the patient.

CONCLUSIONS

A tool kit has been developed to reconstruct 3D LV venous anatomy from dual-view fluoroscopic venograms and to fuse it with LV epicardial surface on SPECT MPI. It is technically accurate for guiding LV lead placement by the 17-segment model and is feasible for clinical use in the catheterization laboratory.

Sites of latest mechanical activation as assessed by SPECT myocardial perfusion imaging in ischemic and dilated cardiomyopathy patients with LBBB

OBJECTIVE

Sites of latest mechanical activation (SOLA) have been recognized as optimal left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT). This study was aimed to investigate SOLA in ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) patients with left bundle branch block (LBBB).

METHODS

Sixty-four consecutive LBBB patients (47 DCM, 17 ICM), who met the standard indications for CRT and underwent resting SPECT myocardial perfusion imaging (MPI), were selected. Phase analysis was used to assess LV dyssynchrony and SOLA. The Emory Cardiac Toolbox was used to measure perfusion defects. LV dyssynchrony and SOLA were compared between the DCM patients with wide (≥150 ms) and moderate (120-150 ms) QRS durations (QRSd). The relationship between SOLA and perfusion defects was analyzed in the ICM patients.

RESULTS

The DCM patients with wide QRSd had significantly more LV dyssynchrony than those with moderate QRSd. Lateral SOLA were significantly more frequent in the DCM patients with wide QRSd than those with moderate QRSd (96% vs. 62%, p = 0.010). In the ICM patients, SOLA were either in the scar segments (82%) or in the segments immediately adjacent to the scar segments (18%), regardless of QRSd.

CONCLUSION

Lateral SOLA were more frequent in the DCM patients with wide QRSd than those with moderate QRSd. Such relationship was not observed in the ICM patients, where SOLA were associated with scar location rather than QRSd. These findings support the use of SPECT MPI to aid the selection of potential CRT responders and guide LV lead placement.

Assessment of cardiac stroke volume in patients with implanted cardiac pacemaker using parametric electrical impedance tomography: a theoretical 2D study

The present theoretical study examines the ability to estimate cardiac stroke volume (CSV) in patients with implanted cardiac pacemaker using parametric electrical impedance tomography (pEIT) in a 2D computerized model of the thorax. CSV is a direct indicator of the cardiac pumping efficiency. The commonly used methods for measuring CSV require the invasive procedure of right heart catheterization or use expensive imaging techniques (i.e., MRI). Hence, experience with these techniques for diagnosis and monitoring has been limited to hospitalized patients. In the present study, pEIT scheme was applied in a computerized 2D model of the human thorax with implanted cardiac device to determine the left ventricular (LV) volume at different cardiac cycle phases. The LV was simulated as a prolate ellipse with its axes' lengths as the reconstruction parameters while all other geometries and conductivity values remained constant. An optimization was carried out in order to ensure that the ellipse is the appropriate model for the LV at each cardiac cycle phase. LV volumes calculated by both the pEIT algorithm and the ellipsoid model are consistent. A high correlation (ρ = 0.99) between the true and reconstructed volumes was found. The SV calculation error was ∼1%. The results suggest that the LV volume can be estimated using the pEIT method in a 2D computerized model, and that the method has the potential to be used for monitoring patients with implanted cardiac pacemaker.

The impact of left ventricular lead position on left ventricular reverse remodelling and improvement in mechanical dyssynchrony in cardiac resynchronization therapy

AIMS

To investigate the influence of left ventricular (LV) lead position on LV dyssynchrony in cardiac resynchronization therapy (CRT).

METHODS AND RESULTS

The LV lead was prospectively targeted to the latest activated LV segment (concordant) evaluated by two-dimensional speckle tracking radial strain (ST-RS) echocardiography in 103 CRT recipients (67 ± 12 years). Mechanical dyssynchrony was assessed by anteroseptal-to-posterior (AS-P) delay and interventricular mechanical delay (IVMD). Concordant LV leads were obtained in 72 (70%) patients. Superior LV reverse remodelling (LV-RR; ≥ 15% LV end-systolic volume reduction at 6-month follow-up) was observed in the concordant LV leads compared with the discordant LV leads [51 (76%) vs. 13 (45%); P = 0.003]. Mechanical resynchronization responders (≥ 50% AS-P delay reduction at 6-month follow-up) obtained in the concordant LV leads [44 (66%)] was greater than in the discordant LV leads [10 (34%); P = 0.005]. The discordant LV leads located adjacent to the concordant LV leads (+1 segment; n = 22) and 2 segments apart (+2 segments; n = 9) were evaluated in a subgroup analysis. Mechanical resynchronization responders 6 months after CRT were as follows: in +1 segment [n = 10 (48%)] and in +2 segments (n = 0; P = 0.001). The concordant LV lead was the only independent predictor of LV-RR at 6-month follow-up (odds ratio, 4.177; P = 0.004). Independent predictors of mechanical resynchronization responders were AS-P delay (odds ratio, 1.007; P = 0.032), IVMD (odds ratio, 1.024; P = 0.038), and concordant LV lead (odds ratio, 4.691; P = 0.004).

CONCLUSION

Concordant LV leads in CRT provided more responders according to both LV reverse remodelling and mechanical resynchronization.

First prospective, multi-centre clinical experience with a novel left ventricular quadripolar lead

AIMS

Cardiac resynchronization therapy (CRT) is sometimes complicated by elevated pacing thresholds and phrenic nerve stimulation (PNS), both of which may require that the coronary sinus lead be repositioned. The purpose of this study was to evaluate the performance of a novel quadripolar electrode lead and cardiac resynchronization therapy-defibrillator (CRT-D) device that enables electrical repositioning, potentially obviating a lead reposition procedure.

METHODS AND RESULTS

Patients indicated for CRT were enrolled and received a quadripolar electrode lead and CRT-D device (Quartetmodel 1458Q and Promote Q; St Jude Medical, Sylmar, CA, USA). Electrical data, and the presence of PNS during pacing from each left ventricular (LV) configuration, were documented at pre-hospital discharge and at 1 month. Seventy-five patients were enrolled and 71 were successfully implanted with a Quartetlead. Electrical measurements were stable over the follow-up period. Ninety-seven per cent (64 of 66) of patients had one or more programmable configurations with a threshold < 2.5 V and no PNS vs. 86% (57 of 66) if only conventional bipolar configurations were considered. Physicians were able to use the increased programming options to manage threshold changes and PNS.

CONCLUSION

The new quadripolar electrode LV lead provides more programming options to address common problems faced when managing CRT patients. Electrical measurements from new vectors are comparable with conventional configurations. Furthermore, 11% of patients in the study suffered PNS on all conventional bipolar vectors.

Implantation of a biventricular implantable cardioverter-defibrillator guided by an electroanatomic mapping system

Aims

The aim of this study is to show the feasibility of a biventricular implantable cardioverter-defibrillator [cardiac resynchronization therapy (CRT)–ICD] implantation using an electroanatomic navigation system and a low dose of fluoroscopy. Here four case reports of patients affected by dilated cardiomyopathy, who underwent cardiac resynchronization therapy, are described.

Methods and results

During 2010, four patients were admitted to our Cardiology Department for implantation of an CRT–ICD device in primary prevention. All had an ejection fraction of <35% and were in New York Heart Association class III despite optimal medical therapy. The implantations were performed using the EnSite NavX system. All the leads were positioned in the cardiac chambers utilizing the three-dimensional navigation system and only using X-ray to check that the leads had been positioned correctly. To our knowledge, these cases are the first use of an electroanatomic system for implantation of an CRT–ICD device and in all four cases the cannulation of the coronary sinus (CS) was performed only using the mapping system. Electroanatomic navigation made it possible to minimize X-ray exposure during the implantation of the CRT–ICD device; in addition, the mapping system was used to choose the optimum position of the CS catheter using as reference the maximum activation delay between the two ventricles.

Conclusions

The NavX system shows great potential during the implantation of an CRT–ICD device. It seems to be feasible, safe, and extremely beneficial in terms of a reduction in X-ray exposure. Furthermore, there is benefit of more detailed information and accuracy during the CS lead placement.

A modified echocardiographic protocol with intrinsic plausibility control to determine intraventricular asynchrony based on TDI and TSI

Background

Established methods to determine asynchrony suffer from high intra- and interobserver variability and failed to improve patient selection for cardiac resynchronization therapy (CRT). Thus, there is a need for easy and robust approaches to reliably assess cardiac asynchrony.

Methods and Results

We performed echocardiography in 100 healthy subjects and 33 patients with left bundle branch block (LBBB). To detect intraventricular asynchrony, we combined two established methods, i.e., tissue synchronization imaging (TSI) and tissue Doppler imaging (TDI). The time intervals from the onset of aortic valve opening (AVO) to the peak systolic velocity (S') were measured separately in six basal segments in the apical four-, two-, and three-chamber view. Color-coded TSI served as an intrinsic plausibility control and helped to identify the correct S' measuring point in the TDI curves. Next, we identified the segment with the shortest AVO-S' interval. Since this segment most likely represents vital and intact myocardium it served as a reference for other segments. Segments were considered asynchronous when the delay between the segment in question and the reference segment was above the upper limit of normal delays derived from the control population. Intra- and interobserver variability were 7.0% and 7.7%, respectively.

Conclusion

Our results suggest that combination of TDI and TSI with intrinsic plausibility control improves intra- and interobserver variability and allows easy and reliable assessment of cardiac asynchrony.