Clinical outcomes and predictors of delayed echocardiographic response to cardiac resynchronization therapy.

INTRODUCTION: The clinical outcomes and mechanisms of delayed responses to cardiac resynchronization therapy (CRT) remain unclear. We aimed to investigate the differences in outcomes and gain insight into the mechanisms of early and delayed responses to CRT. METHODS: This retrospective study included 110 patients who underwent CRT implantation. Positive response to CRT was defined as ≥15% reduction of left ventricular (LV) end-systolic volume on echocardiography at 1 year (early phase) and 3 years (delayed phase) after implantation. The latest mechanical activation site (LMAS) of the LV was identified using two-dimensional speckle-tracking radial strain analysis. RESULTS: Seventy-eight (71%) patients exhibited an early response 1 year after CRT implantation. Of 32 non-responders in the early phase, 12 (38%) demonstrated a delayed response, and 20 (62%) were classified as non-responders after 3 years. During the follow-up time of 10.3 ± 0.5 years, the delayed and early responders had a similar prognosis of mortality and heart failure (HF) hospitalization. In contrast, non-responders had a worse prognosis. Multivariate analysis revealed that a longer duration (months) between initial HF hospitalization and CRT (odds ratio [OR]: 1.126; 95% confidence interval [CI]: 1.036-1.222; p = .005), non-exact concordance of LV lead location with LMAS (OR: 32.744; 95% CI: 1.101-973.518; p = .044), and pre-QRS duration (OR: 0.901; 95% CI: 0.827-0.981; p = .016) were independent predictors of delayed response to CRT compared with early response. CONCLUSION: The prognoses were similar regardless of the response time after CRT. A longer history of HF, suboptimal LV lead position, and shorter pre-QRS duration were related to delayed response than early response.

Preferred left ventricular lead position for upgrade from right ventricular pacing to cardiac resynchronization therapy.

INTRODUCTION: Cardiac resynchronization therapy (CRT) is well-established for treating symptomatic heart failure with electrical dyssynchrony. The left ventricular (LV) lead position is recommended at LV posterolateral to lateral sites in patients with left bundle branch block; however, its preferred region remains unclear in patients being upgraded from right ventricular (RV) apical pacing to CRT. This study aimed to identify the preferred LV lead position for upgrading conventional RV apical pacing to CRT. METHODS: We used electrode catheters positioned at the RV apex and LV anterolateral and posterolateral sites via the coronary sinus (CS) branches to measure the ratio of activation time to QRS duration from the RV apex to the LV anterolateral and posterolateral sites during RV apical pacing. Simultaneous biventricular pacing was performed at the RV apex and each LV site, and the differences in QRS duration and LV dP/dtmax from those of RV apical pacing were measured. RESULTS: Thirty-seven patients with anterolateral and posterolateral LV CS branches were included. During RV apical pacing, the average ratio of activation time to QRS duration was higher at the LV anterolateral site than at the LV posterolateral site (0.90 ± 0.06 vs. 0.71 ± 0.11, p < .001). The decreasing ratio of QRS duration and the increasing ratio of LV dP/dtmax were higher at the LV anterolateral site than at the posterolateral site (45.7 ± 18.0% vs. 32.0 ± 17.6%, p < .001; 12.7 ± 2.9% vs. 3.7 ± 8.2%, p < .001, respectively) during biventricular pacing compared with RV apical pacing. CONCLUSION: The LV anterolateral site is the preferred LV lead position in patients being upgraded from conventional RV apical pacing to CRT.

Targeted left ventricular lead positioning to the site of latest activation in cardiac resynchronization therapy: a systematic review and meta-analysis.

AIMS: Several studies have evaluated the use of electrically- or imaging-guided left ventricular (LV) lead placement in cardiac resynchronization therapy (CRT) recipients. We aimed to assess evidence for a guided strategy that targets LV lead position to the site of latest LV activation. METHODS AND RESULTS: A systematic review and meta-analysis was performed for randomized controlled trials (RCTs) until March 2023 that evaluated electrically- or imaging-guided LV lead positioning on clinical and echocardiographic outcomes. The primary endpoint was a composite of all-cause mortality and heart failure hospitalization, and secondary endpoints were quality of life, 6-min walk test (6MWT), QRS duration, LV end-systolic volume, and LV ejection fraction. We included eight RCTs that comprised 1323 patients. Six RCTs compared guided strategy (n = 638) to routine (n = 468), and two RCTs compared different guiding strategies head-to-head: electrically- (n = 111) vs. imaging-guided (n = 106). Compared to routine, a guided strategy did not significantly reduce the risk of the primary endpoint after 12-24 (RR 0.83, 95% CI 0.52-1.33) months. A guided strategy was associated with slight improvement in 6MWT distance after 6 months of follow-up of absolute 18 (95% CI 6-30) m between groups, but not in remaining secondary endpoints. None of the secondary endpoints differed between the guided strategies. CONCLUSION: In this study, a CRT implantation strategy that targets the latest LV activation did not improve survival or reduce heart failure hospitalizations.

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.

Imaging-guided cardiac resynchronization therapy: A meta-analysis of randomized controlled trials.

BACKGROUND: Among patients with heart failure and left ventricular (LV) dysfunction despite guideline directed medical therapy, cardiac resynchronization (CRT) is an effective technology to reverse LV remodeling. Given that a large portion of patients are non-responders, alternatives to traditional LV-lead placement have been explored. A promising alternative is image targeted placement of an LV-lead to latest mechanically activated segment without scar. METHODS: Electronic database search for randomized controlled trials (RCTs) that evaluated the imaging-guided LV-lead placement on clinical, echocardiographic, and functional outcomes. The primary outcome was a composite of mortality and heart failure hospitalization. The secondary outcomes included CRT responders, New York Heart Association (NYHA), 6-minute walk test, Minnesota Living with Heart Failure Questionnaire (MLHFQ), and ejection fraction (EF) changes. RESULTS: Analysis included 4 RCTs of 691 patients with an average follow-up of 2 years (age 69.5 ± 10.3 years, 76% males, 54% ischemic cardiomyopathy, 81% with NYHA classes III/IV, and EF of 24.4% ± 8). The most common site for LV-lead paced segment was the anterolateral segment (45%) and at mid-LV (49%). Compared with the control, imaging-guided LV-lead placement was associated with a significant reduction of the primary outcome (hazard ratio [HR] = 0.60; 95% CI = 0.40-0.88; p = .01), higher CRT responders (odd ratio [OR] = 2.10; p < .01), more NYHA improvements by ≥1 (OR = 1.89; p = .01), increased 6MWT (mean difference [MD] = 25.78 feet; p < .01), and lower MLHFQ (MD = -4.04; p = .04), without significant differences in the LVEF (p = .08). CONCLUSIONS: In patients undergoing CRT, imaging-guided LV-lead placement was associated with improved clinical, echocardiographic, and functional status.

A novel ECG-based algorithm to determine right ventricular lead placement in permanent pacemaker patients (RVpace study).

INTRODUCTION: Fluoroscopy guidance alone is not sufficient for the accurate localization of the pacing lead (PL) in the right ventricle (RV) during implantation of the cardiac implantable electronic device (CIED). The aim of this study was to create a surface electrocardiogram (ECG) algorithm based on paced QRS (pQRS) morphology to accurately localize PL position in the RV. METHODS AND RESULTS: Thirty consecutive patients scheduled for catheter ablation of right heart arrhythmias were enrolled. After the elimination of index arrhythmia pacing from the RV interventricular septum (IVS), apex and free wall was performed and pQRS were recorded. The pacing site was verified both by fluoroscopy and transthoracic echocardiography. After a careful analysis of pQRS, a stepwise algorithm was developed to aid the proper positioning of the PL in RV. The algorithm was later prospectively validated in 31 pacemaker patients undergoing an elective generator exchange. A clear R wave in I, II, and V5 leads indicated proximal IVS. For a reliable indication of other RV sites, four ECG leads were crucial I, II, V5, and V6. A prospective evaluation of the algorithm revealed 90.3% agreement between RV lead localization obtained by ECG and echocardiography, with sensitivity of 92.5% (95% confidence interval [CI], 83.2%-100.0%) and a positive predictive value of 96.0% (95% CI, 89.0%-100.0%) for desired lead locations in RV. CONCLUSION: A simple ECG algorithm can reliably differentiate between the sites of permanent PL implantation in the RV in CIED recipients.

Optimization of coronary sinus lead placement targeted to the longest right-to-left delay in patients undergoing cardiac resynchronization therapy: The Optimal Pacing SITE 2 (OPSITE 2) acute study and protocol.

AIMS: Left ventricular (LV) lead positioning at the site of delayed electrical activation is associated with better response to cardiac resynchronization therapy (CRT). We hypothesized that a long electrical conduction delay between right ventricular (RV) and coronary sinus (CS) leads during RV pacing (RLD index) is correlated with a better clinical outcome METHODS AND RESULTS: RLD is measured intraprocedurally, during RV pacing, as the time interval between the intracardiac electrograms of RV and CS leads. Initially, we did a prove-of-concept, feasibility, acute study in 97 patients who underwent CRT implantation. The CS lead position was assessed in the 40° right anterior oblique and 40° left anterior oblique views and assigned to one of 11 prespecified segments of a schematic eyeball depiction of the LV walls. Acute outcomes were QRS width during biventricular (BIV) pacing. The longest RLD were found in the basal and mid lateral segments; these accounted for 82% and 78%, respectively, of the total QRS width (%RLD). %RLD was inversely correlated with BIV-paced QRS (P  =  0.0001). A similar slope was present either in the 78 patients with preserved atrioventricular (AV) conduction and in the 19 without AV conduction (- 0.34 vs - 0.27, P  =  0.7). CONCLUSION: We showed that RLD can be used to guide lead placement at the time of CRT implantation and that it is correlated with BIV-QRS width, an indirect predictor of clinical outcome. Based on these findings we started the prospective, multicenter Optimal Pacing SITE 2 (OPSITE 2) trial with the objective to demonstrate a relationship between RLD and clinical outcomes assessed as death, hospitalization for heart failure, New York Heart Association class, and clinical composite score. The protocol is provided.

Comparison of right ventricular septal pacing and right ventricular apical pacing in patients receiving cardiac resynchronization therapy defibrillators: the SEPTAL CRT Study.

AIMS: Cardiac resynchronization therapy (CRT) is a recommended treatment of heart failure (HF) patients with depressed left ventricular ejection fraction and wide QRS. The optimal right ventricular (RV) lead position being a matter of debate, we sought to examine whether RV septal (RVS) pacing was not inferior to RV apical (RVA) pacing on left ventricular reverse remodelling in patients receiving a CRT-defibrillator. METHODS AND RESULTS: Patients (n = 263, age = 63.4 ± 9.5 years) were randomly assigned in a 1:1 ratio to RVS (n = 131) vs. RVA (n = 132) pacing. Left ventricular end-systolic volume (LVESV) reduction between baseline and 6 months was not different between the two groups (-25.3 ± 39.4 mL in RVS group vs. -29.3 ± 44.5 mL in RVA group, P = 0.79). Right ventricular septal pacing was not non-inferior (primary endpoint) to RVA pacing with regard to LVESV reduction (average difference = -4.06 mL; P = 0.006 with a -20 mL non-inferiority margin). The percentage of 'echo-responders' defined by LVESV reduction >15% between baseline and 6 months was similar in both groups (50%) with no difference in the time to first HF hospitalization or death (P = 0.532). Procedural or device-related serious adverse events occurred in 68 patients (RVS = 37) with no difference between the two groups (P = 0.401). CONCLUSION: This study demonstrates that septal RV pacing in CRT is non-inferior to apical RV pacing for LV reverse remodelling at 6 months with no difference in the clinical outcome. No recommendation for optimal RV lead position can hence be drawn from this study. CLINICALTRIALS GOV NUMBER: NCT 00833352.

Optimal Lead Positioning in Sacral Neuromodulation: Which Factors Are Related to Treatment Outcome?

OBJECTIVES: Sacral neuromodulation (SNM) is a well-established treatment for overactive bladder (OAB) and non-obstructive urinary retention (NOR). During test stimulation, the lead is positioned along the third sacral nerve, which ideally results in a response in all four contact points (active electrodes). However, it is unclear whether the position of the lead (depth, angle, deflection) and the number of active electrodes is related to the outcome of SNM. METHODS: All patients who underwent test stimulation using the tined lead between January 2011 and September 2016 were included in this retrospective study. Success was defined as >50% improvement in voiding diary parameters compared to baseline. The correlation between lead position and outcome of test stimulation was evaluated. The lead position was determined by evaluating the depth, angle and deflection with respect to the sacral foramen. Binary logistic regression was used in order to determine the predictive value of these factors. RESULTS: We included 189 patients of whom 105 were diagnosed with OAB and 84 with NOR. After a SNM test period of 4 weeks, 111 patients (59%) were successful and received a permanent implant. The position of the lead and the number of active electrodes did not predict success of test stimulation in neither the OAB group nor the NOR. However, lateral deflection of the lead was associated with finding more active electrodes (p = 0.01). CONCLUSION: In our study, the position of the lead or the number of active electrodes did not predict the outcome of SNM test stimulation. However, the impact of lead positioning and number of active electrodes on long-term outcome remains to be proven.

Impact of the Right Ventricular Lead Position on Clinical End Points in CRT Recipients--A Subanalysis of the Multicenter Randomized SPICE Trial.

BACKGROUND: The impact of right ventricular (RV) lead location on clinical end points in patients undergoing cardiac resynchronization therapy (CRT) is unclear. We evaluated the impact of different RV lead locations on clinical outcome in CRT patients enrolled in the Septal Positioning of ventricular implantable cardioverter-defibrillator (ICD) Electrodes (SPICE) trial, which randomized recipients of implantable cardioverter defibrillators to apical versus midseptal RV lead positioning. METHODS: Ninety-eight CRT recipients were included in the multicenter SPICE trial and followed for 12 months: Fifty-three patients were randomized to receive an apical (A) and 45 to receive a midseptal (S) lead position. We compared echocardiographical and electrocardiographical parameters and outcome. RESULTS: Echocardiographic response with respect to improvement of left ventricular ejection fraction (A: +15.8 ± 14.6%, S: +9.7 ± 12.6%, P = 0.156) and reduction of left ventricular end-diastolic diameter (A: -4.2 ± 10.7 mm, S: -7.5 ± 10.7 mm, P = 0.141) was comparable in apical and midseptal groups. Paced QRS width neither differed at prehospital discharge (A: 129 ± 21 ms, S: 135 ± 21 ms, P = 0.133) nor at 12-month follow-up (A: 131 ± 23 ms, S: 134 ± 28 ms, P = 0.620). No differences were found with respect to the risk of ventricular tachyarrhythmia or ICD therapy. Septal RV lead position, however, was associated with a significant longer time to a first heart failure event (P = 0.040) and a longer survival time (P = 0.019). CONCLUSIONS: In CRT recipients, midseptal RV lead position was not superior with respect to improvement of echocardiographic parameters or paced QRS width. It did not predispose to ventricular arrhythmias or ICD therapy. The finding that midseptal lead position was associated with a longer time to first heart failure event and a longer survival time deserves further investigation.

His Bundle Pacing: Techniques and Outcomes.

Traditional right ventricular pacing prolongs the electrical and mechanical activation of the heart, which reduces the pump function, and in selected patients may lead to pacing-induced heart failure. Pacing the His bundle preserves the normal or near-normal activation pattern of the ventricles that prevents the detrimental effects of right ventricular pacing. This review discusses the techniques, feasibility, outcomes, and clinical impact of permanent His bundle pacing in patients with an indication for a cardiac implantable electronic device.

Sensor-based electromagnetic navigation to facilitate implantation of left ventricular leads in cardiac resynchronization therapy.

INTRODUCTION: Implantation of cardiac resynchronization therapy (CRT) devices can be challenging, time consuming, and fluoroscopy intense. To facilitate placement of left ventricular (LV) leads, a novel electromagnetic navigation system (MediGuide™, St. Jude Medical, St. Paul, MN, USA) has been developed, displaying real-time 3-D location of sensor-embedded delivery tools superimposed on prerecorded X-ray cine-loops of coronary sinus venograms. We report our experience and advanced progress in the use of this new electromagnetic tracking system to guide LV lead implantation. METHODS AND RESULTS: Between January 2012 and December 2013, 71 consecutive patients (69 ± 9 years, 76% male) were implanted with a CRT device using the new electromagnetic tracking system. Demographics, procedural data, and periprocedural adverse events were gathered. The impact of the operator's experience, optimized workflow, and improved software technology on procedural data were analyzed. LV lead implantation was successfully achieved in all patients without severe adverse events. Total procedure time measured 87 ± 37 minutes and the median total fluoroscopy time (skin-to-skin) was 4.9 (2.5-7.8) minutes with a median dose-area-product of 476 (260-1056) cGy*cm(2) . An additional comparison with conventional CRT device implantations showed a significant reduction in fluoroscopy time from 8.0 (5.8; 11.5) to 4.5 (2.8; 7.3) minutes (P = 0.016) and radiation dose from 603 (330; 969) to 338 (176; 680) cGy*cm(2) , respectively (P = 0.044 ). CONCLUSION: Use of the new navigation system enables safe and successful LV lead placement with improved orientation and significantly reduced radiation exposure during CRT implantation.

Left Ventricular Lead Placement Targeted at the Latest Activated Site Guided by Electrophysiological Mapping in Coronary Sinus Branches Improves Response to Cardiac Resynchronization Therapy.

INTRODUCTION: Electrophysiological mapping (EPM) in coronary sinus (CS) branches is feasible for guiding LV lead placement to the optimal, latest activated site at cardiac resynchronization therapy (CRT) procedures. However, whether this procedure optimizes the response to CRT has not been demonstrated. This study was to evaluate effects of targeting LV lead at the latest activated site guided by EPM during CRT. METHODS: Seventy-six consecutive patients with advanced heart failure who were referred for CRT were divided into mapping (MG) and control groups (CG). In MG, the LV lead, also used as a mapping bipolar electrode, was placed at the latest activated site determined by EPM in CS branches. In CG, conventional CRT procedure was performed. Patients were followed for 6 months after CRT. RESULTS: Baseline characteristics were comparable between the 2 groups. In MG (n = 29), EPM was successfully performed in 85 of 91 CS branches during CRT. A LV lead was successfully placed at the latest activated site guided by EPM in 27 (93.1%) patients. Compared with CG (n = 47), MG had a significantly higher rate (86.2% vs. 63.8%, P = 0.039) of response (>15% reduction in LV end-systolic volume) to CRT, a higher percentage of patients with clinical improvement of ≥2 NYHA functional classes (72.4% vs. 44.7%, P = 0.032), and a shorter QRS duration (P = 0.004). CONCLUSIONS: LV lead placed at the latest activated site guided by EPM resulted in a significantly greater CRT response, and a shorter QRS duration.

The paced electrocardiogram cannot be used to identify left and right ventricular pacing sites in cardiac resynchronization therapy: validation by cardiac computed tomography.

AIMS: Paced electrocardiogram characteristics to confirm left ventricular (LV) and right ventricular (RV) pacing sites in cardiac resynchronization therapy (CRT) have not been validated with accurate knowledge of pacing lead positions. We aimed to evaluate the ability of the paced QRS morphology to differentiate between various LV and RV lead positions using cardiac computed tomography (CT) as the reference for LV and RV pacing site. METHODS AND RESULTS: Ninety-seven CRT patients were included. The QRS morphology was evaluated during forced LV-only and RV-only pacing. Pacing lead positions were assessed in a standard LV 16-segment model and a simplistic RV 6-segment model using cardiac CT. Ten patients with LV lead displacement or a LV pacing site outside the non-apical free wall were excluded from the analysis of the LV paced QRS complex. Pacing within the LV free wall was associated with a superior and a right-axis deviation (P = 0.02 and 0.04, respectively). Pacing from basal LV segments mainly produced a late (V5 or later) precordial QRS transition as compared with mid-LV pacing (P = 0.001). No significant associations were found between RV pacing site and QRS axis or precordial transition. Different QRS morphologies were observed during single-chamber pacing from identical LV or RV myocardial segments. CONCLUSION: Weak associations exist between LV and RV pacing sites and the paced QRS axis. None of the paced QRS characteristics can be used to reliably confirm specific LV and RV pacing sites in CRT patients.

Left and right ventricular lead positions are imprecisely determined by fluoroscopy in cardiac resynchronization therapy: a comparison with cardiac computed tomography.

AIMS: Fluoroscopy is the routine method for localizing left ventricular (LV) and right ventricular (RV) lead positions in cardiac resynchronization therapy (CRT). However, the ability of fluoroscopy to determine lead positions in a standard ventricular segmentation is unknown. We aimed to evaluate the accuracy and reproducibility of fluoroscopy to determine LV and RV lead positions in CRT when compared with cardiac computed tomography (CT). METHODS AND RESULTS: Fifty-nine patients undergoing CRT were included. Bi-plane fluoroscopy and cardiac CT were evaluated in all patients. Pacing lead positions were assessed in a standard LV 16-segment model and in a simplistic RV 8-segment model. Four patients with LV lead displacement were excluded from the agreement analysis of LV lead position. Agreement of LV lead position between fluoroscopy and cardiac CT was observed in 19 (35%) patients with fluoroscopy demonstrating a 1-segment and ≥2-segment error in 30 (55%) and 6 (11%) patients, respectively. Agreement of RV lead position was found in 13 (22%) patients with fluoroscopy showing a 1-segment and ≥ 2-segment error in 28 (47%) and 18 (31%) patients, respectively. The interobserver agreement on LV and RV lead positions was poor for fluoroscopy (kappa 0.20 and 0.23, respectively) and excellent for cardiac CT (kappa 0.87 and 0.85, respectively). CONCLUSION: Fluoroscopy is inaccurate and modestly reproducible when assessing LV and RV lead positions in a standard ventricular segmentation when compared with cardiac CT. Cardiac CT should be applied to determine the exact pacing site in future research evaluating the optimal pacing lead position in CRT.

Universal algorithm for diagnosis of biventricular capture in patients with cardiac resynchronization therapy.

BACKGROUND: An accurate and universal method for diagnosis of biventricular (BiV) capture using a standard 12-lead electrocardiogram (ECG) would be useful for assessment of cardiac resynchronization therapy (CRT) patients. Our objective was to develop and validate such an ECG method for BiV capture diagnosis that would be independent of pacing lead positions-a major confounder that significantly influences the morphologies of paced QRS complexes. METHODS: On the basis of an evaluation of 789 ECGs of 443 patients with heart failure and various right ventricular (RV) and left ventricular (LV) lead positions, the following algorithm was constructed and validated. BiV capture was diagnosed if the QRS in lead I was predominantly negative and either V1 QRS was predominantly positive or V6 QRS was of negative onset and predominantly negative (step 1), or if QRS complex duration was <160 ms (step 2). All other ECGs were classified as loss of LV capture. RESULTS: The algorithm showed good accuracy (93%), sensitivity (97%), and specificity (90%) for detection of loss of LV capture. The performance of the algorithm did not differ among apical, midseptal, and outflow tract RV lead positions and various LV lead positions. CONCLUSION: LV capture leaves diagnostic hallmarks in the fused BiV QRS related to different vectors of depolarization and more rapid depolarization of the ventricles. An accurate two-step ECG algorithm for BiV capture diagnosis was developed and validated. This algorithm is universally applicable to all CRT patients, regardless of the positions of the pacing leads.

Long-term clinical response to cardiac resynchronisation therapy under a multidisciplinary model.

BACKGROUND: Cardiac resynchronisation therapy (CRT) is established in the management of cardiac failure in patients with systolic dysfunction. Clinical response to CRT is not uniform, and response has been difficult to predict. AIM: Patient management within a high volume, multidisciplinary service focused on optimal delivery of CRT would improve response rates. METHODS: Four hundred and thirty-five consecutive patients who underwent CRT under a multidisciplinary heart failure service were enrolled prospectively over a 5-year period. Medically optimised, symptomatic patients with an ejection fraction (EF) <35%, widened QRS or abnormal dyssynchrony index were included. Left ventricular lead position was targeted anatomically to the segment of latest mechanical activation, and electrically to a site with maximal intrinsic intracardiac electrogram separation. Routine device and clinical follow up, as well as CRT optimisations, were performed at baseline and at 3-monthly intervals. Responders were defined as having an absolute reduction in left ventricular end-diastolic diameter >10% and an improvement in EF >5%. RESULTS: With a mean follow up of 53 ± 11 months, response rate to CRT was 81%. Mean EF improved from 26 ± 10% to 37 ± 11%, and mean left ventricular end-diastolic diameter reduced from 68.6 ± 9.2 mm to 57.8 ± 9.3 mm. Predictors of response were sinus rhythm, high dyssynchrony index and intrinsic electrical dyssynchrony >80 ms. Successful LV lead implantation at initial procedure was achieved in 99.1%, and at latest follow up 94.6% of initial LV leads were still active. CONCLUSION: CRT undertaken with a unit focus on optimal LV lead positioning and device optimisation, along with a multidisciplinary follow-up model, results in an excellent response rate to CRT.

Cardiac Computed Tomography to Guide the Selection of Better Display Angle of Cardiac Right Ventricular Pacing Electrode in Radiography.

BACKGROUND: Traditional radiography angles do not adequately reveal the shape and position of the right ventricular pacing electrode. OBJECTIVE: This study aimed to explore better radiography angles with the help of cardiac computed tomography (CT). METHODS: We analyzed the cardiac CT images of consecutive outpatients from 2018 to 2019. The right anterior oblique (RAO) 30° and the left anterior oblique (LAO) 40° were found to sufficiently display the shape and position of the right ventricular pacing electrode. RESULTS: A total of 214 consecutive outpatients were enrolled, whose average age was 55.0 ± 13.0 years, and 151 were male (70.6%). Through analyzing the cardiac CT images, the α angle (33.7° ± 6.1) and the γ angle (38.8° ± 8.0) were determined. Furthermore, we verified these angles in 48 patients after pacemaker implantation. The results showed that the ratio of the length of right ventricular electrode using the RAO α angle (≈30°) to the posterior-anterior position (PA position) was 1.099 ± 0.157 vs. 1.053 ± 0.182 (the ratio using the traditional RAO 45°) (P < 0.001). We observed that the relationship between the right ventricular active electrode and the ventricular septum was better identified using the LAO γ angle (≈40°) than the traditional 60° angle. CONCLUSION: With the help of cardiac CT, we found that RAO 30° could better show the shape and length of the right ventricular pacing electrode, and LAO 40° could better show the positional relationship between the pacing electrode and the ventricular septum.

Combination of personalized computational modeling and machine learning for optimization of left ventricular pacing site in cardiac resynchronization therapy.

Introduction: The 30-50% non-response rate to cardiac resynchronization therapy (CRT) calls for improved patient selection and optimized pacing lead placement. The study aimed to develop a novel technique using patient-specific cardiac models and machine learning (ML) to predict an optimal left ventricular (LV) pacing site (ML-PS) that maximizes the likelihood of LV ejection fraction (LVEF) improvement in a given CRT candidate. To validate the approach, we evaluated whether the distance DPS between the clinical LV pacing site (ref-PS) and ML-PS is associated with improved response rate and magnitude. Materials and methods: We reviewed retrospective data for 57 CRT recipients. A positive response was defined as a more than 10% LVEF improvement. Personalized models of ventricular activation and ECG were created from MRI and CT images. The characteristics of ventricular activation during intrinsic rhythm and biventricular (BiV) pacing with ref-PS were derived from the models and used in combination with clinical data to train supervised ML classifiers. The best logistic regression model classified CRT responders with a high accuracy of 0.77 (ROC AUC = 0.84). The LR classifier, model simulations and Bayesian optimization with Gaussian process regression were combined to identify an optimal ML-PS that maximizes the ML-score of CRT response over the LV surface in each patient. Results: The optimal ML-PS improved the ML-score by 17 ± 14% over the ref-PS. Twenty percent of the non-responders were reclassified as positive at ML-PS. Selection of positive patients with a max ML-score >0.5 demonstrated an improved clinical response rate. The distance DPS was shorter in the responders. The max ML-score and DPS were found to be strong predictors of CRT response (ROC AUC = 0.85). In the group with max ML-score > 0.5 and DPS< 30 mm, the response rate was 83% compared to 14% in the rest of the cohort. LVEF improvement in this group was higher than in the other patients (16 ± 8% vs. 7 ± 8%). Conclusion: A new technique combining clinical data, personalized heart modelling and supervised ML demonstrates the potential for use in clinical practice to assist in optimizing patient selection and predicting optimal LV pacing lead position in HF candidates for CRT.

Cardiac computed tomography-verified right ventricular lead position and outcomes in cardiac resynchronization therapy.

PURPOSE: To evaluate the association between different right ventricular (RV) lead positions as assessed by cardiac computed tomography (CT) and echocardiographic and clinical outcomes in patients receiving cardiac resynchronization therapy (CRT). METHODS: We reviewed patient records of all 278 patients included in two randomized controlled trials (ImagingCRT and ElectroCRT) for occurrence of heart failure (HF) hospitalization or all-cause death (primary endpoint) during long-term follow-up. Outcomes were compared between RV lead positions using adjusted Cox regression analysis. Six months after CRT implantation, we estimated left ventricular (LV) reverse remodeling by measuring LV end-systolic and end-diastolic volumes by echocardiography. Changes from baseline to 6 months follow-up were compared between RV lead positions. Device-related complications were recorded at 6-month follow-up. RESULTS: During median (interquartile range) follow-up of 4.7 (2.9-7.1) years, the risk of meeting the primary endpoint was similar for patients with non-apical vs. apical RV lead position (adjusted hazard ratio (HR) 0.78, 95% confidence interval (CI) 0.54-1.12, p = 0.17) and free wall vs. septal RV lead position (adjusted HR 1.03, 95% CI 0.72-1.47, p = 0.86). Changes in LV ejection fraction and dimensions were similar with the different RV lead positions. We observed no differences in device-related complications relative to the RV lead position. CONCLUSIONS: In patients receiving CRT, the risk of HF hospitalization or all-cause death during long-term follow-up, and LV remodeling and incidence of device-related complications after 6 months are not associated with different anatomical RV lead position as assessed by cardiac CT.