RESUMEN
AIMS: Physiological activation of the heart using algorithms to minimize right ventricular pacing (RVPm) may be an effective strategy to reduce adverse events in patients requiring anti-bradycardia therapies. This systematic review and meta-analysis aimed to evaluate current evidence on clinical outcomes for patients treated with RVPm algorithms compared to dual-chamber pacing (DDD). METHODS AND RESULTS: We conducted a systematic search of the PubMed database. The predefined endpoints were the occurrence of persistent/permanent atrial fibrillation (PerAF), cardiovascular (CV) hospitalization, all-cause death, and adverse symptoms. We also aimed to explore the differential effects of algorithms in studies enrolling a high percentage of atrioventricular block (AVB) patients. Eight studies (7229 patients) were included in the analysis. Compared to DDD pacing, patients using RVPm algorithms showed a lower risk of PerAF [odds ratio (OR) 0.74, 95% confidence interval (CI) 0.57-0.97] and CV hospitalization (OR 0.77, 95% CI 0.61-0.97). No significant difference was found for all-cause death (OR 1.01, 95% CI 0.78-1.30) or adverse symptoms (OR 1.03, 95% CI 0.81-1.29). No significant interaction was found between the use of the RVPm strategy and studies enrolling a high percentage of AVB patients. The pooled mean RVP percentage for RVPm algorithms was 7.96% (95% CI 3.13-20.25), as compared with 45.11% (95% CI 26.64-76.38) of DDD pacing. CONCLUSION: Algorithms for RVPm may be effective in reducing the risk of PerAF and CV hospitalization in patients requiring anti-bradycardia therapies, without an increased risk of adverse symptoms. These results are also consistent for studies enrolling a high percentage of AVB patients.
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Algoritmos , Fibrilación Atrial , Estimulación Cardíaca Artificial , Anciano , Femenino , Humanos , Masculino , Fibrilación Atrial/terapia , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/fisiopatología , Fibrilación Atrial/mortalidad , Bloqueo Atrioventricular/diagnóstico , Bloqueo Atrioventricular/mortalidad , Bloqueo Atrioventricular/fisiopatología , Bloqueo Atrioventricular/terapia , Bradicardia/terapia , Bradicardia/prevención & control , Bradicardia/mortalidad , Bradicardia/diagnóstico , Estimulación Cardíaca Artificial/efectos adversos , Estimulación Cardíaca Artificial/métodos , Frecuencia Cardíaca , Ventrículos Cardíacos/fisiopatología , Hospitalización/estadística & datos numéricos , Marcapaso Artificial/efectos adversos , Factores de Riesgo , Resultado del Tratamiento , Función Ventricular DerechaRESUMEN
AIMS: The application of conduction system pacing (CSP) in clinical practice is growing, and the need for lead extraction will also increase. The data on outcomes and safety of CSP lead extraction are limited. The aim of this study was to assess procedural outcomes and safety of CSP lead removal. METHODS AND RESULTS: Forty-seven patients from the EXTRACT Registry with the indication for CSP lead removal were enrolled in the study conducted at the Department of Electrocardiology in Katowice, Poland. Extraction technique, outcomes, safety, and complication were evaluated. Forty-three (91.5%) leads were successfully removed, and 41 (87.2%) were removed with traction only. The dwelling time of 28 extracted leads was longer than 1 year, and the oldest extracted lead was implanted for 89 months. Seven (14.9%) leads were removed from the left bundle branch (LBB) area and 36 from the His bundle (HB). Transient complete atrioventricular block occurred during the procedure in two patients. In 27 out of 31 attempts (87.1%), new CSP leads were implanted: nine (33.3%) HB pacing leads and 18 (66.7%) LBB area pacing leads. CONCLUSION: The CSP lead extraction is safe and feasible with a low complication rate and high rate of CSP lead reimplantation.
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Fascículo Atrioventricular , Estimulación Cardíaca Artificial , Remoción de Dispositivos , Marcapaso Artificial , Sistema de Registros , Humanos , Masculino , Femenino , Fascículo Atrioventricular/fisiopatología , Fascículo Atrioventricular/cirugía , Anciano , Resultado del Tratamiento , Estimulación Cardíaca Artificial/métodos , Persona de Mediana Edad , Remoción de Dispositivos/métodos , Remoción de Dispositivos/efectos adversos , Polonia , Hospitales de Alto Volumen , Anciano de 80 o más Años , Factores de TiempoRESUMEN
The impact of age (≥ 85 vs < 85 years) on clinical outcomes and pacemaker performance of conduction system pacing (CSP) compared to right ventricular pacing (RVP) were examined. Consecutive patients from a prospective, observational, multicenter study with pacemakers implanted for bradycardia were studied. The primary endpoint was a composite of heart failure (HF)-hospitalizations, pacing-induced cardiomyopathy requiring cardiac resynchronization therapy or all-cause mortality. Secondary endpoints were acutely successful CSP, absence of pacing-complications, optimal pacemaker performance defined as pacing thresholds < 2.5 V, R-wave amplitude ≥ 5 V and absence of complications, threshold stability (no increases of > 1 V) and persistence of His-Purkinje capture on follow-up. Among 984 patients (age 74.1 ± 11.2 years, 41% CSP, 16% ≥ 85 years), CSP was independently associated with reduced hazard of the primary endpoint compared to RVP, regardless of age-group (< 85 years: adjusted hazard ratio [AHR] 0.63, 95% confidence interval [CI] 0.40-0.98; ≥ 85 years: AHR 0.40, 95% CI 0.17-0.94). Among patients with CSP, age did not significantly impact the secondary endpoints of acute CSP success (86% vs 88%), pacing complications (19% vs 11%), optimal pacemaker performance (64% vs 69%), threshold stability (96% vs 96%) and persistent His-Purkinje capture (86% vs 91%) on follow-up (all p > 0.05). CSP improves clinical outcomes in all age-groups, without compromising procedural safety or pacemaker performance in the very elderly.
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Bradicardia , Humanos , Anciano de 80 o más Años , Anciano , Masculino , Femenino , Bradicardia/terapia , Estudios Prospectivos , Resultado del Tratamiento , Estudios de Factibilidad , Estimulación Cardíaca Artificial/métodos , Estimulación Cardíaca Artificial/efectos adversos , Insuficiencia Cardíaca/terapia , Insuficiencia Cardíaca/mortalidad , Insuficiencia Cardíaca/fisiopatología , Marcapaso Artificial , Terapia de Resincronización Cardíaca/métodos , Terapia de Resincronización Cardíaca/efectos adversosRESUMEN
AIMS: Leadless pacemaker therapy was introduced to overcome lead- and pocket-related complications in conventional transvenous pacemaker systems. Implantation via the femoral vein, however, may not always be feasible. The aim of this study was to evaluate leadless pacemaker implantation using a jugular vein approach and compare it to the standard implantation via the femoral vein. METHODS AND RESULTS: The records of the first consecutive 100 patients undergoing Micra™ leadless pacemaker implantation via the right internal jugular vein from two centres were included in this study. Peri-procedural safety and efficacy of the jugular approach were compared to the first 100 patients using a femoral implantation approach at the University Hospital Zurich. One hundred patients underwent successful implantation of a leadless pacemaker via the internal jugular vein (mean age, 81.18 ± 8.29, 60% males). Mean procedure time was 35.63 ± 10.29 min with a mean fluoroscopy time of 4.66 ± 5.16 min. The device was positioned at the inferior septum in 25 patients, at the high septum in 24 patients, and mid-septum in 51 patients. The mean pacing threshold was 0.56 ± 0.35 V at 0.24 ms pulse width with a sensed amplitude of 10.0 ± 4.4 mV. At follow-up, electrical parameters remained stable in all patients. Compared with femoral implantation, patients undergoing the jugular approach were of similar age and had similar comorbidities. Mean procedure (48.9 ± 21.0 min) and fluoroscopy times (7.7 ± 7.8 min, both P < 0.01) were shorter compared to the femoral approach. Electrical parameters were similar between the two approaches. There were only two complications during jugular veinous implantations (1 pericardial effusion and 1 dislocation), compared to 16 complications using the femoral approach (1 pericardial effusion, 2 femoral artery injuries, and 13 major groin haematomas). CONCLUSION: The jugular approach may represent a safe and efficient alternative to femoral implantation of the Micra leadless pacemaker.
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Estimulación Cardíaca Artificial , Vena Femoral , Venas Yugulares , Marcapaso Artificial , Humanos , Masculino , Femenino , Anciano de 80 o más Años , Anciano , Estimulación Cardíaca Artificial/métodos , Resultado del Tratamiento , Implantación de Prótesis/métodos , Diseño de Equipo , Estudios Retrospectivos , Arritmias Cardíacas/terapia , Arritmias Cardíacas/fisiopatología , Factores de TiempoRESUMEN
BACKGROUND: A dual-chamber leadless pacemaker system has been designed for atrioventricular synchronous pacing using wireless, beat-to-beat, implant-to-implant (i2i) communication between distinct atrial and ventricular leadless pacemakers. The atrioventricular synchrony achieved across various ambulatory scenarios has yet to be systematically evaluated. METHODS: A prospective, single-arm, unblinded, multicenter, international clinical trial of the leadless pacemaker system was conducted in patients with a conventional dual-chamber pacing indication enrolled from February 2022 to March 2023. Leadless pacemaker systems were implanted, and 12-lead Holter electrocardiographic recordings were collected 3 months after implantation over various postures/activities: sitting, supine, left lateral recumbent, right lateral recumbent, standing, normal walk, and fast walk. An independent Holter core laboratory performed a manual adjudication of the percent of atrioventricular synchronous beats using the standard 300-millisecond PR interval limit. Atrium-to-ventricle and ventricle-to-atrium i2i communication success rates were also assessed. Post hoc summary statistics describing the relationships between atrioventricular synchrony and i2i success, posture/activity, implantation indication, atrioventricular event, and heart rate were calculated. RESULTS: In the evaluable population (n=384 of 464 enrolled [83%]; 61% male; age, 70 years; weight, 82 kg; 60% ejection fraction; 95% of beats evaluable), the mean atrioventricular synchrony of 98% of beats observed across all postures using the standard 300-millisecond limit was greater than both atrial-to-ventricular i2i (94%) and ventricular-to-atrial i2i (94%; P<0.001), exceeding both i2i values in 95% of patients. Atrioventricular synchrony was achieved in >95% of evaluable beats across all postures/activities, implantation indications, atrioventricular paced/sensed event combinations, and heart rate ranges (including >100 bpm). CONCLUSIONS: This dual-chamber leadless pacemaker system demonstrated atrioventricular synchrony in 98% of evaluable beats at 3 months after implantation. Atrioventricular synchrony was maintained across postures/activities and remained robust for heart rates >100 bpm.
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Marcapaso Artificial , Humanos , Masculino , Femenino , Anciano , Estudios Prospectivos , Anciano de 80 o más Años , Frecuencia Cardíaca , Electrocardiografía Ambulatoria , Persona de Mediana Edad , Estimulación Cardíaca Artificial/métodosRESUMEN
AIMS: Right phrenic nerve (RPN) injury is a disabling but uncommon complication of atrial fibrillation (AF) radiofrequency ablation. Pace-mapping is widely used to infer RPN's course, for limiting the risk of palsy by avoiding ablation at capture sites. However, information is lacking regarding the distance between the endocardial sites of capture and the actual anatomic RPN location. We aimed at determining the distance between endocardial sites of capture and anatomic CT location of the RPN, depending on the capture threshold. METHODS AND RESULTS: In consecutive patients undergoing AF radiofrequency ablation, we defined the course of the RPN on the electroanatomical map with high-output pacing at up to 50â mA/2â ms, and assessed RPN capture threshold (RPN-t). The true anatomic course of the RPN was delineated and segmented using CT scan, then merged with the electroanatomical map. The distance between pacing sites and the RPN was assessed. In 45 patients, 1033 pacing sites were analysed. Distances from pacing sites to RPN ranged from 7.5 ± 3.0â mm (min 1) when RPN-t was ≤10â mA to 19.2 ± 6.5â mm (min 9.4) in cases of non-capture at 50â mA. A distance to the phrenic nerve > 10â mm was predicted by RPN-t with a ROC curve area of 0.846 [0.821-0.870] (P < 0.001), with Se = 80.8% and Sp = 77.5% if RPN-t > 20â mA, Se = 68.0% and Sp = 91.6% if RPN-t > 30â mA, and Se = 42.4% and Sp = 97.6% if non-capture at 50â mA. CONCLUSION: These data emphasize the utility of high-output pace-mapping of the RPN. Non-capture at 50â mA/2â ms demonstrated very high specificity for predicting a distance to the RPN > 10â mm, ensuring safe radiofrequency delivery.
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Fibrilación Atrial , Ablación por Catéter , Imagenología Tridimensional , Traumatismos de los Nervios Periféricos , Nervio Frénico , Valor Predictivo de las Pruebas , Humanos , Nervio Frénico/lesiones , Nervio Frénico/diagnóstico por imagen , Fibrilación Atrial/cirugía , Fibrilación Atrial/diagnóstico por imagen , Fibrilación Atrial/fisiopatología , Femenino , Masculino , Persona de Mediana Edad , Anciano , Ablación por Catéter/métodos , Traumatismos de los Nervios Periféricos/etiología , Traumatismos de los Nervios Periféricos/prevención & control , Resultado del Tratamiento , Técnicas Electrofisiológicas Cardíacas , Tomografía Computarizada por Rayos X , Estimulación Cardíaca Artificial/métodos , Interpretación de Imagen Radiográfica Asistida por Computador , Potenciales de Acción , Curva ROCRESUMEN
One of the most common complications of tricuspid valve replacement is atrioventricular block (AVB), often requiring permanent pacing. The endocardial pacemaker lead, placed in the right ventricle, may sometimes interfere with the implanted prosthesis, causing its early dysfunction and the need for alternative sites of pacing. To the best of our knowledge, we present the first case of a successful combined percutaneous procedure consisting of the implantation of two leads in the coronary sinus for univentricular bifocal pacing and a transcatheter tricuspid valve-in-valve implantation in a young patient with severe dysfunction of the tricuspid bioprosthesis, requiring permanent pacing for a postsurgical complete atrioventricular block.
Tricuspid valve replacement with surgery can often lead to cardiac rhythm disorders requiring a permanent pacemaker. This device may occasionally damage the tricuspid prosthesis. We present the first case of a combined procedure of tricuspid valve replacement and device implantation distant from the prosthesis without the need for a surgical approach in a young patient with severe tricuspid prosthesis malfunctioning and permanent pacing.
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Cateterismo Cardíaco , Estimulación Cardíaca Artificial , Seno Coronario , Implantación de Prótesis de Válvulas Cardíacas , Válvula Tricúspide , Humanos , Válvula Tricúspide/cirugía , Implantación de Prótesis de Válvulas Cardíacas/métodos , Seno Coronario/cirugía , Cateterismo Cardíaco/métodos , Estimulación Cardíaca Artificial/métodos , Bloqueo Atrioventricular/terapia , Bloqueo Atrioventricular/etiología , Bioprótesis , Prótesis Valvulares Cardíacas , Insuficiencia de la Válvula Tricúspide/cirugía , Insuficiencia de la Válvula Tricúspide/diagnóstico , Marcapaso Artificial , Femenino , Masculino , AdultoAsunto(s)
Remoción de Dispositivos , Marcapaso Artificial , Infecciones Relacionadas con Prótesis , Humanos , Remoción de Dispositivos/métodos , Infecciones Relacionadas con Prótesis/diagnóstico , Infecciones Relacionadas con Prótesis/terapia , Infecciones Relacionadas con Prótesis/cirugía , Masculino , Reimplantación/métodos , Anciano , Femenino , Resultado del Tratamiento , Estimulación Cardíaca Artificial/métodosRESUMEN
BACKGROUND: High-grade atrioventricular block is the primary reason for epicardial permanent pacemaker implantation during the perioperative period in patients with congenital heart disease. Due to the smaller diameter of venous vessels in children, epicardial permanent pacemaker implantation is usually a preferred choice, we report one pediatric patient who received epicardial permanent pacemaker implantation using a new approach. CASE PRESENTATION: We present the case of a 2-year-old girl who underwent the modified Konno procedure and Pulmonary valvuloplasty surgery and presented after surgery with a High-grade atrioventricular block. At over 20 days after the patient underwent a redo-sternotomy which epicardial permanent pacemaker implantation. Medtronic Model 4965 Capsure Epi ® steroid-eluting unipolar epicardial pacing lead was immobilized on the surface of the right ear. The Medtronic 3830 pacing lead was screwed obliquely and clockwise under direct view from the surface of the right ventricle to the endocardium near the interventricular septum. The patient's recovery was uneventful. CONCLUSION: In this case report, we demonstrate the feasibility and potential benefits of using the Medtronic 3830 lead for epicardial pacing in a pediatric patient with severe cardiac complications following surgery for congenital heart disease. This approach offers a viable alternative to traditional epicardial pacing methods, particularly in complex cases where conventional leads fail to provide stable pacing thresholds.
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Bloqueo Atrioventricular , Marcapaso Artificial , Humanos , Femenino , Preescolar , Bloqueo Atrioventricular/terapia , Bloqueo Atrioventricular/etiología , Estudios de Factibilidad , Pericardio/cirugía , Cardiopatías Congénitas/cirugía , Estimulación Cardíaca Artificial/métodosRESUMEN
BACKGROUND: Currently, the interrupted recording technique is commonly used to perform left bundle branch (LBB) pacing (LBBP). However, this method requires repeated testing to confirm that the LBB is captured and perforations are avoided. An automated solution may make this repetitive work easier. CASE SUMMARY: LBBP was performed using an uninterrupted recording technique in an 86-year-old woman. Lead position and LBB capture was confirmed by the characteristics of the intrinsic filtered and unfiltered intracardiac electrograms. CONCLUSION: Continuous mapping and recording technique may help achieve more accurate positioning of LBBP lead in the ventricular septum.
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Bloqueo de Rama , Electrocardiografía , Humanos , Femenino , Anciano de 80 o más Años , Bloqueo de Rama/fisiopatología , Bloqueo de Rama/diagnóstico , Electrocardiografía/métodos , Estimulación Cardíaca Artificial/métodos , Técnicas Electrofisiológicas Cardíacas/métodosRESUMEN
Right ventricular pacing (RVP) is conventionally preferred in the treatment of patients with atrioventricular block. However, long-term RVP may lead to pacing-induced cardiomyopathy (PICM), characterized by new-onset or worsening ventricular functions due to dyssynchronous ventricular electrical activation, abnormal ventricular remodeling, and increased energy expenditure. Historically, biventricular pacing (BVP) and guideline-directed medical therapy were the only treatment option for PICM. Recently, conduction system pacing, including left bundle branch area pacing (LBBaP), has emerged as a physiological alternative to BVP, showing better results in electro-mechanical ventricular synchronization and hemodynamic parameters compared to BVP. We present a case involving a patient from whom the PICM was successfully recovered shortly after LBBaP.
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Estimulación Cardíaca Artificial , Cardiomiopatías , Humanos , Cardiomiopatías/terapia , Cardiomiopatías/etiología , Estimulación Cardíaca Artificial/métodos , Estimulación Cardíaca Artificial/efectos adversos , Electrocardiografía , Masculino , Ventrículos Cardíacos/fisiopatologíaRESUMEN
PURPOSE OF THE REVIEW: Cardiac pacing has evolved in recent years currently culminating in the specific stimulation of the cardiac conduction system (conduction system pacing, CSP). This review aims to provide a comprehensive overview of the available literature on CSP, focusing on a critical classification of studies comparing CSP with standard treatment in the two fields of pacing for bradycardia and cardiac resynchronization therapy in patients with heart failure. The article will also elaborate specific benefits and limitations associated with CSP modalities of His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). RECENT FINDINGS: Based on a growing number of observational studies for different indications of pacing therapy, both CSP modalities investigated are advantageous over standard treatment in terms of narrowing the paced QRS complex and preserving or improving left ventricular systolic function. Less consistent evidence exists with regard to the improvement of heart failure-related rehospitalization rates or mortality, and effect sizes vary between HBP and LBBAP. LBBAP is superior over HBP in terms of lead measurements and procedural duration. With regard to all reported outcomes, evidence from large scale randomized controlled clinical trials (RCT) is still scarce. CSP has the potential to sustainably improve patient care in cardiac pacing therapy if patients are appropriately selected and limitations are considered. With this review, we offer not only a summary of existing data, but also an outlook on probable future developments in the field, as well as a detailed summary of upcoming RCTs that provide insights into how the journey of CSP continues.
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Bradicardia , Estimulación Cardíaca Artificial , Terapia de Resincronización Cardíaca , Insuficiencia Cardíaca , Humanos , Insuficiencia Cardíaca/terapia , Insuficiencia Cardíaca/fisiopatología , Terapia de Resincronización Cardíaca/métodos , Estimulación Cardíaca Artificial/métodos , Bradicardia/terapia , Bradicardia/fisiopatología , Sistema de Conducción Cardíaco/fisiopatología , Fascículo Atrioventricular/fisiopatología , Resultado del TratamientoRESUMEN
In patients with a reduced left ventricular (LV) systolic function (ejection fraction <â¯35%) and a left bundle branch block with a QRS duration >â¯130â¯ms, cardiac resynchronization therapy (CRT) can contribute to an improvement in the quality of life and a reduction in mortality. The resynchronization is mostly achieved by pacing via an epicardial LV lead in the coronary sinus; however, this approach is often limited by the patient's venous anatomy and an increase in the stimulation threshold over time. In addition, up to 30% of patients do not respond to the intervention. New treatment approaches involve direct stimulation of the conduction system by pacing of the bundle of His or left bundle branch. This enables a more physiological propagation of the stimulus. Pacing of the left bundle branch is achieved by advancing the lead into the right ventricle and screwing it deep into the interventricular septum. Due to the relatively large target area of the left bundle branch the success rate is very high (currently >â¯90%). Observational studies have shown a greater reduction in the QRS duration, a more pronounced improvement in systolic function and a lower hospitalization rate for heart failure associated with conduction system pacing compared to CRT using a coronary sinus lead. These findings have been confirmed in small randomized trials. Therefore, the use of left bundle branch pacing should be considered not only as a bail out in the case of failed resynchronization using coronary sinus lead placement but increasingly also as an initial pacing strategy. The results of the first large randomized trials are expected to be released in late 2024.
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Terapia de Resincronización Cardíaca , Insuficiencia Cardíaca , Humanos , Insuficiencia Cardíaca/terapia , Insuficiencia Cardíaca/fisiopatología , Terapia de Resincronización Cardíaca/métodos , Bloqueo de Rama/terapia , Bloqueo de Rama/fisiopatología , Estimulación Cardíaca Artificial/métodos , Calidad de VidaRESUMEN
INTRODUCTION: Successful implantations of the Aveir VR, have been effectively demonstrated in adults; however, there remain limited reports supporting safe and feasible implantation of the Aveir VR in the young population. METHODS: Retrospective, observational study of Aveir VR implantation of young patients (â¦21 years old) at UC Davis Medical Center from November 2022 to January 2024 via the internal jugular or femoral vein implantation approaches. Indications for pacing, patient demographics, pacing thresholds and longevity were reported at the time of implantation and last follow-up. RESULTS: A total of 10 patients received the Aveir VR with a median age of years (IQR 12.5-17) and median weight of 50.8 kg (IQR 44.6-60.9) kg. The majority were male (80%). Aveir VR leadless pacemaker occurred via internal jugular venous (90%) or femoral venous (10%) approaches. Indications for placement were intermittent complete heart block (60%) and sinus pauses (40%). Adequate impedance, sensing and thresholds were maintained from implantation to a median follow-up of 9 months. Predicted pacemaker longevity at follow-up median was 23.8 years. There were no complications in any of the 10 patients. CONCLUSION: Aveir VR implantation via the internal jugular and femoral veins is feasible in the young patient population with stable pacing parameters at follow-up.
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Vena Femoral , Marcapaso Artificial , Humanos , Masculino , Femenino , Estudios Retrospectivos , Adolescente , Niño , Venas Yugulares , Remoción de Dispositivos , Estimulación Cardíaca Artificial/métodosRESUMEN
BACKGROUND: Patients with refractory, symptomatic left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy have few therapeutic options. Right ventricular pacing is associated with modest hemodynamic and symptomatic improvement, and LV pacing pilot data suggest therapeutic potential. We hypothesized that site-specific pacing would reduce LVMCO gradients and improve symptoms. METHODS: Patients with symptomatic-drug-refractory LVMCO were recruited for a randomized, blinded trial of personalized prescription of pacing (PPoP). Multiple LV and apical right ventricular pacing sites were assessed during an invasive hemodynamic study of multisite pacing. Patient-specific pacing-site and atrioventricular delays, defining PPoP, were selected on the basis of LVMCO gradient reduction and acceptable pacing parameters. Patients were randomized to 6 months of active PPoP or backup pacing in a crossover design. The primary outcome examined invasive gradient change with best-site pacing. Secondary outcomes assessed quality of life and exercise following randomization to PPoP. RESULTS: A total of 17 patients were recruited; 16 of whom met primary end points. Baseline New York Heart Association was 3±0.6, despite optimal medical therapy. Hemodynamic effects were assessed during pacing at the right ventricular apex and at a mean of 8 LV sites. The gradients in all 16 patients fell with pacing, with maximum gradient reduction achieved via LV pacing in 14 (88%) patients and right ventricular apex in 2. The mean baseline gradient of 80±29 mmâ Hg fell to 31±21 mmâ Hg with best-site pacing, a 60% reduction (P<0.0001). One cardiac vein perforation occurred in 1 case, and 15 subjects entered crossover; 2 withdrawals occurred during crossover. Of the 13 completing crossover, 9 (69%) chose active pacing in PPoP configuration as preferred setting. PPoP was associated with improved 6-minute walking test performance (328.5±99.9 versus 285.8±105.5 m; P=0.018); other outcome measures also indicated benefit with PPoP. CONCLUSIONS: In a randomized placebo-controlled trial, PPoP reduces obstruction and improves exercise performance in severely symptomatic patients with LVMCO. REGISTRATION: URL: https://clinicaltrials.gov/study; Unique Identifier: NCT03450252.