Abstract
Background
Many patients with drug-refractory hypertrophic obstructive cardiomyopathy (HOCM) decline or are ineligible for surgical myectomy or alcohol septal ablation. Although conventional unipolar percutaneous endocardial septal radiofrequency ablation is a minimally invasive alternative, its limited lesion depth yields only modest left ventricular outflow tract gradient (LVOTG) relief. Bipolar radiofrequency catheter ablation creates deeper lesions in the treatment of ventricular arrhythmias; however, its role in HOCM remains unreported.
First-In-Human/Early Reports Summary
We present the first in-human case of combined bipolar ablation and percutaneous endocardial septal radiofrequency ablation (Bi-PESA) in an older patient with drug-refractory HOCM. Ultimately, the patient experienced significant reduction in the LVOTG, translating to significant symptomatic improvement.
Discussion
This case suggests Bi-PESA could be a novel, effective, and safe septal reduction option for patients with drug-refractory HOCM.
Novelty
To our knowledge, this is the first-in-human report of Bi-PESA for HOCM to reduce LVOTG and improve symptoms.
Take-Home Message
Bi-PESA may offer a feasible and potentially preferable alternative for patients with HOCM who decline or are ineligible for surgical myectomy or alcohol septal ablation.
Key words: 3-dimensional imaging, ablation, cardiomyopathy, echocardiography, electroanatomic mapping, electrophysiology
Visual Summary
Visual Summary.
Schematic Diagram of the Bipolar Percutaneous Endocaridal Septal Radiofrequency Ablation Procedure
(A) Bipolar percutaneous endocardial septal radiofrequency ablation procedure. (B) Dedicated connections of the bipolar ablation catheters. RF = radiofrequency.
Percutaneous endocardial septal radiofrequency ablation (PESA) has emerged as a promising alternative for patients with drug-refractory hypertrophic obstructive cardiomyopathy (HOCM) who decline or are ineligible for surgical myectomy (SM) or alcohol septal ablation (ASA) because of its favorable safety profile and minimally invasive nature.1 To preserve the conduction system, conventional PESA intentionally confines ablation to the obstructive segment and uses a power setting of approximately 40 to 50 W.2 These safety constraints, however, produce smaller lesions and, consequently, a less pronounced reduction in the left ventricular outflow tract gradient (LVOTG) than SM or ASA.3,4
Here, we report the first clinical application of bipolar percutaneous endocardial septal radiofrequency ablation (Bi-PESA) in HOCM. By configuring 2 separate catheters as active electrode (AE) and return electrode (RE), bipolar radiofrequency energy produces contiguous, transmural lesions that overcome the anatomic and power limitations inherent to unipolar ablation.5
Case Presentation
A 73-year-old woman with a 6-year history of exertional chest pain was diagnosed with HOCM in 2019 and refused SM and ASA after careful consideration. Transthoracic echocardiography revealed asymmetrical septal hypertrophy (maximum thickness: 14 mm) (Figure 1A), a resting peak LVOTG of 73 mm Hg (Figure 1B, Video 1), and a regional longitudinal strain of −17% in the anteroseptal segment (Figure 1C). Cardiac magnetic resonance confirmed basal septal hypertrophy (Figure 1D) and nonpatchy late gadolinium enhancement (Figure 1E). The ECG is normal (Supplemental Figure 1). Despite maximal tolerated β-blocker and diltiazem, she remained symptomatic—NYHA functional class III dyspnea, chest pain, dizziness, and markedly reduced exercise capacity—prompting referral for Bi-PESA.
Figure 1.
Baseline Transthoracic Echocardiography and Cardiac Magnetic Resonance
(A) Parasternal long-axis view demonstrating basal septal hypertrophy preprocedure. (B) Resting left ventricular outflow tract gradient at baseline. (C) Baseline regional longitudinal strain of the anteroseptal segment. (D) Baseline cardiac magnetic resonance. (E) Baseline late gadolinium enhancement.
Procedure Details
The procedure was performed under deep sedation with intracardiac echocardiography (ICE) guidance. A 6-F pigtail catheter was advanced through the right femoral artery into the left ventricle to measure the LVOTG: 20 mm Hg at rest and 140 mm Hg after a 4-μg isoproterenol peripheral intravenous infusion. The ICE catheter (SoundStar, Johnson & Johnson, Inc) was introduced via the right femoral vein into the right ventricle. Using the CartoSound module (Biosense Webster) of the CARTO 3 (Biosense Webster) mapping system, we reconstructed 3-dimensional ultrasonic anatomy of the left and right ventricles, the septum, and the His bundle layer by both long- and short-axis layers (Video 2). The obstructive area (target zone for ablation), defined as the septal region contacting the anterior mitral leaflet, covered an area of 8 cm2 (Figure 2A).
Figure 2.
Step-by-Step Procedural Sequence
(A) Intracardiac echocardiography (ICE) 3-dimensional reconstruction of the left and right ventricles, interventricular septum, and the obstructive area (colored brown). (B and C) Three-dimensional mapping system displaying AE and RE catheter positions in left anterior oblique 45° and right anterior oblique 45° views, respectively (yellow, the obstructive area; white, His bundle; red, ablation site; purple, branches potentials). (D and E) Fluoroscopic images showing AE and RE catheter positions at left anterior oblique 30° and right anterior oblique 30° views, respectively. (F) ICE image demonstrating an edema bright band (circled in red) within an ablation zone. (G) Quantitative measurement of the ablation region (colored red) relative to the predefined target area (colored yellow). AE = active electrode; RE = return electrode.
A 56-hole saline-irrigated SmartTouch SF radiofrequency ablation catheter (AE, Johnson & Johnson, Inc) was advanced to the right ventricular septum through the right femoral vein to map the right septal endocardium. A therapeutic 3.5-mm-tip catheter (RE, Synaptic Medical) was then positioned on the right septal surface within an 8.5-F Navigo sheath (Synaptic Medical), whereas the saline-irrigated SmartTouch SF catheter (AE) was placed opposite, on the left basal septum, directed toward the RE (Figures 2B to 2E). Energy was delivered at 50 W for 90 to 120 seconds per lesion (total ablation time: 840 seconds) with maximum tip temperatures of 38 °C on the AE and 41 °C on the RE. Key conduction fibers, including the His bundle, bundle branches, and Purkinje fibers, were tagged with different colors to ensure avoidance. ICE revealed an edematous bright band in the ablation zone (Figure 2F). Immediately after ablation, the LVOTG dropped to 10 mm Hg at rest and 50 mm Hg postisoproterenol provoked. The final ablated area measured 1.9 cm2 (23.5% of the target zone) (Figure 2G) and exhibited delayed local activation on mapping (Video 3, Video 4). On day 4, transthoracic echocardiography showed a resting LVOTG of 13 mm Hg (Figure 3B, Video 5), and the anteroseptal longitudinal strain decreased to −14% compared with baseline (Figure 3C). ECG showed no dynamic changes compared to pre-ablation (Supplemental Figure 1).
Figure 3.
Postprocedural Transthoracic Echocardiography
(A) Parasternal long-axis view of the intraventricular septum 4 days after the procedure. (B) Resting left ventricular outflow tract gradient (LVOTG) 4 days postprocedure. (C) Regional longitudinal strain of the anteroseptal segment 4 days postprocedure. (D) Parasternal long-axis view of intraventricular septum at 1-month follow-up. (E) Resting LVOTG at 1-month follow-up. (F) Regional longitudinal strain of the anteroseptal segment at 1-month follow-up.
Follow-Up
The patient was discharged 4 days postprocedure without any complications. At 1-month follow-up, she remained asymptomatic; resting LVOTG was 28 mm Hg (Figure 3E), and anteroseptal longitudinal strain returned to baseline (Figure 3F). Interventricular septal thickness remained unchanged (Figure 1A, Figures 3A and 3D). The Kansas City Cardiomyopathy Questionnaire score improved from 30.17 preprocedure to 80.17 postprocedure, reflecting marked gains in exercise tolerance and quality of life.
Discussion
This index case demonstrates the first successful clinical use of Bi-PESA for drug-refractory HOCM, showing acute hemodynamic improvement and promising short-term symptomatic and functional recovery. This approach addresses the central limitation of conventional unipolar PESA: the inherent trade-off between safety and efficacy imposed by the need to protect the conduction system.
Conventional unipolar PESA, although a valuable minimally invasive alternative for HOCM patients unsuitable for SM or ASA, is often constrained by intentionally low power (≈40-50 W) and confinement of lesions to the immediate obstructive segment to avoid atrioventricular block.6 This limitation frequently results in smaller, potentially nontransmural lesions, often resulting in modest LVOTG reduction compared with SM or ASA.3,4 Bi-PESA alters the energy delivery paradigm: one catheter serves as the AE on the left septal endocardium and the second as the RE on the right septal surface, driving radiofrequency current directly through the targeted interventricular septum. Preclinical electrophysiological studies indicate that this configuration generates deeper, contiguous, and transmural lesions by concentrating energy within the tissue between the electrodes, overcoming anatomic and power constraints of unipolar ablation.7 In addition,our pre-clinical study in a porcine model of bipolar septal ablation showed the lesion appears during follow up (Supplemental Figure 2).
In this case, Bi-PESA achieved an immediate and dramatic reduction in the provoked LVOTG (from 140 to 50 mm Hg) and resting LVOTG (from 73 to 10 mm Hg intraprocedurally; 13 mm Hg on day 4). The sustained gradient reduction (28 mm Hg at 1 month), complete symptom resolution (NYHA functional class III to I), and remarkable improvement in Kansas City Cardiomyopathy Questionnaire score (30.17 to 80.17) signify profound clinical benefit. Notably, these improvements were accomplished by ablating only 23.5% (1.9 cm2) of the predefined target zone (8 cm2), suggesting that Bi-PESA creates highly efficient lesions capable in relatively limited surface area ablation. The integration of the CARTO 3 mapping system with ICE allowed precise anatomic definition, real-time lesion monitoring, and meticulous avoidance of the His-Purkinje system, resulting in no conduction disturbances.
Novelty of Submission
Conventional unipolar PESA has its shortcomings for LVOTG reduction in HOCM. Bipolar radiofrequency ablation has only been reported for ventricular arrythmias elimination. To our knowledge, this is the first reported experience of successful Bi-PESA for patients with HOCM.
Future Directions
This first-in-human experience is inherently limited by its single-case design and short-term follow-up. Although the acute results are excellent, long-term durability of gradient reduction and symptom relief require validation. Optimal bipolar parameters (power, duration, interelectrode distance, contact force requirements) for creating controlled, effective lesions in the hypertrophied septum need systematic evaluation. The learning curve associated with this technically complex dual-catheter approach and its applicability across a broader HOCM patient spectrum warrant prospective comparison with ASA and conventional PESA.
Conclusions
Bi-PESA affords rapid, substantial, and sustained relief of left ventricular outflow obstruction in HOCM patients while preserving the conduction system. With an experienced team and meticulous preprocedural planning, it represents a novel effective and safe septal reduction strategy for patients with drug-refractory HOCM unsuitable for SM and ASA. Larger cohort studies are warranted.
Funding support and author disclosures
This work was supported by grants from the Chinese Academy of Medical Sciences Clinical and Translational Medical Research Fund (2020-I2M-C&T-B-051) and horizontal research projects within the institution (T2016-ZX015). The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Take-Home Message
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•
Bi-PESA combines the benefits of bipolar RFCA and PESA, providing a feasible and safe modality for septal reduction in drug-refractory HOCM.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For supplemental videos and figures, please see the online version of this paper.
Appendix
Preprocedural Transthoracic Echocardiographic Doppler Spectrum Across the Left Ventricular Outflow Tract
Intracardiac Echocardiography 3-Dimensional Reconstruction of the Left Ventricle, Right Ventricle, Septum, and the Obstructive Area
Preprocedural Activation Sequence of the Septal Myocardium on 3-Dimensional Electroanatomic Mapping
Postprocedural Activation Sequence of the Septal Myocardium on 3-Dimensional Electroanatomic Mapping
Postprocedural Transthoracic Echocardiographic Doppler Spectrum Across the Left Ventricular Outflow Tract
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Associated Data
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Supplementary Materials
Preprocedural Transthoracic Echocardiographic Doppler Spectrum Across the Left Ventricular Outflow Tract
Intracardiac Echocardiography 3-Dimensional Reconstruction of the Left Ventricle, Right Ventricle, Septum, and the Obstructive Area
Preprocedural Activation Sequence of the Septal Myocardium on 3-Dimensional Electroanatomic Mapping
Postprocedural Activation Sequence of the Septal Myocardium on 3-Dimensional Electroanatomic Mapping
Postprocedural Transthoracic Echocardiographic Doppler Spectrum Across the Left Ventricular Outflow Tract
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