First-in-man application of Liwen RF™ ablation system in the treatment of drug-resistant hypertrophic obstructive cardiomyopathy

Advancements in the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: A Comprehensive Review

Hypertrophic cardiomyopathy (HCM) is characterized by excessive growth of myocardial tissue, most commonly due to genetic mutations in sarcomere proteins. This can lead to complications such as heart failure, mitral regurgitation, syncope, arrhythmias, sudden cardiac death, and myocardial ischemia. While we have come a long way in our understanding of the pathophysiology, genetics, and epidemiology of HCM, the past 10 years have seen significant advancements in diagnosis and treatment. As the body of evidence on hypertrophic cardiomyopathy continues to grow, a comprehensive review of the current literature is an invaluable resource in organizing this knowledge. By doing so, the vast progress that has been made thus far will be widely available to all experts in the field. This review provides a comprehensive analysis of the scientific literature, exploring both well-established and cutting-edge diagnostic and therapeutic options. It also presents a unique perspective by incorporating topics such as exercise testing, genetic testing, radiofrequency ablation, risk stratification, and symptomatic management in non-obstructive HCM. Lastly, this review highlights areas where current and future research is at the forefront of innovation in hypertrophic cardiomyopathy.

Analysis of risk factors for complications in echocardiography-guided percutaneous intramyocardial septal radiofrequency ablation

BACKGROUND

The feasibility of percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) for the treatment of hypertrophic obstructive cardiomyopathy (HOCM) has been previously reported. However, limited investigation has been conducted regarding the complications associated with this procedure.

OBJECTIVE

This study aims to analyze the risk factors affecting the occurrence of complications during PIMSRA, such as pericardial effusion, ventricular premature beats, and interventricular septal perforation. In this study, the optimal cut-off values for these risk factors are also explored, and corresponding strategies for prevention are proposed.

METHODS

A total of 101 patients diagnosed with HOCM who underwent the PIMSRA procedure from 2021 to 2022 were included in this retrospective analysis. Patients were classified into subgroups with or without complications based on procedural records. Univariate and multivariate regression analyses were conducted to identify independent risk factors for complications during the PIMSRA procedure.

RESULTS

There were 48 patients with complications and 53 patients without complications. The heart rate at the start of the procedure and the maximum left ventricular outflow tract gradient (LVOTG) were independent risk factors related to PIMSRA complications. The optimal cut-off values for predicting complication occurrence were a heart rate > 49 bpm at the start of the procedure (OR: 3.79, 95% CI: 1.64-8.78, p = 0.002) and a maximum LVOTG > 92 mmHg (OR: 2.57, 95% CI: 1.15-5.75, p = 0.022), respectively.

CONCLUSIONS

The occurrence of PIMSRA complications is primarily associated with the heart rate at the start of the procedure and the maximum LVOTG. It is recommended to establish a comprehensive control plan to minimize the risk of complications during PIMSRA procedures.

Radiofrequency ablation in patients with obstructive hypertrophic cardiomyopathy: An updated comprehensive review and meta-analysis

BACKGROUND

Radiofrequency catheter ablation (RFCA) has emerged as a therapeutic option for surgical myectomy and alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy (HOCM), but its efficacy remains unclear.

AIM

Due to limited research on RFCA for HCM, there is an ongoing attempt to assess its efficacy and safety.

METHODS

PubMed, Embase, and Scopus were systematically searched for studies assessing the efficacy outcomes for patients with HOCM who underwent RFCA. Mean differences (MDs) with 95% confidence intervals (CIs) were computed using a random-effects model and heterogeneity was assessed using I2 statistics.

RESULTS

We included 11 studies comprising 470 patients, of whom 34.6% were female. The mean patient age ranged from 43.7 to 60.7 years. During the follow-up after RFCA, there was a significant decrease in the left ventricular outflow tract (LVOT) gradient at rest (MD -60.25 mmHg; 95% CI [-70.53;-59.14 mmHg]; p < 0.01) and during stimulation (MD -83.56 mmHg; 95% CI [-100.36;-66.76 mmHg]; p < 0.01). Moreover, RFCA reduced interventricular septum (IVS) thickness (MD -3.61 mm; 95% CI [-5.64; -1.59 mm]; p = 0.01) and New York Heart Association (NYHA) class (MD -1.46; 95% CI [-1.69; -1.24]; p < 0.01).

CONCLUSIONS

In patients with HOCM, RFCA was associated with an improved NYHA class, reduced IVS thickness, and decreased LVOT gradient at rest and with stimulation.

Short time effects of two radiofrequency ablation methods on hypertrophic obstructive cardiomyopathy

BACKGROUND

Radiofrequency ablation has been applied for the treatment of hypertrophic obstructive cardiomyopathy (HOCM). The two known procedures are percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) and endocardial radiofrequency septal ablation (ERSA).

METHODS

This study presents a retrospective analysis of the PIMSRA and ERSA procedures in patients with drug-refractory HOCM. A total of 28 patients participated in the study, with 12 receiving PIMSRA and 16 receiving ERSA. The objective of our study was to compare the short-term effects of these two radiofrequency ablation procedures.

RESULTS

At the 30-day follow-up, the PIMSRA group demonstrated a greater reduction in left ventricular outflow tract peak gradient at rest compared to the ERSA group (22.25 [16.72] mmHg versus 47.75 [21.94] mmHg) (p < .01). The values for the PIMSRA group decreased from 99.33 (32.00) mmHg to 22.25 (16.72) mmHg (p < .01), while the ERSA group decreased from 97.75 (30.24) mmHg to 47.75 (21.94) mmHg (p < .01). Only the PIMSRA group exhibited a decrease in mitral regurgitation (MR). The area of MR decreased from 10.13 (4.12) mm2 to 3.65 (2.80) mm2 in the PIMSRA group (p < .01). Additionally, the PIMSRA group experienced reductions in left atrial diameter (LAD) and left ventricular ejection fraction (LVEF)%. The values for LAD changed from 43.58 (7.53) mm to 37.08 (6.92) mm (p = .03), and the values for LVEF% decreased from 65.75 (6.12) pg/mL to 60.83 (4.06) pg/mL (p = .03).

CONCLUSION

In terms of the two types of radiofrequency ablation methods used in HOCM, it has been observed that PIMSRA demonstrates a more favorable early treatment effect compared to ERSA.

Clinical Effect of the Modified Morrow Septal Myectomy Procedure for Biventricular Hypertrophic Cardiomyopathy

Background

Right ventricular involvement in hypertrophic cardiomyopathy is uncommon. This study aimed to evaluate clinical outcomes of the modified septal myectomy in patients diagnosed with biventricular hypertrophic cardiomyopathy (BHCM), a subject seldom explored in the literature.

Methods

We conducted a retrospective cohort study from January 2019 to January 2023, enrolling 12 patients with BHCM. Each patient underwent a modified septal myectomy and was followed postoperatively. Clinical data and echocardiographic parameters, including the ventricular outflow tract peak pressure gradient and maximum interventricular septum thickness, were collected and analyzed.

Results

The study cohort had a median age of 43.0 (interquartile range 14.5-63.0) years at surgery, with four patients (33.3%) being children. Two patients (16.7%) previously underwent percutaneous transluminal septal myocardial ablation. Surgical relief of biventricular outflow tract obstruction (BVOTO) was achieved in five patients (41.7%), aside from those managed solely for left ventricular outflow tract obstruction. In five instances, three-dimensional (3D) printing technology assisted in surgical planning. The postoperative interventricular septum thickness was significantly reduced (21.0 mm preoperative vs. 14.5 mm postoperative, p < 0.001), effectively eliminating residual ventricular outflow tract obstruction. There were no severe complications, such as septal perforation or third-degree atrioventricular block. During a mean follow up of 21.2 ± 15.3 months, no sudden deaths, residual outflow tract obstruction, permanent pacemaker implantation, recurrent systolic anterior motion, or reoperations were reported.

Conclusions

Our findings affirm that the modified septal myectomy remains the gold standard treatment for BHCM, improving patient symptoms and quality of life. BVOTO relief can be safely and effectively achieved through septal myectomy via transaortic and pulmonary valve approaches in selected patients. For intricate cases, the application of 3D printing technology as a preoperative planning tool is advised to optimize surgical precision and safety.

Case Report: Integrated echocardiographic assessment guided Liwen procedure for treating obstructive hypertrophic cardiomyopathy with ventricular aneurysm

Hypertrophic cardiomyopathy (HCM) is a genetic myocardial disease, with an estimated incidence of 0.2%-6%, and is the main cause of sudden cardiac death (SCD) in young athletes. Left ventricular apical aneurysm (LVAA) is a rare subtype of HCM, accounting for about 5% of HCM patients, and has a higher incidence of cardiovascular adverse events. In cases of hypertrophic obstructive cardiomyopathy with LVAA (HOCM-LVAA) that do not respond adequately to optimized medical therapy, the echocardiography-guided percutaneous intra-myocardial septal radiofrequency ablation (PIMSRA, Liwen procedure) emerges as a promising and effective novel therapeutic approach. In this case report, we present for the first time a comprehensive application of echocardiographic techniques, including TTE, 2-D STE, and contrast enhancement, in the diagnosis, treatment, surgical guidance, and assessment of therapeutic outcomes in a case of HOCM-LVAA.