European Journal of Cardiovascular Medicine

One person out of every 500 has the hereditary condition known as hypertrophic cardiomyopathy (HCM) [1]. 70% of HCM patients have obstruction of the left ventricular outflow tract (LVOT) [2]. The etiology of hypertrophic obstructive cardiomyopathy can be described by the mitral valve's systolic anterior motion, the basal septum's enlargement, the contact of mitral–interventricular and septal, and abnormal papillary muscles [3].

Dyspnea, chest discomfort, presyncope, syncope, and an increased risk of arrhythmias are all negative indications of severe LVOT obstruction. Septal reduction therapy can alleviate the harmful effects of LVOT blockage [4].

High-quality surgical septal myectomy (SM) is difficult to obtain since most hospitals lack the operators' knowledge, which is necessary for the procedure to be successful. Endocardial radiofrequency ablation of septal hypertrophy (ERASH) is a new septal reduction treatment. As of right now, it is a minimally intrusive technique that guarantees clinical outcomes [5].

It appears that ERASH is a novel way to lessen septal hypertrophy. In order to lessen LVOT blockage, this catheter-based ablation technique primarily targets the hypertrophied basal interventricular septum. An irrigated radiofrequency catheter is used to deliver targeted lesions at the mitral-septal contact zone under fluoroscopy plus electroanatomic mapping with intracardiac echocardiography guidance using retrograde transaortic or transseptal access. The objective is to lower resting and provocable gradients by inducing localized hypokinesis and reducing SAM-mediated blockage. The main safety concerns are conduction block (which occasionally requires pacing) and, less frequently, pericardial effusion. ERASH is repeatable, prevents coronary damage, and can be carried out with a minimal risk of complications when guided by 3D mapping/ICE [6].

For obstructive HCM, ERASH initially appeared in the early 2000s as a catheter-based substitute for alcohol septal ablation and surgical myectomy. The first clinical experience showed technical viability, as described by Lawrenz and colleagues in 2004. A stable retrograde approach with an irrigated catheter resulted in a significant reduction in resting and provocable LVOT gradients following two unsuccessful transseptal efforts [7].

The purpose of this systematic review was to assess and compare the safety and effectiveness of ERASH and SM in the treatment of hypertrophic obstructive cardiomyopathy, with an emphasis on improvements in the New York Heart Association (NYHA) functional class, changes in the LVOT gradient, and interventricular septal thickness (IVST) across published clinical studies

The 2020 revision of the Preferred Reporting Items for Systematic Review and Metaanalyses (PRISMA) criteria served as the foundation for the planning, carrying out, and reporting of the systematic review [8].

Data sources and searches

The authors searched the PubMed, Science Direct, and Cochrane Library databases using both combined Medical Subject Headings (MeSH) terms and non-MeSH terms "Endocardial Radiofrequency Ablation" or "Septal Myectomy" and "Hypertrophia Obstructive Cardiomyopathy" to find the studies from inception to September 10, 2025.  Additionally, we used Google Scholar and the reference list of relevant papers to search the literature.

Inclusion and exclusion

The selection of eligible studies was done using the participants, intervention, comparison, outcome, and research design method. The inclusion criteria included LVOT gradient, septal thickness, or NYHA class after endocardial radiofrequency ablation or SM; randomized controlled trials (RCT); and articles written in English.

Studies with inadequate outcome information, studies that were not RCTs, studies involving animals, reviews or meeting papers, and studies written in languages other than English were all excluded. The first author vetted publications for eligibility by searching the databases. Every article that was included was double-checked by another author, and any disagreements were settled by consensus.

Data extraction and quality assessment

A second reviewer independently verified the accuracy of the data once it was entered into a standardized data extraction table (Excel). PRISMA 2020 principles were followed in the methodical collection of data. Prior to and during intervention, data on study characteristics, patient demographics, procedural specifics, and important outcomes such as LVOT gradient, interventricular septal thickness, and NYHA class were extracted by two independent reviewers. Additionally, safety metrics including severe problems, arrhythmias, and death were noted. All data were cross-checked and collated for analysis, and any disagreements were settled by consensus.

Data Synthesis

Because of the heterogeneity of the included trials (demographic, aim, design, length, outcome measures, and follow-up), a meta-analysis was not statistically sufficient and could not be conducted. The result was a narrative synthesis. The results of the synthesis of the included trials are presented in this publication as a systematic review, with an explanation.

Risk of bias assessment

The risks of bias were impartially evaluated using the Cochrane Handbook for Systematic Reviews of Interventions tool [9]. Random sequence formation (selection bias), allocation concealment (selection bias), participant and staff blinding (performance bias), insufficient outcome data (attrition bias), selective reporting (reporting bias), and other bias were the seven parameters that were used to assess the likelihood of bias. A score of "unclear," "high risk," or "low risk" could be assigned to these items

3190 publications were found using the electronic database search. 2090 articles were identified as possible publications for screening after duplicates were eliminated. The qualitative analyses shown in Figure 1 included 28 studies [10–36] with a total of 1350 people after predetermined inclusion and exclusion criteria were used.

The primary disadvantage was low levels of reported blinding for participants, researchers, and outcome assessors. In every study, there was little chance of bias resulting from the randomization procedure. All 28 studies revealed modest levels of bias in the selection of the reported result, missing outcome data, and variations from the intended interventions (impact of assignment to intervention). There was considerable worry about the possibility of bias in the outcome assessment across all the trials. In general, there was little chance of bias.

Figure 1. PRISMA flow diagram of the literature search and selection

An overview of research comparing ERASH and SM is presented in Table 1. Patients were divided into two groups: those who received SM treatment and those who received ERASH treatment. Adults and children with hypertrophic obstructive cardiomyopathy were included in both groups. While ERASH is a minimally invasive catheter-based treatment and SM is a surgical operation, both methods sought to enhance NYHA functional class and lower LVOT gradient. In both the ERASH and septal myectomy groups, the percentage with improved NHYA was 46.7 and 46.4, respectively.

Table 1. Overview of the Study

The standardized mean difference (SMD) for LVOT gradient reduction in adults was –1.95 (95% CI: –2.45 to –1.45) with ERASH and –3.03 (95% CI: –3.62 to –2.44) with SM, suggesting a larger gradient decrease with SM. The SMD for SM and ERASH in children was –2.67 (95% CI: –3.21 to –2.12) and –2.37 (95% CI: –3.02 to –1.73), respectively, suggesting that both approaches were successful, while SM had a marginally better impact. Resting LVOTG decrease is explained in further detail in Table 2.

Table 2. Resting Left Ventricular Outflow Tract Gradient (LVOTG) Reduction

SM had an SMD of –1.82 (95% CI: –2.29 to –1.34), but ERASH had an SMD of –0.43 (95% CI: –1.00 to 0.13). IVST decrease is shown in Table 3.

Table 3. Interventricular Septal Thickness (IVST) Reduction

ERASH had a slightly greater procedural and periprocedural mortality rate (1.8%) than SM (1.1%). Mortality and safety results are displayed in Table 4.

Table 4. Mortality and Safety Outcomes

The clinical effectiveness and safety of SM and ERASH in patients with hypertrophic obstructive cardiomyopathy were compared in this systematic review. While both modalities increased NYHA functional class and greatly decreased the LVOT gradient, SM's improvement was more pronounced.

Since septal myectomy immediately removes hypertrophied septal tissue and successfully reduces blockage, it has long been regarded as the gold standard treatment for patients with drug-refractory HOCM and severe LVOT obstruction [1, 2]. For LVOT gradient reduction in this review, SM obtained an SMD of –3.03 in adults and –2.67 in children, showing a significant improvement. These results are in line with other research demonstrating that surgical myectomy provides significant hemodynamic and clinical improvements with long-lasting results [37, 38].

Conversely, ERASH is a new, minimally invasive, catheter-based substitute for surgery. It reduces systolic anterior motion (SAM) and LVOT blockage by inducing localized septal hypokinesis using targeted endocardial radiofrequency energy [39]. ERASH showed a considerable but lower gradient reduction (SMD –1.95 in adults and –2.37 in children) in the current analysis, indicating successful but less noticeable septal remodeling in comparison to SM. These results are comparable to those of Poon et al. (2016), who found that in patients who were not candidates for surgery, ERASH consistently reduced the gradient and improved symptoms [40].

Both procedures have low rates of complications in terms of safety outcomes. ERASH had a slightly higher procedural fatality rate (1.8%) than SM (1.1%), although both were within acceptable bounds. Both groups had very few major problems and post-procedural arrhythmias. These findings are consistent with those of Lawrenz et al. (2004) and Shelke et al. (2016), who reported minimal problems and high procedural success with ERASH when carried out under intracardiac echocardiography and electroanatomic guidance [41, 42].

In general, SM is still the best treatment for severe blockage and significant septal hypertrophy, especially in younger, operable patients. For patients who have limited access to specialized surgical centers or who are at high surgical risk, ERASH provides an appealing, minimally invasive option. In certain situations, ERASH may supplement or perhaps completely replace surgical myectomy as technology and operator expertise develop.

In order to maximize therapy choices for hypertrophic obstructive cardiomyopathy, future research should concentrate on long-term comparing outcomes, standardizing ablation methods, and assessing patient selection criteria.

According to the results of this comprehensive review, patients with hypertrophic obstructive cardiomyopathy can improve their functional ability and lower their LVOT gradient with both SM and ERASH. However, especially in adult patients, SM showed a higher decrease in LVOT gradient and septal thickness than ERASH. Because ERASH is less invasive, it is a viable option for patients who are not candidates for surgery or at facilities with insufficient surgical experience. To create consistent procedures and long-term results for ERASH, more extensive, randomized research are required.

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