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Trans-Septal Myocardial Biopsy in Hypertrophic Cardiomyopathy Using the Liwen Procedure: An Introduction of a Novel Technique

What was known?

Myocardial biopsy is useful when other methods cannot differentiate hypertrophic obstructive cardiomyopathy (HOCM) from other aetiologies. Previous studies suggest that the Liwen procedure, an innovative nonsurgical approach for intramyocardial septal ablation, may be a useful alternative approach for myocardial biopsy.

Objective(s):

The aim of this study was to evaluate the feasibility and safety of myocardial biopsy using the Liwen procedure.

What this study adds:

This study has demonstrated the safety and feasibility of a novel minimally invasive procedure, the Liwen procedure, for myocardial biopsy.

Clinical implications:

While this is a preliminary evaluation only, these data suggest that the Liwen procedure is safe and feasible, which is potentially very useful in the diagnosis and research of HOCM with diverse aetiologies.

Study design:

This was a preliminary study of a larger interventional  study (NCT04355260), and enrolled 17 patients in Xijing Hospital. Following general anaesthesia, the patient underwent transthoracic electrocardiography-guided needle biopsy as follows: the puncture sheath was inserted into the ventricular septum. Next, around 2 cm from the myocardial was inserted into the sheath and the inner core pushed 2 cm forward until the inner switch was fired to obtain the biopsy tissue. The cardiac biopsy needle was subsequently withdrawn and an ablation needle then inserted into the same sheath to initiate myocardial tissue ablation. Biopsy results were recorded and the patients were followed up for one month.

Primary endpoint:

  • Any complications at 30 days relating to surgery or instrument use, including death, emergency surgery, severe pericardial tamponade requiring pericardiocentesis or surgery, bleeding, and surgery-related stroke 

Secondary endpoints:

  • Radiofrequency ablation system instruments reach the treatment site, ablation successfully completed and the system is successfully removed

Inclusion criteria:

  • HCOM

Notable exclusion criteria:

  • Heart failure or hypertrophic non-obstructive cardiomyopathy
  • Interventricular septal thickness ≥ 30mm
  • Sudden cardiac death index ≥ 10%
  • Other heart diseases requiring surgical treatment

Findings:

  • 31 tissue samples were successfully acquired from 17 patients
  • One patient experienced pericardial effusion occurred after the biopsy. This was drained by percutaneous catheter
  • There were no incidences of pericardial tamponade, nonsustained or sustained ventricular tachycardia, conduction abnormity, perforation, stroke, and pneumothorax
  • No patients died in hospital and during the 30 days following the biopsies
  • Myocyte hypertrophy was seen, with an increase in the transverse diameter, and nuclei were hyperchromatic with bizarre shapes
  • Interstitial fibrosis was observed in most samples

Interpretation:

Liwen myocardial biopsy obtained adequate tissue  samples with 100% success rate. The procedure is relatively safe: there was one case of pericardial effusion, probably caused by excessive movement of the biopsy needle while positioning within the myocardium, but this was successfully managed. The biopsy needle did not enter any cardiac chamber, meaning that the risk of myocardial perforation was negligible.

Limitations:

  • The study population was small, and this study can only be considered a preliminary evaluation of the feasibility and safety of the procedure