PIMSRA deemed 'safe and effective' at 6 months in case series
Percutaneous therapy for hypertrophic obstructive cardiomyopathy (HCM) appeared promising in a small case series, suggesting a novel alternative to surgery that could expand access to treatment.
Percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) reduced peak left ventricular outflow tract (LVOT) gradients and interventricular septum (IVS) thickness in 15 patients, according to Liwen Liu, MD, of Xijing Hospital of the Fourth Military Medical University in Xi'an, China, and colleagues.
In turn, patients also experienced clinical improvements that were maintained out to 6-month follow-up, the researchers reported in the Oct. 16 issue of the Journal of the American College of Cardiology:
- New York Heart Association functional classification improved from 3 to 1 (P<0.001)
- Total exercise time increased from 6.00 to 9.00 min (P=0.007)
- Pro B-type natriuretic peptide levels dropped from 924.00 to 137.45 pg/mL (P=0.028)
No patient developed bundle branch block or complete heart block, but one did have a pericardial tamponade because of needle injury to the coronary vein.
The advantage of PIMSRA is the "percutaneous intramyocardial, non-transaortic and non-transcoronary approach, which could reduce LVOT obstruction and avoid sternotomy, reliance on alcohol injection, and damage to the conduction system distributed underneath the endocardium," according to the authors.
Liu's group concluded that PIMSRA is "a safe and effective treatment approach for severe, symptomatic [HCM]," though they cautioned that the procedure requires extensive assessment, careful patient selection, and experienced operators to achieve long-term clinical and hemodynamic benefits and acceptable safety outcomes.
Their case study consisted of 15 patients with HCM and drug-refractory symptoms. To be eligible for PIMSRA, they also had to have a left ventricle or coronary morphology ill-suited for surgery or alcohol septal ablation, the current options for HCM.
All received PIMSRA under transthoracic echocardiography (TTE) guidance, general anesthesia, and with a transapical approach. Total ablation times ranged from 28 to 72 minutes, with a mean duration of 58 min.
"The use of CT angiography and echocardiography substantially enhanced the procedural safety. To reduce heparin-associated bleeding risks, we used continuous TTE instead of catheters to measure the gradients," Liu and colleagues noted.
The results of these 15 patients are "quite remarkable," wrote a group led by Paul Sorajja, MD, of Minneapolis Heart Institute, in an accompanying editorial. "Overall, the results in this study share much in common with expertly performed surgical myectomy."
Myectomy is the gold standard therapy for drug-refractory HCM, but the issue is its limited availability given the significant expertise required for the surgery, the editorialists commented, adding that "the investigators should be commended for forging a new therapy for patients with HCM, whose complexity cannot be underestimated."
Nonetheless, many questions remain regarding PIMSRA, according to Sorajja's group, such that the effects of intramyocardial radiofrequency ablation must be subject to further rigorous scientific examination, ideally in a trial with independent adjudication.
The study was supported by International Cooperation Funding of the China Science and Technology Ministry, National Natural Science Foundation of China, a Shaanxi Provincial Key Project, and a Xijing Funded Project for New Technologies and Services.
Liu and Sorajja disclosed no conflicts of interest.