Conference Coverage

Novel percutaneous therapy for HOCM in development


 

REPORTING FROM ACC SNOWMASS 2019

– Percutaneous mitral valve plication shows early promise as a primary therapy for severely symptomatic, drug-refractory hypertrophic obstructive cardiomyopathy (HOCM), Paul Sorajja, MD, said at the Annual Cardiovascular Conference at Snowmass sponsored by the American College of Cardiology.

Bruce Jancin/MDedge News

Dr. Paul Sorajja

He and his coworkers at the Minneapolis Heart Institute developed the novel procedure and published the first experience in the world with it. But further study in a much larger patient population is needed before percutaneous mitral plication is ready for prime time as a treatment for symptomatic HOCM, according to Dr. Sorajja, director of the Center of Valve and Structural Heart Disease at the institute.

Surgical myectomy is the guideline-recommended standard for treatment of patients with disabling symptoms caused by left ventricular outflow tract obstruction in the setting of hypertrophic cardiomyopathy. Alcohol septal ablation is a widely utilized alternative in patients who are frail and elderly or otherwise high-risk surgical candidates, or who lack ready access to an experienced surgical myectomy center, where the best outcomes are achieved. But roughly 20% of patients evaluated for alcohol septal ablation don’t have a septal artery anatomy amenable to the procedure. Other patients are put off by the 10%-50% risk that they will require a permanent pacemaker after alcohol septal ablation, depending upon their baseline ECG. And a small percentage of well-chosen patients – less than 10% – will experience inadequate gradient relief following alcohol septal ablation. So there is room for a novel therapeutic approach.

A percutaneous mitral clip–based solution, while technically challenging, offers several advantages over surgical myectomy and alcohol septal ablation. It’s less invasive, doesn’t create a potentially arrhythmogenic ablation scar requiring a permanent pacemaker, and it targets the mitral valve directly, addressing the mitral regurgitation that causes the left ventricular outflow tract obstruction. In contrast, both surgical myectomy and alcohol septal ablation target the ventricular septum.

Dr. Sorajja summarized his experience to date with percutaneous mitral valve plication for symptomatic HOCM, which encompasses the six patients in the published study (J Am Coll Cardiol. 2016 Jun 21;67[24]:2811-8) and the four others treated since then. The procedure was completed with placement of a single MitraClip in 9 of 10 patients. One patient experienced cardiac tamponade, resulting in a halt of the procedure; in the other nine, the intervention eliminated systolic anterior motion and markedly decreased the intraoperative left ventricular outflow tract gradient and mitral regurgitation.

At 2-5 years of follow-up, all patients have improved from New York Heart Association functional class III preprocedurally to class I or II. One patient required alcohol septal ablation. High systolic left ventricular outflow tract velocities in excess of 4 cm/s have been documented via follow-up echocardiography in some patients, the significance of which is under study.

Dr. Sorajja reported receiving research funding from Abbott Structural, Boston Scientific, Edwards Lifesciences, and Medtronic, and serving as a consultant to those companies and several others.

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