A first experience with percutaneous mitral valve plication with the MitraClip for patients with symptomatic, obstructive hypertrophic cardiomyopathy (HCM) appeared successful.
A single transcatheter MitraClip was successfully placed at the A2-P2 segments in five out of six elderly patients for whom it was attempted due to heart failure from obstructive HCM deemed ill-suited for septal myectomy.
One patient had the plication procedure terminated early due to cardiac tamponade during transseptal puncture and received surgical repair instead, Paul Sorajja, MD, of Abbott Northwestern Hospital in Minneapolis, Minn., and colleagues reported online in the Journal of the American College of Cardiology.
In the five patients with the device implanted, systolic anterior motion of the mitral valve was immediately eliminated and mean mitral regurgitation reduced from grade 3 to 0.8 (P=0.0002). There were also drops in left ventricular outflow tract gradient (91 to 12 mm Hg, P=0.007) and a nonsignificant trend for reduction in left atrial pressure (29 mm Hg to 20 mm Hg, P=0.06).
In the four patients for whom cardiac output was measured, it improved from 3.0 to 4.3 L/min on average (P=0.03). Over 15 months follow-up, all patients made functional gains to New York Heart Association class I or II. Systolic anterior motion was still absent at that point and mitral regurgitation greatly reduced as well (mean grade 0.6).
“This initial experience suggests that percutaneous mitral valve plication may be effective for symptom relief in such patients via reduction of systolic anterior motion and mitral regurgitation,” the authors concluded.
“By directly plicating the valve leaflets and preventing systolic anterior motion, the implanted mitral clip thereby prevents mitral-septal contact, increases left ventricular outflow tract area, normalizes left ventricular pressure, relieves mitral regurgitation, and consequently alleviates heart failure symptoms.”
Surgical myectomy remains the primary therapy for most patients. Yet Sorajja and colleagues noted that the MitraClip strategy does offer several advantages, including direct targeting of the mechanism of left ventricular outflow tract obstruction, minimal invasiveness, hemodynamic measurements prior to clip placement, and a lack of dependence on coronary anatomy.
The other alternative, alcohol septal ablation, “has gained wide acceptance in many centers with limited experience in surgical myectomy,” commented Hartzell V. Schaff, MD, of Mayo Clinic in Rochester, Minn.
“But reduction in septal thickness by iatrogenic myocardial infarction has unknown late consequences regarding ventricular arrhythmias and, compared with septal myectomy, the procedure is associated with twice the risk of need for permanent pacemaker implantation and a 5-fold higher rate of need for subsequent septal reduction therapy,” he wrote in an accompanying editorial.
Participants received general anesthesia and transesophageal echocardiography for procedural guidance.
Three out of the five treated patients showed high systolic left ventricular outflow tract velocities exceeding 5 m/s, however, despite apparent relief of resting left ventricular outflow tract gradients.
Sorajja and colleagues remeasured the left ventricular outflow tract gradient in one individual and it was “substantially higher” (64 mm Hg with simultaneous invasive hemodynamics versus 22 mg Hg with echocardiography alone), they found, “suggesting that the velocity in the left ventricular outflow tract did not reflect true impedance to left ventricular outflow and did not imply an inadequate hemodynamic result.”
Schaff called it “important” to continue studying these patients “to understand whether the Doppler signals are benign and not related to obstruction, or whether these reflect midventricular gradients that can lead to the same symptoms caused by subaortic left ventricular outflow tract gradients.”
“The significance of persistent elevations of left ventricular outflow tract velocities in some patients requires further study,” the authors agreed.
Also, “we wish to emphasize that the experience with percutaneous mitral valve plication in obstructive HCM reported here is early and in only a small number of patients, with the appropriate selection of those who are likely to benefit from this treatment currently incompletely resolved,” Sorajja’s group wrote.
The editorialist noted the importance of patient selection, citing the possibility that elderly patients with obstructive HCM may have mitral annular calcification that can produce mitral stenosis. In turn, that valve narrowing might be worsened by leaflet plication, he suggested.
Sorajja reported consulting and serving on the speakeres bureau for Abbott Vascular.
Schaff declared no relevant conflicts of interest.
Journal of the American College of Cardiology
Sorajja P, et al “First experience with percutaneous mitral valve plication as primary therapy for symptomatic obstructive hypertrophic cardiomyopathy” J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.03.587.
Journal of the American College of Cardiology
Schaff HV “Transcatheter mitral valve plication: innovative approach for relief of LVOT obstruction in high-risk HCM patients” J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.04.022.