Mitral Loop Cerclage Annuloplasty for Secondary Mitral Regurgitation: First Human Results

Abstract

Objectives: This is an early feasibility clinical test of mitral loop cerclage annuloplasty to treat secondary mitral valve regurgitation.

Background: Secondary mitral regurgitation is characterized by cardiomyopathy, mitral annular enlargement, and leaflet traction contributing to malcoaptation. Transcatheter mitral loop cerclage applies circumferential compression to the mitral annulus by creating a loop through the coronary sinus across the interventricular septum, protecting entrapped coronary arteries from compression, and interactive annular reduction under echocardiographic guidance. This is the first human test of mitral loop annuloplasty.

Methods: Five subjects with severe symptomatic secondary mitral regurgitation underwent mitral loop cerclage, with echocardiographic and computed tomography follow-up over 6 months.

Results: Mitral loop cerclage was successful in 4 of 5 subjects and aborted in 1 of the 5 because of unsuitable septal coronary vein anatomy. Immediately and over 6 months, measures of both mitral valve regurgitation (effective orifice area and regurgitation fraction) and chamber dimensions (left atrial and left ventricular volumes) were reduced progressively and ejection fractions increased. Two with persistent and permanent atrial fibrillation spontaneously reverted to sinus rhythm during follow-up. One subject experienced a small myocardial infarction from an unrecognized small branch coronary occlusion. Another, experiencing cardiogenic shock at baseline, died of intractable heart failure after 6 weeks.

Conclusions: In this first human test, mitral loop cerclage annuloplasty was successful in 4 of 5 attempts, caused reverse remodeling (reduction in secondary mitral regurgitation and heart chamber volumes), and suggested electrical remodeling (reversion of atrial fibrillation). Further evaluation is warranted.

Keywords: functional mitral regurgitation; mitral loop cerclage.

Copyright © 2017 American College of Cardiology Foundation. All rights reserved.

Figures

FIGURE 1. Mitral Loop Cerclage Design and Devices

(A) All 4 elements of the mitral loop cerclage implants assembled. (B) Device positioning. (C) The bridge device straddles the tricuspid valve between the coronary sinus and right ventricular septum. (D) Discordant planes of the mitral annulus and cerclage.

FIGURE 2. Representative Mitral Loop Cerclage Procedure

(A) Coronary venography through a balloon wedge catheter identifies a basal septal perforator coronary vein (arrow head) through which a guidewire is advanced (Online Video 1). (B) A target-capture device is positioned into the right ventricular outflow tract to ensnare the guidewire that crossed from the coronary vein. (C) The guidewire is exchanged for tension device containing an integrated coronary artery protection element (arrow head). (D) During application of tension, the protection element prevents compression of entrapped circumflex coronary artery branches. (E) In this caudal left anterior oblique projection, the mitral loop cerclage system is shown to surround the mitral annular plane. (F) The tension locking device was embedded in the left subclavicular pocket.

FIGURE 3. Effect of Mitral Loop Cerclage on Cardiac Chamber Dimensions (Reverse Remodeling)

Left ventricular end-systolic (LVESV) (A), end-diastolic (LVEDV) (B), ejection fraction (EF) (C), and left atrial (LA) volumes (D) all improve over time, suggesting reverse remodeling. Data are presented as in Figure 5.

FIGURE 4. Comparison of Basal Septal Coronary Veins

(A) A good septal vein in Patient #1. (B) A less suitable septal vein in Patient #2.

FIGURE 5. Effect of Mitral Loop Cerclage on Mitral Regurgitation and Geometry

Immediate and follow-up measurements are shown with mean ±SD on the top row and individual subject data on the bottom row. (A) Regurgitant volume. (B) Effective regurgitant orifice area (EROA). (C) Septal-lateral annular dimension. (D) Intercommissural annular dimension.

FIGURE 6. Improved Mitral Regurgitation and Leaflet Coaptation

(A) Volume-rendered computed tomography before (left) and after (right) mitral loop cerclage in Patient #4. (B) Echocardiography before (left) and after (right) mitral loop cerclage in Patient #5. (C to F) Serial echocardiography in Patient #3 showing improvement, from baseline, 30 days, 3 months, and 6 months, respectively, in mitral regurgitation severity.

FIGURE 7. Evidence of Reduced Chamber Dimensions (Reverse Remodeling) in Subject 1

(A and B) Baseline and 6 months posteroanterior radiograph shows reduced cardiothoracic ratio. (C and D) Multiplanar reformatted computed tomography (CT) shows left atrium in diastole before and after mitral loop cerclage. (E and F) Surface rendered CT shows positioning of arch-like coronary artery protection element at baseline and 6 months (arrows = compromised small branch).

FIGURE 8. Reversion of Atrial Fibrillation to Sinus Rhythm

Baseline (A and C) and 3 and 6 months (B and D) pulse-wave Doppler shows atrial fibrillation followed by restoration of sinus rhythm and atrial contraction after mitral loop cerclage in Patient #3 (A and B) and Patient #4 (C and D).