Current State of Transcatheter MVR With the Mitraclip
Current State of Transcatheter MVR With the Mitraclip
All patients referred to our center for consideration of MitraClip therapy were evaluated by an experienced mitral surgeon and a structural heart interventional cardiologist. Initial evaluation included: (I) transthoracic echocardiography to assess severity of MR, mitral valve area, and concomitant structural disease; (II) transesophageal echocardiography (TEE) to characterize valve pathology, and anatomic feasibility of MitraClip. Several additional studies are needed in many cases to assess surgical risk, including: (I) chest computed tomography to assess calcium burden of ascending aorta and degree of mitral annular calcification; (II) right and left heart catheterization to assess pulmonary vascular resistance and coronary artery disease; and (III) pulmonary function testing. Specific requirements for MitraClip placement include a resting effective orifice area greater than 4 cm to limit the risk of post-procedural stenosis, a single dominant regurgitant jet, and leaflet edges free of calcification. Each case was discussed by a multidisciplinary valve team composed of surgeons, interventional cardiologists, nurse practitioners, imaging specialists, as well as pulmonologists, nephrologists, oncologists, geriatricians, and hepatologists as needed, to gauge the optimal treatment for each patient. Our group has been involved in MitraClip trials and registries for nearly ten years, and continues to carefully evaluate each patient's risk profile and suitability for the procedure, whether for a research study or commercial MitraClip use. Patients with symptomatic, degenerative MR 3+ or greater who are at prohibitive risk for surgery are candidates for commercial MitraClip. Patients with functional MR and symptomatic heart failure who are deemed unsuitable for surgery could potentially be enrolled in the COAPT trial with randomization to optimal medical management or medical management plus MitraClip.
The MitraClip procedure is performed in a hybrid operating suite due to the increased space requirements for anesthesia and TEE teams. General anesthesia is used to protect the airway during TEE. Once percutaneous venous access is accomplished, hemodynamic right heart measurements are performed, and then transseptal puncture is made through the atrial septum, guided by TEE. The goal of this method is to secure a transseptal position that is relatively posterior on the septum, and 4 cm above the point of pathology on the mitral valve. Following the initial transseptal puncture, a 0.032 wire is passed into the left atrium. After confirming an appropriate transseptal location with the wire passing, the patient is heparinized, and the atrial septum is dilated. Next, the femoral venous access tract is dilated with an 18 French dilator, and then the 24 French steerable MitraClip guide is passed into the left atrium. Using fluoroscopic and echocardiographic guidance, the MitraClip is driven through the left atrium and positioned over the pathology on the mitral valve with the MitraClip arms perpendicular to the line of coaptation of the valve leaflets. The MitraClip is then passed across the valve and gradually pulled back to the ventricular side of the valve with the clip arms at 120°. Once the clip position is optimized by TEE, the frictional grippers are dropped and the clip arms are closed. If the clip is not in optimal position, it can be released and repositioned prior to release. If significant MR remains and no evidence of mitral stenosis is detected, additional clips may be placed at the area of greatest remnant regurgitation. The guidance system is removed, protamine is given, and femoral venous sheath is removed when the activated clotting time (ACT) has normalized. The femoral access is closed with a silk pursestring in the skin. Antiplatelet therapy is instituted after the procedure, and patients are observed for 24–48 hours prior to discharge.
We reviewed early outcomes data for 115 high-risk patients treated with MitraClip at our institution. Patient demographic information, preoperative evaluation, intraoperative details, and postoperative course data were collected from our valve center database as well as review of the electronic medical record system. We sought to evaluate our entire patient cohort at our institution from the REALISM continued-access registry through the early commercial MitraClip experience.
The primary outcome of interest was 30-day mortality from the MitraClip procedure. Secondary outcomes included degree of reduction of MR, overall improvement in New York Heart Association (NYHA) class, length of stay, and major complications (such as the need for transfusion, stroke, new-onset atrial fibrillation and myocardial infarction).
Methods
Patient Selection
All patients referred to our center for consideration of MitraClip therapy were evaluated by an experienced mitral surgeon and a structural heart interventional cardiologist. Initial evaluation included: (I) transthoracic echocardiography to assess severity of MR, mitral valve area, and concomitant structural disease; (II) transesophageal echocardiography (TEE) to characterize valve pathology, and anatomic feasibility of MitraClip. Several additional studies are needed in many cases to assess surgical risk, including: (I) chest computed tomography to assess calcium burden of ascending aorta and degree of mitral annular calcification; (II) right and left heart catheterization to assess pulmonary vascular resistance and coronary artery disease; and (III) pulmonary function testing. Specific requirements for MitraClip placement include a resting effective orifice area greater than 4 cm to limit the risk of post-procedural stenosis, a single dominant regurgitant jet, and leaflet edges free of calcification. Each case was discussed by a multidisciplinary valve team composed of surgeons, interventional cardiologists, nurse practitioners, imaging specialists, as well as pulmonologists, nephrologists, oncologists, geriatricians, and hepatologists as needed, to gauge the optimal treatment for each patient. Our group has been involved in MitraClip trials and registries for nearly ten years, and continues to carefully evaluate each patient's risk profile and suitability for the procedure, whether for a research study or commercial MitraClip use. Patients with symptomatic, degenerative MR 3+ or greater who are at prohibitive risk for surgery are candidates for commercial MitraClip. Patients with functional MR and symptomatic heart failure who are deemed unsuitable for surgery could potentially be enrolled in the COAPT trial with randomization to optimal medical management or medical management plus MitraClip.
Operative Procedure
The MitraClip procedure is performed in a hybrid operating suite due to the increased space requirements for anesthesia and TEE teams. General anesthesia is used to protect the airway during TEE. Once percutaneous venous access is accomplished, hemodynamic right heart measurements are performed, and then transseptal puncture is made through the atrial septum, guided by TEE. The goal of this method is to secure a transseptal position that is relatively posterior on the septum, and 4 cm above the point of pathology on the mitral valve. Following the initial transseptal puncture, a 0.032 wire is passed into the left atrium. After confirming an appropriate transseptal location with the wire passing, the patient is heparinized, and the atrial septum is dilated. Next, the femoral venous access tract is dilated with an 18 French dilator, and then the 24 French steerable MitraClip guide is passed into the left atrium. Using fluoroscopic and echocardiographic guidance, the MitraClip is driven through the left atrium and positioned over the pathology on the mitral valve with the MitraClip arms perpendicular to the line of coaptation of the valve leaflets. The MitraClip is then passed across the valve and gradually pulled back to the ventricular side of the valve with the clip arms at 120°. Once the clip position is optimized by TEE, the frictional grippers are dropped and the clip arms are closed. If the clip is not in optimal position, it can be released and repositioned prior to release. If significant MR remains and no evidence of mitral stenosis is detected, additional clips may be placed at the area of greatest remnant regurgitation. The guidance system is removed, protamine is given, and femoral venous sheath is removed when the activated clotting time (ACT) has normalized. The femoral access is closed with a silk pursestring in the skin. Antiplatelet therapy is instituted after the procedure, and patients are observed for 24–48 hours prior to discharge.
Study Design
We reviewed early outcomes data for 115 high-risk patients treated with MitraClip at our institution. Patient demographic information, preoperative evaluation, intraoperative details, and postoperative course data were collected from our valve center database as well as review of the electronic medical record system. We sought to evaluate our entire patient cohort at our institution from the REALISM continued-access registry through the early commercial MitraClip experience.
Outcomes
The primary outcome of interest was 30-day mortality from the MitraClip procedure. Secondary outcomes included degree of reduction of MR, overall improvement in New York Heart Association (NYHA) class, length of stay, and major complications (such as the need for transfusion, stroke, new-onset atrial fibrillation and myocardial infarction).
