Percutaneous mitral valve annuloplasty for functional mitral regurgitation: acute results of the first patient treated with the Viacor permanent device and future perspectives

Abstract

Background

There is a need to develop less invasive techniques to manage moderate or severe functional mitral regurgitation in patients at high surgical risk.

Objective

We report the acute results of the first patient treated with the permanent Viacor percutaneous transvenous mitral annuloplasty (PTMA) device in North America, introduce the PTOLEMY-2 protocol, and briefly discuss the current status of transvenous mitral valve techniques.

Case report

After several episodes of pulmonary edema, an 87-year-old woman was referred for hemodynamic evaluation. Angiography revealed normal coronary arteries and severe mitral regurgitation. Baseline echocardiography showed severe (4+) functional mitral regurgitation. The coronary sinus was cannulated with a 9.5-Fr introducer from a left subclavian approach. After distal positioning of a coronary wire, the 7-Fr PTMA Viacor catheter was advanced to the anterior interventricular vein. Two 130 g/cm rods were then inserted resulting in an acute and dramatic reduction in mitral regurgitation as assessed by continuous transoesophageal echocardiography and which was associated with a sudden rise in arterial blood pressure. The next day, transthoracic echocardiogram showed a significant reduction in effective regurgitant orifice area (EROA) from 41 to 10 mm ². The patient was discharged home the day following the procedure without complication. In accordance with the PTOLEMY-2 protocol, she will undergo 3-D transthoracic echocardiograms, quality of life assessments, and 6-min walk tests at regular intervals for the next 5 years.

Conclusion

PTMA is a promising technique for the treatment of severe mitral regurgitation in selected patients. Further ongoing research will determine the predictors of success and long-term safety and performance of this technique.

1 Introduction

Functional mitral regurgitation is frequently associated with heart failure and influences its long-term prognosis. In North America, 15–20% of patients suffering from heart failure have moderate to severe mitral regurgitation. After myocardial infarction, up to 19% of patients have ischemic mitral regurgitation (IMR) . The pathophysiology of IMR resides in the remodeling of the left ventricular geometry, papillary muscles displacement, mitral annulus dilatation, and leaflet tethering . These changes hamper normal leaflet coaptation.

Surgical management of IMR involves most of the time restrictive mitral annuloplasty with coronary artery bypass graft surgery . However, surgery can be associated with significant risks of mortality and has not been shown to positively impact long-term follow-up . These findings have been correlated with the persistence or recurrence of significant mitral regurgitation after the operation. Besides the increased risks of mortality, moderate or severe IMR significantly impairs the quality of life of patients and may lead to repeat hospitalizations for acute pulmonary edema. Hence, several percutaneous techniques have been recently proposed to reduce functional mitral regurgitation with fewer risks than conventional surgery. Among these devices, the Viacor percutaneous transvenous mitral annuloplasty (PTMA) permanent device consists of a 7-Fr thee-lumen catheter which is advanced into the coronary sinus followed by the insertion of one to three nitinol rods which stiffen the catheter. Temporary use as a bridge to surgery has been previously reported . In this article, we describe patient selection, the procedure, and the early results of the first permanent implantation in North America of the PTMA catheter in a patient with severe nonischemic mitral regurgitation.

2 Case report

An 87-year-old woman was initially referred to the catheterization laboratory for diagnostic evaluation. Her cardiovascular history revealed that she had been hospitalized repeatedly over the previous year for pulmonary edema. Outside these acute episodes, she had remained in NYHA Class II heart classification. She had no cardiovascular risk factors and her medical history was significant for a low-grade non-Hodgkin lymphoma treated by chemotherapy in 1993. The patient was in sinus rhythm with normal QRS width. Diagnostic angiography showed normal coronary arteries with a right dominant circulation. Left ventriculography showed mildly reduced ejection fraction with moderate mitral regurgitation. Transthoracic echocardiography showed a dilated left atrium with a grade 4+ mitral regurgitation. The mechanisms of mitral regurgitation were explained by annular dilatation at 40 mm (as measured in a four-chamber view) and restriction of both leaflets caused by left ventricular dilatation (tenting area of 2.1 cm ², a coaptation distance of 8 mm, and a posterior leaflet angle of 20°) . According to Carpentier’s classification, the mechanism of mitral regurgitation was of type I. Mitral regurgitation was graded 4+ with an effective regurgitant orifice area (EROA) of 41 mm ². The left atrium was severely dilated at 70 ml/m ², and systolic pulmonary artery pressure was estimated at 50–55 mmHg. Considering a Euroscore of 10.84%, she was considered for PTMA and written consent was obtained for participation in the PTOLEMY-2 study. Multislice computed tomography (MSCT) was obtained to assess the anatomical relationships between the coronary sinus, the mitral apparatus, and the circumflex artery. Data were sent to M2S (West Lebanon, NH, USA) for 3-D reconstruction and color rendering ( Fig. 1 ). Interestingly, the coronary sinus was located significantly cranial to the mitral apparatus at a maximum distance close to 2 cm.

During the procedure, the patient was intubated and sedated under general anesthesia to allow real-time transoesophageal echocardiography. The procedure was performed in a bi-plane angiography suite with one plane moved from left anterior oblique with caudal angulation to anterior–posterior and right anterior views, and the second plane remained in lateral view. Left coronary angiography was performed from the left radial artery. Venous access was obtained from the left subclavian approach; a 9.5-Fr delivery catheter was positioned at the origin of the coronary sinus ostium using a standard electrophysiology deflectable catheter. With the use of an inflatable balloon, contrast injection at low pressure was performed to visualize the coronary venous system’s detailed anatomy. A 0.035-inch hydrophilic wire (Magic wire, Boston Scientific) was positioned distally in the anterior interventricular vein. Then, the 7-Fr PTMA catheter was advanced over the wire under fluoroscopic guidance until it reached the proximal part of the anterior interventricular vein. Two 130 g/cm rods were introduced into the PTMA catheter and produced immediate and dramatic reduction of the mitral regurgitation as assessed by transoesophageal echocardiography ( Fig. 2 A and B). At that time, systolic blood pressure rose suddenly from 120/60 to 180/80 mmHg and a nitroglycerin intravenous drip and an intravenous furosemide 40 mg were administered to control the blood pressure. After verifying that the proximal marker of the PTMA catheter was positioned at the ostium of the coronary sinus, the 9.5-Fr introducing catheter was slit and slowly removed under fluoroscopic guidance to avoid any displacement of the PTMA catheter ( Fig. 3 A and B). Final angiography confirmed no external compression of the circumflex artery ( Fig. 4 ). The proximal part of the PTMA catheter was sutured to the pectoral muscle similarly to a pacemaker pocket to prevent later dislodgment. After the procedure, the patient was monitored in the recovery room for 2 h and was then transferred to the coronary care stepdown unit for overnight monitoring. The patient underwent 24-h postprocedure control echocardiography, which showed grade 2+ moderate residual mitral regurgitation with an EROA reduction from 41 to 10 mm ²; mitral geometry was as follows: annular dilatation of 36 mm, tenting area of 1.5 cm ², coaptation distance of 5 mm, and posterior leaflet angle of 20°. The patient was discharged home the day following the procedure without complication ( Fig. 5 A and B, Fig. 6 ). No ECG changes or rise in cardiac biomarkers was observed. At 30 days, MSCT was performed ( Fig. 7 ). At 6-month follow-up, the patient has remained in NYHA Class I with no further hospitalization for pulmonary edema.