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Percutaneous Mitral Annuloplasty for Functional Mitral Regurgitation in Heart Failure
Abstract & Commentary
By Andrew J. Boyle, MBBS, PhD
Source: Schofer J, et al. Percutaneous mitral annuloplasty for functional mitral regurgitation. Results of the CARILLON Mitral Annuloplasty Device European Union Study (AMADEUS). Circulation. 2009;120:326-333.
Functional mitral regurgitation (FMR), occurring in heart failure, portends an adverse prognosis. There is no medical therapy for FMR, and surgery to correct FMR with mitral annuloplasty, mitral valve repair, or mitral valve replacement carries significant morbidity and mortality risk. Recently, percutaneous therapies for FMR have begun to appear in clinical trials, but none have been approved by the FDA for clinical use. Such approaches include percutaneous valve repair using devices or sutures to form a double-lumen mitral orifice, left-ventricular restraining techniques to reduce LV dilatation and, therefore, FMR, and annuloplasty devices to reduce mitral annular dimensions. Schofer et al present their first human experience using a cinching device in the coronary sinus to reduce the mitral annular dimensions and, thereby, reduce MR.
They enrolled 48 patients with heart failure class II-IV due to dilated ischemic or non-ischemic cardiomyopathy, moderate-to-severe FMR, six-minute walk distance 150-450 m, left ventricular (LV) ejection fraction (EF) < 40%, LV end-diastolic diameter > 55 mm, age over 18 years, and on a stable heart failure regimen with angiotensin converting enzyme inhibitor (or receptor blocker) and beta-blocker. Exclusion criteria included hospitalization in the preceding three months for myocardial infarction (MI) or unstable angina, recent percutaneous coronary intervention, prior coronary artery bypass surgery, requirement for cardiac surgery, pacing lead in the coronary sinus, significant leaflet pathology (such as moderate or severe myxomatous degeneration or rheumatic disease), severe mitral annular calcification (MAC), renal impairment with serum creatinine > 2.2 mg/dL, severe tricuspid regurgitation, and chronic atrial fibrillation. This was a prospective, single-arm study with no control group. Under general anesthesia, using trans-esophageal echo and angiographic guidance, the CARILLON device was implanted in the coronary sinus. A distal anchor was deployed and then, under tension to reduce the annular dimension, a more proximal anchor was deployed. Because the circumflex coronary artery runs close to the coronary sinus, circumflex coronary artery occlusion was avoided using intraprocedural coronary angiography. Echocardiographic variables were analyzed by a core laboratory, and included quantitative and semi-quantitative measures of FMR (vena contracta, effective regurgitant orifice, regurgitant volume, and FMR jet area to left atrial area). The primary outcomes were safety and feasibility of device implantation.
Of the 48 patients enrolled, 30 received the device. Of the remaining 18 patients who did not have the device implanted, no device implant was attempted in five (complications during coronary sinus access in three and screen failure in two) and the device was recaptured and removed in 13 (due to inadequate distal anchoring in three, and inadequate FMR reduction or circumflex artery compromise in the others). During the course of the trial, the device was modified to improve the distal anchor and the technique was modified to deploy the distal anchor more distally. Six patients (13%) experienced seven complications (one death, three MI, three coronary dissection/perforations). There was significant improvement in all parameters of mitral regurgitation, ranging from 22% to 32% reduction (p < 0.001 for all) at six-month follow-up echocardiography. In addition, mitral annular diameter reduced from 4.2 ± 0.4 vs. 3.8 ± 0.4 cm (p < 0.001). However, no change was seen in LV systolic or diastolic diameters or LVEF. NYHA class improved from 2.9 to 1.8 (p < 0.001) and the six-minute walk distance improved from 307 ± 87 to 401 ± 137 m (p < 0.001). The Kansas City Cardiomyopathy Questionnaire Overall Summary Score improved from 47 to 69. The authors conclude that percutaneous placement of the CARILLON mitral annuloplasty device in the coronary sinus has the potential to safely and significantly treat FMR in patients with heart failure, with resultant symptomatic benefit. Further studies are required to define the long-term efficacy of this therapy, the optimal timing for intervention and the effects on survival.
Percutaneous device therapy to reduce functional mitral regurgitation would be a welcome addition to the medical armamentarium to treat heart failure. The current study is interesting, and provides preliminary data to suggest that coronary sinus access for mitral annuloplasty may be safe and feasible. The early complications were markedly reduced later in the study with both device and procedural modifications. Importantly, there were no late sequelae attributable to coronary venous congestion. This is a preliminary study that is hampered by a lack of control group and, thus, any efficacy outcomes should be interpreted with caution. It would seem reasonable that reduction in FMR would translate into symptomatic improvement and, perhaps, even reduction in clinical events, but this remains to be tested in future randomized, controlled studies. Schofer et al present provocative, yet very preliminary, data, suggesting that, in the future, there may be interventional approaches to improve FMR.