Percutaneous edge-to-edge mitral valve repair using the MitraClip device has evolved as a new tool for the treatment of severe mitral valve regurgitation. This technique has been evaluated in surgical low- and high-risk patients. Patients with advanced age, multiple morbidities, and heart failure will be the first to be considered for a nonsurgical approach. Thus safety and feasibility data in very high-risk patients are crucial for clinical decision making. The aim of this study was to assess short-term safety and clinical efficacy in high-risk patients with a Society of Thoracic Surgeons (STS) score >15% after MitraClip implantation (mean STS score 24 ± 4%). All relevant complications, mortality, echocardiographic improvement, and changes in brain natriuretic peptide, high-sensitive troponin T, 6-minute walk distance test, and New York Heart Association functional class were collected in patients within 30 days after MitraClip implantation. Mitral regurgitation had significantly decreased after 30 days from grade 2.9 ± 0.2 to 1.7 ± 0.7 (p <0.0001). Accordingly, New York Heart Association functional class had significantly improved from 3.38 ± 0.59 to 2.2 ± 0.4 (p <0.001). Objective parameters of clinical improvement showed a significant increase in 6-minute walk distance test (from 194 ± 44 to 300 ± 70 m, p <0.01) and insignificant trends in brain natriuretic peptide (10,376 ± 1,996 vs 4,385 ± 1,266 ng/L, p = 0.06) and high-sensitive troponin T (43 ± 8.9 vs 36 ± 7.7 pg/L, p = 0.27) improvement. Thirty-day mortality was 0. Two patients developed a left atrial thrombus, 1 patient was on a ventilator for >12 hours, and 1 patient had significant access site bleeding. In conclusion, this study shows that percutaneous edge-to-edge mitral valve repair can be safely performed even in surgical high-risk patients with an STS score >15. At 1-month follow-up most patients showed persistent improvement in mitral regurgitation and a clinical benefit.
Percutaneous edge-to-edge mitral valve repair using the MitraClip device has evolved as a new tool for the treatment of severe mitral valve regurgitation. This technique has been evaluated in surgical low- and high-risk patients. Recently, the first randomized controlled study, the Endovascular Valve Edge-to-Edge Repair Study (EVEREST II), demonstrated superior safety compared to surgical mitral valve repair with inferior clinical efficacy but similar improvements in clinical outcomes. The EVEREST patient cohorts had low- or moderate-risk surgical profiles. However, patients with advanced age, multiple morbidities, and heart failure will be the first to be considered for nonsurgical techniques in the future. This need for nonsurgical options is reflected in the lack of high-risk patients in most large surgical controlled studies and in American and European guidelines regarding surgical mitral valve repair in patients with low ejection fraction. Thus safety and feasibility data in very high-risk patients are important. A few studies have already looked into feasibility and safety in patients with high surgical risks. The aim of this study was to go 1 step further in the risk profile of patients by assessing short-term safety and clinical efficacy in very high-risk patients with a Society of Thoracic Surgeons (STS) score >15% after MitraClip implantation including critically ill intensive care patients.
Methods
From October 2009 through January 2011, 51 consecutive patients were scheduled to be treated with MitraClip implantation at our institution. Of these 51 patients, 36 patients had an STS score >15% and were thus considered very high-risk patients for surgery. Thirty-three of the 36 patients in this high-risk group were successfully treated with 1 MitraClip or 2 MitraClips (92%). All patients had symptomatic severe mitral valve regurgitation and already had optimal medical therapy. Before MitraClip implantation all patients underwent heart catheterization to identify relevant coronary artery disease. Furthermore, patients underwent transthoracic and transesophageal echocardiography to quantify mitral valve regurgitation and to judge morphologic suitability for MitraClip implantation. Main exclusion criteria were morphologic properties of the mitral valve that would make MitraClip implantation impossible or unlikely, as published previously. All patients were informed about specific risks and alternatives and gave informed written consent to the MitraClip procedure and pre- and postinterventional monitoring (data collection). The study protocol was in accordance with the local ethics committee.
Transthoracic and transesophageal echocardiograms were obtained using commercially available ultrasound diagnostic systems (iE33, Philips Medical Systems, Andover, Massachusetts) by experienced investigators unaware of the study and according to current recommendations. Three cardiac cycles were stored in cine-loop format for off-line analysis. Off-line analysis of echocardiographic examinations were conducted on a commercial workstation (Centricity Cardiology CA1000 2.0, GE Medical Systems, Milwaukee, Wisconsin) by 2 independent expert investigators who were unaware of patients’ clinical status and were not involved in MitraClip implantation procedures. Because the prevalence of eccentric mitral regurgitation in the study population was high, the method of the proximal isovelocity surface area for grading mitral regurgitation was not employed. Instead, mitral regurgitation was graded in a semiquantitative manner with color Doppler and added to the assessment of the width of the vena contracta. This was similarly used for grading of mitral regurgitation after implantation.
The endovascular edge-to-edge mitral valve repair has been previously described. All procedures were performed using the 24Fr MitraClip device (Abbott Vascular, Santa Clara, California). All clips were implanted under general anesthesia and transesophageal echocardiographic control. Hemostasis was achieved by compression of the vein for 12 hours. Patients were transferred to our intensive care unit after the procedure (for ≥24 hours).
Before and 30 days after MitraClip implantation various parameters were collected including transesophageal echocardiographic assessment of mitral regurgitation, heart function and clip position, New York Heart Association (NYHA) functional class, N-terminal pro–brain natriuretic peptide and high-sensitive troponin T levels, and 6-minute walk distance test.
Continuous variables are expressed as mean ± SD when normal distribution is present or as median (twenty-fifth to seventy-fifth percentiles). Categorical variables are presented as absolute numbers and percentages. Normality was assessed with Kolmogorov–Smirnov test. Comparisons between groups were made using Student’s t test or Mann–Whitney U test as appropriate. A p value <0.05 was considered statistically significant.
Results
Patients’ baseline characteristics are presented in Table 1 . Thirty-three high-risk patients underwent successful implantation with 1 MitraClip (n = 24) or 2 MitraClips (n = 9). One patient refused to attend the follow-up examination 1 month after implantation. Patients’ average age was 76 ± 13 years. As required for this study all patients had an increased surgical mortality risk as assessed by the STS score (24 ± 4%) and the logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE; 41 ± 7%). Four patients were considered as critically ill because they had been in an intensive care unit for ≥3 weeks before MitraClip implantation. One patient was on a high urgency list for heart transplantation.
| Age (years) | 76 ± 13 |
| Men | 20 (61%) |
| Logistic European System for Cardiac Operative Risk Evaluation score (%) | 41 ± 7 |
| Society of Thoracic Surgeons score (%) | 24 ± 4 |
| Ejection fraction (%) | 39 ± 8 |
| In patients with functional mitral regurgitation (%) | 35 ± 9 |
| In patients with degenerative mitral regurgitation (%) | 42 ± 12 |
| Mitral regurgitation cause | |
| Functional | 21 (63%) |
| Degenerative | 12 (36%) |
| Mitral regurgitation severity | |
| Moderate to severe (2–3) | 4 (12%) |
| Severe (3) | 29 (88%) |
| New York Heart Association functional class | |
| III | 16 (49%) |
| III to IV | 9 (27%) |
| IV | 8 (24%) |
| Invasive systolic pulmonary artery pressure (mm Hg) | 59 ± 7 |
| Left ventricular end-diastolic diameter (mm) | 59 ± 12 |
| Left ventricular end-systolic diameter (mm) | 47 ± 9 |
| Left ventricular end-systolic diameter >55 mm | 7 (21%) |
| Left atrial diameter (mm) | 58 ± 11 |
| Vena contracta (mm) | 7 ± 1 |
| Previous coronary artery bypass grafting | 13 (39%) |
| Implantable cardioverter–defibrillator | 8 (24%) |
| Previous stroke | 5 (15%) |
| Chronic lung disease | 12 (36%) |
| Long-term dialysis | 4 (12%) |
| Creatinine (mg/dl) | 1.5 ± 0.25 |
| Atrial fibrillation | 26 (78%) |
In patients with an unsuccessful attempt of MitraClip implantation (n = 3), no complication was recorded. MitraClip implantation was unsuccessful in these patients because of an insignificant decrease of mitral regurgitation (n = 1), unsuccessful guide insertion in the left atrium (n = 1), or induction of relevant mitral stenosis (n = 1). In those 33 high-risk patients with successful implantation, 30-day mortality was 0. However, 1 patient died at day 31 because of low cardiac output and pneumonia (STS score 49%, EuroSCORE 63%). Two patients developed a left atrial thrombus, 1 patient was on a ventilator for >12 hours, and 1 patient had significant access site bleeding that required a blood transfusion of 2 U. Table 2 lists all complications.
| 30-day mortality | 0 (0%) |
| Significant access site bleeding | 1 (3%) |
| Ventilator >12 hours to <24 hours | 1 (3%) |
| Ventilator >24 hours | 0 (0%) |
| Left atrial thrombus | 2 (6%) |
| Stroke | 0 (0%) |
| Pericardial effusion or tamponade | 0 (0%) |
| Esophageal bleeding | 0 (0%) |
| Myocardial infarction | 0 (0%) |
| Postoperative delirium | 1 (3%) |
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