Author + information
- Holger Eggebrecht, MD∗ (, )
- Rajendra H. Mehta, MD, MS,
- Edith Lubos, MD,
- Peter Boekstegers, MD,
- Joachim Schofer, MD,
- Horst Sievert, MD,
- Taoufik Ouarrak,
- Jochen Senges, MD,
- Wolfgang Schillinger, MD and
- Axel Schmermund, MD
- ↵∗Cardioangiological Center Bethanien, Im Prüfling 23, 60389 Frankfurt, Germany
Previous studies have suggested lower rates of operative mortality for elderly patients >65 years of age undergoing mitral valve surgery in hospitals with higher annual volumes and increasing repair rates (1). Transcatheter mitral valve repair using the MitraClip (Abbott Vascular, Santa Clara, California) has recently become an option for elderly patients with mitral regurgitation (MR) deemed inoperable or at high risk for conventional surgery (2). So far, no data exist on potential volume-outcome relationship with MitraClip therapy.
We analyzed data from 828 patients prospectively enrolled into the German multicenter TRAMI (TRAnscatheter Mitral valve Interventions) registry undergoing MitraClip implantation August 2010 and August 2013. The TRAMI registry has been described previously (3). For the present analysis participating hospitals were divided into 2 groups: the 3 top-enrolling centers performed 433 MitraClip procedures (annual procedure number 48.1 ± 13.5, range 32 to 78) during the study period and were considered “high-volume” hospitals. The remaining 395 (48%) patients underwent MitraClip implantation in 18 “low-volume” hospitals (annual procedure number 7.7 ± 10.0, range 1 to 37). Analyses were conducted using SAS statistical package version 9.3 (SAS Institute, Cary, North Carolina).
Patients undergoing MitraClip implantation in high- and low-volume centers were comparable with respect to age and risk scores (Table 1). The majority of patients (overall 70.2%) underwent the procedure for functional MR. However, in low-volume centers the proportion of patients with mitral valve prolapse was higher (Table 1). Although a minority in both groups, patients with acute cardiogenic shock were more frequent in high-volume centers (23 of 431 [5.3%] vs. 6 of 367 [1.6%]; p = 0.005).
Procedure (113.3 ± 58.4 min vs. 95.3 ± 49.2 min; p < 0.001) and fluoroscopy times (28.3 ± 20.3 min vs. 30.0 ± 83.3 min; p < 0.001) were significantly shorter in high-volume centers. Hospital stay was also shorter at high-volume centers (median 9.0 days [interquartile range (IQR): 6.0 to 15.0 days] vs. 8.0 days [IQR: 6.0 to 13.0 days]; p < 0.001). At discharge, rates of residual moderate (16.0% vs. 28.4%) or severe (2.0% vs. 6.5%) MR were lower in high-volume centers (p < 0.001). In-hospital complications and mortality rates, and rehospitalization for heart failure, need for post-procedural mitral valve surgery, and mortality at 1 year were similar in the 2 groups with better functional New York Heart Association functional class at 1 year among patients at high-volume centers (Table 1). Quality of life as measured by the EQ-5D-3L questionnaire and self-rated health status by the EQ visual analogue scale was similar in high- and low-volume centers (EQol-D5-3L score: 0.9 [IQR: 0.7 to 0.9] vs. 0.8 [IQR: 0.7 to 0.9]; p = 0.42; EQ visual analogue scale: 60 [IQR: 50 to 70] vs. 55 [IQR: 50 to 70]).
For patients undergoing MitraClip implantation for functional MR (70.2% of the overall cohort), procedure times were again shorter and residual MR at discharge was less in high-volume hospitals (Table 2). Yet similar to the overall cohort, rates of in-hospital complications as well as short-term and midterm mortality were not different between high- and low-volume centers.
The present analysis is the first to evaluate volume-outcome relationship in 828 “real-world” MitraClip patients and suggested better efficiency (shorter procedure times) and higher procedural success (lower rates of post-procedural moderate or severe MR) as well as shorter hospital stays in high-volume centers, likely as a result of better practical experience with the procedure (4). Despite these differences, the acute and midterm outcomes of patients undergoing MitraClip implantation at high-volume centers were not different from those patients treated at low(er)-volume centers. This is in contrast to that reported for patients undergoing surgical mitral valve repair, where higher hospital volume was associated with better outcomes (1). Nevertheless, the lower rates of relevant post-procedural MR were associated with better functional New York Heart Association functional class at 1 year, although patients’ quality of life was not different between high- and low-volume centers.
Finally, our analyses indicated that MitraClip therapy appears to be safe with procedural mortality rates in the lower single-digit numbers even in the high-risk patients undergoing this procedure at both high- and low-volume centers. It is possible that the modest sample size of the present analysis together with small number of events might have lacked the statistical power to detect relevant differences in acute outcomes between high- and low-volume centers. Midterm outcomes appeared to be largely related to the underlying comorbid conditions and the disease as mirrored by high rates of rehospitalizations (66%) within 1 year in both groups. Our data suggest that more research in larger cohorts with extended follow-up are needed before making policy implications.
Our analysis was limited by its observational character. Centers were arbitrarily differentiated into high- and low-volume centers based on the number of patients enrolled into the registry. Level of training, efficiency of the heart team, and variability of intraprocedural imaging could not be evaluated in this study.
Please note: The TRAMI registry has been supported by the IHF (Stiftung Institut für Herzinfarktforschung) and an unrestricted grant of Abbott Vascular (Germany) and Deutsche Herzstiftung. Dr. Lubos has received speaker honoraria, research funding, and travel compensation from Abbott Vascular. Dr. Boekstegers has served as proctor for Abbott Vascular. Dr. Sievert has received study honoraria, travel expenses, consulting fees from: 4tech Cardio, Abbott, Ablative Solutions, Ancona Heart, Bavaria Medizin Technologie GmbH, Bioventrix, Boston Scientific, Carag, Cardiac Dimensions, Celonova, Cibiem, CGuard, Comed B.V., Contego, CVRx, Edwards Lifesciences, Hemoteq, InspireMD, Kona Medical, Lifetech, Maquet Getinge Group, Medtronic, Occlutech, pfm Medical, Recor, St. Jude Medical, Terumo, Trivascular, Vascular Dynamics, Venus, and Veryan. Dr. Schillinger has received lecture and proctor fees as well as travel expenses from Abbott Vascular. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation