Mitral Repair Rates and Mortality vs. Hospital Volume | Journal Scan

Study Questions:

Is hospital volume associated with rates of mitral valve repair and mortality after mitral valve surgery in an elderly population?


Using Medicare Provider Analysis and Review (MEDPAR) and corresponding Beneficiary Annual Summary Files (BASF), all Medicare beneficiaries aged ≥65 years who underwent mitral valve repair or replacement from 2000 through 2009 were considered for inclusion. Patients with significant concomitant procedures or other nonvalvular procedures were excluded, as were patients with <12 months of Medicare Part A and Part B coverage in the year preceding their index admission, and patients with emergency admissions. The Vital Status file for February 2012 was used to calculate long-term survival.


Of 1,239 hospitals performing mitral valve surgery on Medicare beneficiaries from 2000 through 2009, only 9% of hospitals performed >40 mitral operations per year, 29% performed ≤5, and 51% performed ≤10. Mitral repair rates were low: 22.7% of hospitals performed ≤1, 65.1% performed ≤5, and only 5.6% performed >20 mitral repairs per year in those aged ≥65 years. Repair rates increased with increasing volume of mitral operations per year: ≤5, 30.5%; 6-10, 32.9%; 11-20, 34.9%; 21-40, 38.8%; and >40, 42.0% (p = 0.0001). Hospitals with lower volume had significantly higher adjusted operative mortality compared with hospitals performing >40 cases per year: ≤5 cases per year, odds ratio (OR) 1.58 (95% confidence interval [CI], 1.40-1.78); 6-10 cases per year, OR 1.29 (95% CI, 1.17-1.43); 11-20 cases per year, OR 1.17 (95% CI, 1.07-1.28); 21-40 cases per year, OR 1.15 (95% CI, 1.05-1.26). Hospitals with lower mitral repair rates had an increased likelihood of operative mortality relative to the top quartile: lowest quartile, OR 1.31 (95% CI, 1.20-1.44); second quartile, OR 1.18 (95% CI, 1.09-1.29); and third quartile, OR 1.14 (95% CI, 1.05-1.24). Long-term mortality beyond 6 months was also higher in low-volume hospitals: ≤5 cases year, hazard ratio 1.11 (95% CI, 1.06-1.18); 6-10 cases per year, OR 1.06 (95% CI, 1.02-1.10) compared with hospitals performing >40 cases per year.


Most hospitals perform few mitral valve operations on elderly patients. Greater volume of mitral procedures was associated with higher repair rates. Both greater volume of mitral procedures and increasing mitral repair rates were associated with decreased mortality.


This is not the first study that demonstrates a relationship between mitral surgical volume and rates of mitral valve repair (see also Bolling SF, et al. Ann Thorac Surg 2010;90:1904-12; Kilic A, et al. J Thorac Cardiovasc Surg 2013;146:638-46; and Weiner MM, et al. J Thorac Cardiovasc Surg 2014;148:2021-6). As with some earlier studies, this study also shows an affect between volume and mortality: higher mitral surgical volume and higher rates of mitral repair both were associated with decreased mortality rates. These data give further weight to the current American Heart Association/American College of Cardiology guideline recommendations that many patients with heart valve disease are best served in a Center of Excellence.

Clinical Topics: Cardiac Surgery, Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Cardiac Surgery and VHD, Interventions and Structural Heart Disease

Keywords: Aged, Cardiac Surgical Procedures, Heart Valve Diseases, Hospitals, Low-Volume, Hospitals, Medicare, Mitral Valve, Mitral Valve Annuloplasty, Mortality, Probability

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