Isolated mitral valve surgery risk in 77,836 patients from the Society of Thoracic Surgeons database

Background: Understanding the operative outcomes of mitral valve (MV) surgery across the spectrum of predicted risk of mortality (PROM) is necessary to determine the best use of novel percutaneous approaches.

Methods: The Society of Thoracic Surgeons Adult Cardiac Surgery Database was utilized to study isolated MV operations during two time periods: era 1 (2002 to 2006, n = 37,743) and era 2 (2007 to 2010, n = 40,093). In each era, four PROM groups were defined: low risk (PROM 0% to <4%); intermediate risk (PROM 4% to <8%); high risk (PROM 8% to <12%); and extreme risk (PROM ≥ 12%). In each risk group, mortality rates and observed to expected mortality ratios were compared across eras.

Results: A total of 63,645 cases (82%) were classified as low risk, 8,032 (10%) as intermediate risk, 2,765 (4%) as high risk, and 3,394 (4%) as extreme risk. Sixty-seven percent of MV repairs (n = 30,488) and 18% of MV replacements (n = 5,749) had a PROM less than 1%. PROM less than 4% was seen for 93% of MV repairs (n = 42,196) and 66% of replacements (n = 21,449). Across the two eras, the MV repair rate increased from 54.8% to 61.8% (p = 0.0017); and a significant reduction in operative mortality was observed in high risk and extreme risk cohorts (p < 0.05).

Conclusions: The frequency with which MV repair for isolated MV disease is performed has increased over time and is associated with very low early mortality. A significant reduction in mortality among patients at highest risk has occurred, and must be considered as patients are evaluated for percutaneous therapies.