By Michael H. Crawford, MD, Editor
SYNOPSIS: A contemporary update of the Society of Thoracic Surgeons risk calculator for operative mortality and morbidity in nonemergent primary mitral valve repair for regurgitation shows an operative mortality rate of 1.2%, with a conversion to replacement of 6%, in more than 53,000 patients.
SOURCE: Badhwar V, Chikwe J, Gillinov AM, et al. Risk of surgical mitral valve repair for primary mitral regurgitation. J Am Coll Cardiol 2023; Jan 10:S0735-1097(22)07418-6. doi: 10.1016/j.jacc.2022.11.017. [Online ahead of print].
The Society of Thoracic Surgeons (STS) Adult Cardiac Surgical Database mitral valve (MV) repair risk model includes the spectrum of MV disease etiologies. These are based on operative data collected from 2011 to 2016. A risk assessment model for patients with degenerative lesions of the MV leading to primary MV regurgitation (MVR) would be of value to heart teams weighing the risk of current MV surgical repair, edge-to-edge percutaneous repair, and primary replacement. Also, the STS risk model for MV repair does not include conversion to replacement.
Badhwar et al examined a contemporary national registry from the STS database (data collected from 2014 to 2020) with complete information on all these details to assess the outcomes and risks of MV repair for primary MVR and to develop a new risk model for clinical use. The patient population included nonemergent, isolated MV repair, which could include one other procedure, such as left atrial appendage obliteration, ablation of atrial fibrillation, closure of an atrial septal defect, or tricuspid valve repair, but excluded any other cardiac or noncardiac surgery. This algorithm resulted in 53,462 patients out of 251,229 MV surgeries performed by 2,404 surgeons. The primary outcome was operative mortality (30 days). Secondary outcomes were a composite of mortality and any other major complication or conversion to replacement. Patients from hospitals with less than one MV repair per year were excluded.
The rate of the outcomes studied were low. Operative mortality was 1.2%, mortality plus major morbidity was 8.9%, and conversion to replacement was 6.4%. Mortality was associated with older age; female sex; and higher burdens of comorbid disease, heart failure, and severe tricuspid regurgitation (P < 0.001). Also, higher institutional case volume rates were associated with lower rates of operative mortality and morbidity. Centers with volumes exceeding 50 cases per year recorded a mortality rate of 0.6% and a replacement conversion rate of 2.1%. The case volume associated with an operative mortality rate less than 1% was 25 cases per year. Notably, the mortality risk model area under the curve was 0.81. The authors concluded a contemporary etiology- and procedure-specific risk model demonstrates the mortality rate of MV repair for primary MVR is less than 1% for most patients.
COMMENTARY
Before the development of transcutaneous MV edge-to-edge repair (TEER) devices, such as the MitraClip, surgical repair of the MV for primary MVR was and still may be the gold standard. TEER was FDA-approved for patients with elevated surgical risk; however, no one wants to undergo surgery if they can avoid it. Consequently, there has been a competition between interventional cardiologists and thoracic surgeons over the repair of primary MVR, especially in younger patients with low surgical risk. However, the estimation of surgical risk by the most frequently used method, the STS risk calculator, is believed to be at a disadvantage because the data used to derive the algorithm is older than the contemporary data on TEER. Thus, this was impetus to develop an updated STS risk calculator.
The results of the Badhwar et al study are impressive. The operative mortality risk was less than 2% for almost all the 53,462 nonemergent primary MVR patients in the STS database between 2014 and 2020. Also, 60% of the 881 hospitals and 81% of the 2,404 surgeons exhibited a zero operative mortality rate over the full six years of the study. Using the new risk calculator, the expected operative mortality rate will be less than 1% for more than two-thirds of patients. Remarkably, surgeons managed to repair 94% of valves. When conversion to replacement was required, the authors noted a lower operative mortality rate in busier centers. Even in hospitals with double the observed mean conversion rate (12%), the observed operative mortality rate was 2%.
Badhwar et al suggested that using TEER in younger patients with low estimated operative risks is not justified currently. They recommended restricting the procedure to those at prohibitively high surgical risk.
Despite the impressive results, there were some limitations worth considering. The STS risk calculator depends on the accuracy of the data entered at each center. In addition, the authors did not include specific echocardiographic data that could help heart valve teams in decision-making. Finally, the follow-up was limited to 30 days. Nevertheless, this updated information will be of value to patients making decisions about whether to undergo MV repair. However, they also are interested in recovery times, which the authors did not address in this study.
A contemporary update of the Society of Thoracic Surgeons risk calculator for operative mortality and morbidity in nonemergent primary mitral valve repair for regurgitation shows an operative mortality rate of 1.2%, with a conversion to replacement of 6%, in more than 53,000 patients.
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