By Jeffrey Zimmet, MD, PhD
Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center
SYNOPSIS: The authors of an analysis of more than 31,000 patients from the Society of Thoracic Surgeons’ database identified patients undergoing surgical aortic valve replacement (SAVR) after prior transcutaneous AVR (TAVR) or SAVR. SAVR after TAVR raised the risk of mortality vs. SAVR after SAVR.
SOURCE: Hawkins RB, Deeb GM, Sukul D, et al. Redo surgical aortic valve replacement after prior transcatheter versus surgical aortic valve replacement. JACC Cardiovasc Interv 2023;16:942-953.
Transcatheter aortic valve replacement (TAVR) initially was approved only for patients who were at high or prohibitive risk for valve surgery. Those restrictions are no longer in place, and the largest growth in the TAVR population is among patients at low surgical risk. One of the side effects of this change is that a significant and growing proportion of patients undergoing TAVR procedures can be expected to outlive the lifespan of their valves.
Concurrently, we have come to recognize a significant proportion of TAVR patients are unsuitable for a second TAVR procedure. This is partly because of the relatively high implant depth that is targeted to avoid heart block and permanent pacing and the insufficient valve-to-coronary distance that results. While redo surgical AVR (SAVR) is performed routinely on prior SAVR patients, with acceptable morbidity and mortality rates, the results of TAVR explant and SAVR have been less well studied.
Hawkins et al used the Society of Thoracic Surgeons’ (STS) national database to identify patients undergoing redo SAVR. Of the 31,106 patients who fit this description, 29,306 had undergone a prior SAVR (SAVR-SAVR), 1,126 had undergone a prior TAVR (TAVR-SAVR), and 674 had undergone a prior SAVR and TAVR (SAVR-TAVR-SAVR). As expected, in the decade between 2011 and 2021, there was a significant increase in redo SAVR cases in each category.
Compared with the SAVR-SAVR group, patients in the TAVR-SAVR groups were older and were living with a greater burden of comorbid disease. The TAVR-SAVR group was the oldest (median age = 74 years), followed by the SAVR-TAVR-SAVR group (median age = 71 years), and the SAVR-SAVR patients (median age = 67 years; P < 0.0001). TAVR-SAVR surgeries were less likely to be elective, and those patients recorded higher rates of prior coronary artery bypass grafting or aortic or mitral surgery. Unadjusted operative mortality was correspondingly highest in the TAVR-SAVR group (17%) vs. 12% for SAVR-TAVR-SAVR patients and 9% for SAVR-SAVR patients (P < 0.0001). Interpretation of these data were complicated by the frequent requirement for complex surgery. For example, unplanned mitral surgery was performed in 25% of TAVR-SAVR patients, and in only 19% of SAVR-SAVR patients.
Therefore, the authors performed a separate analysis for isolated redo SAVR procedures, yielding 531 TAVR-SAVR patients and 11,531 SAVR-SAVR patients. In this analysis, perioperative mortality was three times higher for TAVR-SAVR vs. SAVR-SAVR patients (15% vs. 5%; P < 0.0001). After propensity score matching, operative morality remained higher for the TAVR-SAVR patients vs. the SAVR-SAVR group (11.3% vs. 6.7%; P = 0.02, correlating to an odds ratio of 1.7). Despite overall shorter median cardiopulmonary bypass and aortic cross-clamp times, the TAVR-SAVR patients also recorded higher rates of failure-to-rescue and renal failure, stayed longer in the ICU, and were less likely to be discharged home.
The authors concluded SAVR after TAVR is increasing in frequency and is an independent risk factor for mortality. They made the case for considering SAVR as a first intervention for patients whose life expectancy is expected to exceed that of a TAVR valve.
COMMENTARY
For most of the history of TAVR as a generally available procedure, TAVR has been applied to older, sicker patients for whom the valve itself is likely to outlast the patient’s life expectancy. In this context, the choice between TAVR and SAVR has focused primarily on the risks of the initial procedure. As TAVR has expanded to lower-risk and younger patients, this calculus has begun to change. The data presented here suggest SAVR after TAVR — TAVR explant followed by surgical valve replacement — is a relatively complex endeavor, with higher risks of major complications. Therefore, for patients whose expected lifespan exceeds the estimated durability of a valve prosthesis, heart teams must look beyond the initial procedure to consider the lifetime management of the aortic valve for those patients.
In most cases, we should look to the feasibility of valve-in-valve TAVR as a second procedure. SAVR as an initial intervention should be performed in patients with anatomy that is projected to be unsuitable for redo TAVR. The CT scan conducted for TAVR planning can show those patients with small aortic roots, effaced sinuses, and low coronary takeoffs that make coronary obstruction and sinus sequestration likely in a second TAVR procedure. Surgeons also should be mindful of the specific bioprostheses they implant and avoid those types (i.e., stentless valves, externally mounted leaflets) that are less amenable to downstream TAVR-in-SAVR procedures.
The authors of an analysis of more than 31,000 patients from the Society of Thoracic Surgeons’ database identified patients undergoing surgical aortic valve replacement (SAVR) after prior transcutaneous AVR (TAVR) or SAVR. SAVR after TAVR raised the risk of mortality vs. SAVR after SAVR.
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