Tissue Versus Mechanical Aortic Valves in Young Patients: Further Evidence from Large Retrospective Studies

Over the past several years, there has been significant attention on optimal aortic valve choice among patients between the ages of 50–65. Current national guidelines note that uncertainty regarding optimal valve choice exists within this age group.

Concurrently, there has been a national trend toward more tissue valves in younger patients, driven, in part, by patient preferences against warfarin and the potential for valve-in-valve transcatheter aortic valve replacement (TAVR).

As valve choice is largely an individualized decision between the patient and surgeon, the majority of data on this topic have been through retrospective analyses rather than randomized trials. This year at the 98th American Association for Thoracic Surgery (AATS) Annual Meeting, two more large retrospective studies added further data to this topic.

My colleagues from the Northern New England Cardiovascular Disease Study Group and I had examined long-term outcomes among tissue versus mechanical aortic valves in patients aged 50–65 across 7 hospitals in New Hampshire, Vermont, and Maine from 1991 to 2015. At the conference, Dr. Bruce J Leavitt of the University of Vermont Medical Center presented the analysis that included 1,629 patients undergoing aortic valve replacement (AVR), which included 980 tissue (tAVR) and 649 mechanical aortic valve (mAVR) patients. The authors demonstrated a significant regional shift in ratio of tAVR to mAVR of 0.52 in the first half of the series to 3.87 in the later half of the series. There was no significant difference in long-term survival between groups, but an expected higher rate of aortic valve re-operations among tAVR patients. Moreover, the authors demonstrated no difference between groups in 30-day mortality or in-hospital morbidity. The authors concluded that, consistent with current guidelines, either valve choice is reasonable in patients aged 50–65 years and should be an individualized decision.

Dr. Tamar Attia and colleagues from the Cleveland Clinic similarly examined long-term outcomes with tissue versus mechanical aortic valves and presented research at the conferences. The study duration was from 1990 to 2017 and included 5,836 patients. After conducting a propensity match, there were a total of 497 matched pairs with a mean age of 55 years in the mAVR group and 54 years in the tAVR group. The authors demonstrated no difference in in-hospital morbidity or mortality between groups. Moreover, there was no significant difference between groups in long-term survival with a higher frequency of aortic valve re-operation in tAVR patients. Importantly, however, the authors demonstrated no difference in survival among patients who did require re-operations. Similar to findings from the Northern New England Cardiovascular Disease Study Group, the authors concluded that among younger patients both mechanical and tissue aortic valves are reasonable options.

These two presentations at AATS 2018 follow two other large, statewide registry studies on outcomes with tissue versus mechanical valves. In a 2014 study, Chiang and colleagues examined survival and major morbidity among patients aged 50–69 years-old undergoing AVR in New York state from 1997 to 2004. The analysis included 1001 propensity-matched patients. The authors demonstrated that there was no significant difference in 15-year survival or stroke between groups. Additionally, the authors showed that patients receiving tissues valves had a lower risk of major bleeding but a higher risk of re-operations.

Next, this past year Goldstone and colleagues examined tissue versus mechanical aortic valves in the state of California from 1996 to 2013. The authors found that among patients 45–54 years-old, there was a survival advantage associated with mAVR, however, the difference was not significant among patients aged 55–64 years-old. The survival advantage associated with mAVR persisted until age 53. In addition, there was a significantly lower risk of bleeding and stroke associated with tAVR as well as a higher risk of re-operation.

The two large retrospective studies presented at AATS 2018 by the Northern New England Cardiovascular Disease Study Group and the Cleveland Clinic support the previous two statewide registry studies that showed equivalent long-term survival among tissue versus mechanical aortic valve replacement patients. Taken as a whole, these data support current national guidelines that recommend an individualized approach toward valve choice in young patients over 50 years of age. As national trends continue toward more tissue aortic valves in this younger patient population, further longitudinal survival analysis will be needed as well as a detailed examination of long-term outcomes with valve-in-valve TAVR.

Dr. Alexander Irabarne is a board-certified thoracic surgeon at the Heart & Vascular Center at Dartmouth-Hitchcock Medical Center.

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