Shift From Mechanical to Bioprosthetic Aortic Valves in Middle-Aged Patients Gets Boost in Analysis

The tide is turning in the field of surgical aortic valve replacement (AVR), with bioprosthetic devices increasingly being seen as an alternative to mechanical valves in middle-aged patients. That shift appears to be justified, according to a meta-analysis published this week in the Annals of Thoracic Surgery.

Culling 15-year follow-up data on nearly 8,500 patients from 13 studies comparing mechanical and bioprosthetic valves in patients aged 40 to 70 years, Paul G. Bannon, MBBS, PhD, of the Baird Institute of Applied Heart and Lung Surgical Research (Newtown, Australia), conclude that their systematic review supports the “current trend.” 

Isaac George, MD, of Columbia University Medical Center (New York, NY), told TCTMD in an email that, today, “most patients now come to the office asking for bioprosthetic valves—they are informed, educated, and actually know much more nuances than patients of the older generation. This is largely in part due to the wide range of access to up-to-date medical information: the Internet, blogs, TV, media.” Patients also arrive with the idea that a valve-in-valve (ViV) procedure using a TAVR device will be an option were they to need a second intervention, he added.

Some Differences Seen Between Device Types

The meta-analysis found similar survival, freedom from stroke, and freedom from endocarditis between the 2 device types. As a whole, patients with mechanical valves were less likely to need reoperation but also tended to have more thromboembolic events and major bleeding over the 15 years after treatment.

“Traditionally surgeons felt that tissue valves should be offered only to those over 70 to avoid the need for and risk of reoperation,” Bannon told TCTMD in an email. “As new evidence for valve durability and reoperative risk appeared, however, the guidelines reflected this and the current recommendation is for consideration of a tissue valve after age 65. We now find that this consideration should be lowered to those from [age] 60, so it is true that practice has changed.”

Moreover, another important driver is that surgical AVR has become so low risk that, even in the case of reoperation, the mortality rate is less than 10%. This risk, he explained, “is less than the reported mortality from major bleeding complicating anticoagulation for mechanical valves. Patients aged 60-70 may therefore choose to accept the possibility of reoperation rather than the risk of bleeding and lifestyle limitations from anticoagulation. The simple reality we face is that increasingly patients just do not want to take warfarin, if an acceptable alternative is present.”

George agreed that the main reason for choosing a bioprosthetic valve is being able to avoid warfarin and the drug’s “deleterious effects on an active patient’s lifestyle,” specifically its potential to increase bleeding in younger patients and raise the risk of thromboembolism in older patients. “Compliance, hassle, or inability to tolerate anticoagulation are important other reasons to avoid a mechanical valve,” he noted.

Additionally, Bannon said, “the advent of minimal-access surgical AVR is expected to further reduce the risk of reoperation due to reduced pericardial adhesions and a lower risk from redo sternotomy.”

Valve-in-Valve an Option for Many But Not All

While ViV may be a way to deal with the increased need for reoperation in bioprosthetic valves, something to keep in mind is that the repeat implants “must progressively limit the available valve area, with important effects on hemodynamics in active younger patients and over a greater duration of implant,” Bannon noted.

According to George, patients’ assumption that ViV is an option for everyone is “often carte blanche reaffirmed by non-TAVR physicians erroneously who may not take into account valve, size, hemodynamics, or other anatomy that may make a TAVR ViV high risk. Nonetheless, ViV as a first-line second intervention to delay or prevent repeat sternotomy in tissue valves is a rational and widely used justification.”

Depending on the particular circumstances, bioprosthetic and mechanical valves are “both good options,” George confirmed. “The physician should present an unbiased view and allow the patient to decide, based on patient priorities of quality of life, compliance, fear of reoperation, and durability. Physicians should be able to screen patients or refer to a TAVR specialist who can evaluate for possible ViV. These implications for treatment early in the course of valvular disease will ultimately dictate the course of the patient’s life for 5, 10, and 20 years.”

Ultimately, Bannon advised, the choice between valves depends on the skills and results of the particular surgeon and should be made “with up-to-date information, and ideally between the patient and both their cardiologist and surgeon so that the patient may be fully informed.”

Source:
Wu JJ, Seco M, Edelman JB, et al. Mechanical versus bioprosthetic aortic valve replacement in patients aged 40 to 70 years: a systematic review and meta-analysis. Ann Thorac Surg. 2016;Epub ahead of print.

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