Significant Mortality Benefits of Mechanical Valves

MECHANICAL valves have very good long-term mortality benefits and should be used more often, particularly in younger patients who require mitral-valve replacements, according to a study conducted at the Stanford School of Medicine, Stanford University, Stanford, California, USA. The findings have the potential to alter current guidance for physicians along with the advice given to patients.

Over 50,000 people in the USA undergo aortic or mitral valve surgery each year to replace diseased valves. National guidelines from the American Heart Association (AHA) and American College of Cardiology (ACC) state that patients between the ages of 50 and 70 should have the choice of either a mechanical or biological valve. For patients below the age of 50, a mechanical valve is recommended, and in patients over 70 years of age, a biological valve is suggested. Mechanical valves can last a lifetime as opposed to biological valves, which wear out within 10–15 years. However, younger patients often choose a biological valve because of the associated risks of a mechanical valve, including bleeding and blood clotting, and, as a result, the need to take the blood-thinning drug, warfarin.

In the study, mortality, stroke, bleeding, and reoperation rates of 25,445 patients were observed; the largest number of patients ever studied on the topic. The study included 9,942 patients who had aortic-valve replacement, and 15,503 who underwent mitral-valve replacement. These data were taken from 142 hospitals in California between 1996 and 2013.

It was found that there was a long-term mortality benefit associated with mechanical valves, until the age of 70, in patients who undergo mitral-valve replacements, although this benefit was only seen in patients who underwent surgery before they were 55 years old in the case of aortic valve replacement. The results suggest that younger patients in particular should undergo mechanical valve replacements opposed to biological valves. This is important data to share in order to enlighten the large numbers of such patients who are reluctant to receive a mechanical valve replacement.

“For most heart surgeons who have to face this conversation every single day, this choice is very much on our minds,” commented the study’s senior author, Prof Joseph Woo, Chair of Cardiothoracic Surgery, Stanford University. “For many heart surgeons throughout the country and beyond, this study could have a major impact.”

The researchers believe this study could change the current clinical guidelines on the matter, which are based on small studies of valves that are now obsolete.

James Coker, Senior Editorial Assistant

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