A multinational study led by researchers at Stanford Medicine has found that the risks of major complications after stenting or bypass surgery are similar, even several years out.

The risk of death and stroke were the same whether patients received bypass surgery or stenting, and the risk of heart attack was only slightly higher after a stenting procedure. Most prior research comparing the two procedures has suggested that bypass surgeries had better outcomes.

The new results likely reflect advances in medical technology and practices, the study authors say. They provide an important resource for patients and physicians evaluating the best options for patients who need a procedure to restore adequate blood flow through the heart.

“Overall, the difference in outcomes has narrowed dramatically between stenting and bypass surgery,” said William Fearon, MD, professor of cardiovascular medicine and principal investigator of the trial. “This is the first study to consider contemporary approaches when comparing the two procedures, and it gives us a big, much-needed update.”

The study involved 48 sites and included hundreds of patients tracked over five years. The results were published last month in The Lancet. Fearon shares lead authorship with Frederick Zimmermann, MD, of Catharina Hospital in the Netherlands. Nico Pijls, MD, PhD, of Catharina Hospital was the paper’s senior author.

Shifting outcomes

During bypass surgery, doctors create an entirely new pathway for blood flow in the heart using a blood vessel taken from another part of the patient’s body. This new pathway “bypasses” blocked or narrowed arteries that, without intervention, prevent blood from circulating properly and can cause a heart attack or other complications. Stenting involves re-widening existing pathways by inserting expandable mesh tubes into blocked arteries. In severe cases, patients often receive multiple stents.

A bypass is a major surgery, requiring cutting through a patient’s breastbone and opening their rib cage to access the heart. With stents, on the other hand, doctors insert the devices into a blood vessel at a patient’s wrist or groin, then guide them to the blocked arteries using a catheter and X-rays. While bypass patients spend days recovering in the hospital and on average two months recovering at home, stenting is often an outpatient procedure.

Most previous studies evaluating the two procedures have suggested that bypass surgery produces better and longer-lasting results. Experts reasoned that bypass surgeries “bypass” entire problematic sections of the heart, whereas each stent will address only a specific and constrained stretch of a narrowed artery. Prior evidence also suggested that patients who opted for bypass fared better long term.

Results from the new trial, however, largely refute this, suggesting that the two procedures are similarly successful. Among 1,500 patients – each suffering from blockages in three coronary arteries – about half were randomly assigned to undergo bypass surgery while the other half were assigned to receive stents. Researchers kept track of the patients for the next five years. In the end, the risk of major complications was similar. The researchers found that the risk of heart attack was only slightly higher among those receiving stents – 8.2% versus 5.3% – and that the risk of stroke and death were the same.

“We saw no difference in your risk of dying, even five years out,” Fearon said. “That’s an important change since previous studies.”

We’ve armed patients and their physicians with contemporary data reflecting the modern reality of these procedures. This is the kind of information you need to make the best possible decision for each case.”
William Fearon, MDProfessor of Cardiovascular Medicine

A notable caveat to the findings is that stents were more likely to require a repeat procedure. While this was needed for only 7.8% of study participants who underwent bypass surgery, 15.6% of those who received stents required a second procedure. Fearon notes, however, that a second stenting procedure would be as minimally invasive as the first.

Precision practices

The reason for these shifting outcomes is almost certainly due to advances in stenting technology and approaches, Fearon said. Modern stent designs incorporate breakthroughs in material science, resulting in structures that are more flexible, are less likely to drive inflammation, and more effectively deliver drugs to help stave off artery narrowing.

Medical practices involving stenting have also improved. For example, in the new trial, doctors used a measure called fractional flow reserve, or FFR, to determine whether a stent was necessary to address a particular narrowing in an artery. FFR, which has been steadily gaining popularity among cardiologists over the last two decades, involves inserting a sensor into the artery to measure how well blood is flowing. Previously, doctors relied only on X-ray images, called angiograms, to decide how many stents a patient needed and where to place them. The new study showed that using FFR resulted in fewer unnecessary stent placements and fewer complications overall than when doctors used only angiograms to guide stenting procedures.

“The approach that was taken with this study is one that really embodies the idea of precision medicine because we’re applying therapies based on precise data that we’ve taken,” Fearon said. “Our results suggest that if you take these extra measurements, it really does result in improved outcomes.”

Despite the improvements in stenting, bypass surgery may still be the best choice for certain groups, Fearon said, adding that it’s important for each patient to carefully evaluate the decision with a doctor. For example, patients with a high number of blockages may opt for bypass surgery because it would address all blockages simultaneously. Bypass surgeries also tend to have better outcomes than stenting in patients with diabetes, he said.

“What we’ve done here is we’ve armed patients and their physicians with contemporary data reflecting the modern reality of these procedures,” Fearon said. “This is the kind of information you need to make the best possible decision for each case.”

For more information

Medtronic Inc. and Abbott Vascular Inc. provided research grants for the study but were not involved in its design or implementation.

Researchers from dozens of other institutions in the United States and abroad also contributed to the work.

This story was originally published by Stanford Medicine.

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