The Heart Bypass Surgery That Leaves the Breastbone Whole

For the first time anywhere, researchers have run a proper randomized trial of heart bypass surgery done through a small cut between the ribs instead of a sawn-open breastbone — and the patients with the smaller incision were physically better off a month later. The work was led by the University of Ottawa Heart Institute and published in The Lancet.

The trial is called MIST, short for Minimally Invasive versus STernotomy. It enrolled 170 people with blockages in more than one coronary artery, spread across seven centres in six countries: Canada, the United States, Germany, Japan, China and India. Recruitment ran from 2018 to 2024. Each patient got a median of three grafts, so this was not a token single-vessel operation — it was the real thing, done sideways.

Why should anyone outside a cardiac ward care? Because bypass is one of the most common major operations in the country, tracked by the Canadian Institute for Health Information as a priority procedure with published wait times. And the part patients dread most isn't the heart work. It's the breastbone.

A cut between the ribs, not a split chest

Conventional bypass starts with a sternotomy: the surgeon divides the breastbone down the middle to reach the heart, then wires it back together at the end. It works, and it has worked for decades. But that bone has to knit afterwards, which typically means weeks of restrictions on lifting, pushing and pulling — no groceries, no grandchildren, no steering wheel for a while.

The alternative used in MIST goes in through a short opening between the ribs on the left side, leaving the sternum untouched. CBC News reported that patients who have the smaller-incision version are often discharged within two or three days and can be back to their normal activity level within a few weeks. Until now, that claim rested on surgeon experience and registry data, not on a randomized head-to-head.

What the heart bypass surgery trial measured

The main yardstick wasn't survival. It was the SF-36 physical component summary score at one month — a standard questionnaire about what you can actually do: climb stairs, carry things, walk a block without stopping. That choice tells you the question the team was asking.

Better physical function at one month

Patients randomly assigned to the less-invasive operation reported meaningfully better physical recovery at the four-week mark than those who had the sternotomy. That's the headline result, and it lands exactly where patients feel it — in the weeks between leaving hospital and getting their life back, which is the stretch most people underestimate before surgery.

Fewer transfusions, less time on a ventilator

Two hard, objective measures went the same way. The minimally invasive group needed fewer blood transfusions and spent less time on mechanical ventilation after the operation. Those aren't just comfort metrics. Less ventilator time and less donor blood both correlate with fewer complications downstream, and both ease pressure on stretched intensive care resources.

No deaths or strokes at one year

By twelve months the two groups had converged. Relief from chest pain was comparable, and the trial recorded no deaths and no strokes in either arm. The fair reading is not that the smaller cut is better medicine — it's that it bought a faster start without costing anything measurable a year out.

Why nobody ran this comparison until now

Randomized surgical trials are brutally hard. You can't blind a patient to a scar, and MIST was open-label, which means people knew which operation they'd had when they filled in that recovery questionnaire. With 170 participants, this is a modest study by drug-trial standards. It also took six years across three continents, largely because the technique demands surgeons who have already climbed a steep learning curve. Principal investigator Dr. Marc Ruel, who holds the endowed chair in minimally invasive cardiac research at the Ottawa Heart Institute, has been careful to frame the finding as applying in experienced hands.

What it means if you're facing bypass here

In Canada the question isn't cost — provincial plans cover the operation either way — it's access and suitability. Not every patient qualifies. MIST enrolled selected people with multivessel disease, and factors like previous chest surgery, body habitus, emergency presentation or where the blockages sit can rule the approach out. The number of Canadian centres doing multivessel bypass this way is small, and the surgeon's volume matters more than the hospital's brochure.

So the practical move is to ask, early: is the small-incision approach an option for my anatomy, does this team do it routinely, and how many do they do a year? A referral elsewhere may add weeks to a wait that is already measured in weeks. That trade-off is a real conversation to have with your cardiologist, not a decision to make from a news article.

What to watch over the next five years

The MIST team plans to reassess these patients at five years, and that follow-up is the one that counts. Grafts can narrow over time, and a one-year snapshot can't tell you whether a technically harder operation holds up as well as the standard one. Watch too for whether cardiac surgery guidelines pick this up and whether training programs expand. If you or a family member has a bypass scheduled, bring the question to your surgical consult — and don't assume the answer is no.