Do Triathletes Need to Worry About Heart Attacks?

Published August 30, 2021 08:40AM

With the high-profile news of Tim O’Donnell suffering a heart attack—the big one, the widowmaker—while in the middle of a race, it’s enough to make the average tri-er a little, you know, nervous. If heart attacks can happen to healthy, fit, highly competitive pro athletes, how worried do regular triathletes need to be?

Thomas Allison, exercise physiologist and co-director of the sports cardiology clinic at Mayo Clinic in Rochester, Minnesota, wants you to keep this fact firmly in your fevered mind: The risk of sitting on your butt all day watching TV is far greater than the risk involved in training for a triathlon. To put it in perspective, he calls up a study of the medical records of 10.9 million marathoners and half-marathoners over a 10-year period that revealed just 59 cardiac arrests. Which is an outrageously low rate! So, it absolutely does happen, but your chances of being hit by a car while crossing the street are much greater. And you can reduce your heart attack risk even further with simple, easy precautions, said Allison.

First off, let’s get into the details of what a left anterior descending (LAD) blockage is, and why it’s called “the widowmaker.”

There are three coronary arteries—one from the right and one from the left, and on the left there’s also a short segment called the left main that splits into the left anterior descending (LAD) and the circumflex. Worst case scenario, Allison said, would be a blockage of the left main because that would shut down both the LAD and circumflex, but those are uncommon because the left main is short and straight. Instead, plaque tends to build up where arteries bend or bifurcate, like where the LAD branches off the left main.

The LAD supplies blood to the front of the large and important left ventricle in your heart. So an LAD blockage restricts or shuts off blood to the left ventricle, damaging the heart muscle. That’s a heart attack. This lack of blood can trigger ventricular fibrillation, a chaotic rapid heartbeat that is, as Allison puts it clinically, “incompatible with life.” If that event went unnoticed by bystanders for five or ten minutes, if a defibrillator and an ambulance were not handy, “you’re cooked,” he said.

How Can LAD Blockages Happen to Young Fit People?

Plaque buildup in coronary arteries actually starts in the teenage years, but it develops slowly and doesn’t usually present until people are in their 60s and 70s. The grim 12% survival rate for an out-of-hospital “widowmaker” heart attack comes from the fact that most people of that age group are less fit and often have other complicating health issues.

Allison described three common reasons behind those rare instances when the widowmaker comes to the young and fit. (It should be noted these are general explanations for those rare scary times, not specific to any one individual case.) One common reason is your genes. You can blame your parents for abnormal cholesterol metabolism, arteries that are susceptible to tears, or a particularly contorted LAD. Diet and exercise can help reduce your chances, but can’t eliminate this risk factor entirely.

Second, many athletes feel that because they exercise and are fit, they can eat whatever they want, and don’t need to have their cholesterol or blood pressure checked. In fact, this teflon theory was promoted in 1975 by pathologist and runner Thomas Bassler, who claimed running a marathon would render you immune from coronary artery disease. “That’s since been disproven, of course, but the idea persists,” said Allison.

Third, and this is a corollary of the second factor, precisely because these athletes are young and fit and likely have not felt the need to go to the doctor, they don’t notice symptoms until the disease is pretty far progressed. An unfit person will notice symptoms right away—they get out of breath going up a flight of stairs. But blockages develop slowly enough that the athlete’s heart frequently creates collaterals—essentially natural bypasses—that allow enough blood flow to mask the fact that something’s wrong in normal circumstances.

Why Are Men At More Risk Than Women?

The answer, said Allison, is partly behavior and partly biology. “How many women do you know who say, ‘Watch this!’ Male ego is a risk factor,” Allison said, meaning in general men do things that put themselves at higher risk, but that’s not the primary issue. He also noted that, because of childbirth and gynecological issues, women get medical checkups at a younger age, and more frequently and more regularly thereafter than men. And estrogen seems to protect women against atherosclerosis or plaque buildup, as heart attack rates are lower in women than men, at least until older age.

There are gender differences too in the symptoms that warn of a heart attack. Women, Allison said, have more generalized fatigue and shortness of breath, and are less likely to have the chest pain men experience. Doctors surmise that’s because women’s blockages are more diffuse, frequently occurring in several smaller downstream arteries, while men tend to have one big blockage in a critical location.

Does Endurance Training Help or Hurt Heart Attack Risk?

Triathletes train a lot. Does that put them at risk or give them some level of immunity?

The discomfiting answer is both, Allison said. Exercise in general is good for the heart. And remember up a few paragraphs ago, where Allison talked about the heart creating its own bypasses? That’s a nifty adaptation to the intense demands endurance training puts on your heart. And while those collaterals may mask a serious blockage, in the event of a heart attack, they may also provide enough blood flow to the heart that ventricular fibrillation doesn’t happen, giving you a fighting chance. It’s likely that O’Donnell’s years of intense training provided him a robust network of collateral arteries that ended up saving his life.

But (the other shoe drops), if you have heart disease—plaque buildup or a structural problem—high-intensity exercise can be dangerous, Allison said. “I’ve had patients who have blockages, and they can train and feel fine, but when they get in a competitive situation and don’t feel well, they’ll say, ‘Only three more miles. I’m going to finish.’ And they have a heart attack.” Point being, the type-A attitude that fuels intense training is likely to blow by warning signs, thereby putting that person at greater risk than a less driven individual.

Athletes are, in fact, notoriously bad patients. They don’t think they need regular checkups, they resist drugs like cholesterol-lowering statins, and they may imagine training can erase years of unhealthy living. Allison recalled the tragic story of author and running evangelist Jim Fixx. “For years, he was a sedentary, 220-pound, pack-a-day smoker. When he found running, it was like religion. The story is that Fixx was talking to Frank Shorter, saying he wasn’t feeling good, tired, whatnot. Shorter told him to go to Ken Cooper at the Aerobics Institute in Dallas and get his heart checked out, but Fixx put it down to stress. So instead of going to the doctor, he rented a cabin in Vermont, went out for a 10-mile run, and never came back.”

A-fib and Athletes

But athletes are at greater risk of A-fib, right? We’ve all heard a growing number of stories about extreme exercise being linked to electrical issues in the heart.

“Yes, there probably is something to that, but the link is not that strong,” Allison said. And A-fib (atrial fibrillation) does not necessarily lead to heart attacks. A-fib is an irregular rhythm in the upper chambers of the heart, that’s been likened to a quivering bag of worms. Intense training—heart muscles pumping more blood over a period of many years—causes the atria to stretch and enlarge, which seems to make A-fib more likely. “There is more A-fib in endurance athletes, but intense exercise is just one risk factor. Alcohol consumption is also a common cause,” Allison said. “If there’s potential to develop A-fib after 36 years of doing something you love that has a lot of other health benefits, does that mean you shouldn’t do that sport? I don’t know—you make that call.”

Risk Factors of a LAD/Widowmaker Heart Attack

In general, Allison’s advice to endurance athletes is to keep doing what they’re doing, but he has a list of guidelines to keep in mind.

The first is periodization. He recommends taking a month off out of every year to let your body and mind relax. That’s pretty standard training advice.

And don’t assume that because you’re young and active, you don’t need regular medical checkups, particularly if you have a family history of heart disease. That said, you may need to see a sports specialist in order to understand your physical demands and body. “A lot of evaluations need to be interpreted differently for someone who’s very fit and used to intense exercise.”

If you don’t feel well or if you’re sick, don’t train. And don’t compete if you’re not prepared.

Atherosclerosis develops over time. The older you get, the more likely you are to have chronic diseases that exacerbate heart disease like high blood pressure or diabetes. The older athlete needs to be more vigilant, especially if they used to be unhealthy.

If you’ve had a heart attack, start by working out in a gym, so you can stop immediately if you feel symptoms. When you graduate to outdoors, train with a partner and stay in cellphone range. Races may actually be a safer way to get in a long workout than heading off on your own, since there are usually spectators and officials on the course.

Keep it in perspective. “Most people are not making their living as a triathlete. Taking time off, not pushing through pain or fatigue—these things are easier if you keep athletics in perspective,” Allison said.

Another perspective to bear firmly in mind, going back to the start of our conversation, is that the risk for healthy people of having a widowmaker is vanishingly small. Scary, but rare. Doing something you love, on the other hand, is known to be good for the ticker.