A Doctor Breaks Down Advanced Lipid Testing for Triathletes — Triathlete

There are many reasons why people come to endurance sports. Some do so for the thrill of competition, others want to push themselves to accomplish things that they never thought possible, and still more do so to find camaraderie with friends old and new within the endurance sport community. But the majority come for the health and wellness benefits of swim, bike, and run.

Improved physical fitness is not a panacea, though. Yes, there is abundant evidence in the scientific literature that an active lifestyle improves both the quality and duration of life, but also numerous examples of men and women at the peak of their athletic potential being felled by sudden, unexpected ailments, usually of a cardiovascular nature. These events are always tragic and raise understandable concern among those who are left behind. How could this happen, we wonder, to someone who was doing everything right?

Unexpected cardiac mortality in athletes

In the end, most of the unexpected cardiac morbidity and mortality in young athletes is attributable to previously unrecognized inherited disorders.

Flo Hyman, the 1984 Olympic silver medalist in volleyball for the United States, died suddenly at age 31 from undiagnosed Marfan Syndrome (a connective tissue disease affecting the heart and vessels).

Professional soccer player Christian Ericksen experienced cardiac arrest during the Euro 2020 competition from an inherited dysrhythmia.

And of course, professional triathlete Tim O’Donnell had a heart attack during a race because of a previously unknown inherited condition, which affected his lipid profile and led to early coronary atherosclerosis (a buildup of fats and cholesterol in the arteries of the heart). As he said in a later interview with Triathlete, “Know that fitness isn’t health…Just because we do Ironmans doesn’t mean that we’re immortal.”

Rising risk and routine screening for aging triathletes

It isn’t just younger professional athletes who are affected. As athletes age, the risk of heart disease rises as well, but it can be more significant for those who have a predilection for metabolic traits that result in higher cholesterol levels despite being active.

These individuals are generally asymptomatic until their coronary arteries have become significantly affected, and then they may only present with a major event. For this reason, the American College of Cardiology and the American Heart Association recommend routine screening for men and women over 40 that includes a physical exam and an assessment of lipid profile (LDL, HDL, and cholesterol levels). Additional testing is recommended for those with risk factors (such as smoking, strong family history, or diabetes) or those in whom the initial screen is abnormal.

An Ironman case study questions screening adequacy

A recent paper called into question whether standard health screening is adequate for those who are regularly training and competing in endurance sports. That study presented a case of a 55-year-old Ironman athlete who was previously asymptomatic but collapsed in cardiac arrest during the bike portion of an Ironman race. Fortunately, the man was resuscitated rapidly and recovered, and in the aftermath was found to have been known to have only mildly elevated cholesterol levels out of keeping with the finding on his coronary angiogram that showed significant disease.

Doctors did additional tests, which revealed the athlete had very high levels of small dense LDL particles (sdLDL) despite his only mildly elevated LDL cholesterol. These sdLDL are believed to be important in the development of coronary artery plaques (buildup and blockages), but are not routinely measured as part of screening.

The authors of this study point out that this may need to be reconsidered. They argue, “This case underscores challenges in cardiovascular risk assessment among endurance athletes. High levels of cardiorespiratory fitness, favorable lipid ratios, and absence of traditional metabolic risk factors commonly yield low estimated atherosclerotic cardiovascular disease risk, potentially contributing to under-recognition of progressive coronary disease until an acute event occurs. While endurance exercise confers substantial cardiovascular benefit for most individuals, observational data suggest coronary atherosclerosis can still be present in some lifelong endurance athletes even when conventional risk metrics appear favorable.”

Small dense LDL and the argument for advanced testing

What, then, do the study authors recommend as a means of addressing this risk? They believe that advanced lipid testing that measures sdLDL, among other kinds of specific assays not normally screened for on basic lipid profiles, is indicated for some (though not all) middle-aged endurance athletes. The authors did not weigh in as to who exactly those athletes are.

It is important to note here that this opinion is not shared universally. A task force of the American College of Cardiology, in conjunction with the American Heart Association, found that while these markers associate with cardiovascular outcomes, they perform similarly to and do not improve risk reclassification beyond traditional lipid parameters.

Instead, the broader consensus appears to be that these kinds of advanced lipid profiles should be reserved for athletes with a family history of premature atherosclerotic cardiovascular disease or in patients with known elevated triglycerides to identify genetic disorders.

Reevaluating risk via basic lipid profiles in endurance athletes

Unfortunately, while there is no exact answer for how to identify who is most likely at risk for cardiac events despite participating in endurance sport, you may take solace in knowing that you are still far less likely to have something like this happen by being an endurance athlete than not being one.

Additionally, a basic lipid profile is still a very reasonable and accepted way of assessing your 10-year risk of disease in most cases.