November 11th, 2013
Case: An Ironman with a Proximal Circumflex Lesion
A 48-year-old man who runs 4 to 6 Ironman races per year reports non-exertional chest pain and is referred for a stress echocardiogram. His two sisters suffered MIs and died in their fifties, and his brother underwent CABG at age 49.
The patient goes for 17 minutes on the Bruce stress protocol, with lateral and anterolateral wall hypokinesis at peak stress. He is referred for coronary angiography, which shows a 50% proximal circumflex lesion deemed best treated with medical management.
He is referred to me and asks me how much should he exercise — specifically, whether he should run an Ironman in the Grand Tetons this coming weekend.
What would you advise this patient?
1. Keep running at your current level. (If he has an MI during a marathon, I will obviously feel awful.)
2. Keep running for exercise, but do not compete in marathons.
3. Simply reduce the amount of exercise you do. (It seems strange to tell someone to exercise less.)
4. Reduce your level of exercise, and repeat a stress test in 3 months. If the stress test is normal, you will have a green light to compete again.
5. Something else?
Response (November 11, 2013)
Sometimes I like to think about these situations backwards. A man with very high functional capacity who completes long-distance triathlons is diagnosed with a 50% circumflex lesion. If we assume that an abnormal stress test is generally caused by high-grade lesions, then the 50% circumflex stenosis is potentially not the cause of the positive stress test in this case. The patient could actually have had a false-positive stress test with non-anginal chest pain and an incidental 50% non-culprit lesion. Even if the lesion is causing the positive stress test (FFR would be another consideration), then we still doubt that he is experiencing classic angina because he has been training for hours at a time with no symptoms.
So let’s assume we are diagnosing coronary artery disease that is likely asymptomatic but we still want to recommend that this runner limit his exercise. In that case, it would be a more consistent practice pattern to recommend stress-test screening for CAD before allowing anyone to train for endurance sports — or even to advocate coronary angiography, given the possibility of false-negative stress tests. But that is obviously not how we practice — or how we should practice. In general, when a patient tells you that he or she wants to run a marathon, you take a history and make sure there is no angina, or you might consider an electrocardiogram. Stress testing for asymptomatic patients is generally reserved for those older than 65, or for younger patients who are at significant risk for coronary disease.
This patient likely had the same 50% circumflex lesion during the previous Ironman race he completed 2 months ago and during his 100-km bike ride the weekend before seeing you. I would tell him that his risk goes up in a small but incremental way during these endurance events and that limited evidence suggests that persistent endurance training is associated with arrhythmia and, possibly, myocardial fibrosis.
Fortunately, the event rate during endurance races is low. The 2012 NEJM article from the RACER Study Group showed that the risk for cardiac arrest during marathons is on the order of 1 in 100,000. The risk in triathlons is similar, with the majority of deaths during the swim. ESPN recently published an article, called “Trouble Beneath the Surface,” about deaths during triathlons, especially the swim component. The reasons are unclear, but there are theories about autonomic conflict, when both the sympathetic and parasympathetic systems are activated simultaneously and may provoke arrhythmias. In terms of marathons, note that a higher percentage of events occurs during the last mile, as people have a surge in adrenaline and speed when they are trying to achieve a certain time or beat a personal record.
A big-picture question is whether training more than 15 to 20 hours a week is good for our long-term heart health. I tend to agree with practitioners in this field who suggest that you are not doing multiple long-distance triathlons or marathons primarily for heart health — something else is motivating you. By taking on that additional training, the person must appreciate the possibility of short- or long-term cardiac consequences. And, of course, cardiologists have their own biases. Some who support endurance exercise may be more likely to do it themselves. To be fair, the debate is less about comparing endurance activity to a sedentary lifestyle than about comparing endurance exercise to a lower dose of activity.
Regarding your patient, I would not tell him that he may never participate in an endurance event again. I would be realistic about his risks and recommend that he take any symptoms on the course very seriously. He should also avoid bursts of speed to achieve a certain time. He should do everything he can medically to reduce his risk, such as taking aspirin and a statin. I would empower him with information that is realistic without being alarmist, and help him reach the decision that makes the most sense for him.
Response (November 20, 2013)
Jim Fang, MD
This fit middle-aged man has aggressive atherosclerosis (an obstructive lesion at age 48) and appears to be symptomatic. A 50% angiographic stenosis, corresponding to 70% cross-sectional stenosis, can produce angina. This correlation is why many of the classic angiographic CAD studies have deemed 50% angiographic stenosis to be clinically relevant. FFR (or IVUS to demonstrate true cross-sectional stenosis) may have proven this, but the stress test shows ischemia in the distribution of the lesion, and the patient has typical symptoms. I believe he has probably developed ischemic preconditioning, which likely has allowed him to have this degree of exertional capacity in addition to his peripheral muscle and respiratory conditioning.
Medical therapy would be my first recommendation (aspirin, statin, beta-blocker), but the chronotropic effects of beta-blockade are likely to affect the patient’s athletic performance. I would not be comfortable with prolonged-demand ischemia despite the high workload, given the family history of MI and early death. Although ventricular fibrillation from chronic ischemic heart disease is not common, as noted in the NEJM paper that Dr. Beckerman cites, it may have a familial tendency.
Therefore, I would curtail the patient’s marathon running until he decides what course he wants to elect. I agree that running 4 to 6 Ironman races per year is not of any health benefit to him. Remember, Jim Fixx died of sudden cardiac death.
Wrap-Up (November 25, 2013)
John Ryan, MD
After extensive consultation and discussion, the patient and I opted for aspirin 81 mg, atorvastatin 40 mg, and continued exercise. However, I advised him to take any chest-pain symptoms seriously and also prescribed nitroglycerin for use as needed. He has not had any symptoms while exercising and has reduced his intensity to half marathons for the next 6 months. Since he and I first met, he has successfully run one noncompetitive half marathon, has opted not to run competitively, and is no longer trying to break personal records.