Athletes with Coronary Artery Calcifications: A Case Report

Authors: Deepak Ravi, MD; Timothy Canan, MD, Division of Cardiology, Department of Medicine, University of California, Los Angeles

Discussion The development of computed tomographic protocols to study coronary artery disease has provided useful tools to assess cardiovascular risk, although the interpretation of findings in athletes compared to sedentary individuals has become an area of increasing interest. In particular, the coronary artery calcification score (CACS), expressed in Agatston units, has been shown to be predictive of future cardiovascular events.3,4 The CACS is calculated as the product of coronary artery calcification (CAC) volume and density as evaluated by non-contrast CT. Interestingly, several studies have demonstrated an increased prevalence of CACS >100 in active subjects. In a study of 244 men with low 10-year Framingham coronary risk scores, Merghani, et al found an increased prevalence of CACS >300 Agatston units amongst athletes with elevated CACS compared to sedentary males.4 Similarly, Angevaeran, et al demonstrated a significantly elevated CACS among athletes who reported lifelong high-volume vigorous exercise in comparison to those reporting low volumes of exercise.5 Reconciling these seemingly paradoxical results has been an area of ongoing research.

Several factors may underlie the findings of increased coronary calcium scores amongst athletes. Evaluation of coronary plaque using CT coronary angiography allows for morphologic characterization of atherosclerotic disease. Calcified plaques are thought to confer the lowest risk of resulting in cardiovascular events, while mixed plaques are associated with the highest risk; non-calcified plaques carry intermediate risk4. As such, plaque identified in male athletes have been found to be mostly calcific in nature, whereas mixed morphology plaque is more commonly identified in sedentary males4,6. Moreover, the Agatston unit is calculated as the product of plaque density and volume. While plaque volume is associated with increased cardiovascular disease, plaque density is inversely correlated with cardiovascular disease.5 Thus, calcific plaque identified among athletes may represent lower risk disease than the lipid-rich, mixed plaque prevalent amongst sedentary individuals. Moreover, there is large variability in the reported prevalence of CACS. In a review article, Angevarean, et al, reported CAC prevalence of 34 to 71% amongst athletic cohorts.6 As above, Merghani et al’s findings suggest that while most endurance athletes with a low risk CV profile at baseline have normal CAC scores, those predisposed to coronary calcifications may carry a greater burden of disease.5 Finally, given the relatively homogenous nature of study populations, more research investigating the qualitative and quantitative burden of disease amongst gender specific and race specific populations is required, as well as among non-endurance athletes. Evidence informing the management of the athlete with an elevated coronary artery calcium score is sparse and necessitates further research. While athletes with elevated CACS tend to have lower risk plaque morphology, it is well established that individuals with an elevated CACS carry significantly increased risk of major cardiac events in comparison with those with a CACS of 0. CACS >400 is associated with an estimated 34% risk of MACE, compared with 2.1% for CACS of 0.8 Individuals with CACS >1000 in particular appear to represent very high risk of CVD and all cause mortality.9 Thus, athletes with significant atherosclerotic disease should be managed aggressively with statin and antiplatelet therapy as appropriate, even though their true risk profile may be somewhat different from the general population. However, increased levels of cardiorespiratory fitness have been linked to lower rates of cardiovascular disease, even in the setting of elevated CAC scores. Radford, et al found an 11% decrease in risk of CVD events for each additional MET of fitness in all CAC groups, establishing the beneficial effect of exercise in preventing cardiovascular disease in patients with elevated CACS.10. Individuals with significantly elevated CACS, such as the patient from our case, would likely benefit from maximal exercise testing to evaluate for inducible ischemia or electrical instability, as well as evaluation of left ventricular function, in keeping with the AHA/ACC recommendations for competitive athletes.11 Moreover, in patients such as ours with very elevated CACS, a secondary prevention strategy with antiplatelet therapy daily or periodically prior to races may be appropriate if not at increased bleeding risk. While more research is warranted to fully elucidate the optimal management of asymptomatic individuals with very high CACS, it is reasonable to pursue the most aggressive preventative strategies regardless of physical activity level.

Take home message

CACS is a useful tool in evaluating cardiovascular disease risk. While physical activity is associated with an improved cardiovascular risk profile, athletes have also been found to have elevated CACS. Although the clinical implications of these findings are unclear, management of the athlete with an elevated CACS should take into account individual risk factors and the patient’s preferences. Those with a significantly elevated risk profile should undergo aggressive guideline-based risk mitigation.

References

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