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Downloaded from https://academic.oup.com/milmed/article/183/11-12/e783/5025892 by DeepDyve user on 19 July 2022 MILITARY MEDICINE, 183, 11/12:e783, 2018 Aviator’s Heart: A Case of Athlete’s Heart in an Active Duty Male Naval Aviator CPT Ilya V. Ryaboy, MC USA*; LTC James A. Watts, MC USA†; MAJ Megan L. Barnwell, MC USA† ABSTRACT Athlete’s heart is the condition of cardiac remodeling as a result of physiologic stress induced by regu- lar strenuous physical activity by professional or elite amateur individuals. The literature describes several characteris- tics of the athletic heart, including left ventricular hypertrophy, increased left ventricular mass, right ventricular dilatation, atrial enlargement, electrocardiographic changes, and abnormalities on cardiac magnetic resonance imaging. We present a case of athletic heart in an exceptionally physically ﬁt active duty naval aviator who experienced syncope and underwent extensive cardiac testing. He was found to have borderline hypertrophic changes as well as delayed gadolinium enhancement initially concerning for myocarditis. Cardiopulmonary exercise testing revealed an exercise capacity of 120% above the maximum measurable value for his age and gender. He was then diagnosed with athlete’s heart and released to active duty with no limitations to his ﬂight status. A challenge is posed to the practicing clinician in differentiating the athletic heart from the heart of an athlete suffering from underlying pathophysiology. Athlete’s heart is an elusive diagnosis and may be associated with ﬁndings concerning for more insidious pathology, including hypertrophic cardiomyopathy and dilated cardiomyopathy. Additionally, patients with athlete’s heart have been noted to have delayed gadolinium enhancement similar to that seen in patients with a history of myocarditis; the clinical sig- niﬁcance of this ﬁnding is yet to be fully elucidated. In a military setting, distinguishing the heart of the healthy and athletic service member from the unfortunate one who has cardiomyopathy remains an important clinical distinction warranting further study. INTRODUCTION episode of syncope occurred while seated and was associated Athlete’s heart is a condition characterized by cardiac remo- with a prodrome of diaphoresis, ﬂushing, and tunnel vision; deling that is the result of physiologic stress induced by reg- this occurred in the setting of extensive caffeine and energy ular strenuous physical activity. Electrophysiologic and supplement use. Given his high-risk occupation, he under- anatomic changes characteristic of the athlete’s heart are went a thorough cardiovascular diagnostic evaluation con- readily identiﬁed on electrocardiogram (ECG), transthoracic sisting of a resting 12 lead ECG, a TTE, exercise nuclear echocardiogram (TTE), and cardiac magnetic resonance stress test, and a 28-d ambulatory ECG monitor. Resting 12 imaging (cMRI) . A common clinical dilemma posed to the lead ECG was normal. TTE revealed mild concentric left military healthcare provider is the differentiation of the ath- ventricular hypertrophy (LVH) with intraventricular septal letic heart from the heart of an athlete suffering from under- thickness of 1.5 cm, dilation of the left atrium to 4.1 cm, nor- lying pathology. We present a case of athlete’s heart mal ﬁlling pressure with E/A ratio 0.93, and left ventricular diagnosed during evaluation of syncope in an active duty ejection fraction (LVEF) of 56%. Twenty eight-day ECG naval aviator. monitor was normal. An exercise nuclear stress test revealed a partially reversible defect in the distribution of the left anterior descending artery. He was then referred for coronary CASE DISCUSSION angiography, which revealed mild non-obstructive coronary A 40-year-old active duty naval aviator was referred to the artery atherosclerosis and started on Metoprolol Tartrate Brooke Army Medical Center (BAMC) Cardiology Service 12.5 mg twice daily. He subsequently underwent tilt-table for evaluation of recurrent syncope. The patient reported testing twice; on the ﬁrst occasion, he had a positive result being very physically active; his usual regimen includes a attributed to beta blockade. Metoprolol was discontinued 2-mile run in the morning and a 4-mile run in the afternoon, and repeat tilt-table testing was negative. At this point, he approximately 6 d a week. He additionally performs weight was diagnosed with orthostatic syncope attributed to poor training for 45–60 min 5 d weekly. The patient’s ﬁrst oral intake and heavy coffee use the day of the event, and he was released to full duty without limitation. *Department of Medicine, San Antonio Uniformed Health Sciences Consortium, 3551 Roger Brooke Dr, San Antonio, TX 78234. One year later, the patient experienced a second episode †Department of Cardiology, San Antonio Uniformed Health Sciences of syncope, again while seated, in the setting of decreased Consortium, 3551 Roger Brooke Dr, San Antonio, TX 78234. sleep, moderate alcohol consumption, and low oral intake doi: 10.1093/milmed/usy130 over the course of a day. His blood alcohol level on arrival Published by Oxford University Press on behalf of the Association of was 110 mg/dL. He regained consciousness and, upon stand- Military Surgeons of the United States 2018. This work is written by (a) US Government employee(s) and is in the public domain in the US. ing, experienced syncope a third time. He was subsequently MILITARY MEDICINE, Vol. 183, November/December 2018 e783 Downloaded from https://academic.oup.com/milmed/article/183/11-12/e783/5025892 by DeepDyve user on 19 July 2022 Case Report referred to cardiology at Brooke Army Medical Center. On attention paid to known ﬁndings in athlete’s heart including initial evaluation, his cardiac exam and ECG were normal. sinus bradycardia, increased voltage in the precordial leads, Given prior ﬁndings of scar on prior nuclear study, cMRI early repolarization, incomplete right bundle branch block, was performed which revealed a mildly dilated left ventricle, and ﬁrst degree atrioventricular block. An echocardiogram dilated left atrium, a normal ejection fraction of 60%, and a is indicated with attention paid to the dimensions of the mid-wall late gadolinium enhancement (LGE) (51–75% LV, the interventricular septum, and ejection fraction. An involvement) of the basal inferior wall. To objectively quan- increased LV wall thickness must be distinguished from tify the patient’s cardiovascular conditioning, he underwent hypertrophic cardiomyopathy (HCM), as the latter would cardiopulmonary exercise testing which revealed excellent lead to an increased risk of sudden cardiac death and the rec- exercise capacity with a VO max of 47.7 mL/kg/min, which ommendation to cease strenuous exercise. A series of crite- represents 120% of the maximum measurable value for the ria for individuals with an increased LV thickness of patient’s age and gender. His episode of syncope was 13–15 mm have been proposed to distinguish HCM and ath- favored to again be orthostatic, and he was diagnosed with lete’s heart. Higher risk characteristics include unusual athlete’s heart with no cardiogenic etiology of syncope LVH pattern, diastolic dysfunction, left atrial enlarge- identiﬁed. ment, female sex, a family history of HCM, bizarre ECG pattern, and LV end-diastolic diameter below 45 mm should suggest a diagnosis of HCM rather than athlete’s heart. ATHLETE’S HEART More recently, advanced imaging with cMRI has been The term “Athlete’s Heart” is used to describe the structural, undertaken to further elucidate characteristics of the athlete’s 1,2,4,5,9 functional, and electrical remodeling of the heart in response heart, with the increasingly common ﬁnding of LGE to physical stimuli placed on it by regular athletic training. In in the competitive athlete. In a study of veteran male endur- the late 19th century, a hypertrophied heart and bradycardia ance athletes with a mean age of 65 compared with both were noted to be more common in highly trained athletes. age-matched healthy controls and young athletes with a Today, advanced imaging modalities, particularly echocardi- mean age of 30. Expected ﬁndings were conﬁrmed: athletes ography, have allowed for more precise measurements and demonstrated increased left and right ventricular volumes, diagnostic criteria. In the athlete’s heart, LVEF is usually preserved systolic function, and increased septal thickness that of the normal healthy population, though in extreme compared to healthy controls. Notably, 50% of evaluated cases, world-class endurance athletes such as cyclists may veteran athletes displayed LGE indicating myocardial ﬁbro- experience left ventricular dilation to the point of decreasing sis, as was noted in the patient presented in this case. Of the LVEF to abnormal values; importantly, these athletes dem- six cases, one had a probable past myocarditis, one had a onstrate appropriate response and augmentation during activ- probable previous silent myocardial infarction, and four ity. Right ventricular dilatation may also be noted, and the were of undetermined etiology. Neither younger athletes nor atria generally enlarge proportional to ventricular growth. A age-matched controls demonstrated LGE, and the distribu- 2003 review of athlete’s heart demonstrated that signiﬁcant tion of LGE among those in which it was found was not increases in peak VO , left ventricular mass, and decreases in associated with age, height, weight, or body surface area, but resting heart rate occurred only in those athletes who exercised was associated with number of years trained and number of greater than 3 h per week. In athletic individuals, form deter- marathons ran. The researchers noted a link between lifelong mines function – a meta-analysis of almost 1,500 athletes endurance exercise and myocardial ﬁbrosis with an etiology divided into endurance-, strength-, and combination-trained still to be determined. athletes compared to controls noted that while all athletes had Additionally, a 2008 study compared Framingham Risk an increased left ventricular internal diameter, interventricular Score, coronary artery calcium, and LGE in 102 marathon septal thickness, and posterior wall thickness, there were nota- runners over the age of 50 compared to age-matched con- ble differences between diverging training styles. Speciﬁcally, trols. Interestingly, the number of marathons run was again exclusively strength-trained athletes had a much higher mean found to be an independent predictor of increasing incidence relative LV wall thickness (44 mm) than endurance athletes of LGE, which was noted in 12% of athletes. Of the 12 (39 mm) and controls (36 mm). Similarly, strength-trained ath- patients with LGE, 5 had a scar pattern typical of ischemia letes achieved a septal thickness 11.8 mm, compared to and 7 displayed a non-ischemic patchy pattern, suggesting 10.5 mm in endurance-trained athletes and 8.8 mm in controls. again that regular athletic training carries with it a risk of Healthcare providers must differentiate between the physi- cardiac remodeling. This is further supported by a rat ologic changes characteristic of the athlete’s heart and patho- model that has reported inﬂammatory and pro-ﬁbrotic inﬁl- logic abnormalities signaling underlying disease. A thorough trates in the myocardium of rats undergoing an intensive history and physical examination should be obtained; speciﬁ- exercise regimen. Indeed, ventricular tachycardia could be cally, the precise amount of exercise undertaken. A physical induced in a statistically higher percentage of “athletic” rats exam may reveal bradycardia and possibly a displaced point than controls. Such a relationship has yet to be deﬁnitively of maximal impulse (PMI). An ECG should follow with demonstrated in humans. e784 MILITARY MEDICINE, Vol. 183, November/December 2018 Downloaded from https://academic.oup.com/milmed/article/183/11-12/e783/5025892 by DeepDyve user on 19 July 2022 Case Report Normal (Utilize Seattle History, Exam, ECG Abnormal Criteria) Transthoracic Echocardiogram Specific Pathology Normal “Grey Zone” of Suggested LV wall 13-15mm Consistent with AH Concerning for HCM LVID >55mm, normal LVID<45mm, LA LA, responds to enlargement, deconditioning abnormal LV filling, unusual LVH pattern Cardiopulmonary Exercise Testing Not Acceptable Acceptable VO2 max < 110% predicted VO2 max>45ml/kg/min, for endurance athletes, >110% predicted, <85% for all other athletes, appropriate Low anaerobic threshold augmentation (<40%) cMRI Abnormal Reassurance Normal Specific rx, cease physical activity FIGURE 1. Recommended evaluation for patients with cardinal manifestations of cardiac disease (chest pain, palpitations, dyspnea, syncope). Seattle crite- ria refer to criteria considered normal in athletes (7), hx, history; LVID, LV internal diameter; AH, athlete’s heart; LA, left atrium; VO max, maximal oxy- 2 8 gen consumption; rx, treatment. Adapted from Prior and La Gerche and B J Maron. DISCUSSION provided as Figure 1.His ﬁnding of LGE is an interesting inci- The case in question highlights several interesting points dental note that warrants further study as the deﬁnite cause – regarding athletic heart. First, the patient could be described and implication – of this in the adult athlete has yet to be as being at an elite amateur level of ﬁtness. His personal and elucidated. family history was unrevealing of any cardiac disease, physi- cal exam was unremarkable, and ECG was normal. His eval- REFERENCES uation revealed characteristics of the athlete’s heart on echocardiography with mild concentric LVH, an enlarged 1. 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Military Medicine – Oxford University Press
Published: Nov 5, 2018
Keywords: athlete's heart; gadolinium; heart; pilots; athlete
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