LETTER TO THE EDITOR
Suggested new upper limit of physiologic cardiac hypertrophy determined in Japanese ultramarathon runners must be interpreted cautiously
Jürgen Scharhag, MDa,
Axel Urhausen, MD, PhD, FACSMa and
Wilfried Kindermann, MD, PhD
a Institute of Sports and Preventive Medicine, University of Saarland, Campus Building 39.1, 66123 Saarbrücken, GermanyGermany
j.scharhag{at}mx.uni-saarland.de j.scharhag{at}mx.uni-saarland.de
With great interest and surprise we read the study by Nagashima et al. (1). The researchers report that 11% of the participants (33 of 291) had a left ventricular end-diastolic diameter (Dd) larger than 70 mm. In addition, further extraordinary values for the end-Dd (mean value, 61.8 ± 6.9 mm; range, 42 to 75 mm), the end-systolic diameter (mean value, 39.6 ± 6.9 mm; range, 23 to 55 mm), and the intraventricular septal thickness (range, 5 to 19 mm) are presented, which are in great contrast to results reported previously (2–5).
The data presented are even more surprising when normalized to the body surface area (BSA; mean value, 1.66 ± 0.1 m2), resulting in an unbelievable mean Dd-to-BSA ratio of approximately 37 mm/m2. Such a high value seems unrealistic, especially when compared with the data of Pelliccia et al. (3), who found the highest mean Dd-to-BSA ratio of about 31 mm/m2 in healthy endurance athletes competing at national and international levels (59 track-and-field athletes, 49 cyclists, and 41 cross-country skiers). Also, the range of the intraventricular septal thickness (5 to 19 mm) is suspicious for at least some pathologically hypertrophied hearts. Consequently, based on the data of previous reports (2–6), hearts with an end-Dd  60 mm or an intraventricular septal thickness 13 mm in athletes with a BSA <1.82 m2 are highly suspicious for pathologic hypertrophy (2) and would have required further cardiologic examinations to confirm the statement of a physiologic hypertrophy. Therefore, the data presented by Nagashima et al. (1) suggesting a new upper limit of physiologic cardiac hypertrophy may lead to confusion and to misinterpretations in daily routine (diagnosis of athlete's heart instead of pathologic hypertrophy), and put athletes at an avoidable risk.
The main confounding variable of the study (1) seems to be the age of the subjects (mean age, 41.8 + 9.7 years; range, 20 to 73 years). As it is well known that the incidence of cardiovascular diseases rises with age (especially above 35 to 40 years) (7), cardiovascular diseases in the participants should have been excluded by cardiologic examinations. It is not sufficient to assess the state of an athlete's health by taking only the resting blood pressure or replies to questionnaires (1). Furthermore, relevant additional examinations should have been performed, and important parameters should have been given in the study: ejection fraction to describe the systolic function; E/A ratio to evaluate the diastolic function; Doppler-echocardiography to exclude valvular diseases resulting in pathologic ventricular overload and dilation; 12-lead electrocardiogram at rest and exercise (including blood pressure measurements) to detect possible coronary artery disease or exercise-related hypertension; and spiroergometry to obtain maximal oxygen consumption, which describes the state of physical fitness and is closely related to cardiac dimensions [8–10]. Moreover, the convention of echocardiographic measures is not given (Penn or American Society of Echocardiography convention [11,12]).
In conclusion, it seems that the study by Nagashima and co-workers does not define a new upper limit (which now would be 70 mm or even 75 mm, when the 95% confidence interval for the left ventricular end-Dd is calculated), but a wrong upper limit of physiologic cardiac hypertrophy.
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References
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1. Nagashima J, Musha H, Takada H, Murayama M. New upper limit of physiologic cardiac hypertrophy in Japanese participants in the 100-km ultramarathon. J Am Coll Cardiol. 2003;42:1617–1623[Abstract/Free Full Text]
2. Pelliccia A, Maron B, Spataro A, Proschan M, Spirito P. The upper limit of physiologic cardiac hypertrophy in highly trained elite athletes. N Engl J Med. 1991;324:295–301[Medline]
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10. Wernstedt P, Sjostedt C, Ekman I, et al. Adaptation of cardiac morphology and function to endurance and strength training—a comparative study using MR imaging and echocardiography in males and females. Scand J Med Sci Sports. 2002;12:17–25[CrossRef][Medline]
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12. Sahn D, DeMaria A, Kisslo J, et al. Recommendations regarding quantitation in M-mode echocardiography: results of a survey of echocardiographic measurements. Circulation. 1978;58:1072–1082[Abstract/Free Full Text]
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