European Journal of Preventive Cardiology | 2019
Comment on: Acute impact of an endurance race on cardiac function and biomarkers of myocardial injury in triathletes with and without myocardial fibrosis
Abstract
We have read with interest the study by Tahir et al. addressing possible causes of cardiac fibrosis in triathletes. The authors have examined how a triathlon of a mean total race time of 3.3 2.7 hours influences cardiac function and biomarkers of myocardial function. Of 30 asymptomatic male triathletes with a mean age of 45 10 years, 10 individuals exhibited non-ischemic myocardial fibrosis based on a positive late gadolinium enhancement (LGEþ) in cardiac magnetic resonance. Briefly, LGEþ triathletes had higher peak exercise systolic blood pressure (222 21mmHg) compared to LGE triathletes (192 30mm Hg). In the past, myocardial fibrosis has been repeatedly described in middle-aged and older endurance athletes. The mechanisms are largely unknown. In the present study it is hypothesized that the higher exercise blood pressure in LGEþ triathletes could explain myocardial fibrosis in triathletes. The following issues contradict this assumption. The presented systolic blood pressure of 222 21mmHg at mean maximal exercise of 348 83 Watt corresponds to the upper normal limits reported in some studies. Furthermore, healthy athletes can even achieve markedly higher blood pressure levels. The increase in systolic blood pressure during exercise results from the increased cardiac output. Accordingly, typical endurance athletes such as triathletes have the highest blood pressure during exercise. Moreover, it should be taken into account that LGEþ athletes were older than the LGE athletes in the present study. Blood pressure measurements during maximal bicycle ergometry are methodically susceptible and not sufficient to assess the blood pressure behavior. Therefore, it would have been important to report exactly how the blood pressure during exercise testing was measured (which is also not the case in Tahir et al. 2018.) Furthermore, there exists no generally accepted threshold for exaggerated blood pressure values or hypertension during exercise in athletes. The clinical relevance of hypertensive blood pressure values at exercise for predicting cardiovascular events or mortality is unclear. The systolic blood pressure at maximum exercise is apparently not associated with an increased rate of cardiovascular outcomes. With regard to the assessment of exercise blood pressure in athletes, 24 h ambulatory blood pressure monitoring including typical training sessions is necessary. In this context, it should be noted that the reported maximal blood pressure only exists during very limited and short periods during training sessions of triathletes, as more than 90% of endurance training takes place clearly under the maximum, i.e. in the aerobic range. This means that most of the training is performed at only moderately increased blood pressure values. In general, it should be noted that the presented findings are not suitable to explain myocardial fibrosis in endurance athletes. In the future, long-term studies will be important and necessary for identifying intermittent diseases such as myocarditis as a possible cause of myocardial fibrosis in athletes. It is noteworthy that myocardial fibrosis is predominately reported in middle-aged and older endurance athletes. Therefore, in respect to the given mean age of 45 10 years in athletes of the present study, it has to be noted that