Abstract 1538: Acute Cardiac Effects of Marathon Running: Evidence of Right-Heart Overload
Background. Cardiac dysfunction and elevated blood markers of myocardial injury have been reported after prolonged strenuous exercise. We sought to clarify the significance of these responses in healthy, middle-aged subjects immediately after running 26.2 miles.
Methods. From 425 volunteers, thirteen women and 12 men were randomly selected, provided medical and training history, and underwent baseline cardiopulmonary exercise testing to exhaustion. Blood biomarkers, cardiovascular magnetic resonance imaging, and 24-hour ambulatory electrocardiography were performed 4 weeks before and immediately after the race.
Results. Participants were 38.7±9.0 years old, had baseline peak oxygen consumption of 52.9±5.6 mL/kg/min, and completed the marathon in 256.2±43.5 minutes. Troponin I increased from 0.03±0.003 at baseline to 0.20±0.30 ng/mL immediately following the race, P=0.001. Cardiovascular magnetic resonance-determined pre-and post-marathon left ventricular ejection fractions were comparable, 57.7±4.1% and 58.7±4.3%, respectively, P=0.32. Right atrial volume index increased from 46.7±14.4 to 57.0±14.5 mL/m2, P<0.0001. Similarly, right ventricular end-systolic volume index increased from 47.4±11.2 to 57.0±14.6 mL/m2 (P<0.0001) whereas the right ventricular ejection fraction dropped from 53.6±7.1 to 45.5±8.5%, P<0.0001. There were no morphologic changes observed in the left atrium or ventricle nor evidence of ischemic injury to any chamber by late gadolinium enhancement. There were no significant arrhythmias.
Conclusions. Marathon running causes dilation of the right atrium and right ventricle, reduction of right ventricular ejection fraction, release of troponin I and B-type natriuretic peptide, but does not appear to result in ischemic injury to any chamber. (ClinicalTrials.gov number, NCT00752752.)