BACKGROUND: To analyze the effect of myocardial fibrosis on left ventricular (LV) function evaluated by feature-tracking strain analysis by cine cardiac magnetic resonance (CMR) in competitive male triathletes with normal ejection fraction (EF).Methods and Results:78 asymptomatic male triathletes with >10 weekly training hours (43±11 years) and 28 male age-matched controls were studied by late gadolinium enhancement (LGE) and cine CMR. Global and segmental radial, longitudinal and circumferential strains were analyzed using feature-tracking cine CMR. Focal non-ischemic LGE was observed in 15 of 78 triathletes (19%, LGE+) with predominance in the basal inferolateral segments. LVEF was normal in LGE+ (62±6%) and LGE- triathletes (62±5%, P=0.958). In contrast, global radial strain was lower in LGE+ triathletes at 40±7% compared with LGE- triathletes (45±7%, P<0.05). Reduced segmental radial strain occurred either in LGE+ segments or in directly adjacent segments. Strain analysis revealed regional differences in controls, with the highest radial and longitudinal strain in the inferolateral segments, which were typically affected by fibrosis in LGE+ triathletes.
CONCLUSIONS: Reduced global and regional radial strain suggests a negative effect of myocardial fibrosis on LV function in LGE+ triathletes with normal EF. The observed regional differences in controls with the highest radial and longitudinal strain in the inferolateral segments may explain the typical occurrence of fibrosis in this myocardial region in triathletes.