Aims: The differential diagnosis of patients with early non-ischaemic dilated cardiomyopathy (DCM) and those with physiological adaptation to exercise ('athlete's heart') may be difficult as many of the morphological adaptations are shared in the two conditions. Increased physical fitness is becoming more common in later adulthood, a group in whom there may be even more diagnostic difficulty. We hypothesized that tissue characterization using cardiovascular magnetic resonance (CMR) T1 and T2 mapping would be able to differentiate between patients with left ventricular (LV) dilatation due to early DCM and exercisers.
Methods and results: Fifty-eight middle-aged males [21 healthy controls, 21 males with a history of aerobic exercise and LV ejection fraction (LVEF) 45-55%, and 16 patients with DCM and LVEF 45-55%] underwent a CMR protocol including T1 and T2 mapping and calculation of extracellular volume (ECV) using a 1.5 T MRI scanner. Native T1, ECV, and T2 relaxation times were significantly increased in DCM patients compared with controls (native T1 1017 ± 42 vs. 952 ± 31 ms, P < 0.001; ECV 31.2 ± 4.1 vs. 26.2 ± 2.9%, P = 0.003; T2 55.9 ± 4.4 vs. 52.9 ± 3.3 ms, P = 0.05) and exercisers (native T1 957 ± 32 ms, P < 0.001; ECV 26.3 ± 3.6%, P = 0.004; T2 52.8 ± 3.2 ms, P = 0.042). Using multivariable logistic regression, native T1 gave the best differentiation between exercisers and sedentary patients with early DCM (area under the curve 0.91).
Conclusion: T1 and T2 mapping are potentially useful tools for differentiating between athlete's heart and patients with early DCM, and could be used whenever differentiation between these two phenotypes is inconclusive using standard imaging techniques.
Keywords: Athletes; Cardiovascular magnetic resonance; Dilated cardiomyopathy; T1 mapping; T2 mapping.
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