Immunohistological findings
Myocardial infiltration with large amounts of macrophages and T-cells is
regularly observed in ICM [8] and was also present in ICM patients
in our group. Patients fulfilling the criteria of TCM had a distinct
pattern compared to ICM patients. The presence of macrophages and
T-cells was significantly lower in the TCM group and more comparable to
alterations seen in DCM patients. These findings are in some contrast to
a study of EMB results in TCM patients, where the authors demonstrated a
macrophage-dominated myocardial inflammation [8], which has been
described in animal studies as well [20]. These differences to our
results might be, at least in part, explained by the relatively short
duration of tachycardia in our cohort, which was 25 % shorter compared
to the animal studies; Mueller and colleagues did not report the
duration of symptoms [8]. However, the relationship between
arrhythmia to cardiomyopathy and the development of symptoms is
difficult to determine because an arrhythmia could exist for a long time
before its recognition and before TCM develops [18]. A study of 24
patients with TCM and HF, the median time from onset of arrhythmia to
cardiomyopathy, and the development of HF was 4.2 years [21]. Also,
in animal rapid atrial pacing TCM-models, there is a compensatory phase
whereby LV dilatation, extracellular matrix remodeling, and neurohumoral
activation occurs, but severe LV dysfunction does not. This phase is
followed by a phase in which LV dysfunction becomes manifest and
associated with defects in excitation-contraction coupling and LV
myocyte remodeling and dysfunction [18]. So, the time point of EMB
during the disease course will most probably have a significant impact
on the results of the immunohistochemical analysis.