Correlation
between T wave alternans and endomyocardial biopsy findings in patients with
dilated cardiomyopathy
Markus Zabel
Authors: Heinz P Schultheiss; Christian Sticherling; Michel Noutsias; Uwe Kühl;
Markus Zabel; Steffen Behrens
2:15 - 2:30
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Background and Objective:
Patients (pts) with dilated cardiomyopathy (DCM) frequently suffer from
malignant ventricular arrhythmias. T wave alternans (TWA) testing has been
proposed for risk stratification, however, the genesis of the high incidence
of positive (pos) TWA in DCM pts is as yet unknown. Fibrosis and
immunohistochemically proven intramyocardial inflammation in endomyocardial
biopsies (EMB) are common features of DCM patients. We therefore hypothesized
that TWA positivity is related to pathological EMB findings in DCM. Methods:
TWA was assessed in n=103 DCM pts (LVEF: 38 +/- 16%) utilizing the Cambridge
Heart exercise method. Pos TWA was defined as a TWA amplitude > 1.9 mV for
> 1 min in > 1 ECG lead. Tracings were graded "indeterminate"
if noise or premature ventricular beats prevented definite classification
into pos or negative (neg) TWA or the heart rate threshold was not reached. Fibrosis
was assessed with standardized histological techniques, and intramyocardial
inflammation (CD2/CD3+ T-lymphocyte infiltrates >7.0 mm2, abundance of
cell adhesion molecules/CAMs: HLA class I, HLA DR, ICAM-1) was analyzed
immunohistochemically, respectively. Results: In 51/103 pts (50%), TWA was
graded pos, in 41/103 pts (40%) TWA was found neg, while the remaining tests
were indeterminate. Significantly increased CD2/CD3+ T-lymphocytes were found
in 22/103 EMB specimens, 64/103 (62%) demonstrated CAMs abundance, and 68/103
patients (66%) showed interstitial fibrosis, respectively. TWA positivity was
significantly associated with LVEF (47 +/- 13% if TWA neg, vs. 27 +/- 9% if
TWA pos, vs. 42 +/- 12% if TWA indeterminate, p = 0.004). However, the TWA
finding did not correlate with interstitial fibrosis (yes/no: 35/68=51% vs.
16/35=46% pos TWA, p=ns), T-lymphocytic infiltration (CD2/CD3+ infiltrates
yes/no: 12/22=55% vs. 39/81=48% pos TWA, p=ns) and CAMs abundance (yes/no:
28/64=44% vs. 23/39=59% pos TWA, p=ns). Conclusions: TWA testing yields a pos
finding in 50% of DCM pts. The TWA result is unrelated to histological and
immunohistological EMB findings (fibrosis and intramyocardial inflammation)
but particularly depends on LVEF. |