POSITIVE MICROVOLT T-WAVE ALTERNANS IS ASSOCIATED WITH
ORGANIC HEART DISEASE IN PATIENTS WITH VENTRICULAR ARRHYTHMIAS AND RIGHT
VENTRICULAR OUTFLOW TRACT PATTERN.
D. Malaspina, F. Casazza, G. Guenzati, M. Pala, M. Bernasconi, M.
Marzegalli.
UO Cardiologia, Ospedale S.Carlo Borromeo, Milan, Italy.
Background. It is commonly believed
that occurrence of ventricular arrhythmias (VA) with a left bundle branch block
(LBBB) and inferior axis suggests a right ventricular outflow tract (RVOT) or,
less commonly, a left ventricular outflow tract origin. Such arrhythmias are
not considered a marker of organic heart disease and therefore should have a
benign prognosis, though it is well-known that a similar aspect could be seen
in arrhythmogenic right ventricular dysplasia (ARVD).
Methods. Since microvolt T wave alternans
(MTWA) can identify patients at higher risk of death, either after a myocardial
infarction or in dilated cardiomyopathy, we submitted to such examination 18
pts (13 males and 5 females, mean age 45 years) showing VA and a RVOT pattern:
13 presented with frequent and isolated monomorphic ectopic beats, 4 with
nonsustained and 1 sustained ventricular tachycardia. The entire group
performed echocardiography, Holter and exercise stress testing, while
myocardial SPECT imaging, magnetic resonance and coronaroangiography were
obtained whenever necessary to complete diagnostic assessment.
Results. MTWA was
positive in 4 pts, negative in 11 and undetermined in 3 (always due to several
disturbing ectopic beats during test). All pts with negative test had no
evidence of structural heart disease while in all positive-test pts we
discovered some organic abnormalities: one past myocarditis, one significant
stenosis of right coronary artery, one "minor" ARVD, one hypertensive
heart disease. All positive patients presented simply with isolated ectopic
beats.
Conclusions.1) Among patients with VA and
a RVOT pattern, positive MTWA was detected solely in pts with organic heart
disease; 2) The relatively high number of indetermined results could represent
a limitation of the test; 3) The clinical prognostic significance of a positive
test remains to be determined in a follow-up study.