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.