Exercise-induced TWN on IRLs at low work loads is a sensitive and specific index for the presence of residual viability in the infarct area. Sensitivity and diagnostic accuracy of this sign are higher for anterior infarctions.
Background and Methods. Exercise‐induced T wave normalization occurring at a low (≤ 50 watt) workload in infarct‐related electrocardiographic leads was studied in 30 consecutive patients with a recent transmural anterior acute myocardial infarction. Patients underwent both ergometric stress testing (within 30 days after the infarction) and low dose dobutamine echocardiography. The T wave normalization was considered significant when it occurred in at least two infarct‐related leads. A significant contractile reserve was considered present in an infarcted region when 50% or more of the dyskinetic segments functionally improved on exercise during dobutamine infusion. Results. Eighteen patients showed exercise‐induced T wave normalization (group 1), and 12 patients did not (group 2). Myocardial contractile reserve in the infarct area was detected in 16 patients of group 1 (88%) and in 3 patients (25%) of group 2 (p=0.004). The overall sensitivity, specificity, and diagnostic accuracy of T wave normalization, as it reflects contractile reserve in the infarct area, were 84%, 82%, and 83%, respectively. Conclusion. Low load exercise‐induced T wave normalization in infarct‐related leads appears to be an accurate marker of residual contractile reserve in the infarct area in patients with recent transmural acute anterior myocardial infarction.
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