In the second group are patients with impending myocardial infarction who have minimal ST segment elevation and deep T wave inversion in leads V2 and V3 and less frequently in other chest leads. Cardiac enzymes are either normal or slightly elevated. According to de Zwaan et al, this ECG finding can be a manifestation of severe proximal stenosis of the LAD and presents an increased risk for the development of extensive anterior myocardial infarction. However, because the ECG does not accurately localize the site of LAD obstruction, these patients should undergo early coronary angiography.
The limited value of the ECG to localize the site of LAD stenosis is shown in the next two figures. The ECG in Figure 2 was recorded from a patient with 90 percent mid-LAD stenosis 24 hours after a prolonged episode of rest pain. A similar ECG, with slightly less prominent repolarization abnormalities, is from a patient with unstable angina during chest pain who had a 90 percent proximal LAD obstruction (Fig 3). buy levaquin online
The third group of patients with unstable angina who are at higher risk for developing extensive anterior myocardial infarction are those with slight increase of CK-MB and intermittent ST segment elevation in leads V,-V5 and occasionally in 1 and aVL.
Figure2. Minimal ST segment elevation in lead V,, with symmetrical T wave inversion in \24 and less prominent T wave inversion in 1, aVL and VVf). The inferior leads show nondiagnostic Q waves. This ECG was recorded 24 hours after an episode of rest pain. The coronary angiography showed 90 percent obstruction of the mid LAD.
Figure 3. Symmetrical T wave inversion between 1 and 6 mm in 1, aVL, V2_s as well as Q waves in lead 2, 3, and aVF with ST segment elevation consistent with inferior myocardial infarction. The ECG changes in the inferior leads were present for the last two years. This ECG was recorded during chest pain in a patient with unstable angina who had a 90 percent proximal LAD obstruction.