The electrocardiogram in infarction of the anterolateral papillary muscle

An electrocardiographic syndrome has been described which allows fairly reliable prediction of the presence of infarction of the left ventricular anterolateral papillary muscle. The changes in the electrocardiogram generally fall into three major groups. One consists of moderate to marked depression of junction J in the middle and left precordial leads associated with a concavity-upward deformity of the ST-T interval. Another consists of changes in the same leads with, however, slight depression of junction J and a convexity-upward deformity of the ST-T interval and terminal inversion of the T wave. The third consists of changes in these leads with, however, an extremely marked depression of junction J, associated usually with slight initial convexity-upward deformity of the ST-T interval. The presence of apparent T-U segment depression or U-wave inversion was detectable in the majority of electrocardiograms in all three groups.