THE UNSTABLE ST SEGMENT EARLY AFTER THROMBOLYSIS FOR ACUTE INFARCTION AND ITS USEFULNESS AS A MARKER OF RECURRENT CORONARY-OCCLUSION

To investigate the incidence of early recurrent ST elevation after intravenous thrombolytic therapy for acute myocardial infarction, 12-lead electrocardiograms were continuously monitored for 571 +/- 326 minutes in 31 patients presenting within 4 hours of symptom onset. The study group comprised 9 women and 22 men (mean age +/- standard deviation 53 +/- 12 years), with ST elevation (anterior in 15, inferior in 16) on the initial electrocardiogram, who were given either tissue plasminogen activator (22 patients) or streptokinase (9 patients). Angiography was performed in 30 of 31 patients at 7 to 10 days. Early (< 3 hours) resolution of ST elevation occurred in 19 patients (61%) at a median of 94 minutes (interquartile range 57 to 113) after thrombolysis, whereas 12 (39%) had no or late (> 6 hours) resolution. Eleven of the 19 with early resolution (58%) had either transient (5 patients) or sustained (6 patients) recurrences of ST elevation. Recurrent ST elevation was equal to or more than the initial peak elevation in 9 of 11 patients, and > 75% of initial peak in 2. A total of 25 episodes of recurrent ST elevation were observed in the 11 patients (19 transient and 6 sustained episodes), of which 8 (32%) were silent. The proportion of silent episodes was similar for transient (35%) and sustained (33%) recurrences. All patients with sustained recurrent ST elevation has at least 1 preceding transient recurrence. The median duration of transient recurrent ST elevation was 43 minutes (28 to 63). The median time from initiating thrombolysis to the first transient recurrence was 151 minutes (40 to 192), and 328 minutes (120 to 704) to sustained recurrence. Recurrent ST elevation was associated with a delay in time to peak creatine kinase, and sustained recurrent ST elevation was associated with reduced arterial patency and worse residual stenosis at 7- to 10-day angiography. Recurrent ST elevation occurred in 10 of 15 patients with early ST resolution given tissue plasminogen activator despite conventional heparin therapy administered to 9. Transient recurrent ST elevation after ST resolution from thrombolysis is common, may be silent or prolonged, and may presage sustained recurrent ST elevation. This marked lability of ST segments probably represents recurrent coronary occlusion.