Silent left ventricular dysfunction during routine activity after thrombolytic Therapy for acute myocardial infarction

To investigate prospectively the occurrence and significance of postinfarction transient left ventricular dysfunction, 33 ambulatory patients who underwent thrombolytic therapy after myocardial infarction were monitored continuously for 187 ± 56 min during normal activity with a radionuclide left ventricular function detector at the time of hospital discharge. Twelve patients demonstrated 19 episodes off transient left ventricular dysfunction (>0.05 decrease in ejection fraction, lasting ≥ 1 min), with no change in heart rate. Only two episodes in one patient were associated with chest pain and electrocardiographic changes. The baseline ejection fraction was 0.52 ± 0.12 in patients with transient left ventricular dysfunction and 0.51 ± 0.13 in patients without dysfunction (p = NS). At follow-up study (19.2 ± 5.4 months), cardiac events (unstable angina, myocardial infarction or death) occurred in 8 of 12 patients with but in only 3 of 21 patients without transient left ventricular dysfunction (p < 0.01). During submaximal supine bicycle exercise, only two patients demonstrated a decrease in ejection fraction >0.05 at peak exercise; neither had a subsequent cardiac event. These data suggest that transient episodes of silent left ventricular dysfunction at hospital discharge in patients treated with thrombolysis after myocardial infarction are common and associated with a poor outcome. Continuous left ventricular function monitoring during normal activity may provide prognostic information not available from submaximal exercise test results.