Radionuclide assessment of infarct size and left ventricular function in clinical trials of thrombolysis.

Mortality, left ventricular ejection fraction, and infarct size are important end points in evaluating the efficiency of thrombolytic treatment in clinical trials. Radionuclide assessment of ejection fraction and infarct size is safe, accurate, reproducible, and readily available. Its use in clinical trials supplements mortality data and allows meaningful results in trials with smaller patient numbers. Single photon emission computed tomography improves the detection and quantification of infarct size, and its use with new radiopharmaceuticals will assume an important role in future trials. For an 8-year period, these radionuclide techniques have been used in the Western Washington Thrombolysis Trials and have generally shown smaller infarct size and higher ejection fractions in patients receiving streptokinase and tissue-type plasminogen activator. However, in the most recent trial there was no direct relation between these end points and the time between symptom onset and initiation of treatment. Future trials that direct efforts to treatment in the first hour after symptom onset should further clarify this observation.