A prospective study of the diagnostic value of urinary thromboxane in patients presenting with acute chest pain.

In chance single-case observations thromboxane excretion has been reported to increase several days prior to myocardial infarction. To test its frequency and potential diagnostic value we prospectively measured thromboxane excretion in 166 consecutive patients who had presented to the emergency unit with acute chest pain indicative of ischaemia. Thromboxane excretion at presentation was increased, sometimes dramatically, in 17 of 33 (52%) patients with unstable angina, in 42 of 73 (57%) patients with definite myocardial infarction, but in only two of 14 (14%) patients with stable angina. Nineteen of 29 patients undergoing early angiography had detectable intracoronary thrombi, and these patients excreted significantly more thromboxane than patients without thrombi. Ongoing platelet activation may be detected by increased thromboxane excretion in more than 50% of the patients presenting with unstable angina and myocardial infarction, particularly in those with intracoronary thrombi, but it is not a general phenomenon that can be used in diagnosis.