Summary
The bleeding time is shortened and the mean platelet volume is increased in the acute
phase of myocardial infarction. In this follow-up study we repeated the measurement
of the bleeding time, the platelet count and the platelet volume distribution in 18
patients who had suffered from a definite acute myocardial infarction two years before
and in 16 control patients who had been admitted with chest pain but no definite myocardial
infarction at that time. At the time of follow-up the bleeding time was significantly
lengthened in the myocardial infarction group (median values = 169 s and 209 s respectively),
whereas it had shortened in the control group (median values = 258 s and 228 s respectively).
Comparison of the platelet volume distribution curves of the myocardial infarction
patients at time of infarction and 2 years later revealed a significantly higher percentage
of small platelets and significantly lower percentages of both medium-sized and large
platelets at the time of infarction. These changes in the platelet volume distribution
could indicate consumption of medium-sized and large platelets at the time of myocardial
infarction. None of the measured variables predicted which of the patients with acute
myocardial infarction would subsequently re-infarct or die. In the patients studied
with definite ischaemic heart disease (n = 26) a significant negative correlation
between bleeding time and mean platelet volume was found. The shortened bleeding time
in myocardial infarction is related to the acute event itself or preceeds it, but
is reversed two years later.
Keywords
Acute myocardial infarction - Bleeding time - Platelets - Platelet volume
