Related Experiment Videos
Bleeding time and platelet volume in acute myocardial infarction--a 2 year follow-up study
S Dalby Kristensen1, P C Milner, J F Martin
1University Department of Medicine, Royal Hallamshire Hospital, Sheffield, UK.
Insights
In acute myocardial infarction, bleeding time shortens and platelet volume increases. Two years later, bleeding time normalizes, suggesting platelet consumption during the initial event.
Area of Science:
- Cardiology
- Hematology
- Thrombosis Research
Background:
- Acute myocardial infarction is associated with altered platelet function, including shortened bleeding time and increased mean platelet volume.
- Platelet volume distribution changes may reflect platelet activation and consumption during acute cardiac events.
Purpose of the Study:
- To investigate the long-term changes in bleeding time and platelet volume distribution in patients following acute myocardial infarction.
- To determine if these hematological parameters predict future cardiovascular events.
Main Methods:
- Prospective follow-up study of 18 patients with acute myocardial infarction and 16 controls.
- Repeated measurements of bleeding time, platelet count, and platelet volume distribution at the time of infarction and two years later.
Main Results:
- Bleeding time significantly lengthened in the myocardial infarction group at two-year follow-up (169s to 209s), while it shortened in controls (258s to 228s).
- At the time of infarction, patients showed a higher percentage of small platelets and lower percentages of medium and large platelets, suggesting consumption.
- No measured variables predicted re-infarction or death; a negative correlation between bleeding time and mean platelet volume was observed in patients with ischemic heart disease.
Conclusions:
- The shortened bleeding time in acute myocardial infarction is transient, reversing within two years.
- Changes in platelet volume distribution indicate potential consumption of medium and large platelets during the acute phase.
- Bleeding time and platelet volume parameters do not predict long-term outcomes in myocardial infarction survivors.
Abstract:
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 proceeds it, but is reversed two years later.