"Spontaneous" platelet aggregation in whole blood in diabetic and non diabetic survivors of acute myocardial infarction.

There is increasing evidence that platelet thrombi play an important role in the pathogenesis of acute myocardial infarction (AMI). We compared "spontaneous" platelet aggregation in whole blood in 17 non-diabetic and 12 diabetic subjects on admission with AMI. There was no significant difference in the fall in platelet count between the two groups, expressed as platelets remaining (75.2 +/- 7.9% vs 77.3 +/- 6.9% at 10 min, 66.6 +/- 8.9% vs 68.5 +/- 6.3% at 20 min, 63.5 +/- 8.2% vs 64.9 +/- 6.7% at 30 min and 59.4 +/- 10.3% vs 61.3 +/- 7.6% at 60 min). The rate of "spontaneous" aggregation was increased in subjects with evidence of heart failure on admission compared to those without (59.9 +/- 7.9% vs 66.2 +/- 6.6% at 30 min [p = 0.05] and 55.4 +/- 9.6% vs 63.1 +/- 7.7% at 60 min [p = 0.04]). There was no correlation between the fall in platelet count and admission plasma glucose, glycated haemoglobin or peak aspartate amino-transferase. The subjects studied on admission with AMI had greater rates of "spontaneous" aggregation than 8 subjects studied between 6 and 12 months after acute myocardial infarction (75.9 +/- 7.4% vs 85.8 +/- 5.4% at 10 min; p = 0.001 and 64.3 +/- 7.5% vs 75.0 +/- 7.8% at 30 min; p = 0.006) and compared to normal controls (90.7 +/- 4.4% at 10 min; p < 0.001 and 83.4 +/- 6.5 at 30 min; p < 0.001). This study provides evidence of increased "spontaneous" platelet aggregation in subjects admitted with acute myocardial infarction but no difference between diabetic and non-diabetic subjects was observed.