Background: Coronary artery disease is mainly caused by atherosclerosis and its complications. Platelets and their activity have an important role in initiation of atherosclerotic lesions and coronary thrombus formation. Larger platelets are enzymatically and metabolically more active and have a higher potential thrombotic ability as compared with smaller platelets. Variation in platelet size (anisocytosis) can be measured by Platelet distribution width.

Aim: To study the changes in platelet distribution width in patients with stable coronary artery disease and acute myocardial infarction.

Material and method: A total of 200 cases were studied, 100 patients were of acute myocardial infarction (AMI) and 100 patients were of stable coronary artery disease consisting of those who were either admitted for coronary angiography or who had AMI at least 5weeks prior. Venous samples were drawn and collected in standardized EDTA sample tubes. Platelet count and platelet volume indices were assayed using BECKMAN COULTER (USA) LH–750 auto–analyzer with regular quality control and the results were analyzed using appropriate statistics.

Results: Platelet distribution width (PDW) and Mean platelet volume (MPV) were found to be increased in AMI patients (17.89±0.61fl and 9.86±1.27 fl respectively) as compared to stable CAD patients (16.51±0.34fl and 8.55±0.81fl respectively). The difference was found to be statistically significant for PDW and MPV among the two groups.

Conclusion: The study concludes that Platelet Indices especially MPV & PDW is raised in patients suffering from AMI as compared to stable CAD patients and they can be used for predicting impending acute coronary events.