Frequency of Dual Anti Platelet Resistance in Patients with Coronary Artery Disease

Objectives: To find the frequency of dual antiplatelet resistance in patients with coronary artery disease. Material and Methods: This study was conducted in the Department of Cardiology, Lady Reading Hospital, Peshawar, from January 2007 to February 2008. A total of 105 normal individuals not taking any anti platelet drug and 108 patients taking dual anti platelet drugs for coronary artery diseases were included. Blood was taken for measuring platelet aggregation using whole blood aggregometer and results were recorded on a proforma. Patients who were on warfarin and heparin were excluded from the study. Chi-square and independent t-test were used to find significant differences between different groups and variables. Results: Platelet aggregability in 105 normal subjects, not taking aspirin was 9.28±3.23ohms. So cutoff for dual anti platelet non responsiveness was taken as 9.28-3.23=6.0 ohms. Patients who were taking dual antiplatelets were 108. Their mean age was 51.94±8.36 years. Male were 64(59.3%) and female were 44(40.7%). Mean aggregability of all these patients was found to be 3.91±3.50 ohms. Patients having aggregability of >6 ohms (dual antiplatelets resistance) were 29.6% (n=32), while patients having aggregability of < 6 ohms (dual antiplatelets sensitive) were70.4% (n=76). Mean aggregability of sensitive patients was 2.06±1.76 ohms, while mean aggregability of resistant patients was 8.31±2.55 ohms. Mean aggregability of all the male patients was 4.00±3.38 ohms, while mean aggregability of female patients was 3.79±3.70 ohms. (p=0.769). When age was correlated with aggregability, both have a weak positive correlation r= .121(p=0.213). Conclusion: Dual anti platelet resistance as defined by inhibition of platelet aggregation measured with Whole Blood Aggregometery, is a common problem. Gender and age has no significant affect on platelet aggregability.