Platelet aggregability and occurrence of restenosis following coronary angioplasty

Restenosis following percutaneous coronary angioplasty (PTCA) is a complex medical problem occurring in nearly a third of the patients undergoing PTCA with no single definite predictor demonstrated in an individual patient. Platelets are known to play an important role in the pathogenesis of the restenotic process. However, no known parameter of platelet function or activity has been studied as a risk factor predicting the occurrence of restenosis. We prospectively assessed platelet activation in twenty two consecutive patients with stable angina who underwent a successful PTCA for single vessel coronary artery disease. Platelet activation levels were measured using aggregability curves derived from unclotted blood samples on a platelet aggregometer using varying concentrations of adenosine di-phosphate (ADP) in the following time sequence: (1) Basal i.e. pre-PTCA, (2) post-PTCA day 1, (3) post-PTCA day 7, and (4) post-PTCA day 28. Occurrence of restenosis was studied using angiographic follow-up in all patients. At follow-up, seven of the twenty two patients studied developed restenosis. There was no significant difference or any specific trend noted over time in the levels of platelet aggregability in the study group as a whole (basal: 30.0±15.4%, post-PTCA day 1: 32.5±16.1%, post-PTCA day 7: 34.6±15.4% and post-PTCA day 28: 32.6±16.1%). However, when the patients were subgrouped into those with and without restenosis, the patients with restenosis had a significantly higher basal platelet aggregability (38.7±16.3%) versus those who did not develop restenosis (25.0±12.1%), p=0.0128. We conclude that patients developing restenosis after PTCA have a significantly higher basal platelet aggregability and this could be used as a marker for its occurrence in an individual patient.