In the practice of percutaneous coronary intervention, post-dilation often is performed after stent deployment to improve stent expansion. However, aggressive mechanical expansion is a risk factor of distal embolization and microvascular injury, especially for patients with acute myocardial infarction (AMI). Few studies have investigated the effects of post-dilation on medium-term clinical outcomes.

Patients enrolled in the multicenter NHLBI Dynamic Registry between 2001 and 2006 were evaluated. Patients who were treated with ≥1 stent were studied. Patients with cardiogenic shock or history of coronary artery bypass graft surgery were excluded. Patients were followed up to 1 year. Because of the significant statistical interaction (P = .02) between post-dilation and AMI status on the hazard of death/myocardial infarction (MI), post-dilation effects were estimated separately for patients who did and did not present with an AMI. Among the 1,358 patients who presented with an AMI, post-dilation was associated with a significantly higher risk of death/MI (hazard ratio [HR] = 1.78, 95% CI 1.12-2.83, P = .01), not associated with the risk of repeat revascularization (HR = 1.15, 95% CI 0.81-1.62, P = .43). Among the 3,001 patients who did not present with AMI, post-dilation was not associated with risks of death/MI (HR = 1.08, 95% CI 0.77-1.50, P = .67) or repeat revascularization (HR = 1.17, 95% CI 0.93-1.47, P = .19). Similar effects were observed for the restricted analysis with additional adjustment for lesion characteristics among the 1,039 AMI patients and 2,179 non-AMI patients with a single lesion treated.

Stent post-dilation is associated with an increased risk of death/MI in AMI patients but not in non-AMI patients. Further investigation is warranted.