Current cigarette smoking is an independent risk factor for subacute stent thrombosis in acute myocardial infarction patients

Abstract

Background: Acute myocardial infarction (AMI) is prevalent and has serious consequences including re-infarction and death. Cigarette smoking is a coronary risk factor for AMI, although a "smoker's paradox" for AMI has been reported in Western countries. On the other hand, some researchers have reported that smoking is associated with subacute stent thrombosis (SAST) after AMI. However, the occurrence of this condition is not well documented in Japan. The aim of this study was to clarify how prior smoking status may affect prognosis, including SAST, in Japanese patients with AMI.

Methods: A total of 266 consecutive patients with AMI were enrolled retrospectively in the study if they had undergone emergency coronary intervention (bare metal stent) within 24h of symptom onset, and had a 5-10 month follow-up examination. The patients were divided into three groups based on their cigarette smoking status (non-smokers, past smokers, and current smokers).

Results: Current smokers were significantly younger than the other two groups, although their levels of low density lipoprotein-cholesterol and triglyceride were significantly higher. White blood cell count and hemoglobin level on admission were also significantly higher in current smokers compared with the other two groups. The incidence of SAST was significantly higher in current smokers than in the other groups, although the occurrence of heart failure after AMI was similar in the three groups. On the other hand, improvement in left ventricular ejection fraction was observed in non-smokers and past smokers, but not in current smokers. Multiple logistic analysis revealed that current smoking was an independent risk factor for SAST (odds ratio 5.4; p<0.05). Current smokers were about five times more likely to have a SAST compared with non-smokers.

Conclusions: These findings indicate that current cigarette smoking predicts SAST after primary percutaneous coronary intervention for AMI in Japanese patients.

Keywords: Acute myocardial infarction; Current smoker; Subacute stent thrombosis.