Patients were queried about their smoking habits at base line and during follow-up; a patient reporting any cigarette smoking in the prior six months was considered a smoker. The study population was divided into four groups on the basis of smoking status at base line: nonsmokers, defined as patients who had never smoked cigarettes regularly; former smokers, those who had quit smoking at least six months before the index procedure; quitters, those who permanently quit smoking immediately after the index procedure; and persistent smokers, those who smoked before and after the index procedure. The small number of patients (13) who first started to smoke during the follow-up period were excluded from our analysis