Aim: Khat chewing is a common habit in Yemen and east African countries. Millions of people chew khat leaves daily for its euphoric and energetic effects and to increase alertness. Cathinone, the main active substance in fresh khat leaves, has sympathomimetic effects which increase heart rate and blood pressure. The aim was to examine the hypothesis that khat chewing is a risk factor for acute myocardial infarction (AMI) using a hospital-based matched case-control study.
Method: Between 1997 and 1999, we selected 100 patients admitted to the Al-Thawra teaching hospital Sana'a ICU, Yemen with acute myocardial infarction. 100 control subjects, matched to cases for sex and age, were recruited from the outpatients clinics of the same hospital. A questionnaire was completed for case and control groups covering personal history of khat chewing, smoking, hypertension, diabetes and any family history of myocardial infarction. A blood sample was collected for performing lipid profiles. Cases and controls were compared by analysis conducted using conditional logistic regression which corrected for baseline imbalances leading to less biased estimations of odds ratio (OR). The risk associated with each classical factor and khat chewing habits was then investigated. OR values greater than 2.5 indicated a significant risk factor.
Results: Khat chewing was significantly higher among the AMI case group than control group (OR = 5.0, 95% CI 1.9-13.1). A dose-response relationship was observed, the heavy khat chewers having a 39-fold increased risk of AMI.
Conclusion: This study indicates that khat chewing is associated with AMI and is an independent dose-related risk factor for the development of myocardial infarction.