Circadian Pattern of Acute Myocardial Infarction Symptom Onset and Associated Clinical Outcomes Among Habitual Khat Chewers: A Prospective Observational Study from Yemen

Objective: This study aimed to investigate the circadian pattern of AMI symptom onset among habitual khat chewers and to evaluate differences in clinical presentation, angiographic findings, and in-hospital outcomes according to periods of active khat exposure. Methodology: This prospective observational study enrolled 200 consecutive habitual khat chewers with confirmed AMI who were admitted to the Cardiac Center of Al-Thawra General Teaching Hospital, Sana’a, Yemen, between January and September 2024. Symptom onset times were analyzed across the 24-hour cycle and categorized into a khat-inactive period (00:01–14:59) and a khat-effective period (15:00–00:00). Results: AMI symptom onset demonstrated a non-uniform circadian distribution, with clustering during the early morning and late evening/night hours. Of the 200 participants, 109 (54.5%) experienced symptom onset during the khat-effective period and 91 (45.5%) during the khat-inactive period, with no significant difference in overall distribution (p = 0.203). Baseline demographic, clinical, behavioral, and angiographic characteristics were largely comparable between groups. However, acute heart failure occurred significantly more frequently among patients presenting during the khat-effective period than among those presenting during the khat-inactive period (14.7% vs. 5.5%, p = 0.035). Similarly, cardiogenic shock was more common during the khat-effective period (12.8% vs. 2.2%, p = 0.006). No independent clinical or behavioral predictors of symptom onset during the khat-effective period were identified in multivariable analysis. Conclusions: Among habitual khat chewers, AMI symptom onset exhibited a distinctive circadian pattern characterized by clustering during the early morning and late evening/night hours. Although the overall distribution of events did not differ significantly between khat activity periods, symptom onset during the khat-effective period was associated with a higher incidence of acute heart failure and cardiogenic shock.