Influence of smoking on the location of acute myocardial infarctions
Lakshman Chandra Barai
Introduction: Cigarette smoking is a major, independent risk factor for coronary heart disease (CHD) and acute myocardial infarction (AMI). The mechanism for the adverse eﬀect of cigarette smoking on the coronary arterial circulation is complex and multifactorial. Smoking increases both heart rate and blood pressure (and therefore the rate-pressure product), thereby augmenting myocardial oxygen demand. Objective: To determine whether there is an association between smoking and the location of acute myocardial infarctions. Methods: This study was done in the Department of Cardiology, National Institute of Cardiovascular Diseases and Hospital, Dhaka, Bangladesh during July 2017 to June 2018. Using a cohort from our hospital and published cohorts from Bangladesh. We calculated odds of having an inferior wall as opposed to an anterior wall acute myocardial infarction among smokers and nonsmokers. Results: In our cohort, there was a higher proportion of smokers than nonsmokers in patients with inferior acute myocardial infarctions than in patients with anterior infarctions. This diﬀerence was also present in each of the other cohorts. Odds ratios for an inferior versus an anterior acute myocardial infarction among smokers ranged from 1.15 to 2.00 (median odds ratio, 1.32). When the cohorts were combined (n=3, 160), the pooled odds ratio for an inferior as opposed to an anterior acute myocardial infarction among smokers was 1.38 (95% confidence interval, 1.20 to 1.58) (P<.002). Conclusions: Cigarette smoking increases the risk of inferior wall acute myocardial infarction more than the risk of anterior wall infarction. Smoking thus appears to adversely aﬀect the right coronary arterial circulation to a greater extent than the left coronary arterial circulation by a mechanism not yet understood.