ST-segment elevation acute myocardial infarction in young people: influence of age in the smoke paradox

Abstract

Introduction and objectivesSmoking has been related with lower short-term mortality among patients with acute myocardial infarction. This may be caused by different baseline characteristics, since smokers are significantly younger at the time of infarction. Our purpose was to study the smoking paradox focusing on age. MethodsWe retrospectively studied 118 consecutive people aged<45 years and compared them to 236 patients aged 45–75 years, matched by sex and date of admission; all were admitted with an ST-segment elevation acute myocardial infarction (STEMI). Baseline characteristics, treatment patterns, cardiac catheterization parameters, in-hospital and 30 day-outcomes were thoroughly assessed and adjusted to the habit of smoking. ResultsArterial hypertension and diabetes mellitus, were more frequent in the older group (P<.005). Advanced Killip grade on admission (P=.030) and decreased creatinine clearance (P < 0.001) were more frequent in the ≥ 45-year cohort. The younger cohort displayed a trend to have higher pre/post PCI TIMI 3 percentages, collaterals and a good myocardial perfusion after PCI. Stratifying by smoking habit, non-smokers presented more frequently hypertension (P=.037), diabetes (P=.039), higher Killip degrees and less TIMI 3 post-PCI (P=.078). Thus, the combined event (MACE) and reinfarctions tended to be more frequent in non-smokers (P=.052 and P=.055). The overall multivariate model revealed a 30-day MACE-relationship with smoking habit (OR, 0.918; 95%CI, 0.854–0.987, P=.020). ConclusionsYoung smokers maintained the lower short-term events paradox. Our findings can contribute to explain the apparently different course of myocardial infarction in young people and point out a different mechanism of infarction in smokers.