Impact of smoking on cardiac magnetic resonance infarct characteristics and clinical outcome in patients with non-ST-elevation myocardial infarction

Data derived from several studies suggest a better survival in smokers with acute myocardial infarction, a phenomenon referred to as the ‘smoker’s paradox’. We aimed to investigate the association of smoking with cardiac magnetic resonance (CMR) imaging determined infarct severity and major adverse cardiac events (MACE) defined as the occurrence of death, reinfarction, and congestive heart failure at 12 months in patients with non-ST-elevation myocardial infarction (NSTEMI) reperfused by early percutaneous coronary intervention (PCI). In this multicenter, registry study 311 NSTEMI patients underwent CMR imaging 3 (interquartile range [IQR] 2–4) days after PCI. Myocardial salvage index (MSI), infarct size (IS), and microvascular obstruction (MVO) as well as MACE rate were compared according to admission smoking status. Approximately one-third of patients were current smokers (n = 122, 39%). Smokers were significantly younger and less likely to have hypertension as compared to non-smokers (all p < 0.05). The extent of MSI (63.2, IQR 28.9–85.4 vs. 65.6, IQR 42.2–82.9, p = 0.30), and IS (7.2, IQR 2.3–15.7%LV vs. 7.0, IQR 2.2–12.4%LV, p = 0.27) did not differ significantly between smokers and non-smokers. Despite similar prevalence of MVO, MVO (%LV) was higher in smokers compared to non-smokers (2.0, IQR 0.9–4.7%LV vs. 1.2, IQR 0.7–2.2%LV, p = 0.03). MACE rates at 12 months were comparable in smokers and non-smokers (5.7% vs. 7.4%, p = 0.65). In NSTEMI patients, smoking is neither associated with increased myocardial salvage nor less severe myocardial damage. Clinical outcome at 12 months was similar in smokers and non-smokers.