Coronary artery disease extent, severity and risk among active smokers, past smokers and non-smokers: a prospective study of 13,372 patients undergoing coronary CT angiography

Abstract

Objective: Although smoking is an established risk factor for major cardiac adverse events (MACE), the relative risk of current versus past smoking is poorly understood. We evaluated coronary artery disease (CAD) extent, severity and risk of MACE for active smokers and past smokers undergoing coronary CT angiography (CCTA). Methods: From a prospective multicenter international study, we enrolled patients without known CAD who underwent CCTA [2853 current smokers (21%); 3175 past smokers who quit >3 months prior to CCTA (24%); and 7344 non-smokers (55%)]. By risk-adjusted Cox proportional hazards models, adjusting for age, gender, risk-factors, segment involvement score, ≥50% stenosis, we related smoking status to incident risk of MACE, as defined by death, myocardial infarction or unstable angina. We further performed 1:1:1 propensity matching for 1000 current smokers, past smokers and non-smokers each to evaluate MACE risk amongst individuals who were of similar age, gender, CAD risk factors and symptom presentation. Results: 13372 patients (56.2±12.8 years, 51% male) were followed for 2.0±0.9 years follow-up, with 279 (2.1%) MACE occurring. Compared to non-smokers, current and past smokers had higher prevalence of obstructive CAD (≥50%) [1-vessel disease (VD); 11.2% vs. 16.6% vs. 16.2%, p<0.001, 2VD; 4.8% vs. 7.3% vs. 7.8%, p<0.001, 3VD; 2.3% vs. 5.1% vs. 5.0%, p<0.001]. Current smokers experienced higher risk of MACE compared to non-smokers (HR 1.9, 95% CI 1.4-2.5, p<0.001), while past smokers did not (HR 1.2, 95% CI 0.9-1.6, p=0.29). Even amongst matched individuals, current smoking was associated with MACE risk (HR 2.3, 95% CI 1.2-4.4, p=0.01), while past smoking was not (HR1.0, 95% CI 0.5-2.1, p=0.98). Conclusion: While both current and past smokers possess a greater prevalence, extent and severity of CAD compared to non-smokers, current smokers experience higher risk of MACE than past smokers and non-smokers.