Current but not past smoking increases the risk of cardiac events: insights from coronary computed tomographic angiography

Abstract

Aims: We evaluated coronary artery disease (CAD) extent, severity, and major adverse cardiac events (MACEs) in never, past, and current smokers undergoing coronary CT angiography (CCTA).

Methods and results: We evaluated 9456 patients (57.1 ± 12.3 years, 55.5% male) without known CAD (1588 current smokers; 2183 past smokers who quit ≥3 months before CCTA; and 5685 never smokers). By risk-adjusted Cox proportional-hazards models, we related smoking status to MACE (all-cause death or non-fatal myocardial infarction). We further performed 1:1:1 propensity matching for 1000 in each group evaluate event risk among individuals with similar age, gender, CAD risk factors, and symptom presentation. During a mean follow-up of 2.8 ± 1.9 years, 297 MACE occurred. Compared with never smokers, current and past smokers had greater atherosclerotic burden including extent of plaque defined as segments with any plaque (2.1 ± 2.8 vs. 2.6 ± 3.2 vs. 3.1 ± 3.3, P < 0.0001) and prevalence of obstructive CAD [1-vessel disease (VD): 10.6% vs. 14.9% vs. 15.2%, P < 0.001; 2-VD: 4.4% vs. 6.1% vs. 6.2%, P = 0.001; 3-VD: 3.1% vs. 5.2% vs. 4.3%, P < 0.001]. Compared with never smokers, current smokers experienced higher MACE risk [hazard ratio (HR) 1.9, 95% confidence interval (CI) 1.4-2.6, P < 0.001], while past smokers did not (HR 1.2, 95% CI 0.8-1.6, P = 0.35). Among matched individuals, current smokers had higher MACE risk (HR 2.6, 95% CI 1.6-4.2, P < 0.001), while past smokers did not (HR 1.3, 95% CI 0.7-2.4, P = 0.39). Similar findings were observed for risk of all-cause death.

Conclusion: Among patients without known CAD undergoing CCTA, current and past smokers had increased burden of atherosclerosis compared with never smokers; however, risk of MACE was heightened only in current smokers.

Keywords: Coronary atherosclerosis; Coronary computed tomographic angiography; Major adverse cardiovascular risk; Smoking risk.

Figure 1

(A) Risk-adjusted event-free survival curves for major adverse cardiac event among never, past, and current smokers (n = 9456). (B) Risk-adjusted event-free survival curves for all-cause death among never, past, and current smokers (n = 9456). Adjusted for age, gender, symptoms, dyslipidemia, hypertension, diabetes, family history, all chest symptoms, segment involvement scores, and stenosis severity ≥50%. MACE, major adverse cardiac events.

Figure 2

(A) Risk-adjusted Cox proportional-hazards models for major adverse cardiac event by SIS 0, 1–5, and >5 among never, past, and current smokers (n = 9456). (B) Risk-adjusted Cox proportional-hazards models for major adverse cardiac event by normal, non-obstructive, and obstructive CAD among never, past, and current smokers (n = 9456). Adjusted for age, sex, symptoms, dyslipidemia, hypertension, diabetes, family history, and all chest symptoms. MACE, major adverse cardiac events; SIS, segment involvement score; CAD, coronary artery disease. *P < 0.001 and **P < 0.05 for the comparison with never smokers with normal coronary CT angiography.

Figure 3

(A) Risk-adjusted event-free survival curves for major adverse cardiac event among matched never, past, and current smokers (n = 3000). (B) Risk-adjusted event-free survival curves for all-cause death among matched never, past, and current smokers (n = 3000). Adjusted for age, gender, symptoms, dyslipidemia, hypertension, diabetes, family history, all chest symptoms, segment involvement scores, and stenosis severity ≥50%. Abbreviations as in Figure 1.