Introduction: Smoking is a major risk factor for heart disease. When combined with other risk factors (such as unhealthy blood cholesterol levels, high blood pressure, and overweight or obesity) smoking further raises the risk of heart disease.
Hypothesis: We tested the hypothesis that smoking has an impact on cardiovascular event risk in angiographied coronary patients.
Methods: We enrolled 1804 consecutive patients undergoing coronary angiography for the evaluation of established or suspected stable coronary disease (CAD). Patients who had smoked within 30 days prior to angiography were considered current smokers. Prospectively, cardiovascular events were recorded over a mean follow-up time of 6.3±3.7 years.
Results: At baseline, both in patients with T2DM (n=522; 28.9% of the study population) and in nondiabetic subjects the prevalence of a past (44.1 and 39.5%; p=0.035), and, albeit less so, of current smoking (18.0 and 17.7%; p = 0.247) was high. Among patients with T2DM the prevalence of significant CAD with lumen narrowing ≥50% was 61.0% in those who had never smoked vs. 70.9%, p=0.032 and 70.8%, p=0.101 in past and current smokers, respectively. Among nondiabetic patients the corresponding prevalence rates of significant CAD were 45.9% vs. 63.8%, p<0.001 and 53.7%, p=0.046, respectively. Prospectively, current smoking independently predicted cardiovascular events after multivariate adjustment including baseline CAD in patients with diabetes (HR 1.93 [1.20-3.08]; p=0.006) as well as in nondiabetic patients (HR 1.50 [1.07-2.09]; p=0.019), whereas past smoking neither in patients with T2DM nor in nondiabetic subjects was associated with cardiovascular events (HRs 1.07 [0.74-1.55]; p=0.715 and HR 1.11 [0.87-1.41]; p=0.415). An interaction term diabetes x current smoking was not significant (p=0.350), indicating that current smoking was equally predictive of cardiovascular events in patients with T2DM and in nondiabetic subjects.
Conclusions: We conclude that current but not past smoking strongly increases cardiovascular event risk in angiographied coronary patients with diabetes independently from the baseline CAD state.