Difference in risk factors between acute coronary syndrome and stable angina pectoris in the Japanese: smoking as a crucial risk factor of acute coronary syndrome

Background and purpose: Metabolic syndrome and chronic kidney disease (CKD) have received attention as new risk factors for cardiovascular disease. This study evaluated differences in key risk factors between acute coronary syndrome (ACS) and stable angina pectoris (SAP) by using traditional coronary risk factors, metabolic syndrome, and CKD.

Methods: Among 1890 consecutive patients admitted to our institution, we studied 140 patients with initially diagnosed ACS and 163 patients with initially diagnosed SAP and compared risk factors between the two groups. Next, the relationship between smoking status after the initial diagnosis of coronary artery disease (CAD) and the incidence of subsequent cardiac event was examined after discharge in 284 patients.

Results: Adjusted multivariate analysis showed that only current smoking was an independent predictor of ACS (odds ratio, 2.20; 95% CI, 1.28-3.78; p=0.004) among all risk factors we examined. Treatment with a calcium-channel blocker had a preventive effect on ACS (odds ratio, 0.44; 95% CI, 0.26-0.75; p=0.003), but treatment with a beta-blocker did not. Patients who continued to smoke after CAD was diagnosed had a risk of cardiac events about 5 times that of smokers who quit (adjusted hazard ratio, 5.05; 95% CI, 1.33-19.20; p=0.02).

Conclusions: The risk factors were significantly different between initially diagnosed ACS and SAP. Smoking was a more important risk factor of initially diagnosed ACS. Smoking cessation might have a preventive effect on subsequent cardiac events. Also, we found that treatment with a calcium-channel blocker would help prevent ACS in Japanese patients.