Angiographic severity in acute coronary syndrome patients with and without standard modifiable risk factors

Abstract

Background: Routine coronary artery disease (CAD) secondary prevention strategies target standard modifiable cardiovascular risk factors (SMuRFs), which include: diabetes mellitus, dyslipidemia, hypertension, and smoking. However, a significant proportion of patients with acute coronary syndrome (ACS) present without any SMuRFs. The angiographic severity of disease in this population has not yet been investigated.

Methods: After propensity score matching of patients without SMuRFs and patients with ≥1 SMuRFs (ratio 1:3), we used zero-inflated negative binomial regression modeling to investigate the relationship of SMuRF-less status with the angiographic severity of CAD, as measured by the SYNTAX score. Survival analysis was performed to investigate differences in all-cause mortality at 30 days and at the end of follow-up period.

Results: We analyzed 534 patients presenting with ACS who underwent coronary angiography. Of them, 56 (10.5%) presented without any SMuRF. After propensity score matching, the median SYNTAX score was 13.8 (IQR 0-22.1) in 56 SMuRF-less patients and 14 (IQR 5-25) in 166 patients with ≥1 SMuRFs. SMuRF-less status was associated with increased odds of zero SYNTAX score [zero-part model: odds ratio = 2.11, 95% confidence interval (CI): 1.03-4.33], but not with decreased SYNTAX score among patients with non-zero SYNTAX score (count-part model: incidence rate ratio = 0.99, 95% CI: 0.79-1.24); the overall distribution of the SYNTAX score was similar between the two groups (p = 0.26). The 30-day risk for all-cause mortality was higher for SMuRF-less patients compared to patients with ≥1 SMuRFs [hazard ratio (HR) = 3.58, 95% CI: 1.30-9.88]; however, the all-cause mortality risk was not different between the two groups over a median 1.7-year follow-up (HR = 1.72, 95% CI: 0.83-3.57).

Conclusion: Among patients with ACS, the absence of SMuRFs is associated with increased odds for non-obstructive CAD and with increased short-term mortality rates.

Keywords: SYNTAX score; acute coronary syndrome; angiographic severity; myocardial infarction; standard modifiable cardiovascular disease risk factors.

FIGURE 1

SYNTAX score distribution by the presence of SMuRFs. (A) The boxplots depict almost equal median SYNTAX score among patients with and without SMuRFs. (B) The histogram indicates the higher proportion of zero SYNTAX score in SMuRF-less patients. SMuRF, standard modifiable risk factors.

FIGURE 2

Kaplan–Meier curves depending on the presence of SMuRFs for: (A) 30-day all-cause mortality rates, (B) long-term all-cause mortality rates. SMuRF-less patients had significantly higher incidence of 30-day all-cause mortality; however, long-term mortality rates did not differ significantly among patients with and without SMuRFs. Both survival analyses included 206/224 matched participants since follow-up data were not available for the remaining ones.