Mortality and Cardiovascular Outcomes in Patients Presenting With Non-ST Elevation Myocardial Infarction Despite No Standard Modifiable Risk Factors: Results From the SWEDEHEART Registry

Abstract

Background A significant proportion of patients with ST-segment-elevation myocardial infarction (MI) have no standard modifiable cardiovascular risk factors (SMuRFs) and have unexpected worse 30-day outcomes compared with those with SMuRFs. The aim of this article is to examine outcomes of patients with non-ST-segment-elevation MI in the absence of SMuRFs. Methods and Results Presenting features, management, and outcomes of patients with non-ST-segment-elevation MI without SmuRFs (hypertension, diabetes, hypercholesterolemia, smoking) were compared with those with SmuRFs in the Swedish MI registry SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies; 2005-2018). Cox proportional hazard models were used. Out of 99 718 patients with non-ST-segment-elevation MI, 11 131 (11.2%) had no SMuRFs. Patients without SMuRFs had higher all-cause and cardiovascular mortality at 30 days (hazard ratio [HR], 1.20 [95% CI, 1.10-1.30], P<0.0001; and HR, 1.25 [95% CI, 1.13-1.38]), a difference that remained after adjustment for age and sex. SMuRF-less patients were less likely to receive secondary prevention statins (76% versus 82%); angiotensin-converting enzyme inhibitors/angiotensin receptor blockade (54% versus 72%); or β-blockers (81% versus 87%, P for all <0.0001), with lowest rates observed in women without SMuRFs. In patients who survived to 30 days, rates of all-cause and cardiovascular death were lower in patients without SMuRFs compared with those with risk factors, over 12 years. Conclusions One in 10 patients presenting with non-ST-segment-elevation MI present without traditional risk factors. The excess 30-day mortality rate in this group emphasizes the need for both improved population-based strategies for prevention of MI, as well as the need for equitable evidence-based treatment at the time of an MI.

Keywords: atherosclerosis; coronary artery disease; myocardial infarction; risk factors.

Figure 1. Hazard ratios (95% CI) for SMuRF‐less versus >0 SMuRF status for 30‐day all‐cause mortality, cardiovascular mortality, recurrent myocardial infarction, heart failure, stroke, bleeding, and revascularization.

Point estimates and 95% CIs are presented. Unadjusted (A), and adjusted for sex, age, body mass index, and preadmission cardiovascular medications (B). CV indicates cardiovascular; HR, hazard ratio; MI, myocardial infarction; and SMuRF, standard modifiable cardiovascular risk factor.

Figure 2. Kaplan‐Meier survival curves for cardiovascular death (upper panels) and all‐cause death (lower panels) to 30 days for 0 SMuRFs and >0 SMuRFs for all patients and by sex.

Difference assessed by log‐rank test. CV indicates cardiovascular; and SMuRF, standard modifiable cardiovascular risk factor.

Figure 3. Kaplan‐Meier survival curves for cardiovascular death (upper panels) and all‐cause death (lower panels) for those who survived to 30 days with up to 12 years of follow‐up for 0 SMuRFs and >0 SMuRFs for all patients and by sex.

Difference assessed by log‐rank test. CV indicates cardiovascular; and SMuRF, standard modifiable cardiovascular risk factor.