Women without CV risk factors have the highest mortality risk after STEMI
Mortality in STEMI patients without standard modifiable risk factors: a sex-disaggregated analysis of SWEDEHEART registry data
Introduction and methods
Targeted therapies against standard modifiable cardiovascular risk factors (SMuRFs; hypertension, diabetes, hypercholesterolemia, and smoking) have led to improvements in the prevention and treatment of coronary artery diseases [1,2]. However, ST-elevation myocardial infarction (STEMI) in patients without modifiable risk factors is not uncommon . Several studies have shown an increase in the proportion of SMuRF-less patients who present with STEMI [3-6]. Data on the characteristics and outcomes of SMuRF-less patients is often missing in clinical trial publications. This study examined the characteristics and outcomes in STEMI patients without SMuRFs using data from the SWEDEHEART registry.
The SWEDEHEART registry enrolls all patients with MI admitted to cardiac care units in Sweden. This study analyzed data from 62048 patients (32.9% women) who were ≥18 years, presented with suspected ACS, and had a hospital diagnosis of STEMI. Patients with a known history of CAD (PCI, CABG, or MI) were excluded. Of the 62048 patients, 9228 (14.9%) were SMuRF-less. The primary outcome was all-cause mortality at 30 days after STEMI. Secondary outcomes included MACE, CV mortality, rehospitalization for HF, stroke, coronary revascularization, major bleeding, and in-hospital cardiogenic shock. Median follow-up was 4.9 (IQR 1.8-8.5) years.
- The SMuRF-less group had significantly higher concentrations of troponins and significantly lower LVEF, compared with patients with at least 1 SMuRF. However, the SMuRF-less group received less prescriptions for ACEi or ARBs and β-blocker, compared with patients with SMuRFs (ACEi or ARBs: 6261/8324 [75.2%] vs. 40444/49343 [82.0%], P<0.0001; β-blocker: 7382/8324 [88.7%] vs. 44914/49333 [91.0%, P<0.0001). The difference in prescriptions for ACEi/ARB or β-blocker was greatest for SMuRF-less women, compared to women with ≥1 SMuRF (ACEi or ARBs: 1261/1872 [69.0%] vs. 12905/16469 [78.4%]; β-blocker: 1557/1827 [85.2%] vs. 14793/16464 [89.9%]). Patients without SMuRFs were also less likely to receive a prescription for a statin at discharge compared to those with SMuRFs (7597/8942 [85.0%] vs 45876/51812 [88.5%], P<0.0001).
- Unadjusted rates of in-hospital death, cardiogenic shock and combined MACE were significantly higher in the SMuRF-less group compared to patients with ≥1 SMuRF (in-hospital death: 9.6% vs 6.5%, P<0.0001; cardiogenic shock: 6.3% vs 4.1%, P<0.0001; combined MACE: 30.2% vs 28.9%, P=0.0095).
- All-cause mortality at 30 days after STEMI presentation was significantly higher in SMuRF-less patients than in patients with ≥1 SMuRF (1104/9228 [11.3%] vs. 4149/52820 [7.9%]; HR 1.47, 95%CI 1.37-1.57, P<0.0001). This disparity appeared to be caused by CV mortality, as the rates of recurrent MI and stroke were similar between groups, and rates of HF rehospitalization and revascularization were lower in patients without SMuRFs, compared to patients with SMuRFs. The increased risk of 30-day all-cause mortality in SMuRF-less patients remained significant after adjustment for age, sex, LVEF, creatinine, and BP.
- Highest 30-day mortality was found in SMuRF-less women (381/2164 [17.6%]), followed by women with SMuRFs (2032/18 220 [11.1%]), SMuRF-less men (660/7064 [9.3%]), and men with SMuRFs (2117/34 600 [6.1%]).
- In analyses adjusted for therapy at discharge, prescription of each therapy was associated with expected lower mortality at 30 days, without accounting for SMuRF status. Inclusion of ACEi or ARB and statin resulted in loss of the significant association of SMuRF-less status with 30-day mortality. Inclusion of β-blocker resulted in attenuation of the association.
- Unadjusted CV mortality remained higher in the SMuRF-less group, compared to patients with ≥1 SMuRF, for up to 12 years in both men and women. All-cause mortality remained higher in SMuRF-less patients for more than 8 years in men and up to the follow-up endpoint at 12 years in women.
- The proportion of SCAD underlying STEMI presentations was significantly higher in the SMuRF-less group than in patients with ≥1 SMuRF. However, absolute numbers were low. 30-day mortality in women with SCAD was lower than in women without SCAD (2/31 [6.5%] vs 241/1710 [14.1%]). Numbers in men were too low for meaningful analysis.
All-cause mortality at 30 days after STEMI was significantly higher in patients without SMuRFs, compared to patients with at least one SMuRF. The association of SMuRF-less status with increased mortality was particularly evident in women. The authors state that these findings counter the assumption that less traditional risk factors for atherosclerosis result in lower risk after MI, and that evidence-based pharmacotherapy should be prescribed during the immediate post-infarct period irrespective of baseline risk factors or sex.