ST-elevation myocardial infarctions in the absence of standard modifiable cardiovascular risk factors may have worse outcomes

1. Patients without standard modifiable cardiovascular risk factors (SMuRFs) had a significantly higher all-cause mortality at 30 days after first presentation of STEMI.

2. Patients without SMuRFs were significantly less likely to receive statins, ACEIs, ARBs, or beta-blockers at discharge.

 Evidence Rating Level: 2 (Good)

Study Rundown: Standard modifiable cardiovascular risk factors (SMuRFs: smoking, hypertension, diabetes, and hypercholesterolemia) significantly increase the risk of ST-elevation myocardial infarction (STEMI). However, a notable proportion of patients with no previous symptoms and no modifiable risk factors (SMuRF-less) present with severe myocardial infarction. SMuRF-less patients are often overlooked in the provision of effective and timely care, resulting in preventable complications. This study aimed to analyze the short-term and long-term clinical outcomes for patients with first presentation STEMI without SMuRFs and those with at least one modifiable risk factor. The primary outcome was all-cause mortality at 30 days after STEMI, whereas secondary outcomes included cardiovascular mortality, heart failure, and myocardial infarction. According to study results, SMuRF-less patients had a significantly higher all-cause mortality rate at 30 days after first presentation. They were also less likely to receive statins, angiotensin converting enzyme inhibitors (ACEIs), angiotensin receptor blockade (ARB), or beta-blockers at discharge. This study was strengthened by a longitudinal follow-up design as patient data was collected for up to 12 years after episode of STEMI. Overall, this study provides valuable insight into use of short-term pharmacotherapy during the acute post-infarct period, regardless of perceived risk.

Click to read the study in The Lancet

Relevant Reading: Coronary Angiography after Cardiac Arrest without ST-Segment Elevation

In-depth [retrospective cohort]: Between Jan 1, 2005, and May 25, 2018, 74 679 patients were assessed for inclusion into the study. Included patients were ≥18 years of age with suspected acute coronary syndrome and a hospital diagnosis of STEMI. Patients with a history of coronary artery disease (i.e., percutaneous coronary intervention, coronary artery bypass graft, or myocardial infarction) were excluded. Altogether, 62 048 patients (of which 9228 were SMuRF-less) were included in the analysis. Median age was similar between patients with SMuRFs (68 years, interquartile range [IQR] 59-78) and those without (69 years, IQR 60-78, p<0.0001).

Among SMuRF patients (n=52 820), common risk factors were hypertension (70.4%), hypercholesterolemia (48.4%), current smoking (32.6%), and diabetes (21.3%). SMuRF-less patients had a significantly lower LDL-C, body-mass index (BMI), HbA_1c, systolic blood pressure, and heart rate than SMuRF patients. They were also less likely to receive statins, angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockage (ARB), and B-blockers upon discharge. However, the rate of percutaneous coronary intervention was similar between both groups. The primary outcome of all-cause mortality at 30 days was significantly higher in SMuRF-less patients than SMuRF patients (hazard ratio [HF] 1.47, 95% confidence interval [CI] 1.37-1.57, p<0.0001). This was true after adjusting for age, sex, left ventricular ejection fraction, creatinine, and blood pressure. SMuRF-less patients had a significantly higher in-hospital mortality rate (n=883, 9.6%) than their counterparts (n=3411, 6.5%, p<0.0001). Secondary outcomes of myocardial infarction and heart failure at 30 days after STEMI were lower in SMuRF-less patients; although, all-cause mortality remained elevated in SMuRF-less men for more than 8 years and SMuRF-less women for more than 12 years. Findings from this study suggest that SMuRF-less STEMI patients have a higher risk of mortality than those with one or more standard risk factor.

Image: PD

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