Prevalence and diagnostic impact of standard modifiable risk factors in suspected myocardial infarction

Background Standard modifiable risk factors (SMuRFs) – including hypertension, diabetes, dyslipidemia, smoking, and overweight - are major determinants of cardiovascular risk. However, a considerable proportion of acute coronary events occurs in the absence of such SMuRFs. Evidence regarding the real-world prevalence of SMuRFs and their impact on diagnostic assessment in the acute setting of suspected myocardial infarction (MI) is sparse. Purpose We therefore sought to investigate the prevalence of SMuRFs, distribution of diagnoses according to SMuRF burden, and its impact on the diagnostic performance of the 0/1-hour algorithm by the European Society of Cardiology (ESC). Methods Patients with suspected MI were prospectively enrolled in an observational cohort study at a tertiary medical center in Germany. Final diagnoses were independently adjudicated by two cardiologists based on the Fourth Universal Definition of MI. High-sensitivity cardiac troponin I (hs-cTn I) was measured in serial blood samples at admission and after one hour. Patients were categorized according to the presence of the five SMuRFs into three SMuRF burden categories: SMuRF-less, SMuRF=1, SMuRF>=2. Rule-out (negative predictive value [NPV], sensitivity) and rule-in (positive predictive value [PPV], sensitivity) performance of the ESC 0/1-hour algorithm for non-ST elevation myocardial infarction (NSTEMI) was calculated for each SMuRF burden category. Results Among 3,522 patients (median 63 years, 64.4% male) with symptoms suggestive of an acute MI, 116 patients were SMuRF-less (3.3%), 720 had one SMuRF (20.4%), and 2686 had at least two SMuRFs (76.3%). Overall, hypertension was the most prevalent SMuRF (91.1%), followed by overweight (55.9%), hyperlipidemia (46.5%), current smoking (22.7%), and diabetes (12.6%). Hs-cTnI levels at baseline were higher with increasing SMuRF burden: 2.3 ng/L (95% CI 1.8 – 5.1) in SMuRF-less, 3.9 ng/L (95% CI 1.9 – 9.8) in SMuRF=1, and 6.9 ng/L (95% CI 3.1 – 25.2) in SMuRF>=2 (p<0.0001). Among 176 patients with STEMI, two patients were SMuRF-less (1.1%), while 159 (90.3%) had at least two SMuRFs. In NSTEMI type 1, none of the 281 patients was SMuRF-less; 91.8% had at least two SMuRFs. In 72.1% of SMuRF-less patients, an acute MI was ruled-out with an NPV of 100 (Table 1). Rule-out performance was lowest in patients with diabetes (rule-out proportion 25.1%, NPV 99%; Table 2). The proportion of patients remaining in the observe zone increased with higher SMuRF burden category from 18.9% in SMuRF-less to 37.7% in SMuRF>=2. Conclusion SMuRFs are highly prevalent among patients with suspected myocardial infarction and only a small proportion is entirely SMuRF-less. Among patients with diagnosed MI, <1% was SMuRF-less. Absence or presence of SMuRFs seem to impact diagnostic performance of pathways for suspected MI.