Unique regional risk profiles and cardiovascular outcomes of patients with acute coronary syndrome in the absence of standard modifiable risk factors: a systematic review and meta-analysis
Authors: Vijay Anand V , Mahesh R , Lim J S , Chong B , Kong G , Lee E C Z , Tan B , Muthiah M , Soh R , Chin Y H , Foo R , Chan M Y Y , Chew N W S 
Published: October 2024

Abstract

Background
With differences in prevalence, risk profile, cardiovascular complications, and mortality of patients with acute coronary syndrome (ACS) in the absence of standard modifiable risk factors (SMuRF-less) worldwide, this study examines the regional differences and the unique risk profiles of this often-understudied group of patients.

Purpose
We hypothesize that differences in non-traditional risk factor profiles may lead to unique ACS-related presentations, complication rates, and secondary preventative strategies across regions. Hence this study was undertaken to assess the cross-regional comparisons of patient characteristics, risk profile, angiographic characteristics that may provide insights into disparate cardiovascular outcomes observed in the SMuRF-less ACS population.

Methods
Medline and Embase databases were searched in November 2022 to identify relevant literature relating to the prevalence of risk factors in SMuRF-less patients with ACS. A single-arm meta-analysis of proportion and means was conducted on baseline and presentation characteristics, outcomes and complications, management, and risk factors in SMuRF-less ACS patients, stratified according to geographical region (Asia-Pacific, Europe, and North America). Risk of bias was assessed using the Newcastle-Ottawa scale.

Results
A total of 25 studies comprising of 1,393,184 individuals with ACS were included, of which 242,929 patients were SMuRF-less. Within this SMuRF-less ACS group, mortality rates were similar across the regions (Asia-Pacific:15.8%, Europe:17.5%, p=0.861), cardiac arrest (6.3%, 95%CI:2.3% to 16.3%, p=0.001) and major bleeding (5.2%, 95%CI:2.9% to 9.2%, p=0.001) were more prevalent in Asia-Pacific, and heart failure more common in Europe (21.7%, 95%CI:18.2% to 25.7%, p&lt;0.001). Prevalence of chronic obstructive lung disease (21.4%, 95%CI:21.2% to 21.6%, p&lt;0.001) and peripheral artery disease (3.8%, 95%CI:3.1% to 4.7%, p=0.001) were highest in SMuRF-less ACS patients from North America, chronic liver disease most prevalent in those from Asia-Pacific (3.5%, 95%CI:2.2% to 5.6%, p&lt;0.001) and family history of coronary artery disease highest in SMuRF-less ACS patients from Europe (25.2%, 95%CI:24.8% to 25.7%, p=0.024). Significantly lower rates of guideline-directed medical therapy prescriptions were observed for SMuRF-less ACS patients in Asia-Pacific compared to other regions.

Conclusion
This regional analysis highlights the different risk profiles, cardiovascular outcomes, and specific needs of individuals presenting with ACS in the absence of cardiovascular risk factors, across Asia-Pacific, Europe, and North America. Whilst unravelling novel pathomechanistic pathways of atherosclerosis will prove beneficial on a global scale, understanding the unique regional profile of these individuals will aid policymakers strategize effective and tailored clinical pathways in the management of SMuRF-less ACS.Graphical AbstractKey Outcomes