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

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