Coronary artery disease patients without standard modifiable risk factors (SMuRFs)- a forgotten group calling out for new discoveries

Abstract

We are interventional cardiologists working in a "whole of pipeline" research program based at the University of Sydney and Royal North Shore Hospital, driven by the increasing number of heart attack patients who look up from the cath-lab table asking "why me?".Coronary heart disease kills 7.2 million people per year, 1 many of whom were unaware of their underlying coronary atherosclerosis until their heart attack.While it is imperative that we target well-established risk factors, this approach "misses" a substantial group of patients who develop disease despite not being identified as "at risk" by traditional measures and cannot benefit from effective primary prevention measures.We are working with a growing international movement recognising the importance of this group of patients who suffer life-threatening heart attacks despite having no standard modifiable risk factors (SMuRFs) (Figure 1).We have coined the term "SMuRFless" for these individuals, and shown in Australia that the proportion of heart attack patients in this category has significantly increased over 10 years 2 from 13% to 27%. 3 Whilst this is a relatively small proportion of the "pie", the vast burden of CAD means these individuals cannot afford to be ignored, estimated to affect, conservatively, 29.6 million people globally, and to account for 1.4 million deaths per year. 7Most often overlooked in clinical trials and guidelines, we recognised the importance of understanding the outcomes for these SMuRFless individuals, and established a fabulous collaboration with the SWEDEHEART team, including Emil Hagstrom, Nermin Hadziosmanovic and Johan Sundstro ¨m.Meeting weekly throughout COVID times, we were able to benefit from the massive and well curated SWEDEHEART national registry, 4,5 which enrols all patients admitted to cardiac care units in Sweden with myocardial infarction.The findings, in 62,048 ST elevation MI patients were stunning and completely unexpected: STEMI patients with no SMuRFs experienced a 47% higher 30-day mortality compared to their counterparts with >0 SMuRFs.This compounded the already recognised poor outcomes in females, with SMuRFless females having an 18% 30-day mortality.

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