Risk factors

Cardiovascular risk calculation needs a major overhaul, experts argue

The way doctors calculate cardiovascular risk will likely need a major overhaul thanks to the growing proportion of STEMI patients presenting without any traditional risk factors, it is being argued.

It comes as the topic of so-called SMuRFless (Standard Modifiable Risk Factor-less) patients heats up in cardiology research, amid recent evidence showing increased mortality in the group after STEMI.

In a new study from Japan,  researchers examined a population of over 1,000 patients enrolled in a percutaneous coronary intervention (PCI) registry.

The team found 6% of patients undergoing PCI for an acute coronary syndrome fell into the SMuRFless category – no hypertension, diabetes, dyslipidaemia, or current smoking.

They noted this was a lower proportion than other studies, which had put the figure closer to 20%.

But concerningly, these SMuRFless patients were also more likely to have major adverse cardiovascular events including death, recurrent MI and stroke during hospitalisation (25.0% vs 9.9%; p<0.001), the researchers found.

On the other hand, the incidence of in-hospital major bleeding was not significantly different between the two groups (9.4% vs 6.7%; p=0.44), the team reported in Heart Lung and Circulation (link here).

Active cancer and autoimmune/inflammatory diseases were also often found in patients with no standard risk factors.

In an accompanying editorial, a pair of Australian experts said the findings highlighted the need to identify new non-traditional risk factors that were contributing to coronary events.

There was major heterogeneity among SMuRFless patients, wrote Dr Elizabeth Paratz and Dr Andre La Gerche of the Baker IDI Heart and Diabetes Institute in Melbourne.

“Other non-traditional risk factors now recognised include sex-based risk factors, psychosocial risk factors and occupational exposures,” they wrote (link here).

“Such non-traditional risk factors are likely to play an increasingly important role as Australians survive previously fatal diseases and accumulate a greater burden of chronic disease.”

Beyond that, some patients had genetic or ethnic contributors to their coronary disease, and if biomarkers were identified, these could one day be incorporated into CVD risk assessments, the experts noted.

Finally there were a number of patients, with no discernible traditional nor non-traditional CVD risk factors.

“This group of patients could best be described as ‘truly SMuRFless’ and their emergence as a prominent group in ACS is analogous to the increasing proportion of patients with an unascertained cause of sudden cardiac arrest,” they wrote.

“In both scenarios, the ‘low-hanging fruit’ of modifiable risk factors and disease-specific initiatives have been successfully addressed and overall disease burden reduced, leaving the challenge of patients without overt symptoms or risk factors.”

Nevertheless, they added: “With refinement of our understanding of the causation of coronary disease beyond four monolithic traditional risk factors, existing clinical models should be restructured to provide more personalised and accurate diagnoses of cardiovascular risk.”

“With progressive identification of novel potentially modifiable risk factors, we can aspire to continue successfully reducing the burden of coronary disease in the 21st century and beyond.”

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