Singapore-specific myocardial infarction risk score goes toe-to-toe with international tools

A myocardial infarction (MI) risk score derived from the Singapore Myocardial Infarction Registry (SMIR) performs just as well as international standards, such as the refined Global Registry of Acute Coronary Events (GRACE 2.0) score, according to a recent study.

In receiver operating characteristic curve analysis, the researchers found no statistical difference between the SMIR and GRACE scores at predicting MI (p=0.075). Nominally, however, SMIR was slightly better than GRACE 2.0, with respective areas under the curve of 0.865 (95 percent confidence interval [CI], 0.833–0.898) and 0.841 (95 percent CI, 0.802–0.880). [Sci Rep 2022;12:14270]

Stratifying analysis according to the three most dominant ethnic groups in Singapore did not meaningfully alter these findings.

“In this real-world population-based study, we showed that the modified SMIR score performed similarly to the GRACE 2.0 score in a multi-ethnic Asian population in predicting 1-year all-cause mortality following ST-segment elevation (STEMI) and non-ST-segment elevation (NSTEMI) MI,” said the researchers, led by Dr Ching-Hui Sia of the Department of Cardiology, National University Heart Centre Singapore.

The team also performed Cox regression analyses to identify the most important components of each score. For GRACE 2.0, needing cardiopulmonary resuscitation (CPR) on admission was the biggest contributor to 1-year all-cause mortality, raising such risk by more than sixfold (adjusted hazard ratio [HR], 6.50, 95 percent CI, 3.82–11.06).

This was followed by a high Killip Class on admission (class IV vs I: adjusted HR, 4.98, 95 percent CI, 3.14–7.91) and age (adjusted HR per 10-year increase, 1.70, 95 percent CI, 1.45–1.99). In contrast, GRACE 2.0 identified high admission systolic blood pressure as significantly protective (adjusted HR per 20-mm Hg increase, 0.84, 95 percent CI, 0.75–0.95).

SMIR also found that old age was the most important indicator of 1-year all-cause mortality. Those who were 70–79 years, for instance, were at more than threefold higher risk of such outcome than comparators aged 40–49 years (adjusted HR, 3.53, 95 percent CI, 1.27–9.81). This risk estimate jumped to nearly eightfold in adults aged 80–89 years (adjusted HR, 7.78, 95 percent CI, 2.68–22.57).

CPR (adjusted HR, 6.34, 95 percent CI, 3.35–12.00) and a high Killip class (adjusted HR, 3.02, 95 percent CI, 1.72–5.31) on admission were also important risk factors for 1-year all-cause mortality.

In contrast, high left ventricular ejection fraction (LVEF) was significantly protective in SMIR (≥50 percent vs <30 percent: adjusted HR 0.23, 95 percent CI, 0.13–0.40). LVEF is a unique component of SMIR and is not factored in risk calculation in GRACE 2.0.

“Previously, it was difficult to perform a dedicated transthoracic echocardiogram study in the acute setting due to time constraints,” the researchers said. “However, with the advent of point-of-care echocardiography with portable handheld devices, [LVEF] can be rapidly obtained by the bedside.”

“Future risk scores may consider the use of variables that were previously not readily available,” they added.

Further studies are needed to improve current risk scores in MI patients, as well as evaluate how well they perform in real-life clinical settings.