Training necessary to improve site SYNTAX score assessment

Assessing the SYNTAX score at the point of care was associated with poor discrimination among low-, intermediate- and high-risk groups, leading researchers to conclude that appropriate training and unbiased assessment are needed when using the score in clinical decision-making.

The researchers of the randomized SYNTAX trial noted that the trial’s results were reported based on core lab-calculated SYNTAX score (SS). However, because core lab technicians have demonstrated better capability at reproducing SS than interventional cardiologists, there is still uncertainty about the prognostic value and clinical implications of site SS.

The aim of the current study was to determine the prognostic value and clinical implications of site SS after PCI or CABG.

Site investigators calculated the site SS before patients were randomly assigned treatment in the trial. They defined site SS in three tertiles ranging from low (0 to 19) to intermediate (20 to 27) to high (≥28) and examined clinical endpoints of the two interventions.

The researchers reported a mean difference between core lab SS and site SS of 3.8 ± 11.2 (mean absolute difference, 8.9 ± 7.8).

Five-year results indicated higher MACCE with site SS for PCI compared with CABG in all three tertiles: 31.9% vs. 24.5% (P=.054) in the low group; 39.5% vs. 29.5% (P=.019) in the intermediate group; and 43% vs. 31.4% (P=.003) in the high tertile group.

Among patients with three-vessel disease, PCI also was associated with higher MACCE rates than CABG regardless of tertile. However, similar MACCE rates were reported for PCI and CABG in all three tertiles among patients with left main disease.

The c-index for the site-based SS II was 0.736, which the researchers noted was similar in terms of predictive value as the core lab-based SS II (c-index: 0.744). They added that the net reclassication index was –0.0062 (P=.79).

Clinicians should be appropriately trained and encouraged to use unbiased assessment when using SS as a clinical decision-making tool, according to the researchers. “[Site] SS and tertiles based on [site] SS showed poor discrimination among low-, intermediate- and high-risk groups,” they wrote. “However, combining clinical factors with [site] SS retained the predictive performance of SS II.”

Robert A. Harrington

In an accompanying editorial, Robert A. Harrington, MD, from the department of medicine at Stanford University in California, echoed the conclusion of the researchers that appropriate training will aid in assessing SS and that including clinical variables is a key element in guiding treatment strategies.

“For the [site] SS-derived SS II to be useful at the point of care, it needs the addition of tools and applications that will facilitate its incorporation into the clinical workflow,” he wrote. “Increasingly, clinicians want to use smartphone applications that can be readily accessed at the point-of-care delivery. Formal, validated risk scores can aid the clinician (and the patient) in the decision-making process, but such scores need to be statistically robust while also having face validity and being easy to use.”

For Harrington, comprehensive electronic health record data that can be accessed immediately is the next step in accurate SS assessment: data on genotyping, imaging, other laboratory data and wearable sensor data should be included.

“Risk assessment and treatment decision algorithms will be updated and recalculated continuously and fed back to providers at the point of care, so that they can integrate each patient’s values and preferences to place them in their individual social and environmental context to arrive at decisions that best fit that individual,” he wrote. “At that point, ‘big data’ will be more than a buzz phrase; it will have turned into useful information.”

For more information:

Harrington RA. J Am Coll Cardiol. 2014;64:433-435.

Zhang YJ. J Am Coll Cardiol. 2014;64:423-432.

Disclosure: The researchers report financial disclosures with Abbott Vascular, Boston Scientific and Medtronic. Harrington reports serving on the scientific advisory board of Adverse Events.