JACC: FFR-guided SYNTAX scores could help predict outcomes
Fractional flow reserve (FFR)-guided SYNTAX scores can better predict clinical outcomes by decreasing the number of higher-risk patients and better discriminating risk for adverse events in multivessel coronary artery disease (CAD) patients, according to a study published Sept. 13 in the Journal of the American College of Cardiology. But is this strategy ready for clinical adoption? Not yet, Neal S. Kleiman, MD, of the Methodist DeBakey Heart and Vascular Center in Houston, wrote in an accompanying editorial.

“The SYNTAX score (SS) is an anatomic scoring system based on the coronary angiogram, which not only quantifies lesion complexity, but also predicts outcome after PCI in patients with multivessel CAD and/or left main disease,” Chang-Wook Nam, MD, PhD, of the Stanford University Medical Center in Stanford, Calif., and colleagues wrote. While syntax scores can stratify risk in multivessel CAD patients, the authors wrote that there are several limitations because it is angiography based.

To determine whether FFR-guided SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) score could better predict clinical outcomes when compared to traditional SYNTAX scores in patients with multivessel CAD, Nam and colleagues collected data from 497 patients enrolled in the FAME (Fractional Flow Reserve vs. Angiography for Multivessel Evaluation) trial and divided patients into tertiles of risk based on SYNTAX scores: low (167 patients), medium (167 patients) and high (163 patients).

Functional SYNTAX scores were determined by counting ischemia-producing lesions. The study’s primary endpoint was FFR-guided SYNTAX scores to predict adverse cardiac event rates at one year.

The researchers reported that after determining functional SYNTAX scores for each patient, 32 percent of patients moved to a lower-risk group. Additionally, 23 percent of the highest SYNTAX scores tertile moved to the medium-risk functional SYNTAX score group and 15 percent moved to the lowest-risk group. Meanwhile, 59 percent of the middle SYNTAX score tertile moved to the lowest-risk group.

After recalculation, three new groups were created: 59 percent had low SYNTAX scores, 21 percent had medium scores and 20 percent had high SYNTAX scores.

For low-, medium- and high-functional SYNTAX score groups, MACE rates occurred in 9 percent, 11.3 percent and 26.7 percent of patients, respectively. Nam et al reported that functional SYNTAX score and procedure time were the only independent predictors of one-year MACE rates. Death or MI occurred in 4.8 percent, 7.5 percent and 15.8 percent of patients with low, medium and high functional SYNTAX scores, respectively. Additionally, the rates of repeat revascularization were 4.5 percent, 3.8 percent and 12.9 percent in the low-, medium- and high-functional SYNTAX score arms.

Functional SYNTAX scores predicted repeat revascularization in the highest score group, who also had a higher repeat revascularization rate compared with the lowest and middle groups, the authors noted. “Therefore, the FSS [functional SYNTAX scores] can not only help to more accurately stratify the risk in each patient with multivessel CAD, but it is also more closely related to prognosis after revascularization,” they wrote.

“FSS [functional SYNTAX score] demonstrated a better predictive accuracy for MACE compared with SS [SYNTAX score],” the authors wrote. “These findings could have significant clinical implications on decision-making regarding the choice of revascularization strategies in patients with multivessel CAD.”

In an accompanying editorial, Kleiman said the current results are not surprising and offered that “if distinguishing patients according to the presence or absence of flow-limiting lesions leads to implantation of fewer stents, then the upfront 'cost' of the procedure (i.e., periprocedural myocardial infarction or stent thrombosis) can be avoided without impairing the patient's short-term risk.”

Additionally, Kleiman said that the broader question will be whether the approach will be adopted, and that currently only 6 percent of U.S. patients undergoing PCI have FFR measured prior to PCI. He noted that adding this procedure to the carestream could be cumbersome and modestly time consuming.

“What is likely to provide incentive to use this technology more broadly?” asked Kleiman. “Although it is very tempting to apply the findings of Nam et al to situations in which decisions must be made between surgery and PCI, it is important to remember that the current findings refer only to clinical events at one year.

“Is the FSS ready for clinical adoption? Probably not,” Kleiman offered. “Although measuring FFR is currently viewed as an established standard for interventional cardiologists deciding whether or not to implant a stent in a particular vessel, applying this technique to distinguish which patients should undergo bypass surgery and to decide how the surgery should be performed is not.”