FFR Plus Syntax Score Equals Better Risk Stratification in Multivessel Patients

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Incorporating functional information from fractional flow reserve (FFR) assessment into standard angiographically based Syntax scoring improves prognostic value, increasing the proportion of patients with multivessel disease who fall into the lowest risk for adverse events after percutaneous coronary intervention (PCI). The findings were published in the September 13, 2011, issue of the Journal of the American College of Cardiology.

Results of the study were first presented February 18, 2011, at the Eighth Annual Chronic Total Occlusion Summit and Left Main Coronary Interventions Course in New York, NY.

Researchers led by William F. Fearon, MD, of the Stanford Medical Center (Stanford, CA), compared standard Syntax scores with the new “functional” Syntax score in 497 patients from the FAME trial. In FAME (Fractional Flow Reserve versus Angiography for Multivessel Evaluation), revascularization based on FFR measurement in addition to angiography resulted in decreased rates of the primary endpoint (MACE, a composite of death, MI, or repeat revascularization) in patients with multivessel CAD.

Functional Assessment Shifts Risk

For the new study, patients were divided into risk tertiles based on their Syntax score:

• Low (34%; n = 167)
• Medium (34%; n = 167)
• High (32%; n = 163)

Functional Syntax scores were then calculated by only counting ischemia-producing lesions with an FFR value ≤ 0.80. By using the functional score, 32% of patients moved from a higher-risk group to a lower-risk group. This resulted in a redistribution:

• Low (59%; n = 290)
• Medium (21%; n = 106)
• High (20%; n = 101)

The changes were driven in part by the conversion of angiographic 3-vessel CAD to functional 1- or 2-vessel CAD.

MACE rates were accordingly increased in the highest-risk group, a difference that was greater in the functional score groups than the classic Syntax score groups. In addition, rates of death or MI were significantly different in the functional score groups, unlike in the classic Syntax score groups (table 1).

Table 1. One-Year Outcomes: Standard vs. Functional Syntax Score

^a For lowest vs. highest tertile.

In multivariate analysis, functional Syntax score and procedure time were the only independent predictors of 1-year MACE. The result was the same when the analysis was repeated to predict only the hard endpoints of death and MI, or to predict 1-year MACE excluding periprocedural MI.

In receiver-operator characteristic analysis, the functional score demonstrated a better predictive accuracy for MACE compared with the standard Syntax score (P = 0.02).

According to Dr. Fearon and colleagues, use of the functional Syntax score “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 according to risk group.”

Furthermore, they say the findings may help decide between PCI and CABG for revascularization. For example, they write, “[i]f the 2010 European myocardial revascularization guidelines are applied to patients in this study, 43% (29 of 69 patients) of patients in whom CABG would be recommended due to 3-vessel CAD with [a classic Syntax score] > 22 would move to a lower-risk group after calculation of the [functional Syntax score] and thereby might have another option,” the study authors write.

On the other hand, the investigators say, since the patients with high functional scores had the worst 1-year outcome after PCI in all studied groups, “surgical revascularization could be considered in the high-risk patients with multivessel CAD classified by [functional Syntax score], and hopefully improve outcomes.”

However, this strategy needs to be tested in another randomized trial, they caution.

Differences in Patient Populations

In an editorial accompanying the study, Neal S. Kleiman, MD, of the Methodist DeBakey Heart and Vascular Center (Houston, TX), adds that while it may be tempting to apply the new findings to decision making for PCI vs. CABG, it is important to keep in mind that they refer only to clinical events at 1 year.

Importantly, Dr. Kleiman points out, the patient populations in SYNTAX and FAME differed, so not only may the risk tertiles be different, but the event rates after CABG may be, as well.

“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,” Dr. Kleiman writes. “Integrating the concept of ‘watchful waiting’ espoused by FAME into a surgical strategy is intriguing but challenging.”

Patient Preference Still Important Factor

“The question surrounding the Syntax score has always been whether just counting lesions is enough to predict outcomes,” said Jeffrey W. Moses, MD, of Weill Cornell Medical College (New York, NY), in a telephone interview with TCTMD. “This study is addressing the question of which lesions you should count. It’s not surprising that, at least over the short term, dealing only with the functional lesions and doing less stenting leads to better outcomes.”

But Dr. Moses said the flip side is that it “opens the door” for more patients to get PCI who might otherwise be ineligible based on angiography and high Syntax score.

“That, ultimately, is a good thing because you have more information on which to base your decision,” he said. “Also, there is the patient’s preference to consider, and unfortunately that aspect isn’t being [incorporated] into the recommendations. When you translate models into practice, [patient choice] is a very important factor.”

 

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Sources:
1. Nam C-W, Mangiacapra F, Entjes R, et al. Functional SYNTAX score for risk assessment in multivessel coronary artery disease. J Am Coll Cardiol. 2011;58:1211-1218.

2. Kleiman NS. Bringing it all together: Integration of physiology with anatomy during cardiac catheterization. J Am Coll Cardiol. 2011;58:1219-1221.

 

 

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