FFR Assessment for Small Vessel Disease Improves Outcomes

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Fractional flow reserve (FFR) guidance for revascularization of small coronary vessel disease is safe and results in better clinical outcomes than angiographic guidance alone, according to a study published online February 7, 2012, ahead of print in Circulation: Cardiovascular Interventions. Moreover, the use of FFR reduces procedural costs.

Emanuele Barbato, MD, PhD, of Cardiovascular Center Aalst (Aalst, Belgium), and colleagues used a retrospective registry to evaluate the long-term clinical outcome of 222 patients slated to undergo PCI in small vessel lesions under FFR guidance from January 2004 to December 2008. A group of 495 age-matched patients who underwent angiographic guidance alone served as controls.

Clear Clinical Benefits

In the FFR-guided group, 78 patients (35.1%) had FFR values below 0.80 and underwent PCI, but 144 patients (64.9%) were deferred to optimal medical therapy based on their test results. By virtue of the study design, all patients in the angiography-guided group underwent PCI.

The number of vessels treated per patient was higher with angiography compared with FFR (1.17 vs. 1.10; P = 0.044). Few patients had multivessel PCI, but the FFR-guided group contained a higher percentage of those who did (17% vs. 9%; P = 0.0026). While there was no difference in stent diameter and length between the 2 groups, the number of stents used per patient was lower in the FFR group (0.45 vs. 1.21; P < 0.001). The proportion of patients treated with DES in the 2 groups was similar (43% vs. 50%; P = 0.25).

At a median follow-up of 3.3 years, patients treated with FFR-guided PCI had significantly lower combined death or nonfatal MI, nonfatal MI, TVR and MACE (defined as cardiac death, nonfatal MI, and TVR). However, no difference was observed in mortality alone (table 1).

 Table 1. Propensity-Score Adjusted Outcomes

 

FFR
(n = 222)

Angiography
(n = 476)

P Value

Death or Nonfatal MI

6%

14%

0.004

Nonfatal MI

1%

7%

0.007

TVR

10%

18%

0.006

MACE

14%

28%

< 0.001

Death

5%

8%

0.255


Stent thrombosis was rare, occurring in 6 patients in the angiography group and none in the FFR group.

Kaplan-Meier analyses were performed to compare patients receiving angiography-guided PCI, those who received FFR-guided PCI, and those deferred by FFR results to optimal medical therapy. In these groups, MACE rates were 29%, 23%, and 15%, respectively. Patients deferred by negative FFR results had a significantly lower MACE rate than those who underwent PCI using angiographic guidance (P = 0.002) but only showed a trend in that direction when compared to those who underwent PCI using FFR guidance (P = 0.16). Looking only at those who underwent PCI, both tests resulted in similar MACE risk (P = 0.19).

The researchers also calculated procedural costs, noting a difference of about €1,400 ($1,900 US) in favor of FFR (P < 0.0001).

According to Dr. Barbato and colleagues, the study is the largest retrospective registry of an FFR-guided PCI strategy in small-vessel disease with the longest clinical follow-up.

“Our results are particularly remarkable when one considers that the clinical benefit derived from revascularizing small vessels is uncertain,” the study authors write. “Optimal medical therapy, in fact, might be more effective than PCI for treating small areas of ischemic myocardium, which is usually the case in a small-vessel stenosis.”

The researchers cite the 59% reduction in death or nonfatal MI risk as well as the 54% reduction in MACE risk as supporting the “concept that a functionally guided revascularization together with optimal medical therapy is beneficial even in small-vessel disease.”

Difficult to Draw Definitive Conclusions

In a telephone interview with TCTMD, Ajay J. Kirtane, MD, SM, of Columbia University Medical Center (New York, NY), spoke in favor of FFR.

“What’s nice about FFR is that it is a hemodynamic test, so compared to something like IVUS where you would try to employ a particular cross-sectional area cutoff that needs to be adjusted by vessel size, in FFR you don’t need to do that,” he commented. “So if you are in doubt about whether to treat a small vessel, by using FFR you can essentially test the hemodynamic significance of the lesion.”

However, he added that since the study was not randomized, it is very difficult to draw definitive conclusions.

“We also don’t know if there was some reason the operators chose to do FFR in some patients as opposed to others,” Dr. Kirtane added. “If [using FFR] leads to more deferrals of things you might otherwise treat that would be great, but in a nonrandomized study that’s difficult to sort out because you can argue that one of the reasons they did FFR was because they were looking to defer.”

According to Dr. Kirtane, there is increasing interest in using FFR to guide PCI.

“I support that, but FFR like any other test needs to be put into context of the clinical presentation of the patient,” he said. “We see that there is a tendency among some people . . . to use FFR as the ‘gold standard’ when ultimately the patient is the ‘gold standard’ and FFR is a test that we use to help treat the patient.”

Consistent with FAME

Morton J. Kern, MD, of the University of California Irvine (Irvine, CA), told TCTMD in a telephone interview that although the current study cannot be compared with the randomized FAME (Fractional Flow Reserve versus Angiography for Multivessel Evaluation) trial, “it is completely consistent with that study as well as FAME II and DEFER in that the event rates are lower when you manage coronary disease appropriately.”

Dr. Kern added that “just eyeballing it” on the part of operators can exaggerate the narrowing of the vessels, and thus lead to unnecessary treatment. “You can do better work if you guide your procedures by FFR rather than stent everything you see,” he said. “It’s safer and better.”

Study Details

BMS used in the study included the Driver Coronary System (Medtronic, Minneapolis, MN) and PROKinetic (Biotronik, Zurich, Switzerland). DES implanted were Cypher (Cordis/Johnson & Johnson, Miami Lakes, FL), Taxus (Boston Scientific, Natick, MA), Endeavor (Medtronic, Minneapolis, MN) and Xience V (Abbott Vascular, Santa Clara, CA).

 


Source:
Puymirat E, Peace A, Mangiacapra F, et al. Long-term clinical outcome after fractional flow reserve-guided percutaneous coronary revascularization in patients with small-vessel disease. Circ Cardiovasc Interv. 2012;Epub ahead of print.

 

 

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Disclosures
  • Drs. Barbato and Kirtane report no relevant conflicts of interest.
  • Dr. Kern reports serving on the speakers bureaus of St. Jude Medical and Volcano Therapeutics.

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