FFR Improves Outcomes in Routine Clinical Practice


In an every-day population, percutaneous coronary intervention (PCI) guided by fractional flow reserve (FFR) measurements improves outcomes compared with angiography guidance alone over long-term follow-up. Results from a large registry study were published online January 23, 2013, ahead of print in the European Heart Journal.

Researchers led by Amir Lerman, MD, of the Mayo Clinic (Rochester, MN), looked at 7,358 patients who were referred for PCI at their institution from October 2002, when FFR was put into clinical practice, to December 2009; 14.8% (n = 1,090) received FFR-guided PCI. For the FFR group, one-third (33.9%) underwent PCI while two-thirds (66.1%) were deferred.

On Kaplan-Meier analysis, numerous outcomes were improved with FFR guidance (table 1).

Table 1. Kaplan-Meier Analysis at 7 Years

 

FFR Guidance
(n = 1,090)

Angiography Guidance
(6,268)

P Value

MACE

50%

57%

0.016

Mortality

21%

32%

< 0.001

MI

8%

15%

0.001

Mortality or MI

26%

41%

< 0.001

Repeat Revascularization

35%

36%

0.97


Among the FFR patients, 7-year outcomes were similar whether patients received PCI or had the procedure deferred. The only exception was MI, which was lower in the deferred group (6% vs. 12%; P = 0.007).

On multivariable analysis, patients undergoing FFR measurement tended to have lower rates of MI compared to those who received angiography-guidance alone, but the difference just missed significance (HR 0.85; 95% CI 0.71-1.01; P = 0.06). However, patients in the FFR group who had PCI deferred did experience fewer MIs than those who underwent intervention after FFR measurement (HR 0.46; 95% CI 0.26-0.82; P = 0.008).

Excluding ‘Gray Zone’ Patients

After excluding patients with FFR measurements in the “gray zone” of 0.75 to 0.80 who had PCI deferred, the incidence of death or MI was lower in the FFR-guidance group compared with those who received angiography guidance alone (HR 0.80; 95% CI 0.66-0.96; P = 0.02). In addition, deferral of PCI after FFR measurement was associated with reduced rates of MI (HR 0.39; 95% CI 0.20-0.73; P = 0.004) and death or MI (HR 0.64; 95% CI 0.45-0.92; P = 0.02).

The researchers note that while FFR has been shown to be effective in determining the appropriateness of PCI in clinical trials, there is less supportive evidence from routine practice, especially since the method is used in less than 10% of PCI procedures in Europe in the absence of clinical evidence of ischemia.

In addition, disparities between clinical trials and general practice may make FFR less effective in daily use. For instance, in practice, FFR is often performed entirely at the operator’s discretion based on angiographic information, a “notoriously poor” guide to functional significance, the researchers explain.

This may lead to unnecessary PCI in some lesions, and inappropriately deferred PCI in others, they add.

Confirming FAME in the Real World

In the current study, coronary stenoses were assessed visually rather than by quantitative coronary angiography or IVUS. “In this registry study, we found a favorable long-term outcome in an FFR-guided group,” the researchers conclude. “This result is in keeping with previous clinical trials, and therefore provides important evidence supporting the rationale for the use of FFR in routine practice.”

According to Massoud Leesar, MD, of the University of Alabama at Birmingham (Birmingham, AL), the results help confirm data from the randomized FAME trial, which showed that measuring FFR in each artery and restricting stenting to ischemia-producing lesions results in a lower risk of major adverse events at 1 year in patients with multivessel disease.

A key difference, he said in a telephone interview with TCTMD, is that in the current study, only about 19% of patients had multivessel disease. “Also, this is a real-world registry study, and the benefits are still there,” he said. “If you don’t stent every vessel, you get better patient care, better cost, and improved outcome.”

William F. Fearon, MD, of Stanford University Medical Center (Stanford, CA), and a FAME investigator, agreed, adding that the current study adds important information regarding patients in the “gray area” of FFR measurements.

“I think the findings regarding the grey zone in this study are hypothesis generating, but not definitive.  We need more controlled data,” Dr. Fearon said in an e-mail communication with TCTMD. “In general, if a patient has typical symptoms and a focal lesion with an FFR of 0.77, then revascularization is likely indicated.  On the other hand, if a patient with an FFR of 0.77 has atypical symptoms and/or diffuse disease, making it challenging to stent a focal spot, then deferral may be more appropriate.

To Dr. Leesar, the take-home message was simpler. “If we defer revascularization in patients with FFR between 0.75 and 0.80, those patients don’t do as well as those with FFR above 0.80,” he said.

US vs. European FFR Use

He noted that in general, FFR is used more in Europe than in the United States. “In the United States, the problem is reimbursement and guidelines,” he said. “At this time, FFR is class IIA, not a class I recommendation because we only have 1 randomized trial, FAME, with about 1,000 patients. We need more randomized studies to show the robust benefits with FFR.”

Dr. Fearon observed that FFR usage in the United States is more difficult to estimate “because if you only look at PCI cases, you miss a number of cases in which FFR was used and the patient never underwent FFR.  If you ask the companies who make the pressure wire, their sales have been consistently increasing every year for the past decade, with big spikes after FAME 1 and FAME 2.”

 


Source:
Li J, Elrashidi MY, Flammer AJ, et al. Long-term outcomes of fractional flow reserve-guided vs. angiography-guided percutaneous coronary intervention in contemporary practice. Eur Heart J. 2013;Epub ahead of print.

 

 

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Disclosures
  • The study was supported by the National Institutes of Health (NIH) and an unrestricted grant from St. Jude Medical.
  • Dr. Lerman reports receiving remuneration as a board member of Itamar Medical and support from an NIH institutional grant.
  • Dr. Leesar reports no relevant conflicts of interest.
  • Dr. Fearon reports receiving research support from St. Jude Medical.

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