FFR Guides Therapy for Proximal LAD Lesions

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Fractional flow reserve (FFR) can accurately identify those patients with equivocal lesions in the proximal left anterior descending (LAD) artery who may not need revascularization and will see comparable outcomes with medical management, according to a study published online October 26, 2011, ahead of print in JACC: Interventions.

Researchers led by Bernard De Bruyne, MD, PhD, of Cardiovascular Center Aalst (Aalst, Belgium), looked at 730 patients at their institution with stable angina and a 30% to 70% stenosis in the proximal LAD. All patients underwent both coronary angiography and FFR measurement (PressureWire, St. Jude Medical, Uppsala, Sweden). Patients with an FFR less than 0.80 were treated by revascularization (n = 166), while those with an FFR of 0.80 or higher received medical management (n = 564).

Baseline characteristics were similar between the groups, with the exception of more smokers and male patients in the revascularization group. On visual estimate, mean diameter stenosis was significantly lower in the medical group (39.8 ± 10.4% vs. 54.0 ± 12.1%; P < 0.0001), but there was a large overlap of patients in the medical group (23%) with diameter stenosis estimated at 50% or greater. When assessed on QCA, mean diameter stenosis was also lower in the medical group (P < 0.0001), while the overlap was markedly less. Mean FFR was 0.87 ± 0.05 in the medical group and 0.71 ± 0.08 in the revascularization group.

Survival Similar to Controls, Better Than with Revascularization

The sensitivity, specificity, positive and negative predictive values of 50% or greater diameter stenosis by visual estimate to predict an FFR value less than 0.80 were 77%, 73%, 45%, and 92%, respectively, with an overall diagnostic accuracy of 74%. These same values on QCA were 68%, 80%, 55%, and 87%, respectively, with an overall diagnostic accuracy of 77%.

Compared with an age- and sex-matched control population from the city of Rotterdam, The Netherlands, 5-year survival estimates were similar to those of the medical group (89.6% vs. 92.9%; P = 0.74), with a mortality hazard ratio for the Rotterdam population that was not significant compared with the medical group (HR 1.03; 95% CI 0.68-1.57; P = 0.87). Over a mean follow-up of 39 months, there was a 1.63% annual mortality rate in the medical group, which is comparable to the 1.5% annual rate reported in individuals without known CAD but with multiple risk factors.

In the revascularization group, the majority received PCI (87%) compared with CABG (13%). Five-year estimates of survival as well as survival free of death/MI or death/MI/TVR all favored the medical group (table 1).

Table 1. Five-Year Survival Estimates

In the medical group, patients with a diameter stenosis of 50% or greater on visual estimate had a 5-year estimated survival similar to patients with a diameter stenosis less than 50% (92.1% vs. 88.8%; P = 0.42).

“This study indicated that patients with an angiographically dubious, but hemodynamically nonsignificant, isolated stenosis in the proximal LAD (as assessed in the catheterization laboratory by FFR measurements) have a favorable long-term outcome without mechanical revascularization,” the authors write.

They note that despite current guidelines that recommend determining the presence of ischemia prior to PCI, as many as half of patients with stable CAD who receive intervention lack such a determination by noninvasive testing. According to the researchers, “a sizable proportion of patients undergo coronary angiography before functional testing. . . . FFR makes it possible to obtain both anatomic and functional data during the same examination (catheterization session).”

Intervention Need Not be Automatic

This would be particularly important in the proximal LAD, where “The presence of a narrowing of more than 50% luminal reduction . . . often triggers a revascularization procedure,” the authors observe.

“Proximal left anterior descending stenosis has traditionally been considered very high risk and revascularization is often recommended,” commented Spencer B. King, MD, of Saint Joseph's Heart and Vascular Institute (Atlanta, GA), in an e-mail communication with TCTMD. “This study challenges that assumption and shows that isolated LAD stenosis does not automatically need intervention and those without hemodynamic impairment may have good survival without intervention.”

In a telephone interview with TCTMD, Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), noted that although the study was not a randomized trial, “in general, this is supportive data that suggest that borderline lesions that are less than 70% stenosis can likely be managed medically.”

Dr. Stone indicated that use of FFR has been increasing in the United States since the FAME trial, which showed the value of the technique in a large, randomized dataset, “but its use is still less than 10%, although I think it should be more.”

Good, Better, Best

This is especially true given the limitations of visual estimation of lesion severity, as shown in the current study. “Visual estimation of coronary angiographic lesion severity is notoriously unreliable and varies markedly among operators, and even for the same operator when looking at the film on separate days,” Dr. Stone said. “That’s why it’s very good to take the guesswork out of it, at a minimum with QCA which can be performed online, or with IVUS, which is better, and for borderline lesions with FFR, which is better still.”

Dr. Stone added that FFR seems most useful for lesions in the range of 50% to 70% stenosis. “These are in the borderline range that depending on the physician and their interpretation of the lesion, some would intervene and some would not,” he said. “This study suggests that FFR would help make that determination.”

He said a key piece of information missing from the study is which type of stents were used, explaining that in FAME, the stents were primarily zotarolimus-eluting and paclitaxel-eluting devices. Dr. Stone observed that the better results achieved by current-generation everolimus-eluting stents, “can substantially change the long-term results of revascularization in borderline lesions compared to medical therapy”

 

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Source:
Muller O, Mangiacapra F, Ntalianis A, et al. Long-term follow-up after fractional flow reserve-guided treatment strategy in patients with an isolated proximal left anterior descending coronary artery stenosis. J Am Coll Cardio Intv. 2011;Epub ahead of print.

 

 

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