In a new analysis of the previously published FAME 3 trial, which compared fractional flow reserve–guided percutaneous coronary interventions to coronary artery bypass surgery (CABG) in patients with three-vessel disease, post-PCI FFR was shown to predict both target vessel failure (TVF) and risk of cardiac events.
“We found that the post-PCI FFR had prognostic value both for the vessel and for the patient,” reported Zsolt Piroth, MD, PhD, deputy head, adult cardiology, György Gottsegen Institute of Cardiology, Budapest.
Dr. Zsolt Piroth
In this post hoc analysis, which was not a prespecified FAME 3 substudy, the goal was to look at the prognostic value of both post-PCI FFR and intravascular ultrasound, which were recommended in the study protocol. Several studies have addressed the value of these measures previously, according to Dr. Piroth, but he said the clinical value “has remained poorly defined” despite the currently available data.
The FAME 3 trial, published in the New England Journal of Medicine, was negative. It failed to confirm the study hypothesis that FFR-guided PCI is noninferior to CABG for the outcome of major adverse cardiac events (MACE) at 12 months.
However, this multinational trial has generated a large body of data with which to explore other issues relevant to revascularization. In this analysis, the goal was to evaluate whether post-PCI FFR predicted outcomes in complex multivessel revascularizations as it has been shown previously to do in single-vessel disease.
Presented at the Transcatheter Cardiovascular Therapeutics annual meeting, the focus of this analysis was on the 461 (61%) of patients in the 757-patient PCI arm of FAME 3 who underwent post-PCI FFR. The authors also looked at the predictive value of intravascular ultrasound, even though this was performed in just 11% of this group of trial participants.
As a continuous value, each 0.1-unit change in the post-PCI FFR was found to be prognostically significant for the outcome of TVF, defined as a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization (only postprocedural events were counted in this analysis). Specifically, for each 0.1-unit increase on a univariate analysis, the risk of TVF was reduced by about one-third (hazard ratio, 0.67; P = .0165).
On a patient level, a 0.1-unit increase in lowest post-PCI FFR of any assessed vessel was also associated with the same relative risk reduction (HR, 0.65; P = .0074) in the outcomes of cardiac death, target vessel MI, or target vessel revascularization, according to Dr. Piroth. On a receiver operating characteristic curve analysis, a value of 0.88 or below was predictive of TVF.
Although several other patient characteristics were also risk predictors of TVF on univariate analysis, only renal disease and the single lowest post-PCI FFR (as a continuous variable) emerged as predictors of TVF on multivariable analysis after adjustment for key clinical parameters, Dr. Piroth reported.
The reason why post-PCI FFR was not performed in almost 40% of patients randomized to PCI is unclear, but Dr. Piroth reported that the baseline characteristics of those who were or were not assessed with FFR after their procedure did not differ to any major degree.
Despite “a trend for improved outcomes in those who underwent post-PCI FFR,” Dr. Piroth, whose substudy was published in Circulation: Cardiovascular Interventions simultaneously with his TCT presentation, acknowledged that the reasons for a potential benefit cannot be derived from this post hoc analysis.
As for the prognostic value of IVUS, any conclusions are limited by the small proportion of patients who underwent this form of imaging. Overall, IVUS imaging was associated with longer procedures and more stents and “if anything, a signal for harm” in this analysis, but Dr. Piroth cautioned against any conclusions because of the small data pool.
The prognostic value of post-PCI FFR in complex multivessel disease is supported by these data, but the analysis was not designed to determine whether post-PCI FFR has relevance to intervention.
According to J. Dawn Abbott, MD, an FFR analysis conducted to identify lesions that are candidates for treatment should not be confused with FFR for physiologically guided PCI to optimize outcomes.
Noting that post-PCI FFR was encouraged in this study but not mandated and that these FFR values did not typically or necessarily lead to a change in management, take home messages about the value of post-PCI FFR in multivessel disease remain limited, said Dr. Abbott, director of interventional cardiology fellowship training, Brown University, Providence, R.I.
“There was a trend toward improved outcomes in patients who had this measurement done, but, unfortunately, we do not have data regarding whether these patients had further interventions performed,” Dr. Piroth acknowledged.
The post-PCI FFR values were made available to the treating physicians, but Dr. Piroth reiterated that it is unknown whether the physicians considered this information actionable. Moreover, “the vast majority had a nonsignificant post-PCI FFR” result, and “all of the patients had an angiographically successful PCI,” Dr. Piroth added.
Dr. Piroth has financial relationships with Abbott Vascular and Boston Scientific. Dr. Abbott reports financial relationships with Abbott Vascular, Boston Scientific, Medtronic, Microport, Philips, Penumbra, Recor, and Shockwave.