iFR and FFR are equal, new long-term analysis confirms
A study analyzing data from 42,000 patients over five years found no significant differences in the safety or effectiveness of two widely-used physiological assessments, instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR). The late-breaking results of the National SWEDEHEART Quality Registry, presented at TCT 2023 in San Francisco, show that both technologies are safe to use for determining the hemodynamic significance of coronary lesions and evaluating if percutaneous coronary intervention (PCI) is required.
"In terms of the results, we couldn't really find any difference at all between the two indices. There was no difference at all between iFR and FFR in terms of major adverse cardiac events (MACE) and obviously we looked at what we call the constituents of MACE, with death, myocardial infarction and unplanned revascularization. And there was no difference at all between the indices," explained lead author Matthias Götberg, MD, PhD, director of the cardiac cath lab at Skane University Hospital in Lund, Sweden.
How long-term results from DEFINE-FLAIR prompted this study
An initial study, known as the SWEDEHEART trial, was conducted five years ago, and the results showed no significant difference in outcomes between patients evaluated with iFR and those evaluated with FFR in terms of death, myocardial infarction and unplanned revascularization. In fact, it found no statistically significant discrepancies between the two methods, Götberg said.
However, five-year results from another iFR vs FFR trial, DEFINE-FLAIR, presented in May at EuroPCR 2023, showed a slight increase in mortality associated with iFR. This raised questions within the medical community regarding the safety and efficacy of iFR, especially in patients who underwent revascularization procedures.
In response to these concerns, Götberg and his team conducted a comprehensive analysis of the National SWEDEHEART Quality Registry, which includes a vast dataset of patients who had either iFR or FFR assessments performed at one of 30 medical centers in Sweden.
"It was just a singled out increase in mortality. And the other thing that was weird was the fact it was among the patient who were revascularized, it was ones who were subject to PCI and CABG. Whereas the ones who were deferred from revascularization had no increase in mortality or any other event rate at all. So it didn't really fit the bill. So essentially, what we did is that we went back to our clinical registry," Götberg said.
While iFR and FFR are fairly similar, Götberg said iFR takes measurements at rest and FFR using adenosine to do induce vasodilation, so there is not an exact correlation in measurements between the two technologies.
"There is about 85% agreement. So there's a little bit of a disagreement, mainly in the cutoff point where we determine whether we should revascularize to defer treatment," he said.
But the findings from the original SWEDEHEART trial and this new, large SWEDEHEART Quality Registry five-year data provided reassuring information for clinicians and patients. He said it also dispelled concerns raised by the DEFINE-FLAIR trial.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: dfornell@innovatehealthcare.com