PARIS – Noninvasive measurement of computed tomography–derived fractional flow reserve is a potential game changer in the management of patients with stable chest pain.
In a 200-patient proof-of-concept study known as FFR-CT RIPCORD, in which three experienced interventional cardiologists initially devised management plans based on coronary anatomy as defined by the results of CT angiography alone, subsequent knowledge of CT-derived fractional flow reserve (FFR-CT) caused them to change their management strategies in fully 36% of cases, Dr. Nick Curzen reported at the annual congress of the European Association of Percutaneous Cardiovascular Interventions.
“If this novel proof-of-concept result can be confirmed in large-scale trials, this suggests that noninvasive FFR-CT can be used as a clinically relevant tool that mimics the well-described ability of invasive FFR to refine management decisions for patients with chest pain that are made by invasive coronary angiography alone. This would indeed have important implications for routine clinical practice. FFR-CT may have potential as a noninvasive default method for simultaneous assessment of coronary anatomy and physiology in angina patients in order to define their management, which would completely change the way we look after them,” observed Dr. Curzen, professor of interventional cardiology at the University of Southampton (England).
EuroPCR codirector Dr. Williams Wijns was favorably impressed by the FFR-CT RIPCORD findings.
“This, I find just stunning. It’s really far reaching. This is a complete change in paradigm. Many patients that today undergo invasive angiography won’t even be sent to the cath lab. The invasive center becomes only for treatment,” commented Dr. Wijns, codirector of the cardiovascular center in Aalst, Belgium.
In FFR-CT RIPCORD, the cardiologists received information about a patient’s history and nonvasive CT angiography findings and were asked to reach consensus in selecting one of four management options: optimal medical therapy (OMT) alone, PCI plus OMT, CABG surgery and OMT, or ‘more information needed’ in the form of FFR findings, which identify those coronary lesions that are actually causing ischemia. Instead of receiving the results of conventional invasive FFR obtained using a pressure wire, however, the cardiologists were provided with the noninvasive FFR-CT findings in all 200 cases.
The resultant changes in management were substantial. Thirty percent of the patients initially slated for PCI were reallocated to OMT alone because no ischemic lesions were present. Twelve percent of patients assigned to OMT-only got reassigned to coronary revascularization. Moreover, in 18% of the PCI group, FFR-CT data led to a change in the vessel or vessels targeted for intervention.
“What particularly impressed me were two of those figures: that one-third of PCI patients are redirected to medical therapy, and – even more impressive to me – is the 18% of PCI patients who had a change in their target vessel. That’s a problem we often have in patients with multivessel disease and intermediate lesions: Sometimes we think, for example, the target is the LAD when in fact it’s another vessel,” commented Dr. Jean Fajadet, codirector of the interventional cardiovascular group at the Clinique Pasteur in Toulouse, France.
Dr. Curzen said the exciting thing about FFR-CT is that it could provide in one fell swoop a standardized way of obtaining both the anatomic and physiologic data necessary for informed clinical decision making, and without exposing patients needlessly to the risks of contrast and radiation exposure entailed in invasive coronary angiography.
“When we assess people with stable angina, if you have a room full of invasive cardiologists, we all do it differently at the moment. It’s crazy. A lot of us will do noninvasive tests like stress echo or MRI or some kind of exercise test, and then refer them for an invasive angiogram where we’ll also do an FFR. Some people will go straight for an angiogram. It’s a real mess. The thing I love about FFR-CT is it would be so slick for patients and their families: You see them in a chest pain clinic or your office and you put them in for this test. They don’t have to waste their time coming back several times for different tests. It’s a really beautiful concept,” Dr. Curzen continued.
Right now the turnaround time on FFR-CT is about 12 hours. The dataset has to be sent off to a supercomputer for a complex modeling analysis before the results come back.
“Of course, if this ever becomes clinically proven, I’m sure the turnaround time would become very quick,” according to the cardiologist.
A cost-effectiveness analysis of FFR-CT versus current standard care is ongoing and the results aren’t yet available. However, Dr. Curzen observed, “The cost to the patient is a very important issue: Who would want to have this done invasively if you have a test that proves you don’t need to have an invasive procedure?”