More than 5,000 patients enrolled in iFR outcome trials


Philips has announced that more than 5,000 patients have been enrolled in three prospective clinical studies to assess the safety of deferring cardiovascular interventions using Philips Volcano’s proprietary instantaneous wave-free ratio (iFR) pressure measurement technology compared with conventional fractional flow reserve (FFR) measurements.

A press release reports that both FFR and iFR measure the differences in blood pressure (and by inference the blood flow) through a partially blocked coronary artery (stenosis) to assess whether the blockage is likely to cause a shortage of oxygen to the heart muscle (myocardial ischemia). Both measurements are performed with the aid of a guidewire-based pressure sensor inserted into the appropriate artery via a small incision in the patient’s leg. They differ in that FFR measurements require the injection of a hyperaemic agent to dilate the artery, whereas iFR’s ability to synchronise pressure measurements to a “wave-free” period in the patient’s heartbeat means that no hyperaemic agent is needed. By eliminating the need for hyperaemic agents, iFR offers the potential for reduced procedure time, cost and complexity.

According to the press release, the combination of three ongoing studies that are comparing iFR with FFR represents one of the largest intra-coronary physiologic data sets ever collected.  With more than 5,000 patients studied, all with physiologic guidance, it is more than twice the size of the combined enrolment of the DEFER, FAME and FAME 2 studies that shaped the field of coronary physiology. Further, with nearly 40% of the patients in these studies presenting with acute coronary syndrome, these studies have the potential to expand the use of physiology above its predominant use today.

Two of the studies, DEFINE-FLAIR and iFR SWEDEHEART will assess whether patient outcomes at one year differ when guided by iFR or FFR. The third study, SYTNAX II will evaluate the relative treatment outcomes of a hybrid iFR/FFR strategy coupled with intravascular ultrasound (IVUS) guidance, to compare the clinical utility of percutaneous coronary intervention (PCI) versus bypass surgery for three-vessel coronary disease. More details on these studies can be found below.

Patrick Serruys (Erasmus MC, Rotterdam, The Netherlands), DEFINE-FLAIR Study Chairman and SYNTAX II Steering Committee Chairman, says: “We are all really excited about completing enrolment for the DEFINE-FLAIR, iFR SWEDEHEART and SYNTAX II studies. Together, these three major clinical outcome studies will more than double the randomized published physiology data, and have the potential to re-shape revascularisation guidelines and help physicians perform PCI procedures more likely to benefit their patients.”